[amsat-bb] Round-world APRS balloons still flying!
As of today those 3 APRS balloons launched in the UK are still flying after more than 3 weeks! Amazing.. One of them over alaska has gone round the world more than 1.5 times, the other two are over Japan and approaching 1.5 orbits. http://aprs.fi/#!mt=roadmap&z=2&call=a%2FM0XER-3%2Ca%2FM0XER-4%2Ca%2FM0XER-6%2Ca%2FM0XER-15&timerange=604800&tail=604800 Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] LEO Flight Opportunity NOW?
If you can make a flight ready amateur payload with some kind of educational association in the next 3 months, there is a ride. You get a temperature controlled 0-60C flat plate about 4" by 7" and 28v power on the outside of a large free-flyer. The bad news is that the mission is low LEO so maybe only a life time of 3 or 4 months. Riding back from the smallsat conference to the airport in the shuttle one of the passengers asked If I wanted to fly an APRS payload. I said sure. THen he said "do you know anyone else too?" Need to involve "students" is important... I apologize that I dont have any of your prior emails (Im transiting airports for the next 14 hours and wont have access to old emails for 2 more days, but didnt want to wast any time. I hate to spin people up like this, and it may take a week for me to get official details, and it may only be a pipe dream, but thought I would share it. Your box will be attached to their plate, and your other side is exposed to space. They will provide another 28v to burn any release mechanisims for your antennas. Assume one edge of your box can be close to a spacecraft edge so your antenna can come out and hang over an edge. Or your box can be a few inches high and can deploy its antenna "up" from the plate and then you have more mounting options. Whether you are on the top, bottom, or side of the mother ship is still open. Spacecraft is well powered and 3 axis stabilized. Serious builders with space experience ONLY. I gotta not only build mine, but also finish two others and should not be wasting time with emails. AND you have to have your IARU frequency coordination and FCC paperwork done too. But power, a platform, an attitude, some temperature control, quick attachment, and a ride are hard to pass up. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Current Launch Costs From Spaceflight
> Can some explain to me and others the big deal about cube sats? > I just dont get it. Standardization! But the real payoff from standardization is REDUCED RISK to the launch provider. Instead of having to micromanage every detail of satellite design so that the launch provider can GURARANTEE the safety to the main payload ($100,000,000) due to secondary small sats, the CUBESAT spec defines all the restraints and details. Thus, orders of magnitudes worth of fussy details necessary to assure absolute safety of the primary payload do not have to be done for each and every secondary small sat, just ONE standard. Then, all the small sats have to do is comply with the spec. This is why we are starting to see large numbers of cubesats, because now the LAUNCH providers only have to deal with ONE set of issues (cubesat spec) and not sixty different payloads, organizations, and 60 different unique risks. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Equatorial Crossing Data (EQX) (easy predictions)
Actually, using simple pass-times, it is possible to predict with a simple pencil, all future pass times for several weeks. Every satelite REPEATs their daily ground track every few days or so. AO51 repeated every 5 days, and GO32 every 9. These were sun synchronous and so not only the ground track repeated but the time of the passes repeated as well. See the examples on: http://aprs.org/MobileLEOtracking.html The ISS is not sun synchronous, but these three rules will predict future ISS passes without any stinkin-confusor: 1) If you hear one pass, 5 out of 7 times, the next one is about 90 minutes later. 2) The ISS REPEATS the same ground track every other day but 51 minutes earlier. 3) For a given day, the same pass the next day is 23 minutes later. This makes portable APRS operations in the wilderness easy. All you need is ONE PASS time, and you can infer all the others for weeks using the simple rules, and just keepin notes on pass TIMES when heard. You don't need no-stinkin-computer. Satellites are in "orbit" and completely predictable. Just take your favorite satellite, print out a week of passes, and then look for the "RULE" that will predict future passes. Then all you need to remember, is the RULE. Bob, WB4aPR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of EMike McCardel Sent: Friday, August 01, 2014 1:40 PM To: Glen Gardner Cc: amsat-bb@amsat.org Subject: Re: [amsat-bb] Equatorial Crossing Data (EQX) Glen, Paul and Joseph, Thank you for your replies. I am learning a lot here. My imagination has been captured by learning to use the Satellabe and OscarLocator prepping for my presentation on tracking satellites at the AMSAT Training Day during the ARRL Centennial. I also discovered a construct involving a globe offering a 3D rendition of of a pass. This is an interesting way to demonstrate how the earth moves independent of the orbit. I can't help but think that some of the analogue tools of the day still have relevancy. EMike EMike McCardel, KC8YLD VP for Educational Relations AMSAT-NA Sent from my iPhone > On Aug 1, 2014, at 11:53 AM, Glen Gardner wrote: > > > > You can easily find the times for equatorial crossing for ascending passes from the element set. > > > Consider Oscar 7 > > > Satellite: AO-07 > Catalog number: 07530 > Epoch time: 14211.80120610 > Element set: 27 > Inclination: 101.4754 deg > RA of node: 192.2023 deg > Eccentricity:0.0011666 > Arg of perigee: 207.8798 deg > Mean anomaly: 270.9717 deg > Mean motion: 12.53605918 rev/day > Decay rate: -2.2e-07 rev/day^2 > Epoch rev: 81698 > Checksum: 281 > > The epoch time is the reference time for that element set. It also happens to be the time for the ascending node (equatorial crossing North-to-South). > In this case it is "14211.80120610" which comes out to the year 2014, day 211 and the hour comes out to 19.22 hours.. or approximately 19 hours, 13 minutes, 44 seconds. > > Ignoring the decay rate, the next ascending node will be in one orbital period. You can get this by dividing the number of minutes in a day by the mean motion: 1440/12.53605918=114.869 minutes after the epoch time. > > Getting the descending node is more problematic if the orbit is highly eccentric. In the case of Oscar 7, the eccentricity is small, and it is close enough to a circular orbit that it is reasonable to assert that the descending crossing of the equator is very close to 1/2 orbital period after the ascending node (unless your TLE's are more than a few days old). > > Glen > AA8C > > > >> On 08/01/2014 03:07 AM, Paul Stoetzer wrote: >> i8CVS posted the directions to calculate EQX and everything else >> needed to use an OSCARLATOR from Keplerian elements back in 2003. >> >> http://www.amsat.org/amsat/archive/amsat-bb/200203/msg00749.html >> >> I haven't done any programming in forever, but maybe I'll try to >> write a short program to automate those calculations at some point >> (unless someone already has). >> >> 73, >> >> Paul, N8HM >> >>> On Thu, Jul 31, 2014 at 10:51 PM, EMike McCardel wrote: >>> Does anyone know of a tracking application or program or some other software or existing source that will still produces or publishes equatorial crossing data for current satellites? >>> >>> EMike >>> >>> EMike McCardel, KC8YLD >>> VP for Educational Relations AMSAT-NA >>> >>> Sent from my iPhone >>> ___ >>> Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. >>> Not an AMSAT-NA member? Join now to support the amateur satellite program! >>> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> ___ >> Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite program! >> Subscription settings: http://amsat.org/mai
Re: [amsat-bb] Round-the-world M0XER-4
Trevor, The M0XER-4 (I thought) did frequency shifting (APRS 144 MHz national channels over Europe and the US), and so I thought it had more complexity. The image shown on the link below only has 434 MHz antennas, no obvious GPS and no VHF antennas. Can you clarify and help us get an idea of what this M0XER4 payload actually looked like? Thanks, Bob, WB4aPR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of M5AKA Sent: Thursday, July 31, 2014 4:06 PM To: AMSAT BB Subject: Re: [amsat-bb] Round-the-world M0XER-4 http://amsat-uk.org/2014/07/31/434-mhz-balloon-b-64-completes-epic-journey / 73 Trevor M5AKA ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Round-the-world M0XER-4
That is why I want so much to continue the 145.825 digipeater on as many satellites as we can*. But we can’t seem to inspire any of the other HUNDREDS of satellite building groups to consider it. I think there were over 100 cubesats launched last year. None with 145.825 APRS… *(and convince the leave-it-on-24/7/365-not-moving user satellite stations to stop beaconing unattended!) Bob, WB4APR *From:* aprsi...@yahoogroups.com *Subject:* RE: [aprsisce] North America M0XER-4 Too bad we can't get the balloon to switch to the ISS frequency and use the digi off of it when over the oceans and arctic! Original message On Thu, Jul 31, 2014 at 12:23 PM, 'Steve' wrote: > Seems the balloon enjoyed itself so much it’s going round again. > Congratulations are in order to Leo M0XER > AFAIK this has never been done before. > Be interesting to see if it makes it twice We're a tough crowd to please... First circumnavigation of the globe by an amateur radio carrying balloon, and as it passes the milestone... "So, can you get another lap out of it?" What about poor old M0XER-3? It's still out there! Sure it got waylaid in Nunavut for a while, and let M0XER-4 slip on by... It needs some encouragement too! [ see present track: http://aprs.fi/M0XER* (and click for 7 day tail)] If the winds are playing nice, and the fates allow, it should be coming into range fairly soon. James, VE6SRV ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Loss of Cubesat Designer?
I heard part of something on the news about one of the victims of the Aircraft shootdown in the Ukraine was a young Aerospace engineer working on a design for a constellation of cubesats for low cost communication with individuals on the ground. Sounds like a HAMsat project to me. Anyone know the story? Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Digital Satellites Question
> The biggest load in a communications satellite > is almost always the downlink RF power amplifier(s)... True for some, not true for others. The locations of ham operators are only about 10% of the earths surface. 90% of transmitter power can be saved if the transmitter is not left on 100% of the time. An APRS satellite takes advantage of this by knowing not only are there users only 10% of the time, but even over a saturated ham area, the TX/RX duty cycle cannot exceed 40% or so. The result is that the transmitter is only on for 4% of the orbit. This means we can run a 5W transmitter to make the packets hearable on an HT with a stock antenna, but that the transmitter AVERAGE power is only 200 mW (less power than the receiver). And by putting the downlink on 2m instead of UHF, there is another 9 dB advantage to OMNI anennas. Add that to the 10 dB advantage of running a 5W transmitter instead of 0.5W and you can see that an APRS cubesat can have almost 19 dB downlink advantage over the typical UHF 0.5W downlink. (theoretically)... Many other factors of course are involved, but we need a mix of satellites and modes, but the above is why I like AX.25 for short bursty texting and data for a large number of people to share in a short period of time. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Inclusion (satcoms?)
But if the goal of satellite operation is from the shack-potato position, why not just use the internet and not bother. Don't forget the TOTAL FAILURE of the original SAT-PHONE industry when they ignored cellphones and fiber. No one would bother with a sat-phone when their $9/mo cell phone could do the job almost 99% of the time and call anywhere on the planet. The only thing SAT-PHONEs turned out to be good for are wilderness communications, and there are plenty of places on earth that fit that category. Probably 90% of the earths surface is a wireless desert. But the 99% of the worlds population lives in that wired-10%. I have also heard that these days, " all of the satellite communications carried by all the comm satellites worldwide could fit on a SINGLE fiber. The value of ham radio is providing communications where other systems cannot. And of course, playing with toys just for fun. Bob, Wb4APR -Original Message- >> I've heard comments that basically imply anyone >> who wants to go outside with an HT and wave a yagi around is stupid. > Standing outside with a yagi in hand and the monsoon > trickling down my neck isn't for me. It is demonstrably > a valid way to make contacts and an excellent way to > demonstrate how satellite operation can occur with minimalist equipment. > But as far as I'm concerned, it IS NOT the ultimate objective > of a satellite operator ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Round-world balloon approaching Noth America M0XER-3
Regarding real LOW Earth “orbits”, G6UIM reports a Balloon launched in the UK is approaching Washington state from across Asia and the Pacific right now. See: http://spacenear.us/tracker/ look for Balloon B-63 It is being well received by the APRS network in Canada, Washington and Oregon as it approaches Vancoover Island as shown here: http://aprs.org/balloons/M0XER-3.jpg That image from Lynn, author of APRSIS32. Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - AMSAT Fox-1C Launch Opportunity Announced
Hummh, We get an equilibrium of a cube to be about 55F (13C) when exposed to the sun on one side and all the other sides radiating to cold space. (assuming they are thermally connected). I wonder why the big difference between our calculations? Bob, WB4aPR On Sun, Jul 20, 2014 at 6:59 AM, Phil Karn wrote: > On 07/19/2014 09:23 PM, Robert Bruninga wrote: > > > I cannot believe that. The equilibrium of a nominally black (solar > panels > > on all sides) spacecraft is something like about 0 to 30 C (32F to 90F) a > > very benign operational range. The only time you DO have thermal issues > is > > when you DO have attitude control and have things that are not equally > over > > time seeing the sun and dark sky. > > See Dick's paper for the details; I'm just quoting his results. I know > the basic physics of heat transfer in space but I would never call > myself an expert. He is. > > But I can do a back-of-the-envelope calculation that tells me he's right. > > The solar cells they're using have an absorptivity and emissivity that > is both 0.98, as I recall, so a cubesat covered with them is essentially > a perfect blackbody. > > A blackbody cube with one face normal to the sun at 1 AU will reach an > equilibrium temperature of -21.35 C. The problem is that the ratio of > radiating area to absorbing area for a cube is 6:1 (with the sun normal > to one surface). A sphere would be warmer because its ratio of radiating > to absorbing area is only 4:1. A thin flat plate normal to the sun (like > a solar wing) would be even warmer -- 2:1. > > And that -21.35 C figure is for continuous sunlight. Throw in eclipses > and things get much worse. Yes, it would be a little better when the sun > shines on a corner rather than normal to a face, and Earth albedo and IR > radiation will warm things a little, but not enough to matter. > > --Phil > > PS: Temperature of 10 cm blackbody cube at 1 AU: > > Area facing sun: .01 m^2 > Solar constant: 1367.5 W/m^2 > Absorbed power = 13.675 W > > Total radiating area: .06 m^2 > Emissivity = 1.0 (perfect blackbody) > Stefan-Boltzmann constant = 5.6703e-8 W/(m^2K^4) > > > T = (13.675 W / (5.6703e-8 * 1.0 * .06)) ** (1/4) > = 251.8K == -21.35 C > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - AMSAT Fox-1C Launch Opportunity Announced
Thanks for the FOX-1 thermal data! (36 C variation per orbit) PCSAT (10" cubesat) has less than 15C variation on its sides with its 0.6 RPM spin and 35% eclipses, but this is because the sides are made of 1/8" aluminum and have a huge 1/8" center deck that is thermally connected to the center of each face, providing great communication from the sun side to the other sides. Notice, this was a HEAVY satellite because we just overbuilt it to make sure the heat was evenly distributed. On Sun, Jul 20, 2014 at 10:41 AM, wrote: > I must quickly point out some real data: > > www.warehouse.funcube.org.uk > > Which shows an equilibrium of around +20 degrees after 64 minutes of > sunlight. > Black solar cells on a black surface but some polished Aluminium in the > structure. > > During eclipse, The Earth facing side begins to increase in temperature at > around -16 degrees, but then cools down rapidly as the cube rotates. The > temperature is still heading down rapidly as it exits eclipse after 34 > minutes and at around -24C on the outside surfaces. > > Thanks > > David > > > -Original Message- > From: Phil Karn > To: amsat-bb > Sent: Sun, 20 Jul 2014 11:59 > Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - > AMSAT Fox-1C Launch Opportunity Announced > > On 07/19/2014 09:23 PM, Robert Bruninga wrote: > > > I cannot believe that. The equilibrium of a nominally black (solar panels > > on all sides) spacecraft is something like about 0 to 30 C (32F to 90F) a > > very benign operational range. The only time you DO have thermal issues is > > when you DO have attitude control and have things that are not equally over > > time seeing the sun and dark sky. > > See Dick's paper for the details; I'm just quoting his results. I know > the basic physics of heat transfer in space but I would never call > myself an expert. He is. > > But I can do a back-of-the-envelope calculation that tells me he's right. > > The solar cells they're using have an absorptivity and emissivity that > is both 0.98, as I recall, so a cubesat covered with them is essentially > a perfect blackbody. > > A blackbody cube with one face normal to the sun at 1 AU will reach an > equilibrium temperature of -21.35 C. The problem is that the ratio of > radiating area to absorbing area for a cube is 6:1 (with the sun normal > to one surface). A sphere would be warmer because its ratio of radiating > to absorbing area is only 4:1. A thin flat plate normal to the sun (like > a solar wing) would be even warmer -- 2:1. > > And that -21.35 C figure is for continuous sunlight. Throw in eclipses > and things get much worse. Yes, it would be a little better when the sun > shines on a corner rather than normal to a face, and Earth albedo and IR > radiation will warm things a little, but not enough to matter. > > --Phil > > PS: Temperature of 10 cm blackbody cube at 1 AU: > > Area facing sun: .01 m^2 > Solar constant: 1367.5 W/m^2 > Absorbed power = 13.675 W > > Total radiating area: .06 m^2 > Emissivity = 1.0 (perfect blackbody) > Stefan-Boltzmann constant = 5.6703e-8 W/(m^2K^4) > > > T = (13.675 W / (5.6703e-8 * 1.0 * .06)) ** (1/4) > = 251.8K == -21.35 C > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - AMSAT Fox-1C Launch Opportunity Announced
Yes, that is exactly the temperatures of PCSAT in similar eclipse periods. IE, anything more or less uniformly BLACK (solar panels) no matter the shape and size will assume that average temperature with 35% eclipses. This is because the absorbtivity and emissivity of "black" are both 0.9. (assuming there is some thermal communication within the spacecraft to move the heat evenly (such as an aluminum frame)... If it ever gets into a 0% eclipse period (full sun) those average temps will rise to about 30-40C. Still safe for most electronics. Bob, WB4APR On Sun, Jul 20, 2014 at 11:09 AM, Graham Shirville < g.shirvi...@btinternet.com> wrote: > Hi Phil, > > The reality is, even with no battery heater on FUNcube-1 we seem to have > an acceptable battery temperature of between 0 and +5C. The temp sensor is, > of course, actually external to the battery itself. > > Our orbit is sun synchronous so we "suffer" eclipses for approx 33% of the > orbit ..but then we are relatively close to the earth! > > I would also comment that any active attitude control system will consume > power...which we don't have much of.. > > Probably, if you need continuous operation of the radio system, then a 2U > with deployable solar panels is the minimum configuration for a CubeSat > operating on microwave bands with an active attitude control system. > > best 73 > > Graham > G3VZV > > > -Original Message- From: g0...@aol.com > Sent: Sunday, July 20, 2014 3:41 PM > To: k...@ka9q.net ; amsat-bb@amsat.org ; bruni...@usna.edu > Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - > AMSAT Fox-1C Launch Opportunity Announced > > > I must quickly point out some real data: > > www.warehouse.funcube.org.uk > > Which shows an equilibrium of around +20 degrees after 64 minutes of > sunlight. > Black solar cells on a black surface but some polished Aluminium in the > structure. > > During eclipse, The Earth facing side begins to increase in temperature at > around -16 degrees, but then cools down rapidly as the cube rotates. The > temperature is still heading down rapidly as it exits eclipse after 34 > minutes and at around -24C on the outside surfaces. > > Thanks > > David > > > -Original Message- > From: Phil Karn > To: amsat-bb > Sent: Sun, 20 Jul 2014 11:59 > Subject: Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - > AMSAT Fox-1C Launch Opportunity Announced > > > On 07/19/2014 09:23 PM, Robert Bruninga wrote: > > I cannot believe that. The equilibrium of a nominally black (solar panels >> on all sides) spacecraft is something like about 0 to 30 C (32F to 90F) a >> very benign operational range. The only time you DO have thermal issues >> is >> when you DO have attitude control and have things that are not equally >> over >> time seeing the sun and dark sky. >> > > See Dick's paper for the details; I'm just quoting his results. I know > the basic physics of heat transfer in space but I would never call > myself an expert. He is. > > But I can do a back-of-the-envelope calculation that tells me he's right. > > The solar cells they're using have an absorptivity and emissivity that > is both 0.98, as I recall, so a cubesat covered with them is essentially > a perfect blackbody. > > A blackbody cube with one face normal to the sun at 1 AU will reach an > equilibrium temperature of -21.35 C. The problem is that the ratio of > radiating area to absorbing area for a cube is 6:1 (with the sun normal > to one surface). A sphere would be warmer because its ratio of radiating > to absorbing area is only 4:1. A thin flat plate normal to the sun (like > a solar wing) would be even warmer -- 2:1. > > And that -21.35 C figure is for continuous sunlight. Throw in eclipses > and things get much worse. Yes, it would be a little better when the sun > shines on a corner rather than normal to a face, and Earth albedo and IR > radiation will warm things a little, but not enough to matter. > > --Phil > > PS: Temperature of 10 cm blackbody cube at 1 AU: > > Area facing sun: .01 m^2 > Solar constant: 1367.5 W/m^2 > Absorbed power = 13.675 W > > Total radiating area: .06 m^2 > Emissivity = 1.0 (perfect blackbody) > Stefan-Boltzmann constant = 5.6703e-8 W/(m^2K^4) > > > T = (13.675 W / (5.6703e-8 * 1.0 * .06)) ** (1/4) > = 251.8K == -21.35 C > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > > _
Re: [amsat-bb] ANS-199 AMSAT News Service Special Bulletin - AMSAT Fox-1C Launch Opportunity Announced
> The lack of attitude control forces us to use simple omnidirectional > antennas, which in turn keeps us on the crowded and narrow VHF/UHF > bands. Worse, there's really no such thing as an "omnidirectional > antenna" so our links are plagued by frequent deep fades of unlimited > (or at least unknown) duration. Fading has driven every one of my > modulation/coding designs for AMSAT telemetry links -- at the expense of > making them much less power-efficient. > > And "power efficient" means smaller ground antennas, and that means a > cheaper and more accessible ground station for the average ham. And THAT > means a much larger potential AMSAT membership. > > With attitude control, our satellite could use directional antennas on > the microwave bands. Directional antennas on higher frequencies mean > much better link budgets. Yes, but with who? 95% of everyone in view is more than 45 degrees OUT of the main beam. Directional antennas have zero value on LEO birds that need to serve everyone in view at the same time. And if you only serve those in the main beam, then the duration is under 1 minute. > A lack of attitude control also plagues thermal design > I think he found the equilibrium temperature of a 1U cubesat > to be something like -30 or -40 C! I cannot believe that. The equilibrium of a nominally black (solar panels on all sides) spacecraft is something like about 0 to 30 C (32F to 90F) a very benign operational range. The only time you DO have thermal issues is when you DO have attitude control and have things that are not equally over time seeing the sun and dark sky. PCSAT is now 13 years in orbit and the above range is what it sees. And that range is over a 2 month period. THe orbit-by-orbit temperature changes are less than +/- 10 degrees C. The extremes are due to the "seasons" of the orbit. When it is seeing eclipses it averages to about 10C and when it is in full sun for weeks at a time, it gets up to 30 C (90F) I do agree that attitude control is nice to have, but my point is that it only makes the thermal problem much worse and that "gain" is of no value for a LEO where it must see everyone in a footprint at the same time. (Remmebr you cannot have wide beamwidth and gain at the same time). Gain for HEO's of course is another matter! (think AO-10, AO-13 and AO-40) Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] IEEE Conference on Wireless for Space (neitherlands) seeks papers (APRS?)
If anyone in Europe wants to submit a paper on APRS and other AX.25 satellite relay, this conference might be a good match. We like to think of the 145.825 AMSATs as a continuum of remote-data access for student experiments and remote data access… - IEEE Conference on Wireless for Space & Extreme Environments Seeks Papers WASHINGTON (9 July 2014) -- Organizers of the International Conference on Wireless for Space and Extreme Environments (WiSEE) are seeking papers and posters that address solutions to the significant challenges of wireless sensing and communication in space (and extreme environments). http://sites.ieee.org/wisee/ The submission deadline is 1 August. Areas of particular interest include but are not limited to: * Low-power active wireless sensors, systems & networks * Passive wireless sensors, systems & networks * RFID devices & systems * Protocols & architectures for delay & disruption-tolerant networking * Network architectures, middleware integration & data management * Cognitive radio networks * Localization & tracking over wireless links * Antenna design, smart antennas, beam forming & multiple-antenna techniques * Propagation modelling for planetary surfaces & complex multipath environments * Wireless & cyber security * Optical communication systems * Availability, certification & spaceflight qualification for wireless devices & systems * Integrated vehicle systems For more information and to submit a paper or poster, see http://sites.ieee.org/wisee/call-for-papers/. WiSEE 2014 will be held at the European Space Agency’s European Space and Technology Research Centre in Noordwijk, the Netherlands, 30-31 October 2014. The event will bring together investigators from international space agencies, including ESA, the Canadian Space Agency and NASA, along with aerospace and space defense industries and academic researchers, in an effort to understand and solve emerging problems facing wireless sensing and communication during spaceflight and in extreme environments such as planetary surfaces, space vehicles and space habitats. Background The many challenges faced in space sensing and communication are extremely diverse and overlap significantly with those found in extreme environments on earth. These environments pose significant challenges for radio frequency and optical wireless sensing and communication and will require the application of a broad range of technologies to generate reliable and cost-effective solutions. Although specific challenges vary significantly from one environment to another, many of the solutions offered by sensing, communication and statistical signal processing technologies can be applied in multiple environments. IEEE-USA serves the public good and promotes the careers and public policy interests of more than 200,000 engineering, computing and technology professionals who are U.S. members of IEEE. Web: www.ieeeusa.org Facebook: www.facebook.com/ieeeusa Twitter: www.twitter.com/ieeeusa Benefits of IEEE membership: www.ieee.org/join Contact: Chris McManes IEEE-USA Public Relations Manager 202-530-8356 c.mcma...@ieee.org ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Recordings of FO29 Field Day passband...?
> I have been asked by ICOM to webcast field day this year. Unrelated, but it would be great if someone with a good satcom station recorded the passband of FO29. Not so much to get individual QSO's but to grasp what a full wideband transponder can carry. IE, tune the passband from one end to the other at a constant rate. Then again, and again, and again at the same rate. Maybe separate files for each scan so we can tell when a complete scan begins and ends. This would give those who are unfamiliar with wideband linear transponder operation what the capability really is under FD loading... Just a thought. Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Appearing on http://www.ariss.net/
The beacon while-unattended into a very valuable limited channel such as the ISS and PCSAT digipeaters are disappointing to me. The purpose of the APRS digipeaters in space are for humans to contact humans, or for the rare -out-in-the-atlantic or Pacific lone traveler or experiment. The unattended beacons are intereference to that mission and are not welcome. Bob, WB4aPR On Mon, May 26, 2014 at 11:24 AM, Clayton Coleman wrote: > These days I'm finding less and less stations on APRS via the ISS. > This is a major reason as to why packets digipeated by the ISS aren't > making it into the terrestrial APRS Internet Service. If there are > only one or two stations within your mutual footprint and they can't > hear very well, chances are your position digipeated by the ISS won't > be heard by them. Therein lies your problem and why your packets > aren't making it to the Internet. It is no fault of the APRS-IS or > the ISS digipeater. > > I was on a pass this morning, 63 degree elevation, that covered most > of the western half of the United States. Of that entire pass I only > copied 5 stations, all of which were automated with no live > individuals at the keyboard. I was getting a 100% solid copy of the > ISS. > > I've never quiet understood the fascination with transmitting a packet > and showing up on the Internet. Nowadays there's an app for that. > The APRS-IS, ISS digipeater, and our terrestrial APRS networks are > great resources. Unfortunately operating trends come and go and I > think we are in a down cycle with less people active on the ISS > digipeater over North America. > > 73 > Clayton > W5PFG > > On Mon, May 26, 2014 at 10:10 AM, Mike Sprenger > wrote: > > Used to be able to show up on the ariss.net web page when I digi my > > position via the ISS, now I can't figure out what I've done to cause it > to > > not work any longer(and I can successfully appear by using the new-n > > paradigm on terrestrial APRS on 144.39) > > > > It's not an RF path problem, I can Digi via the ISS no problem on > 145.825, > > hearing my return packets from the ISS. I've digi'ed dozens via the ISS, > > yet, I can no longer gateway to the ARISS web page. > > > > Referring to this page: > > > > > > http://www.aprs.org/iss-faq.html > > > > > > > > ISS145.825145.825ARISS | APRSAT | WIDEAdding an optional SGATE,WIDE on > your > > path allows your > > > > > > I have tried to digi via ARISS using several paths, some of which are: > > > > > > CQ,ARISS,SGATE,WIDE > > CQ,ARISS,SGATE,WIDE > > CQ,ARISS,WIDE1-1 > > > > > > > > So, 2 questions, using UI-View32: > > > > 1. What's the most common Is there something that could cause it *not* > to > > gateway to the www.ariss.net page ? > > 2. What is the Digi Path to end up on www.ariss.net ? > > > > -- > > Thanks, > > Mike > > W4UOO > > (37.9167N 81.1244W is the Summit) > > ___ > > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > > Not an AMSAT-NA member? Join now to support the amateur satellite > program! > > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Re: [amsat-bb] Cub Scout Space Camp Theme
A far less complex and easy to do transmitter hunt is simply bring along a bunch of FRS radios. Put a rubber band and some aluminum foil around one of them to key it and make it very low power (carrier only). With a range only sufficent to barely cover the venue (weak signal at the starting point). Then teach them HT DFing technique. Body blocking for direction and "quieting" for range. Then turn them loose. THey have the energy to almost raster scan the entire venue if needed. I did this once and they found the radio just fine. The only weakness of doing this with FRS, is the inability to "remove" the antnna for the final closing in. I solved this by making the hidden transmitter easy to SEE when they got close. AND not like trying to find one in a cornfield where one has to DF to the final 4 feet to even find it. I have found the attention span of cubscouts to be so short, that they would never finish building a beam... And a beam implies using radios that have antenna connectors (not the FRS they likely already have)... Just a thought. Bob On Sun, May 25, 2014 at 10:42 PM, Mike Sprenger wrote: > Rich, > > Cool, to expand on the idea: > > With the hidden transmitter hunt, the clues could be voice recording > playing out of the hidden transmitter. which they get clues for one phase > of their day, then, tell them for the next phase, make this antenna, and > hook to handheld, and go find the thing thats been giving > instructions...make sure security group nows what you're hiding for a > transmitter and don't put it in a piece of Pipe. > > For the clues, feed the hidden transmitter with an iPod output with 1 long > audio file that loops on the ipod. Record the clue, followed by 1 min of > silence, followed by another clue, silence, clue, silence and set that one > audio file to to play as a loop feeding the hidden transmitter... > > maybe another transmitter with clues on how to make the antenna, where the > instruction paper is hidden, etc... > > We did the tape measure antennas at the National Scouting Jamboree last > summer, effective. 1/2" PVC pipe, tape, and hose clamps, and a piece of > coax with BNC on one end. > > 73 > Mike > W4UOO > > > On Sun, May 25, 2014 at 6:42 PM, Rich/wa4bue >wrote: > > > Great idea. > > > > This one is clues to answer questions. > > > > Maybe we can do that too! > > > > - Original Message - > > *From:* Mike Sprenger > > *To:* Rich/wa4bue > > *Sent:* Sunday, May 25, 2014 5:58 PM > > *Subject:* Re: [amsat-bb] Cub Scout Space Camp Theme > > > > If doing a treasure hunt, do you make a Tape measure yagi for 2 meters > > with a handheld and search for a small hidden transmitter outside ? > > > > > > > > > > On Sun, May 25, 2014 at 11:07 AM, Rich/wa4bue >wrote: > > > >> That was over 2 years ago, but I am sure I can find something. Â It > might > >> take a while. > >> > >> > >> So far we are looking at: > >> A short talk > >> On The Air QSOs > >> RECEIVE WEATHER SAT IN ABSENCE of OSCAR > >> A treasure hunt using clues dealing with space history and technology. > >> Â That might add up to 2 - 2.5 hours of activities and learning. > >> > >> > >> Now new question > >> Ideas for CLUES and finds? > >> > >> > >> > >> - Original Message - From: > >> To: "Rich/wa4bue" > >> Sent: Sunday, May 25, 2014 10:29 AM > >> Subject: Re: [amsat-bb] Cub Scout Space Camp Theme > >> > >> > >> Any chance you have a copy that I can borrow? > >>> George > >>> > >>> > >>> > >>> -Original Message- > >>> From: "Rich/wa4bue" > >>> Sent: Sunday, May 25, 2014 06:25 > >>> To: gkc...@go-express.net > >>> Subject: Re: [amsat-bb] Cub Scout Space Camp Theme > >>> > >>> Members of our group certified as Boy Scout Merit Badge councilors > >>> several > >>> years ago but never got called. We are no longer certified. Â We did > >>> produce > >>> a DVD showing scouts in amateur radio. Â We provided 45 DVDs one for > each > >>> > >>> troop. > >>> > >>> - Original Message - From: > >>> To: "Rich/wa4bue" > >>> Sent: Saturday, May 24, 2014 10:20 PM > >>> Subject: Re: [amsat-bb] Cub Scout Space Camp Theme > >>> > >>> > >>> Not quite related to what you are doing. 5 of us will conduct a 4 hour > class for scouts wishing to achieve the Radio merit badge. 6 times! > Yes, > twic a day, two groups, three weeks. We don't know yet how many in > each > class! > I am taking the first hour of each and preparing a power point > presentation. > > 73 > > George > WA5KBH > > > > > -Original Message- > From: "Rich/wa4bue" > Sent: Saturday, May 24, 2014 13:59 > To: "Mark Spencer" , "AMSAT BB" < > amsat-bb@amsat.org > >, > "'Johnson, Debra K1DMJ'" > Subject: Re: [amsat-bb] Cub Scout Space Camp Theme > > WX SAT GREAT IDEA. > > Which one? Â Guess there are more then one. > > > > - Original Message - From: "Mark S
[amsat-bb] Driving to Dayton (Voice Alert)
Driving to Dayton: For AMSAT guys, even if you don’t have an APRS radio, set an HT in your car to 144.39 with CTCSS 100 and the speaker will be 100% quiet unless there is an APRS mobile in simplex range, and then you will hear his CQ once a minute. If you hear one, then he is in SIMPLEX range and you can call him on voice and tell him to meet you on 52, If you do have an APRS radio: Don’t forget to keep that Voice Alert volume UP and to CLEAR all the messages in your D700 and D7 mailboxes!!! Nothing more frustrating than to hear your CQ PINGS and then you are not listening for Voice Alert responses and your radio is rejecting messages telling you to wake up! If you don’t know what Voice Alert is, crawl out from under your rock and read this: http://aprs.org/VoiceAlert3.html OR, to make it simple, simply set the APRS side of your radio to CTCSS 100 and keep the data channel volume UP to receive voice alert calls (and pings from nearby mobiles in simplex range). Far more effective at finding a fellow driver than calling CQ on 52 every minute. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Balloon Found (and OOps!)
Crowded Air space today over PA! Saturday morning, launched the Naval Academy Balloon (W3ADO-11) from Harpers FY and noticed two other balloons launched about the same time (W3EAX-9 and 11) about 40 miles north. All was going fine until... Our sincere apologies to MD, VA, PA, DE and NJ! At about 3000' our balloon Arduino processor got stuck in a reset-loop and switched from 1 minute rate to one packet as fast as it could re-boot. Less than every 2 seconds! Fortunately they were direct only and at 100 millliwatts. Fortunately, we could still see some packets from the W3EAX balloons, and APRS.FI seems to have copied them all. Then ours went nuts! and appears to have come down very fast, and we raced to towards the impact point (20 miles away), but then 20m later, we got one packet at 38,000 feet 20 miles farther east. Then another race though Amish country and to our horror, the last position report was within 0.1 mile of the river and still at 2000 feet and heading right out to the middle! We were about to give up the search (no more packets heard and river current pretty swift) when our back up system (SPOT system?) gave another report about 60 feet from the water. Low an behold, there it was, 60 feet from waters edge after having flown almost 100 miles. Everything intact includeing HDTV video camera! Apparently the students used a non-high-altitide GPS and it went squirrely until it got back below 38,000 feet. But you should see the track (W3ADO-11) Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: HELP
> deciding if I should buy a new AZ/EL rotator mine current one is 15yrs old and dead. For all current Amateur Satellites, elevation control is not needed 98% of the time. If you are willing to give up the 2%, you can operate with a manual $70 azimuth only TV rotator instead of a $500 full AZ/EL rotator. Just mount the antenna tilted up at 15 degrees above the horizon and you will have plenty of gain throughout any orbital pass, but can also use it terrestrially too because the max gain is still on the horizon where it is needed most. See http://aprs.org/LEO-tracking.html Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Balloon lost near Shrewsbury, PA (FOUND!)
Balloon found. We returned to site on 8 April with post-flight analysis and better estimate of where to look. We were only about 100 yards off. Details: http://aprs.org/balloons.html Final student lesson learned: Turn the Highdef video camera on before release. Since the students have the payload intact, we may try again in the next weeks or so. Bob, WB4APR *From:* Robert Bruninga [mailto:bruni...@usna.edu] *Sent:* Monday, April 07, 2014 10:48 AM *To:* aprs...@tapr.org; a...@yahoogroups.com *Cc:* amsat-bb@amsat.org; k...@usna.edu *Subject:* Balloon lost near Shrewsbury, PA Short Story. The balloon is lost near Shrewsbury, PA. But we are sure (now after post processing) that we know where it is within about an acre. See: http://aprs.org/balloons.html Premature burst (or separation) caused the payload to descend at over 5000 feet per minute slowing to 4000'/min (nearly 50 MPH straight down)at last posit. We did not know this at the time, and wasted our time searching the track 1/2 mile beyond the last data point assuming the much slower parachute design rate of 600'/min. When we got home, post processing revealed the high descent rate and the more likely spot much closer to the last known position. Also the high impact is why it probably ceased transmitting. Also we were looking for a balloon and parachute in the trees, not (as it turns out) for the football sized Styrofoam box (mostly covered in black duct tape!) somewhere on the ground in the underburush. We would not have noticed that between other occasional trash in the area. Contact info is on the balloon. Bob, WB4APR 410-293-6417 ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Balloon lost near Shrewsbury, PA
Short Story. The balloon is lost near Shrewsbury, PA. But we are sure (now after post processing) that we know where it is within about an acre. See: http://aprs.org/balloons.html Premature burst (or separation) caused the payload to descend at over 5000 feet per minute slowing to 4000'/min (nearly 50 MPH straight down)at last posit. We did not know this at the time, and wasted our time searching the track 1/2 mile beyond the last data point assuming the much slower parachute design rate of 600'/min. When we got home, post processing revealed the high descent rate and the more likely spot much closer to the last known position. Also the high impact is why it probably ceased transmitting. Also we were looking for a balloon and parachute in the trees, not (as it turns out) for the football sized Styrofoam box (mostly covered in black duct tape!) somewhere on the ground in the underburush. We would not have noticed that between other occasional trash in the area. Contact info is on the balloon. Bob, WB4APR 410-293-6417 ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Balloon launch SUnday Southern PA
Balloon chase Sunday morning, Southern PA: Should hear it over all Midatantic states! Our balloon will be launched near Chambersburg, PA 9 AM? and will fly across southern PA landing somehwehre near Newark, DE. It will fly faster than the launch team, so we hope other hams will get to the recovery site before we do and catch it on the way down. But when you find it, leave it be, so our students can recvover it. Balloon is W3ADO-11 and will switch to CRASH symbol when near the ground and using WIDE1-1 path.Will use no path at higher altitudes. Will be on 144.39 Our repeater list is as follows: 100 Chambersburg 443.700+ tone 131 101 Haggerstown 442.650+ tone 79 102 Gettysburg 443.100+ tone 103 103 Frederick442.800+ tone 97 104 Lancaster449.275- tone 114 105 449.575- tone 114 106 York 447.275- tone 123 107 Parksburg442.000+ tone 94 108 Newark DE449.025- tone 131 109 simplex 446.000 110 Annapolis444.400+ tone 107 APRS 144.39 (on left side of radio) Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] PCSAT Spin rate still 0.6 RPM
For what it's worth: PCSAT is still maintaining a 0.6 RPM spin about the Z axis. Today for fun, we commanded PCSAT and got 4 minutes of 10 second data. During 100 seconds it completed 1 revolution which equates to 0.6 RPM, the same rate as 13 years ago. >From that we conclude that our (black/white) solar radiation differential pressure spin system is still working fine. AND that the white paint has not changed in 13 years in space (it was very expensive unobtainium two-part white space paint begged from a government launch agency). Only the equatorial antennas are painted black and white on the front and back to give us the Z spin. The others were "Stanley yellow". See the original photo on http://aprs.org/pcsat.html As a refresher, in addition to this 0.6 RPM around the Z axis, there is also the 0.02 RPM tumble about the Z axis since Z has a bar magnet to follow the Earth's magnetic field which then tumbles once over each pole. Users: Routine Digipeating via PCSAT is not encouraged, since every now and then (very rare) we do take a stab at commanding it, and invariably, just when we are getting lucky, someone hits it with a packet for digipeating and robs us of the ONE-PACKET chance we have of getting in. But then we so rarely command it, that it does not make sense to insist that no one use it either. Just glad it is still working (sort of)... Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Ferrite RFI filters and Traps? (yes!)
>> I cut the RFI Ferrite blobs off of all trash Keyboards and stuff. >> These are great Ferrite devices. >> But what are they best for? > Check out this article from Chuck Councilman W1HIS: > http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf Wow, a long one, but on page 24 of 42 I learned a great technique. He says, simply put a turn or two on any ferrite core and hook it to an antenna analyzer. Then look at the impedance over frequency. At DC (or your lowest frequency) the impedance should be very low (and 90 degrees) Meaning the R is very low and the +jX is very high. Keep going up in frequency to where the R and jX terms are equal. That is where the Q is now 1 and the ferrite is starting to get quite lousy. He also said that as you double frequency, the R part of the impedance should also double. When you get to the frequencies where a doubling of frequency no longer doubles R, then you are starting to get into frequencies where this core is less effective. That is exactly the kind of rule-of-thumb advice I was looking for! Now I know what to do with all these cores! Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Ferrite RFI filters and Traps?
I cut the RFI Ferrite blobs off of all trash Keyboards and stuff. These are great Ferrite devices. But what are they best for? IE, 1) are they intentionally lossy or are they High Q? and 2) What is their Optimium Frequency range (all ferrite torroid coil forms come in a variety of materials optimized for different frequency ranges. There is a big difference between the ferrite in a switching power supply (100 kHz) and something usable at VHF or UHF. I assume these ferrite tubes are probably optimized for digital and power supply hash only and so probably only suitable for use at HF, but probably not at VHF and UHF? And what is their Q? Can they be used for making high Q circuits? Today I am using some on the outside of a coax right at the edge of a cubesat to decouple the coax going to the network analyzer from the RF enveolope of the spaceframe for antenna tuning. So today's question had to do with their ability to serve as a high loss filter at UHF. But we may as well list all we know about these ferrites for other applications? p.s. My method for getting them out of the molded rubber is to cut the cable right clean at the ends. Then use a large drill (1/4") to drill out all the internal wires. Then use a hacksaw to cut off one end of the rubber as close as possible to the ferrite but without cutting it. Then pealing back the rubber or nibbling at it with a pair of dikes Got a hobby drawer full now. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Es'HailSat-2
Is that the zero degree horizon footprint or the more usual 10 degree footprint? Bob, Wb4aPR On Sun, Mar 23, 2014 at 10:44 AM, Håkan Harrysson wrote: > Hello! > > If you want to see how footprint looks from 26 degrees east you can > have a look on Picture athttp://www.amsat.se/ > > > This is very exiting news! Thankyou to all working with it. > > > 73 de Hakan SM7WSJ > > > > > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Cubesat 1 axis attitude control?
Need an AMSAT greybeard with attitude control experience. We want to use only one magnetorguer coil (a Z coil) to more or less keep our Z axis aligned with the Earth's axis (+/-30 deg) We figure if we energize the Z coil only twice per orbit while over the equator where the Earth's magnetic field is aligned with the poles we can eventually bring it into alignment. Then we maintain that alignment using white/black differential solar radiation pressure to maintain a fractional RPM about the Z axis. I need help from some greybeards to prove this is possible. Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: 150 cubesats to provide global WIFI multicasting
> for the life of me, I can't think where we could find 70 Mbytes > of ham radio content. Not useful content, anyway. A good example is the way some people stream live tracking data for all satellites in view plus an update to the DX list of passes over the next 3 hours that is captured and displayed on all APRS radios in the local area. The APRS radios capture this and display on the front panel the range and bearing to the satellite, the uplink and downlink freqs and the Doppler. Everything you needed to know to work the satellite while mobile in real time. In addition, if you have the voice module in the radio, the radio will SPEAK the announcement of the satellite in view and will SPEAK the elevation angle as "LOW or HIGH" every minute during the pass. In addition, at any time during the day (or when you arrive in a parking lot and just before you turn off the radio) one can hit the LIST button on the radio and bring up the DX list and it will contain the next three hours of pass times. (useful if there is one only 2 minutes away and worth waiting for). This way one never has to refer to a PC for tracking data, but simply watch (or listen) for satellite alerts on your APRS radio. In fact it is ideal to get alerts while you are in the mobile because that is also where you can work em! There are many satellites that you can work from a mobile with an FM rig, why not? We have had this capability in all Kenwood and now Yaesu APRS radios going back to 1998. You can see examples of the front panel displays on the APRS HT on this web page http://aprs.org/localinfo.html about 90% down the page under the paragraph heading LOCAL SATELLITE ALERTS. And this is only a small part of the continuous streaming data on the APRS channel (useful for the traveler). You also get the following data in real time: * FREQ, and TONE of locally recommended traveler Voice repeaters (accessible with just a press of the TUNE or QSY button) * FREQ, and TONE of nearby IRLP, Echolink or Allstar links * TIMES and days of any local nets on these repeaters * Times and dates of any local club meetings *Announcements about upcoming HAMfests or events * FREQ, location and distance to any other APRS mobile op in voice range * Actual PING alerts if any other APRS mobile operator is in simplex range. Too many people simply ignore APRS as a "tracking system" when it never was intended that way. It was intended as a mobile data resource, pushing relevant local content to the front panel about everything going on in HAM radio in the local area for instant access. (And that includes satellites in view) The APRS radios have over 900 pages of data memory that are being refreshed constantly and are avaialble at any time. (Plus 10 pages of DX list) Plus the data can be sorted for display by age, callsign, or frquency, or distance. See the above web page for all the content already available. But like anything else in Ham radio, if no one is transmitting content in a local area, then no one is even aware of this powerful Ham radio technique. While traveling and just watching the data coming in from APRS, I have stumbled into Hamfests, Pig roasts, club meetings and nets of all kinds to just drop-in on along the road. Bob, WB4APR On Sat, Feb 8, 2014 at 6:15 PM, Gus wrote: > On 02/08/2014 09:24 AM, Robert Bruninga wrote: > > Any ham... to collect this content simply puts his 9600 bd radio > > listing to that repeaer INPUT to join the net! An AP runs together > > building a buffer of that 70 Mbytes of ham radio content per day, which > > is then instantly accessible at any time with is browser. > > Again, we have the sites, the atnennas, the freqs and the radios. > > But for the life of me, I can't think where we could find 70 megabytes > of ham radio content. Not useful content, anyway. > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: 150 cubesats to provide global WIFI multicasting
Already Ham Radio has the technology, bandwidth, and evreything needed to implement distribution of over 70 megabytes of Ham Radio data to every mobile and handheld operator every day. That's a lot of content. And the frequencies exist, and the sites exist. THink about it. Every single VOICE repeater is sitting there with an INPUT channel that NOONE is listenitng to. Therefore, that repeater can stream at 9600 baud this 50 megabytes of ham radio data all day long using existing radios, existing packet and existing TNC's from that repeater site on its input. Every second, it drops the stream for 100ms to listen to see if any VOICE user wants to use the repeater. If no carrier is there, then the stream continues. If a voice user has keyed up, then the repeater acts normally, bringing up its voice transmitter for the duration of the voice contact. When the repeater evntually drops, it goes back to streaming the megabytes of ham data. Any ham wanting to collect this content simply puts his 96000 baud radio listing to that repeaer INPUT to join the net! An AP runs together building a buffer of that 70 megabytes of ham radio content per day, which is then instantly accessible at any time with is browser. Again, we have the sites, the atnennas, the freqs and the radios. Just a thought. Bob, WB4APR On Sat, Feb 8, 2014 at 5:46 AM, Michael Chen wrote: > Maybe my knowledge is out dated, or is this another fiction? > > https://www.outernet.is/ > > Guys responsible for frequency coordination will freak out for such > project. :) > > 发自我的 iPhone > > Michael Chen, BD5RV > AMSAT-CHINA > > > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Possible Balloon launch in VA 8 Feb?
> Sure would had liked advanced notice on this. > A project we would have enjoyed doing. I have some students planning a possible launch in Northern VA sometime this coming weekend. Probably Saturday. Wont know details until the day before. Intent is to predict the path the morning of, and then drive to a launch point to get a desired landing point. It will be a HIGH altitude one with APRS on 144.39 Details (if any) will be posted when avaialble. (This is students, not me, so nothing is guaranteed). Bob, Wb4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Fwd: [APRS] URGENT HELP NEEDED IN EASTERN VIRGINIA
Balloon near Richomnd headed east at 60 MPH. See it on http://aprs.fi/k4wcu-11 and copy it on 144.39 APRS. I'm hearing it direct over 170 miles away in Baltimore. -- Forwarded message -- From: PaulY Date: Sat, Feb 1, 2014 at 1:30 PM Subject: [APRS] URGENT HELP NEEDED IN EASTERN VIRGINIA To: a...@yahoogroups.com K4WCU-11 is a balloon launched by the Physics Department at Western Carolina University in Cullowhee, North Carolina. An as-yet undetermined inflation error resulted in underinflation of the balloon, and slower than expected ascent. As of this moment, it is at approximately 67,000 feet near Keysville, still climbing, and heading 88 degrees at 63 MPH. The current track passes over Petersburg. The balloon may burst over the ocean, or over eastern Virginia. Should it wind up on land, help with recovery from APRS-equipped hams in the area would be greatly appreciated. The equipment package(s) are marked with contact information. For further information, email me at paul at mtnlist dot com, or call me at 828 400 9442. 73 de W4SKI ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] DTMF on HF?
Has anyone had any experience with any success at DTMF working on HF for some rudimentary commands? I know tuning is critical as well as inter-tone noise must be way down. Just thought maybe someone has experimented with it. Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: LEO-satellites-antennas... ?
> I think the QFH throws most of the energy straight up (broad pattern, but not a lot at the low elevation angles). Or another way to look at it, is that satellites at low elevations angles are 10 dB farther away so they will always be weaker by a factor of 10 to 1 to high elevations. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: AO-73 Question (mode efficiency?)
> The satellite is only in transponder mode when it is in eclipse.. > In full sunlight it is in beacon mode only. Just curious about the overall design goals of this operating mode? Putting solar energy into and then taking it out of batteries suffers about a 30% loss in efficiency. All else being equal it is usually better to use solar power directly if possible. Maybe the value of this mode is for hams to use the satellite in the evenings during play time instead of during the day when schools and students could benefit. Just curious. Thanks Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Mystery Satellite Question
Yes, that was UO-11 Comes back to life every now and then and has a LOUD downlink on 145.825 but it is not AX.25 packet. Bob, WB4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Dave Marthouse Sent: Friday, December 20, 2013 11:39 AM To: amsat-bb@amsat.org Subject: [amsat-bb] Mystery Satellite Question I forgot that one of the rigs here was on. It happened to be set for 145.825mHZ in FM. A few minutes ago the squelch was broken by what sounded like 1200BPS AFSK. It almost sounded like the old UOSATS. Checking my satellite tracking program I determined it wasn't CAPE-2, TRITON-1 or DELFIN3XT. What birds are up now that have downlinks on or around 145.825mHZ fm? Maybe I have a set of erroneous keps. Any information on this would be appreciated. Dave Marthouse N2AAM dmartho...@gmail.com ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: satellite average elevation & new birds
> ... asking Bob to comment on his earlier thoughts on using antennae at fixed elevations? The geometry of LEO satellites has not changed. The optimum angle for a fixed tilt modest gain YAGI is about 15 degrees (assuming you have a decent horizon). See: http://aprs.org/LEO-tracking.html That said, if your antenna is seriously blocked from all directions below say 10 degrees, then you are not going to hear anything down there anyway. So bump it up to say 20 or 25. But 70% of all LEO passes are below 22 degrees so just recognize that you are giving up most of your operations. Bob, Wb4aPR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Clayton Coleman Sent: Tuesday, December 17, 2013 8:35 PM To: Ted Cc: AMSAT-BB Subject: [amsat-bb] Re: satellite average elevation & new birds Just a short time ago after I moved into a new shack, I operated for a month with an Elk at 15 degrees on a tripod. Armstrong rotor. I worked all the current satellites right up through the first week we had AO-73's transponder available. Pay close attention to comments WB4APR has made about setting the fixed elevation based on the lowest horizon you can work. For example, if it takes ten degrees for you to clear a mountain, twenty five degrees is probably okay. If you have a clear horizon view, fifteen is probably okay. The goal is to have as much gain available at your lowest elevation to increase your available range. YMMV PS A preamp goes a long way in a fixed elevation setup. 73 Clayton W5PFG On Dec 17, 2013 7:24 PM, "Ted" wrote: > I'm kind of looking for an update from Bob, but can't find his email > right now... > > But the question is, in view of what appears to be some renewed > interest in working the new cube sats, et al, is asking Bob to comment > on his earlier thoughts on using antennae at fixed elevations. For me, > I'm using my Elk on a Rat Shack rotor at a fixed el per Bob's > recommendations. (I'm still struggling with PCSAT32...!!!%^&*!!) but, > this antenna set up is very cost effective and seems to perform pretty well. > > For example, Joel Black has asked for some advice in an earlier > posting. My concern is that new operators or those returning run out > and spend a bunch of $$$ on a new setup. No one knows how long the > current crop will last or if a new crop is in the future, so probably > some caution on the Visa is warranted. > > Just asking (and especially Bob) > > 73, Ted > K7TRK > > > -Original Message- > From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] > On Behalf Of Bob Bruninga > Sent: Tuesday, April 12, 2011 8:23 AM > To: amsat-bb@AMSAT.Org > Subject: [amsat-bb] Re: satellite average elevation > > > we used a horizontally polarized yagi fixed at 30 degrees above the > > horizon. That worked very well.. > > Thanks for the confirmation. Yes, elevation rotation is simply not > needed at all for LEO spacecraft and modest beams. A mild, fixed tilt > modest beam is just perfect. > > But, the "30 degree" angle myth is very pervasive throughout amsat, > whereas, the optimum angle is more like 15 degrees. > > A 30 degree up-tilt gives up too much gain (-3 dB!) on the horizon > where signals are weakest and where satellites spend most of their > time, and puts the gain in an area of the sky where the satellite is > already 6 dB stronger and is rarely there (giving you max beam gain where you need it least). > > If you look at the sketches on the web page, the optimum angle is more > like > 15 degrees up-tilt. It preserves max gain on the horizon within 1 dB > (where it is needed most) and focuses the breadth of its gain on the > area of the sky where the satellites spend something like 95% of their > time. For the missing 5%, the satellite is right on top of you and > almost 10 dB stronger without any beam at all. Oh, and the 15 degree > up-tilt beam is also perfect for Terrestrial operations as well. > > See the sketch on: http://aprs.org/rotator1.html > > In some future life, if we ever get back to HEO's and huge OSCAR > arrays, then elevation rotors have a place. These high-gain beams > have such narrow gain patterns, that higher precision tracking is a > must. (Though it is complete overkill for LEO's). > > Using these OVERKILL arrays for LEO's adds significant complexity to > LEO operation requiring higher precision tracking, elevation rotors, > better timing, fresher element sets and automated operation. > > Using a TV rotator and 15 degree fixed tilt beam is much more forgiving... > > Bob, Wb4APR > > > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > > > > > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the a
[amsat-bb] Re: General Telemetry Question (PITFALL!)
> To follow up on Bob's comment. If you send the raw analog sensor data... > Change calibration values if found to be wrong after launch... We did on PCSAT! Caution to Satellite Builders: Be careful when using an EXCEL TREND LINE equation for doing Engineering Unit conversion back to original units. It was a big lesson for us back on PCSAT in 2001. The problem is, generally, EXCEL displays trend line equations in a nice GENERAL human readable form. For example, for our thermistors, the 3rd order trend line equation to convert from telemetry count back to degrees C was displayed by EXCEL as something like this: 2E-7 X^3 - 2E-4 X^2 + 1.804E-1 X + 2.379E2. One would think one is getting a very precise to 4-significant digit equation. WRONG. Notice the Cubed and Squared terms (which can be very big at warmer temperatures) are only represented to a single decimal digit(+/- 10%)!!! (2 and 2)... When this trend line is used (as displayed), to give back our temperatures from the incoming COUNT, the temperatures were way off! The key is to make sure the trend line equation is displayed in SCIENTIFIC format before you write it down and then try to use it. Then the first two terms above are properly displayed by EXCEL as 1.544E-7 X^3 and -2.069E-4 X^2. (instead of 2E-7 and 2E-4). We catch this error in a lot of student's work... Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] DragonSat - new test (SSB)
> Nothing heard from DragonSat on 145.870. (9600 baud AX.25) A crude test of a Dragonsat model with the antenna un-released was still radiating on the order of 26 to 36 dB down. >From now on, instead of FM, we are going to listen with an SSB receiver and see if we hear the 30 second chirps. Listening on SSB should improve our listening sensitivity 20 dB or so, plus an added 10 dB on direct overhead passes might make it detectible if the only problem is antenna deployment. Should be a less than one second burst every 30 seconds on 145.870. Should be near the pass times of CAPE... Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: General Telemetry Question
Answer: Engineering efficiency.. There is far more computing power on the ground than the satellite. Also, KISS principle. Also, calibration can be done without modifying flight code. And finally, it is far more compact to send binary or hex than human readable decimal. Bob, WB4aPR -Original Message- > why not provide the engineering values in the downlink without the extra step having to be done on the ground? What is the logic of doing this? ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: EZnec experts? (cubesat Circ Antenna) (corrected)
EZnec kibitzers welcome: (corrected version) See this model image: http://aprs.org/psat/VHF-circ-tuned-ask.gif We are placing two ¼ wave VHF whip antennas on a single feed at the corner of a 1.5U cubesat. We want them +/-45 degrees out of phase so that we get cross polarization when paralleled to a single feed point for simplicity. Modeling each one individually, we got the desired short one to -45 degrees with a coordinate of 23.4” and the long one to +45 degrees with a coordinate of 25.68”. Great… But when we connect them both to the same feed point, we get a combined29-j68 ohms and a significantly higher resonant frequency. The R Real part seems reasonable, but do not get the desired J0 term. To fix that, we lengthened each exactly the same amount to get the resonance down to 145.8 MHz and J=0 term. Good antenna…. The QUESTION IS: Are they still 90 degrees out of phase and will they work as a cross polarized antenna? And how can we verify that? The feed point is the center of a 0.1” wire between the cubesat wire frame and the combined end point of the antennas which are also 0.1” above the top of the cubesat. Maybe I should have included both wires in the original model, but only connected one at a time to a source and grounded the other one while trying to find their individual +/-45 degree lengths. This way, their passive action as a possible counterpoinse to the whole frame may be accounted for. Also, to get within the 500 data points for EZnec, we had to make all of the wire model 1” segments be a single segment per wire. Is fidelity maintained with only 1 segment per 1” wire? Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: EZnec experts? (cubesat Circ Antenna)(oops)
OOPS, One error I made is confusing R+j45 ohms as “45 degrees”, when +45 degrees is really R+jR… Right? So I am now starting over. Ignore my post until I fix it and repost the results. Bob --- EZnec kibitzers welcome: See this model image: http://aprs.org/psat/VHF-circ-tuned-ask.gif We are placing two ¼ wave VHF whip antennas on a single feed at the corner of a 1.5U cubesat. We want them +/-45 degrees out of phase so that we get cross polarization when paralleled to a single feed point for simplicity. Modeling each one individually, we got the desired short one to -45 degrees with a coordinate of 23.04” and the long one to +45 degrees with a coordinate of 25.7”. Great… But when we connect them both to the same feed point, we get a combined real R term about half of the others as expected, but do not get the desired J0 term but get something near -45 degrees and a resonance several MHz higher. To fix that, we lengthened each exactly the same amount to get the resonance down to 145.8 MHz and J=0 term. Good antenna…. The QUESTION IS: Are they still 90 degrees out of phase and will they work as a cross polarized antenna? And how can we verify that? The feed point is the center of a 0.1” wire between the cubesat wire frame and the combined end point of the antennas which are also 0.1” above the top of the cubesat. Maybe I should have included both wires in the original model, but only connected one at a time to a source and grounded the other one while trying to find their individual +/-45 degree lengths. This way, their passive action as a possible counterpoinse to the whole frame may be accounted for. Also, to get within the 500 data points for EZnec, we had to make all of the wire model 1” segments be a single segment per wire. Is fidelity maintained with only 1 segment per 1” wire? Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] EZnec experts? (cubesat Circ Antenna)
EZnec kibitzers welcome: See this model image: http://aprs.org/psat/VHF-circ-tuned-ask.gif We are placing two ¼ wave VHF whip antennas on a single feed at the corner of a 1.5U cubesat. We want them +/-45 degrees out of phase so that we get cross polarization when paralleled to a single feed point for simplicity. Modeling each one individually, we got the desired short one to -45 degrees with a coordinate of 23.04” and the long one to +45 degrees with a coordinate of 25.7”. Great… But when we connect them both to the same feed point, we get a combined real R term about half of the others as expected, but do not get the desired J0 term but get something near -45 degrees and a resonance several MHz higher. To fix that, we lengthened each exactly the same amount to get the resonance down to 145.8 MHz and J=0 term. Good antenna…. The QUESTION IS: Are they still 90 degrees out of phase and will they work as a cross polarized antenna? And how can we verify that? The feed point is the center of a 0.1” wire between the cubesat wire frame and the combined end point of the antennas which are also 0.1” above the top of the cubesat. Maybe I should have included both wires in the original model, but only connected one at a time to a source and grounded the other one while trying to find their individual +/-45 degree lengths. This way, their passive action as a possible counterpoinse to the whole frame may be accounted for. Also, to get within the 500 data points for EZnec, we had to make all of the wire model 1” segments be a single segment per wire. Is fidelity maintained with only 1 segment per 1” wire? Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] CAPE cubesat spinning?
At 1748z today 26 Nov, in Maryland, I heard what sounded like a solid carrier on 145.825 Cape frequency with clear spin modulation. It was right on schedule with the other Wallops launch birds. Like I said, sounded like a carrier only, so the spin modulation of the antenna was very obvious. Though it could have been some other data or modulation. Just thought Cape would like to know. Come to think about it, the rate was pretty high like 1 RPS and I doubt it was spinning that fast, so donno what it was. I was late for a meeting with my boss, so didn’t have time to figure out more. Bob, Wb4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Multiple satellite launches (rates?)
> The following link is of Picodragon and 2 other satellites > being released from ISS. There is a picture and short video. > http://amsat-uk.org/tag/picodragon/ Looking at the video, my uncalibrated eyeball counts the deployment rate at about ½ meter per second? Ie, in the first second of video, the 3 cubes move about the same distance as their overall combined length. And in 2 seconds about the same again. Using the still photo at the top of the page, I estimate about 10cm of additional spacing between the 3 cubesats total or about ½ meter for this overall length. Of course there is some parallax difference between the two views, but my guess is about 1/2m per second if the frame-timer in the video is a rough guess. But this is the ISS launcher which might be different from the PPOD launchers on the Dnepr and Minotaur. Just guessing of course.. Bob, Wb4aPR -original message - Doesn’t much matter when they are released, they still are all in the same orbit more or less for quite a while. Even if the springs release them at 1/2 meter per second, they are all going at 7000 meters per second so it takes days for them to separate very much. Let’s see, at ½ meter per second separation, then they are 100’ apart after the first minute, 1 mile after the first hour. And not until they are a few miles apart can NORAD distinguish them enough to start getting good tracks on them. By then it is impossible to know which is which. Hence the guessing game until each owner decides which object best fits his downlink experience. Continuing on, they will be 24 miles apart after the first day where they will be about 5 seconds apart when tracked from the ground. After a week, then maybe 175 miles and ½ minute apart. After a month, maybe 750 miles and 2 minutes apart. After a year, maybe 9000 miles and 30 minutes apart. And finally, after about a year and a half, they will be half an orbit or about 45 minutes apart, beyond which, they start getting closer again… Something like that unless I screwed up… Bob ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Multiple satellite launches
Ø When there is a launch of several satellites in a single payload, several cubesats for example, I assume they release each at different locations on the deployer trajectory. Preliminary keps are based on the trajectory when each is released? Ø Otherwise if they were released all at once, how would NORAD know which is which? Doesn’t much matter when they are released, they still are all in the same orbit more or less for quite a while. Even if the springs release them at 1/2 meter per second, they are all going at 7000 meters per second so it takes days for them to separate very much. Let’s see, at ½ meter per second separation, then they are 100’ apart after the first minute, 1 mile after the first hour. And not until they are a few miles apart can NORAD distinguish them enough to start getting good tracks on them. By then it is impossible to know which is which. Hence the guessing game until each owner decides which object best fits his downlink experience. Continuing on, they will be 24 miles apart after the first day where they will be about 5 seconds apart when tracked from the ground. After a week, then maybe 175 miles and ½ minute apart. After a month, maybe 750 miles and 2 minutes apart. After a year, maybe 9000 miles and 30 minutes apart. And finally, after about a year and a half, they will be half an orbit or about 45 minutes apart, beyond which, they start getting closer again… Something like that unless I screwed up… Bob ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Listening for Dragonsat
Listen on 145.870 too. Most of these new satellites have downlinks on UHF. So if you are listening for them, could you also use your dual band radio to also listen for DRAGONsat on 145.870? It is a ver brief 9600 baud once every 30 seconds. So far, not heard. Its in the 40 degree inclination orbit along with the other dozen satellites launched from Wallops. Coming over mid northern latitudes 6 passes in a row in the Afternoon/evenings. Thanks Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Wallops Launching 12 Cubesats Tuesday 7:30 PM
We are hearing some interesting things from CAPE, one of the Cubesats from Wallops. We are hearing 1 minute AX.25 telemetry, and we have heard two Voice tests, and it has a CW message. All three modes in a Cubesat and on the APRS 145.825 downlink... neat. The voice might be DSB? And we are monitoiring in FM. We haven't copied the AX.25 because all our primary receivers are monitoring for DRAGONSAT on other frequency. -Original Messages- > because they are designed and operated by students and teachers with a valid ham radio licence! >> Then why are those cubesats using amateur frequencies? >>> None of these cubesat developers has made any significant attempt to >>> rally the amateur radio satellite community. In contrast, Funcube has >>> a great community PR "machine" and we are all very excited for them. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Wallops Launching 12 Cubesats Tuesday 7:30 PM
Ø None of these cubesat developers has made any significant attempt Ø to rally the amateur radio satellite community. Yes, the lack of promotion was surprising to me. But hams might get a kick out of trying to listen for EIGHT different cubesats all during 8 minutes of the next passes to help figure out which of these 12 new objects are which. Think of it as a DFing mission or Signals Intelligence challenge. See who is first to correctly ID each one to their Keplarian elements. Our first pass after launch is only 3 degrees to the west, and then we have to wait 12 hours till the next day for a good pass. Our fingers are crossed. The Naval Academy/Drexel satellite downlink is the only one with a 2m downlink which is every 30 seconds at 9600 baud on 145.870 and we would appreaciate any captured telemetry verifying it is alive. It has a camera. Woop. Bob, Wb4aPR -- On Mon, Nov 18, 2013 at 4:25 PM, Robert Bruninga wrote: Watch for a dozen new cubesats Tuesday from Wallops at about 7:30 PM. I have seen a lot of email about Funcube, but haven’t seen much about the Wallops launch. All of them downlink on 435 MHz band except for Naval Academy downlinkning on 145.870. Seven downlinks are at 9600 baud, one at 1200 baud and the others are CW or other. See: http://cubesat.org/index.php/missions/upcoming-launches/135-ors3-launch-alert Sorry if this is a dupe, I hve not been following the AMSAT-BB that closely. Plus, you can see this launch from the east coast in the dark! Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Wallops Launching 12 Cubesats Tuesday 7:30 PM
Watch for a dozen new cubesats Tuesday from Wallops at about 7:30 PM. I have seen a lot of email about Funcube, but haven’t seen much about the Wallops launch. All of them downlink on 435 MHz band except for Naval Academy downlinkning on 145.870. Seven downlinks are at 9600 baud, one at 1200 baud and the others are CW or other. See: http://cubesat.org/index.php/missions/upcoming-launches/135-ors3-launch-alert Sorry if this is a dupe, I hve not been following the AMSAT-BB that closely. Plus, you can see this launch from the east coast in the dark! Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] RF, another alternate energy technology (hogwash)
A fellow came to me convinced that capturing RF energy from cell phones, and radio and TV waves was free energy. He couldn’t wait to invest in these pocket sized antennas that have achieved the same 37% energy reception efficiencies as do the most expensive solar cells:. http://www.sciencedaily.com/releases/2013/11/131107154818.htm I told him to not believe everthing he hears and you Amsat radio guys might get a kick out of my response: -- Thanks for sending me this interesting example of hype gone ridiculous. I was glad to receive it. The problem is apples and oranges. Yes, they got ”37% efficiency, similar to the most expensive solar cells”, but the difference is that solar energy imparts about 100 watts of energy per square foot on a solar panel – remember, ONE HUNDRED WATTS/sqft. The amount of energy from a Cell tower onto a small antenna 1 mile away from the cell tower (typical) is only 0.0004 Watts. So there is about a one hundred trillionth of the practicality. Or another way to look at it. If you could hold their RF energy collecting antenna 1 inch from the cell phone tower (not one mile), to get more power, then the most power he could get would be only 3 watts. Still nothing close to what the sun provides. Plus, he would be absorbing all the power from the cell phone tower making it useless, plus the energy is not free. SO to get the same power as a palm sized solar panel, his RF capture antenna would have to be ONE INCH away from THIRTY cell phone towers. And, to generate that same 100 watts worth of RF energy, it takes about 300 watts of electrical power. (1 inch away) All to deliver about 1 Watt of power compared to the Sun which is free. Thanks. A great lesson in hype! Bob Bruninga, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Digital QRM on FO-29 (DF opportunity!)
Wow, a GREAT DF opportunity and exercise. The Doppler info is there to determine its location. Just plot the doppler and note the center point and draw a line of bearing through it. Combine with others and find the source. heh heh... though, complicated by having to subtract out your own... But we should develop these techniques. They are the basis of all of the original Search And Rescue satellite systems. In fact!!! Why not get a few hams in a few areas of the country to operate a CW carrier (at low power) at a known frequency in 4 corners of the US and let evreyone practice their techniques. This way, we learn how to do it on a known signal. Just a thought. Bob, WB4APR On Fri, Oct 4, 2013 at 4:51 PM, Paul Stoetzer wrote: > During two passes of FO-29 - at around 0120Z last night and around 1430Z > this morning, I've heard some QRM that sounds like a digital signal. I > confirmed that others heard it too and it wasn't local QRM, so it's > obviously being relayed by the satellite. Downlink is around 435.860 MHz (I > heard it around 435.865 last night as the satellite was approaching and > around 435.855 MHz this morning as the satellite was moving away), so the > signal is likely being transmitted around 145.940 MHz. > > Has anybody else heard it? Any ideas on what the source might be? > > 73, > > Paul Stoetzer, N8HM > Washington, DC > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Helix matching
Why don’t we see simple ¼ wave 75 ohm lines used as a first step in matching a 140 Ohm Helix to 50 ohms? The ¼ wave line would give an easy 112 ohms and then it shouldn’t be that hard to do a little additional construction matching to get to 140? (building a 2.4 GHz pop-out helix that compresses flat for launch) Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Odd Question (answer-fixed)
OOPS... Corrected... --- When the Earth image is about 4" across (8,000km), and the satellites are one pixel across (say .001") then each dot is actually to scale a spacecraft that is 2km wide. Which is about 4000 times bigger in diameter than a real spacecraft. So what you are seeing is what space would look like if every one of our satellies was the size of a EARTH-KILLER asteroid. Actually the impact concern is the AREA so in effect, the 4000 times smaller spacecraft are actually 16,000,000 times smaller in cross section than the dot on the image. (unless I made another stupid math error). Bob, Wb4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Franklin Antonio Sent: Tuesday, September 24, 2013 1:30 AM To: MICHAEL Cc: AMSAT-BB@amsat.org Subject: [amsat-bb] Re: Odd Question At 09:22 PM 9/23/2013, MICHAEL wrote: >For the longest time I have been wondering how a satellite is placed in >orbit without hitting anything else? I have seen pictures of all the >stuff circling the Earth and it just baffles me how anyone can get >anything in orbit without hitting anything. Can anyone explain this? Sure. Those pictures you've been looking at are not drawn to scale. The dots representing the satellites should be a lot smaller. If they were, you'd see there's a lot of "space" out there. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Odd Question (answer)
When the Earth image is about 4" across (8,000km), and the satellites are one pixel across (say .001") then each dot is actually to scale a spacecraft that is 8km wide. Which is about 8000 times bigger in diameter than a real spacecraft. So what you are seeing is what space would look like if every one of our satellies was the size of a EARTH-KILLER asteroid. Actually the impact concern is the AREA so in effect, the 8000 times smaller spacecraft are actually 64,000,000 times smaller in cross section than the dot on the image. (unless I made a stupid math error). Bob, Wb4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Franklin Antonio Sent: Tuesday, September 24, 2013 1:30 AM To: MICHAEL Cc: AMSAT-BB@amsat.org Subject: [amsat-bb] Re: Odd Question At 09:22 PM 9/23/2013, MICHAEL wrote: >For the longest time I have been wondering how a satellite is placed in >orbit without hitting anything else? I have seen pictures of all the >stuff circling the Earth and it just baffles me how anyone can get >anything in orbit without hitting anything. Can anyone explain this? Sure. Those pictures you've been looking at are not drawn to scale. The dots representing the satellites should be a lot smaller. If they were, you'd see there's a lot of "space" out there. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Linear Transponder Needed for Launch Opportunity
If someone will build a linear PSK-31 transponder, I have a launch opportunity in 9 months. All it needs to be is a PSK31 Linear receiver on 28.120 MHz (3 KHz bandwidth) with AGC coupled to a downlink UHF FM transmitter of about 1 Watt. Should fit on a 3.5" square card. This is the same as Brno University has built for prior missions of PCSAT2 on the ISS back in 2006 and the two on the shelf awaiting flights. Flight delivery by May 2014 (9 months from now). Brno, may not have the man power to make a third one for this new flight opportunity. Jusst a thought for someone looking for a project. Bob, Wb4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] A0 40 replacement (PSK31-Best of FM and Linear!)
> As long as AMSAT-NA needs to concentrate on... Cubesats... > I would really like to see the pursuit of linear transponders... > on them instead of single-channel FM repeaters. We can have the best of BOTH FM and Linear! > But we used to use a ucc1 in the navy to receive messages. > http://www.virhistory.com/navy/rtty-mux-ucc1.htm > It would allow us to receive something like 16 or 32 separate traffic channels on one frequency. We have that now in PSK31. Up to 30 channels in a single audio channel. So the ideal AMSAT transponder is a linear receiver (on 28.120 MHz) and an FM downlink of that single channel on UHF. This has the advantage of 30 individual linear uplinks to share amongst everyone, and the advantage of FM downlink so that everyone gets the same waterfall without added Doppler. It's a win/win. And it is FULL duplex so that everyone can transmit simultaneously and everyone can receive everyone simultaneously. What more fun can that be!!! See the design: http://aprs.org/psk31uplink2.html And it all fits on a single 3.4" circuit board. Easy to fit in any Cubesat. Two such flight ready boards are ready by the Brno University in the CZECH Republic. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: High orbit satellites?
Amen, Just go to the biggest SmallSat conference on earth at the annual AIAA/USU conference in Utah. Unlike AMSAT, the registration is $600 each, and it lasts 6 days and all 500 to 1000 attendees are fully into Small Cubesat like missions. And very expensive instruments. Every space related Commercial and Governmnet entity is there. A complete industry has grown up to support this new spearhead of interest and you can buy a VHF/UHF transceiver board for only $5000. Or a small 4" solar panel for $10,000 or an attitude sensor suite for $8000 or an antenna for $3000 or a chassis (cubesat) for $5000. Or a complete 3U cubesat for only $250,000. And everyone of these hundreds of cubesat missions ALL want a cheap ride to space. Dan is right, the days of free rides is long-long gone because the demand for paying rides is so high. Bob, WB4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Daniel Schultz Sent: Thursday, August 29, 2013 10:56 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: High orbit satellites? In the 1980's era of AO-10 and AO-13, AMSAT was just about the only outfit interested in launching small satellites, there was no commercial market for secondary launches, and we got them free or very cheap. In today's world, every university on Earth is building a Cubesat and commercial and government organizations are developing real missions around Cubesats. If they gave AMSAT a free launch today, they would have to give free launches to everybody. That is the main problem that we have today. The NASA Cubesat launch initiative is accepting applications for up to a 6U Cubesat with proposals due in November, it MIGHT be possible to get a launch to GTO through this program (or it might not be). Can AMSAT design a high altitude satellite in a 6U Cubesat frame with sufficient solar power generation and antenna gain to provide a viable ham radio mission in HEO? It is worth further study over the next two months. Dan Schultz N8FGV >Date: Wed, 28 Aug 2013 23:58:57 -0700 >From: Peter Klein >To: amsat-bb@amsat.org >Subject: [amsat-bb] High orbit satellites? >Message-ID: <521ef131.6080...@threshinc.com> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed >What are the chances that there will be another high-orbit satellite >like AO-10 and AO-13? Does AMSAT have any plans in that direction >since the demise of AO-40? My main satellite interest is live >communication with faraway places, and I really miss those Molnya birds. >--Peter, KD7MW ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] APRS Destination Address for satellites
APRS has standardized an ID series for amateur Oscar spacecraft. APOxxx. At the request of Juan Carlos, LU9DO, AMSAT-LUwanted a series of APRS designators for uniquely identifying AMSAT APRS applications. He suggested those beginning with the letter O for OSCARS. ALL APRS applications include this identifier in their packets so that the source of APRS data can be known. See the list http://aprs.org/aprs11/tocalls.txt Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Non-mechanical feedback follow up
Just to clarify, the "time tracking" works just as well for the elevation rotor. You can see my balloon chasing 2.4 GHz antenna on my van here: http://aprs.org/balloons.html about 1/3rd down the page (the second balloon mission). But it used a full Yaesu AZ/EL system so I did have feedback. My controller had two serial inputs, one was for the GPS in the van and the other was to a TNC to receive the APRS posits from the balloon. THen the controler does the math so the antenna remains pointed at the balloon (or UAV or what have you)... (though you cannot stop very long or you lose heading info). Bob, WB4APR On Fri, Aug 9, 2013 at 8:56 AM, Zach Leffke wrote: > Hello again everyone, > > I have received a couple of emails off list asking about > details of how I'm planning to use the magnetometer for the azimuth > feedback. Instead of individually replying I'm placing my response here so > everyone gets the same info (skip to the end of this long winded email for > the details). Before I get into that I want to address Bob's (WB4APR) note > about the constant rate of these motors. Basically, I like the idea because > of its simplicity. That's something I hadn't considered, but will look > into. My logic there is run my system through a few dozen trials to really > lock down the turn rate baseline. Then all I have to do is keep track of > the amount of time and in which direction I'm telling the motors to turn, > and voila I should know the azimuth/elevation. As Bob mentioned with the > beamwidth of these antennas that should get me close enough. > > > > If I were only planning to use the system for tracking LEO birds at VHF/UHF > frequencies, I would probably just go with that. However, I was slightly > understating my goals when I initially brought up this issue. In addition > to LEO birds, I plan to also use this system for UAV tracking and High > Altitude Balloon Tracking. I am an EE graduate student at Virginia Tech and > each semester I help out with an Undergraduate Lab with Aerospace and EE > students that design and fly a high altitude balloon (generally with APRS > tracking and some kind of camera/sensor suite payload). One of the > professor in charge's (Dr. Dennis Sweeney, WA4LPR, some folks might know him > for his filter design work among many other things) goals is to up the data > rate in order to attempt a high speed real time data link. So in my own > time I want to use this tracking pedestal for LEO tracking (and for my > Master's Thesis prototype), but for this HAB project, the elevation can get > quite high depending on the geometry of our chase scenario, and beamwidths > can get quite small depending on the frequency we finally choose. In the > end it might not matter much, but when we get to that point I want to at > least have the OPTION for tight control over the pointing. This whole thing > will likely get vehicle mounted in the bed of my pickup, and though I > haven't completely thought out the details yet, My gut is telling me the use > of a magnetometer for azimuth feedback could have a slight advantage because > as the vehicle is moving the system could automatically compensate for the > turning of the vehicle, where as a potentiometer type solution would not. > With position updates from the HAB and a local GPS in the chase vehicle, > calculation of Az/El to the target is pretty straight forward. Combine that > with magnetometer feedback about the antennas' azimuth and elevation > feedback from an accelerometer (which should also be somewhat "self > compensating", say if the vehicle were moving up or down a hill), and I > should be able to come up with a fairly sexy tracking pedestal that > automatically compensates for the vehicle's motion to keep the antennas "on > target." > > > > All that being said, here is my plan for the magnetometer implementation: > > > > I don't really have the details locked down yet, but I can give the overall > plans. First I plan to use the HMC5883L from sparkfun. This device is > $14.95 + Shipping and handling. It is a 3 axis magnetometer. When dealing > with magnetometers it is important to understand whether or not your device > is tilt compensated. This particular device is NOT tilt compensated. What > that means is that it must be kept oriented parallel with the Earth (within > say maybe + or - ten degrees or so). Assuming it remains oriented properly, > the device will output (over I2C) the magnetic field strength in the X, Y, > and Z directions. The Z direction is essentially pointed straight up at > zenith (and should remain near zero since it is orthogonal to the earth's > magnetic field). Also assuming no other strong magnetic fields exist near > the sensor, it will detect Earth's magnetic field (the sensor just returns > the highest magnetic field for a particular direction, so if other magnetic > fields exist near the sensor, it can ruin the readings). In order to get > the bearing, or azim
[amsat-bb] Re: magnetic reed switches f(not really needed)
These motors run at a nearly constant rate. ALl you have to do to know position is to keep track of the time they are on. It remains calibated because at the end of every pass (it ends at zero elevation) so you konw you are at 0 (include say a 10% overshoot after the pass to be sure it is at 0). Same for Azimuth. Each time you find yourself within 45 degrees of the mechanical stop at south (or north), after the pass, send the rotator to the stop with again, 10% overshoot, this re-establishes that reference. So, no feedback needed (for the beamwidths of VHF and UHF anyway). Oh, and you dont need elevation at all really for all LEO satellites. See http://aprs.org/rotator1.html Bob, WB4APR On Fri, Aug 9, 2013 at 6:00 AM, Robert C. Campbell wrote: > I am using reed switches for both my AZ and EL visual feed back on my > newest build. I have had to slow the motors down with a PWM so that the > reeds don't skip a count. Both AZ and EL are still within the speed of > keeping up with ISS. You can determine the ratio of motor turns to one > revolution of the AZ full 360 or 90/180 for the EL and use that ratio to > determine the position in degrees. Repeat-ability seems very good. If you > are going visual/manual positioning you can check on utube or > instructables.com and find a easy build for a modified $ 2.00 Dollar > General calculator that then becomes a pulse counter by simply connecting > the enter button to your reed and entering the ratio and pressing the plus > sign. Then each rotation the calculator will tell you the degrees the > antenna is looking at. Yes, it does need reset after each pass, and yes, if > you run by the bird and go back the calculator will give you some extra > counts since it is counting reed switch contacts not true degrees of > indication. Purchase 5 of them, one for practice, 2 for EL and 2 for AL > then if you start from the same standard position each time one can add and > one can subtract. This should work fine assuming that the driver maintains > mental focus. It is a small fun project and cheaper then happy hour at the > local pub. The Pulse Width Modulator works good with this because you can > adjust the speed of the motors to keep up with the bird. This of course > assumes you are working with direct current motors. > > Bob > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] 1/2 Wave "cavity" filter design?
Given the classic 1/2 wave cavity filter, what is the relationship between inner cavity and center conductor sizes? Of course bigger is better, but what is "OK". This is a 1/2 wavelength tube with a center conductor shorted at each end. The input is loop coupled at one end, an output is loop coupled at the other end. In the middle is a tiny variable capacitor (usually just a screw) to tune to resonance. In the limit, as the cavity size shrinks, you can end up with what could be considered as just a piece of 1/2wave coax. Im looking for a really cheap Home-Depot plumbing design that 15 people can reproduce to give them good front end antenna filtering when operating on mountain tops adjacent to other RF souces. (say within 100 yards, not permanent installations which of course should spare no expense at getting the best cavities possible). We just finished our 4th annual Golden Packet attempt from Maine to Georgia along the Appalachian trail and many stations were plagued with front end overload. http://aprs.org/at-golden-packet.html I'd like to come up with a 3/4" copper pipe design that is robust, provides sevral dB of out of band rejection. Im trying to understand the parameters that drive the size of the center conductor. Normally bigger is better for better bandwidth, but I think smaller will give me steeper skirts and better rejection? I dont mind say 2 or more dB insertion loss, because as it is, front end-overload is making us totally deaf and anything would be bettter. Lastly, I think such a 1/2wave filter will also pass as a 1.5wave pass filter on UHF. We need dual band, since we use dual band rigs and coordinate on UHF voice from the same antennas and coax used for the VHF packet. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: APRS & Twitter
> CAPE-2 ... [is] planning to fly a digipeater... > I am currently developing software to distribute to you guys > later this year that will copy our telemetry and have it automatically sent back to us. I hope your telemetry is APRS compatible so that it can also be distributed by the global APRS-IS system already in place. If nothing else, it only takes a leading ">" byte to make it "aprs compatible". > We have already implemented the ability to send APRS emails, > but would now like to do the same with twitter. Yes, Emails automatically work for anything that can digipeat because APRS-IS stations automatically link those packets into the APRS-IS where they are picked-up by existing APRS-to-Email engines. In this case then, the ability to send a tweet via APRS is simply an application that monitors the APRS-IS for any APRS packets that looks like they contain a "tweet". If we do not already have such an engine somewhere in the world, then we do surely need one. And so your request is a good one. And this is basically what PA3GUO is suggesting below.. Bob Bruninga, WB4APR (of an age that is tweetless) On Wed, Jul 10, 2013 at 1:52 AM, PA3GUO wrote: > Hi Rizwan, > > First of all: we are all very interested in your CAPE-2 project. > Would you be able to share some more information on CAPE-2 ? > > In case you involve radio-amateurs in capturing telemetry/data from your satellite you will have an huge increase in coverage, as we are spread across the entire globe. We do have the APRS system up-and-running, and NO-44 (PCSAT-1) and ISS-APRS data packets for example are monitored and automatically forwarded to the internet already. > > On messaging to twitter email: > In case of a malfunction or wrong software setting the satellite may not be able to change its transmission pattern, when it is in space and cannot be reached anymore (e.g. up-link broken). Alternative would be to break it up in two steps: > > Step 1 > Transmit a status in APRS format, and have that captured/received as > regular packets. Here is for example how all the ISS data (real-time) > looks like: http://www.ariss.net, and here is how NO-44 looks like: > http://www.findu.com/cgi-bin/pcsat.cgi > > Step 2 > Have a software program running that looks at the the received APRS telemetry, and derive from that a Twitter tweet (every hour, every day, ...). For example if the telemetry says: "CAPE 012000105" this could mean I am alive and battery voltage is 10.5 volt and temperature is 12 degrees Celsius. The tweet could be: "Hi this is CAPE-2 in space, I feel cold (12C) and my battery is good (10.5V)". > > Just a thought. > > Regarding APRS email: http://www.aprs.org/aprs-messaging.html explains how to do this. > > Here is an example on how this worked on ANDE-1: > ANDE-1 digipeat: > !T 12:26:38 PA3GUO-8>APRS,ANDE-1*,qAO,PE1ITR::email :pe1...@spamsat.org Hi ROb > !S 12:26:36 :email :pe1...@spamsat.org Hi ROb > > Here an example on how this worked on ISS: > TNC settings an email to PE1ABC (pe1...@spamsat.org) via ISS (RS0ISS-3): > MYCALL PA3GUO-5 > U APRS VIA RS0ISS-3 > BEACON EVERY 1 > BTEXT :EMAIL :pe1...@spamsat.org Hi there! > > The result (the email received by pe1abc): > From: kspr...@rci.rutgers.edu > Date: 25-02-2004 08:00 > > To: pe1...@spamsat.org > cc: > Subject: APRS Message from PA3GUO-5 > Hi there! > > Please let us know if this helped & success with CAPE-2! > > Henk, PA3GUO > www.pa3guo.com > >>Greetings AMSAT! >> I am one of the software engineers on the CAPE-2 Cubesat project at > the University of Louisiana at Lafayette. I am interested in > information on how to set up our satellite to tweet over APRS to a > specific twitter account. > > For example: > If i want our satellite to tweet once a day what our satellite's > status is, and have it be posted to a CAPE-2 twitter account, how can > i make this happen? We've seen other groups do it, and we are > wondering how to replicate this. > > Thanks for your help! > > Sincerely, > Rizwan Merchant > Call Sign: KF5BNL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Solar Impulse flying up Jersey Coast NOW
Solar Impulse flying up Jersey Coast NOW (9 AM Saturday). Need an APRS operator to watch position on http://live.solarimpulse.com/ and then maintain an active object on APRS RF so that all mobiles can see the aircraft on their mobile radios and be able to lookup and see it. Its the size of a 747 wingspan but the mass of a volkswagon and completely solar powered. Use the OBJECT NAME of SOLAR1. Thanks, Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Golden Packet 20 July gaps: Killington, VT and Smokie Mountain!
Only two Mountains remaining to be covered for this historic event. Killington, Vermont and Clingman’s dome in the Great Smokies National Park. On Saturday, 20 July, Just drive up to the parking lots, set up a small mast to clear the cars with an Omni dual band vertical and play APRS (and other) Radios for 4 hours starting at noon. Ideally you have a D700, D710 or D72 APRS radio that can digipeate the special event packets. To understand the entire event, getting a live APRS packet from Georgia/Alabama to Maine/Canada see the main web page: http://aprs.org/at-golden-packet.html Sorry, Im having FTP problems so that page has not yet been fully updated to 2013 participants but you can see them here: https://docs.google.com/spreadsheet/ccc?key=0AiYno6C9YkfGdHlkNHlVYUNyZEJ4S3RlTnNPZzREeFE#gid=0 We must have all 14 mountain tops manned to complete the DX link. Thanks, WB4APR *From:* Robert Bruninga [mailto:bruni...@usna.edu] *Sent:* Tuesday, July 02, 2013 11:32 PM *To:* amsat-bb@amsat.org; aprs...@tapr.org; a...@yahoogroups.com *Cc:* bruni...@usna.edu *Subject:* Golden Packet 20 July gaps: NH, MA, NY, NC/TN We have an urgent need for Ham Packet Ops on mountain tops in New Hampshire, Mount Greylock, MA, Sams Point, NY, Clingmans Dome in the Smokie Mountains and Roan Mountain NC. This is a 4 hour event making our annual attempt at the Golden Packet, an APRS packet message from Maine to Georgia along the Appalachian Mountain Chain on Saturday 20 July. All you need is an APRS radio that can digipeat (D72, D700, D710) and a power source and antenna. (and Know how to operate it!) All of these sites are “drive up” except Sam’s point in New York. The attempt is from noon to 4 PM. Remember, Tim, KA1YBS has to begin in the dark to climb a full MILE straight up to get to the top of Mt Katahdin in Main and then get back down before sunset. Hence, the 4 hour window. This is our 4th annual attempt and last year we were successful except for only one broken link in NH. Will you be available to help make history? The Golden Packet was proposed back in the early 80’s. It has never been claimed since the rise of the Internet that has eclipsed all DX packet attempts. We will do this every year even beyond success. It is a good test of emergency long distance packet techniques. If you can activate one of the above 5 sites, please see detail links on this page for each site and learn all you can: http://aprs.org/at-golden-packet.html Think of this as Packet Radio FIELD DAY! These 14 sites have been well surveyed and we know the links will work, if everyone can get in place and KNOW how to operate their radio. Other secondary sites are also invited on Stone Mountain, GA, Lookout Mountain TN, and Huntsville Mountain Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: [APRS] Golden Packet 20 July gaps: NH, MA, NY, NC/TN
> WHy only those 3 radios? > Cannot any 2m rig with any [TNC] or one of their other devices, or even a venerable kpc3+, digipeat? Yes, but it is all about risk. Generallly, 90% of all packet radio/TNC's on the air are misconfigured in someway or another. It has been this way for the last 40 years of packet..., and although they "work" some suffer as much as 20 dB or more loss of weak signal performance (but no one notices because it "works"). Most are just plug-n-play till it "works" with no attention to levels, deviation, clipping, compression, skew, balance, bandwidth, pre-and de-emphasis, etc. When trying to do a one-time long-chain national test, the risk of a single station not meeting 100% optimum settings and causing the whole test to fail is just too high. The kenwoods may not be the perfect of any of the above settings, but they are factory consistent and beyond the owners abilty to screw up. And they are very sensitive to each other, able to decode each other's packets down to only 3 bars (about -116 dBm) where as some TNC's and Trackers must have 60 dB over S9 full scale dead full quieting signals before they are decoded. Yet their owners claim "the work"... > All you need is an APRS radio that can digipeat (D72, D700, D710) and > a power source and antenna. (and Know how to operate it!) And said another way, These radios all use a flat passband and most all TNC/Radio combos use pre and de-emphasis. I'm not saying one is better than the other, but we must have consistency. Many Many dB of weak signal performance is lost when one tries to talk to the other. Thanks Bob, WB4APR -- Thanks! & 73, KD4E.com David Colburn - Nevils, Georgia USA Search with: duckduckgo.com Android for Hams: groups.yahoo.com/group/hamdroid Creative Tech: groups.yahoo.com/group/ham-macguyver Raspi Alternative: groups.yahoo.com/group/beagleboneblack/ Restored to design-spec at Heaven's gate 1Cor15:22 Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/APRS/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/APRS/join (Yahoo! ID required) <*> To change settings via email: aprs-dig...@yahoogroups.com aprs-fullfeatu...@yahoogroups.com <*> To unsubscribe from this group, send an email to: aprs-unsubscr...@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/ ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Golden Packet 20 July gaps: NH, MA, NY, NC/TN
We have an urgent need for Ham Packet Ops on mountain tops in New Hampshire, Mount Greylock, MA, Sams Point, NY, Clingmans Dome in the Smokie Mountains and Roan Mountain NC. This is a 4 hour event making our annual attempt at the Golden Packet, an APRS packet message from Maine to Georgia along the Appalachian Mountain Chain on Saturday 20 July. All you need is an APRS radio that can digipeat (D72, D700, D710) and a power source and antenna. (and Know how to operate it!) All of these sites are “drive up” except Sam’s point in New York. The attempt is from noon to 4 PM. Remember, Tim, KA1YBS has to begin in the dark to climb a full MILE straight up to get to the top of Mt Katahdin in Main and then get back down before sunset. Hence, the 4 hour window. This is our 4th annual attempt and last year we were successful except for only one broken link in NH. Will you be available to help make history? The Golden Packet was proposed back in the early 80’s. It has never been claimed since the rise of the Internet that has eclipsed all DX packet attempts. We will do this every year even beyond success. It is a good test of emergency long distance packet techniques. If you can activate one of the above 5 sites, please see detail links on this page for each site and learn all you can: http://aprs.org/at-golden-packet.html Think of this as Packet Radio FIELD DAY! These 14 sites have been well surveyed and we know the links will work, if everyone can get in place and KNOW how to operate their radio. Other secondary sites are also invited on Stone Mountain, GA, Lookout Mountain TN, and Huntsville Mountain Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Sub orbital launch from Wallops Island Virgina
> A Sub orbital launch from Wallops Island.. > some of you... with high gain 2 meter antennas and possibly elevation control > (depending on where you are- approx 70 miles elevation at apogee) will give a > listen for it Assuming the ground track is out to sea for range safety, then I would assume it may also add as much as 70 miles distance too.. THus, high angle elevation control for most of us is not needed and from Washington DC (range 120 miles+70) the elevation angle will not rise above maybe 20 degrees which is well within the beamwidth of all terrestrial azimuth-only beams. Just point at Wallops and see what you capture. Remember, this channel is already wall-to-wall packets and so we are looking for the needles in the haystack. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Pass prediction - New Option - ALL
The pass prediction page is wonderful! Great work! But it is tedious if you simply want to know what is the next satellite to demo. I's like to ask the programmers to add a second link to an ALL-SATELLITES page. This page would simply list the next 10 satellites to come in view at the subscribers location. This is what I need because I never know when someone is going to walk through the door and I need to give a quick demo. Or when I have a few minutes in the shack and just want to see if something is in view in the next 10 minutes. The page would have these entries: LAT/LONG and TIME (defaults to now). Then there are several buttons: * FM only * ALL mode * Voice * Digital * All beacons If ALL BEACONS is checked, then all satellites with telemetry in the ham bands are included in the list including all the bleepsats. If this is not checked, then the other 4 buttons are used to filter. The result is a LIST of the next 10 passes of any satellite that meets the criteria. This type of pass prediction engine is of extreme value to people that want to DEMO Amateur satellites without having to go run pass predictions on over 30 different satellites just to see what might be in view. With that many satellites there is almost always coming coming up real soon, and this is invaluable for quick demos. It is also invaluable for the ham that only gets a few minutes in his shack now and then. This page would show him what might be available for the next several minutes... Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Solar Impulse: Dallas to St. Louis in flight!
Solar Powered flight is underway from Dallas to St. Louis. See the flight. http://live.solarimpulse.com/ We need APRS operators in RF range to help maintain an OBJECT track on the bird so that not just those in front of a PC can see this, but also those hams in their APRS mobiles who will see the location of the bird and maybe be able to see it. Imagine an airplane the wingspan of a Jumbo jet that weighs less than a car. So, help out your fellow ham and do what APRS was designed to do… provide INFO in the field to mobile operators. Please use the object name SOLAR1 so that subsequent updates will replace older positions. Those with APRS radios will see SOLAR1 on their GPS maps and the radio will show distance and bearing so they will know where to look. Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Is there anyway to get a linear transponder on the ISS? (PSK31)
> The nicest configuration... would be a 2m FM uplink with CTCSS to avoid interference and a SSB 10m downlink. The problem with that is the same as all our other FM satellites. Only a single user at a time. Congestion, conflict and little practical value. The better use of SSB is to use the same single channel FM bandwidth for a wideband transponder allowing up to 30 or more simultaneous users. This is equally trivial to do. Just connect the output of a 10m SSB receiver tuned to 28.120 MHz to an FM downlink and use PSK-31 on the uplink. The FM downlink gives everyone in the footprint the identical PSK waterfall spectrum where they can tune all 30 QSO's simultaneously. Then each person sets their PSK-31 uplink to an unused 100 Hz wide area in the spectrum Not only can 30 stations participate at once, the fact that they are transmitting on 10m PSK31 and receiving on 2m or UHF FM at the same time means they are also operating full duplex during the entire pass. Everyone can talk to everyone without conflict or congestion. And no special hardware is required for users. A PC with a sound card can do it all. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Is there anyway to get a linear transponder on the ISS?
> if there were a "real" ham on the ISS things would be different. Yep, then nothing would get done. All he would do is float around and complain about all the things that everyone else should be doing. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: a cheap LEO tracker for single op
I found my old web page with graphics that shows the exact geometry of passes and elevations. See http://aprs.org/LEO-tracking.html 70% of all pass times are below 22 degrees. After the discussion a few weeks ago, I sat down today to begin building a web page on the topic and when I went to save it, there was a page already there that I had made years ago! So there it is. Bob, Wb4aPR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Rolf Krogstad Sent: Tuesday, May 28, 2013 4:17 PM To: Bill (W1PA) Cc: amsat-bb@amsat.org Subject: [amsat-bb] Re: a cheap LEO tracker for single op Bill, You should find something in the reflector archives from 3 or 4 weeks ago where there was a discussion of what percentage of passes were overhead. It is an extremely low percentage. If I recall, most are at a an elevation of 33 degrees or less. Because of the wide beam width of my antenna, tilting the antenna at an angle of 20 to 25 degrees works well for me. I can copy the satellite beacons down to the horizon. And only on the high angle passes do I have a any drop out And because of the beam width of the antenna I don't need to keep a hand on the rotor control all the time. But it takes some practice to remember to look at the azimuth reading on the computer and to adjust the rotor accordingly every couple of minutes. The problem comes on the more overhead passes. Because the bird is closest to my location at that time it seems to accelerate as it gets overhead. On those, though, it doesn't seem to be as critical that the rotor be adjusted anywhere close to the indicated azimuth. I can hear the signal starting to fade and it is a reminder to check the azimuth. I would definitely run a number of passes with the setup before Field Day to make sure that everything works and that you can remember to do all the things that your three hands need to do during a pass! 73 from another newbie, Rolf NR0T On Tue, May 28, 2013 at 11:57 AM, Bill (W1PA) wrote: > Let me ask this another way... > > Assuming minimal setup prior to each pass, can I track a LEO with a > single rotor well enough for QSO’s? (single rotor control in one > hand, VFO/Doppler on my other) > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Up-tilted beams (15 degree optimum)
Did you look at the antenna plot on that web page?: http://aprs.org/rotator1.html At the proper 15 degree tilt of a fixed beam, the gain is down only 1 dB at the horizon. At your proposed 35 degree tilt, the gain is down 4 dB on the horizon where you need it most (70% of all pass times are below 22 degrees). To me, it makes no sense to sacrifice 4 dB in the area where the satellites spend most of their time. The only benefit to the high tilt angle is improved performance during the 3% of the time the satellite is above 60 degrees. And is that worth giving up gain for the 70% of all other pass times? Further, when the satellite is that high the signal is already 6 to 10 dB stronger than it was on the horizon anyway. How much better does one need to hear an already excellent signal? (so as to sacrifice the other 70%)? But again, if the antenna is in a hole and cannot see anywhere close to the horizon anyway, then of course, tilt the main beam up to point right at the lowest available horizon where the gain is needed most. Bob, WB4aPR > Bob, depending on the antenna pattern and the ground, as you say, > 15 degrees might be too low for any additional help toward the horizon. > 30 to 35 degrees will give you a little better results for stuff that isn't just > right at the horizon, I feel. As with all things in this hobby, experimentation > with your equipment will allow you to find the best combination. Also why sacrifice 3 dB for all terrestrial operations too which are also on the horizon? On 5/13/2013 11:29 AM, Robert Bruninga wrote: >> As has been said many times, most satellite passes are never >> "directly overhead", but rather on some inclination across the sky. >> A 5 element yagi antenna, at a 35 degree angle from the horizon, >> with only an asmuth rotator, will let you work far more satellites >> for > the money spent. > > Except that the correct angle is 15 degrees not 30 or 35.At 15 > degrees, the main gain lobe of the antenna still has excellent gain on > the horizon where you need it most and an equal gain all the way up to 30 > degrees or so. Below 30 degrees is where satellites spend 80+% of their > in-view times. This is where you need the gain most. But when the > satellite is above 30 degrees, the satellite is at least 6 to 10 dB > closer and so it makes no sense to sacrifice gain on the horizon > (where you need it most) by placing it at 30 degrees where you need it least. > > See http://aprs.org/rotator1.html > > Ignore the topic of the page but look very carefullyl at the SCALE > drawing (Yes, that is drawn to scale) of a LEO satellite pass Notice > how 95% of all satellite access times are below 50 degrees and 70% of > the time they are below 22 degrees. That is where you need the gain. > Do not waste it by tilting the antenna up more than 15 degrees. > > The only exception is that if your beam antenna cannot see the horizon > anyway, then, yes, tilt it up a little more since you wont hear the > low stuff anyway... > > Bob, WB4aPR > > > > Gregg Wonderly > > On 5/12/2013 12:48 PM, Jeff Moore wrote: >> I wouldn't recommend a J-pole for satellite work unless you expect to >> only work sats on the horizon. The J-Pole antenna has a low take-off >> angle and almost NO radiation overhead, an plain 1/4 wave ground >> plane antenna would work better for the sats. >> >> >> >> J-poles are great terrestrial communications antennas, not so much >> for working overhead satellite passes. An Eggbeater or quadrifiliar >> antenna would be a better choice. >> >> 7 3 >> >> Jeff Moore -- KE7ACY >> >> On 5/12/2013 8:00 AM, Werner, HB9BNK wrote >>> Thank you all for your valuable hints and advices ! >>> >>> I will now build such an antenna and then supply here the results. >>> >>> 73 Werner, HB9BNK >> >> ___ >> Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. >> Not an AMSAT-NA member? Join now to support the amateur satellite > program! >> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb >> > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: J-Pole Antenna
> The antenna, that I want to build, is described in a paper (probably 20 years old) > by Dick, WD4FAB, titled 'Antennas for microsat ground stations', and the paper > describes the large time, a LEO remains at low elevations - about 76 % below 20 degrees - > and then concludes, that this is fine for a J-Pole. Absolutely true with respect to the*antenna pattern* but the current batch of LEO satelltes even though they are in the main beam of the omni antenna at the horizon, are -too-far-away- to be heard with only 2.1 dB of omni dipole antenna gain. So yes, those are good "satellite antennas" for omni coverage, but they wont hear anything that low because the satellites are 3000km away and the current crop of satliltes mostly operate in the 1/2 watt or less area. The only thing you will hear down to the horizon with these antetnnas is the ISS that is operating at 10 watts or more. You are better off simply giving up on the horizon (for an omni) and increasing your gain higher up. And a 1/4 wave whip over a ground screen will give you 5.1 dBi instead of 2.1 dBi. And then you may begin to hear things above about 15 degrees or so (and 3 dB better than you would hear on any antenna optimized for the horizon.. And it is even better to go to a 3/4 wave vertical over a ground screen and then you get almost 7 dBi gain starting around 30 degrees. You wont hear the low satellites (you can't anyway on an omni) but you will hear them much better when they do get above about 25 degrees... (but notice, this is less than 1/4th of all passes). ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: J-Pole Antenna
> As has been said many times, most satellite passes are never > "directly overhead", but rather on some inclination across the sky. > A 5 element yagi antenna, at a 35 degree angle from the horizon, > with only an asmuth rotator, will let you work far more satellites for the money spent. Except that the correct angle is 15 degrees not 30 or 35.At 15 degrees, the main gain lobe of the antenna still has excellent gain on the horizon where you need it most and an equal gain all the way up to 30 degrees or so. Below 30 degrees is where satellites spend 80+% of their in-view times. This is where you need the gain most. But when the satellite is above 30 degrees, the satellite is at least 6 to 10 dB closer and so it makes no sense to sacrifice gain on the horizon (where you need it most) by placing it at 30 degrees where you need it least. See http://aprs.org/rotator1.html Ignore the topic of the page but look very carefullyl at the SCALE drawing (Yes, that is drawn to scale) of a LEO satellite pass Notice how 95% of all satellite access times are below 50 degrees and 70% of the time they are below 22 degrees. That is where you need the gain. Do not waste it by tilting the antenna up more than 15 degrees. The only exception is that if your beam antenna cannot see the horizon anyway, then, yes, tilt it up a little more since you wont hear the low stuff anyway... Bob, WB4aPR Gregg Wonderly On 5/12/2013 12:48 PM, Jeff Moore wrote: > I wouldn't recommend a J-pole for satellite work unless you expect to > only work sats on the horizon. The J-Pole antenna has a low take-off > angle and almost NO radiation overhead, an plain 1/4 wave ground > plane antenna would work better for the sats. > > > > J-poles are great terrestrial communications antennas, not so much for > working overhead satellite passes. An Eggbeater or quadrifiliar > antenna would be a better choice. > > 7 3 > > Jeff Moore -- KE7ACY > > On 5/12/2013 8:00 AM, Werner, HB9BNK wrote >> Thank you all for your valuable hints and advices ! >> >> I will now build such an antenna and then supply here the results. >> >> 73 Werner, HB9BNK > > ___ > Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: ISS HamTV Frequencies (range gain)
One needs to also realize duration. The time say above 70 degree elevation (where rates are highest) are less than 2% of the total pass times. Not worth worrying about. Similarly, a LEO satellite spends 70% of its time below about 22 degrees. (but it is far away and needs max gain). So simply design for the best operation for most of the time when the link will work. Remember, the satellite is 3000 km away on the horizon and very weak, but as it gets into say 1500 km it is twice as close and 4 times (6 dB) stonger which is a heck of a lot of gain. When it goes directly overhead it is another 6 dB closer which is more than *ten* times the signal on the horizon, so don't worry about the 2% of the time it is going to be above 70 degrees. The signa is 10 times stronger and easy to deal with. Bob, WB4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Art McBride Sent: Monday, May 13, 2013 12:44 AM To: 'Roger'; amsat-bb@amsat.org Subject: [amsat-bb] Re: ISS HamTV Frequencies Roger, A SWAG, (Wild Guess) 1 degree per second at a Zenith of 90 degrees. Anything less than 90 degrees will be slower with several minutes spent near the horizon. You can use an orbital program to get exact numbers. With a wide beam width antenna, the lag overhead may never require the antenna to move with the object, as there will be time for the antenna system to catch up after passing overhead. Art, KC6UQH -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Roger Sent: Sunday, May 12, 2013 2:34 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: ISS HamTV Frequencies Anybody off the top of their heads know how many degrees a second swing are (is?) required for direct aim at the ISS? I know there are beam width tolerances, altitude variations and degree above horizon variations but I'm looking at Bob B's fixed antenna aiming of 15-20 degrees above horizon to evaluate swinging a dish without torque eating up the drive train... Roger WA1KAT On 5/12/2013 5:01 PM, M5AKA wrote: > The AMSAT-UK page at > http://amsat-uk.org/2013/05/12/hamtv-from-the-iss/ provides the links, they are: > > Facebook https://www.facebook.com/Hamtvproject > > More information at > http://www.amsat.it/Amsat-Italia_HamTV_brochure.pdf > and http://www.amsat.it/Amsat-Italia_HamTV.pdf > > The HamTV.pdf gives the link budget, looks like there's 7dB of coax/connector losses to overcome between the ISS transmitter and the antenna. That document indicates a 90cm dish should be sufficient. > > I believe that it's going up on ATV 4 which is currently slated for > June 5. > > 73 Trevor M5AKA > > ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
> Going from 310 to 700km in a year is not doing us anything. Im not following this closely, but that statement misses the most important reason for doing this... *to*stay*in*orbit! The lifetime of a cubesat at 310km is only a few weeks at most. The life time at 700km is tens of years. The minimum requirement then for an ION thruster, then, is to be able to at least be slightly greater than the loss on every orbit. Then it is worth its weight in gold! Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: FUNcube Project - 7 dBi omni
> ... which is going to be the best type of antenna... > to receive the 145MHz downlink signals There are lots of good hemispherical satellite antennas that provide equal gain for all satellites in view. However, these designs ignore the fact that satellites on the horizon (LEO passes spend almost 70% of their time below say 22 degrees) are so far away, most of them are too weak to be decoded until they get closer (and higher) anyway. Given the weak downlink (300mw) of FunCube there is no -omni- antenna that is going to decode that signal at the horizon when the satellite is over 1500km away. In this light, it is better to simply sacrifice low angle coverage and concentrate the gain higher up to make sure that when the satellite does get to high angles, then there is plenty of gain to decode it. The simplest and best performance (for LEO satellites) and easiest to construct is a 3/4 wave vertical over a ground plane. It has over 7 dBi gain above 25 or 30 degrees and requires no matching circuit. Just shield to ground plane and center coax to the 3/4 wave whip. The antenna pattern is ideal for LEO satellites because it concentrates the gain above 30 degrees and does not waste gain down on the horizon where satellites are 6 to 10 dB farther away and not decodable on an omni anyway unless the satellite has decent power (which the fun cube does not). Background: In the past, a 19" whip is an ideal 3/4 wave gain vertical for UHF (over 7 dBi) and also acts as a 1/4 wave vertical (5 dBi) for VHF. A nice dual band antenna for satellite work with weak UHF downlinks. But then Funcube is not UHF, but VHF. So you want more gain on the VHF downlink, so you would want to make this antenna almost 58 inches long to be 3/4 wave on VHF (and ignore it for UHF where the gain pattern would be too narrow). Also, by having reduced gain on the horizon, the VHF link will have less noise to contend with. You don’t you see this excellent antenna more often because it is useless for terrestrial operation (negative gain on the horizon), and for satellites, most people think they want omni-gain on the horizon even though for anything other than the 10W transmitter on the ISS, they still won't decode anything on the horizon until the satellite gets higher (and closer) anyway. So my receommendation is the 3/4 wave vertical for unattended fixed omni operation with high gain above say about 25 degrees and use a gain YAGI and tracking antenna if you need to have coverage down to the horizon. The over 7 dBi gain of this simple 3/4 wave antenna plus the nearly 5 dB path-loss (and noise) gain of VHF over UHF for omni antennas makes this link over 12 dB better than a comparable UHF downlink to-an-omni experience with cubesats. My opinion anyway. You can see some of my early writings on this antenna about 80% down this page: http://aprs.org/astars.html Bob, Wb4APR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Graham Shirville Sent: Tuesday, April 09, 2013 3:47 PM To: AMSAT BB Subject: [amsat-bb] FUNcube Project - Your advice requested Hi All, As part of the FUNcube project we now need to urgently decide which is going to be the best type of antenna to propose for use at schools and colleges to receive the 145MHz downlink signals from both FUNcube-1 and FUNcube-2 on UKube after launch. Both spacecraft will be transmitting approx 300mW of BPSK 1k2 telemetry with FEC – FC1- will be using a dipole antenna and will have passive magnetic attitude control. FC-2 on UKube will use a single monopole antenna and the spacecraft is intended to have active attitude control. This is primarily to ensure that the deployed solar panels are illuminated and that the face with the S band patch is usually earth pointing. We believe that the resultant signal should be easily usable using an omnidirectional antenna but the questions is which would be the best type to use. Obviously ease of construction, cost, robustness and safety in a school environment will also be important factors as well as suitable “gain” and circularity from horizon to horizon. We envisage that some operations may be from fixed installations with the antennas mounted permanently but some will be temporary - perhaps hand held or bolted to a step ladder or similar. We know there are many AMSAT members around the globe with great experience in this field and, we suspect, with some strongly held views. So please let us have some constructive input about which type is likely to be best for this purpose - your comments, ideas and lessons learnt will be very valuable for us. Thanks in advance for your support 73 Graham G3VZV - for the FUNcube Project team As part of the FUNcube project we need to decide which is going to be the best antenna to propose for use at schools and colleges to receives the 145MHz downlink signals from both FUNcube-1 and FUNcube-2 on UKube after launch. Both spacec
[amsat-bb] Re: Radio-Archeology (xponder?)
LES1 (I think) has a bent-pipe transponder for military UHF (250 MHz area). I wonder if the billion to one chance that the transponder came on too? Bob, WB4aPR -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of Alan Sent: Wednesday, February 27, 2013 7:48 AM Subject: [amsat-bb] Radio-Archeology Another satellite comes back to life: http://www.southgatearc.org/news/february2013/radio_archeology.htm ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Close encounters of the Asteroidal Kind
> I wonder what 435kw at 28,000 km will do to the surface temperature on that rock? Let's see, power goes down as 1/R squared. So lets compare it to a candle. A candle is about 50 Watts or about (435000/50W) or about 10,000 times less power. Take the square root of that to get about 100/th the range. So that radar at 28,000 km will heat the surface about as much as a candle would at 280km. (unless I screwed up before my morning coffee)... Bob,WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] PCSAT normal(?) operations resume
PCSAT (NO44) is again returned to users (but not usable until a few weeks when sun angles get better). The Transponder on ISS is also operational now. The variation of power available to PCSAT is inversely proportional to the “sun-to-orbitplane-angle” (viewable in Instantrack with the “E” and “D” keys. It is currently above 78 degrees. Once it went above about 65 degrees was our last successful commanding. Recovery did not work this period. But we learned enough to be more successful in the Fall. A “sun-to-orbitplane-angle” means PCsat’s orbit is now over the day/night terminator meaning it is in full sun (no eclipses) with solar power coming in on the (weaker) side panels and little if any on the +Z face(best panel). Attitude is maintained by alignment with the Earth’s magnetic field. It’s the best time for a recovery (no eclipses to cause a reset), but the worst time for commanding. It is too weak to respond to the needed logon and 3 additional commands. Though it will be strong again as the sun angle improves (lower). Then it will have better sun on the +Z face for commanding, but then it will be doing Eclipses. And even though we can then command it to turn off unnecessary loads, it does not have enough time before the next eclipse to charge up enough to survive the next eclipse. What we did (re)learn is a condensed command method where we can put all 3 PCSAT low-power commands in a single packet (using the TNC’s ^V pass character). That way, we only need a successful logon to complete the Restoration. 1) The CONNECT ACK. 2) The password challenge, 3) Then the command prompt. Then we can hit it with the full low-power command set and disconnect all in one packet which cancels the need for PCSAT to respond to each command separately. On the FIRST day available in full sun(our best shot), I not only got logged on, but completed all 3 requried functions. Then signals sounded so good, I got greedy and put in the another three (which also improves power budget, but not as much as the first three). Yep, I gambled and lost. It died on the last one! The next day I got all 3 in, and it died on the 3rdcommand due to a user packet I think. Days since, I have been unable to logon. Hence, end of this attempt period. In most attempts in the past (after successful logon) we would send one command at a time to give it a few seconds rest between each one. But these 3 commands then required 3 ACKS and 3 RESPONSES in addition to the 3 required to get logged. Those extra 6 packets kill it, especially if there was a user packet in there. Next time all we need are the 3 loggon responses. Also, next time, we will give users advance warning to QRT all transmissions when we are trying to command. Each one of their packets robs us of power we need to complete the command. I failed to warn everyone this time, and so we had some interference. As sun angle improves, You may continue to experiment with PCSAT during MIDDAY passes. That is when it is strongest (in the Northern Hemisphere), but do limit yourself to only attended operations so humans can actually contact humans, or if you are doing an unattended test, keep your transmissions to once every 2 minutes. That should let you get one good successful packet per pass. Which is the mission of PCSAT. See the downlink on http://pcsat.aprs.org There you can see the telemetry packets (list at the bottom of page) right now are rarely getting above 001 meaning typically a minute or so of life before it gets overloaded and resets back to 000. It is easy to visualize the relationship of the sun angle to the orbit plane and to see how that affects power budget given that our best panel (out of 5) is on the +Z face and that is magnetically aligned to point towards magnetic South. There is NO panel on the –Z which is why PCsat is rarely usable in the Southern Hemisphere (not planned, but just a result of it crashing in every eclipse). Just thought you would like to know what is going on with one of the oldest student projects in space that is still “semi-operational” for users. Bob, Wb4APR US Naval Academy Satellite Lab *From:* Robert Bruninga [mailto:bruni...@usna.edu] *Sent:* Thursday, January 31, 2013 10:53 AM *To:* amsat-bb@amsat.org *Cc:* aprs...@tapr.org; a...@yahoogroups.com; bruni...@usna.edu *Subject:* QRT all PCSAT transmissions! Please QRT all transmissions to PCsat to save power for COMMANDing. PCSAT (W3ADO-1) is entering its 3 day RECOVERY window this year starting 31 Jan. Today we got logged on for commanding twice, but both times user packets killed the bird. At best PCSAT can usually only save up enough power for 2 or 3 solid packets per pass and we need 3 successfully for command and recover. One user packet in the middle of that and we lose it for the pass. MY fault for not making this announcement earlier. Not their fault. But if you see this email and you are
[amsat-bb] PCSAT batteries!
>,what kind of battery is install on this kind of satellite? > how does it react in the cold space where it is? We placed the batteries in the middle of the satellite. It is quite immune to the +90C and -100C possible fluctuations on (unattached) solar panels (if they were not attached to the sides of the satellite). Since the solar panels are attached to the aluminum frame and the satellite rotates at about 1 RPM, we don't see any temperature variations even on the panels of more than about 10C (per orbit). And then these 10C fluctuations on the sides only penetrate to about a +/- 1 degree variation at the batteries per orbit and per day. Though there is a long term variation with the Sun/Orbit beta angle. The average temperature of PCsat is around 10C, getting as low as 0C during full eclipse seasons (High Beta angles) and as high as 40C for a weak or so when it is in full sun. This cycle moves over a 2 month or so cycle. Right now, PCsat inside is a nice comfortable 25C. Our problems with PCSAT (now 12 years old) is our own fatal flaw of designing it with a reboot-after-fault-detection mode of turning on backup transmitters and backup receivers to regain contact with the command station. Now with 20/20 hindsight, that was dumb... especially if the reason it faulted is due to low power! We can get in and turn off the extra XMTRS and RCVRS any time we want during high beta angles (maximum peak solar power available), but then there is only 15 minutes left before it goes back into eclipse and dies (not enough ttime to charge each orbit). But then 2 or 3 times a year, it enters full sun periods when, if we can get the command in, then we can send those commands to turn off all the spares and they will hold... BUT this time of full sun, is also the time of the worst sun angle (least average power), and so it is iffy if we can get the command in. See http://pcsat.aprs.org (raw packets at the bottom) and you will see that today's attempt resulted in achieving 9 minutes of operation before it died. See the telemetery serial numbers starting at 001 each time it resets. That occurred at 2013-02-02-14:29:24z Hope that helps Bob, Wb4aPR -Original Message- From: a...@yahoogroups.com [mailto:a...@yahoogroups.com] On Behalf Of Gervais Fillion Sent: Saturday, February 02, 2013 9:53 AM To: a...@yahoogroups.com Subject: RE: [APRS] QRT all PCSAT transmissions! Hi Bob,what kind of battery is install on this kind of satellite?i wonder how it react in the cold space where it is?Do you have any data that gave the temperature upthere?i am just curious,here in the Eastern part of Quebec we are used to have in the -20 celciusand battery are built for that,,how it is in space?? 73 Bob Thanks for all the info you are tellng us. Gervaisve2cknLe Bic,Quebec www.michelebard.com4823.73N/06839.65W To: a...@yahoogroups.com From: wb4...@amsat.org Date: Sat, 2 Feb 2013 08:20:00 -0500 Subject: RE: [APRS] QRT all PCSAT transmissions! > Question: PCSAT,does it transmit at 144.390 like other APRS hardware ? No and yes. It operates up and down on 145.825 like all other APRS satellites. But it also has a backup transmitter on 144.39 which we can use as a national broadcast downlink. Problem is, most people cannot hear it due to local QRM on 144.39... but it is there. If you live in the boonies and there is no other local traffic, sometimes you can pick it up. But there is no UPLINK there for obvious reasons. Even in congested areas, sometimes you can receive it on 144.39 if there is a moment of silence when it transmits. In fact, it was that clever idea that kills PCSAT on every orbit. The old batteries do not have enough power to power both XMTRS at the same time which is what it is trying to do. We can send the command to turn off the other XMTR, but then on the next eclipse, it resets back to BOTH ON. Darn... Bob, WB4APR [Non-text portions of this message have been removed] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/APRS/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/APRS/join (Yahoo! ID required) <*> To change settings via email: aprs-dig...@yahoogroups.com aprs-fullfeatu...@yahoogroups.com <*> To unsubscribe from this group, send an email to: aprs-unsubscr...@yahoogroups.com <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/ ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: New poll... (PSK31 xponder)
> Instead of asking what do we "want", maybe a more useful poll might be > "what can you build us?" >> Wel that is easy too, you can grab a off the shelf cubesat... >> and put a pe1ruh space proven linear transponder in it. Amen. Also there are TWO flight ready PSK-31 uplink with FM downlink transponders also ready to fly built By Mirek at Brno University. Ideal for a Cubesat. They allow up to 20 or more simultaneous PSK-31 users on a 28 MHz uplink to all appear full duplex in the 435 MHz FM downlink that anyone can receive on any FH HT. Run PSK31 software and see all the conversations and transmit all 8 minutes of the pass and join the fun talking to everyone at once.. All the advantages of linear transponders (20 simultaneous users) and all the advantages of FM (simple 5 Khz Doppler tuning using any old FM radio). And it fits on a 3" square card. See details: http://aprs.org/psk31uplink2.html All we need is someone to fly it. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: New poll for new OSCAR
That is easy!. The answer is of course ALL OF THE ABOVE. The hard part is what can get built by whom. And who is in the best position to FUND it and get it launched. And then all the polls in the world mean nothing against what -that-person or entity wants or needs. And that is what drives what we "get". Instead of asking what do we "want", maybe a more useful poll might be "what can you build us?" Just an aside. Bob, Wb4APR -Original Message- > If you want a new satellite/OSCAR wich payload/communication mode should it have? > >o Telemetry Beacon >o Packet Radio Mailbox/Digipeater >o FM Repeater >o Linear Transponder >o Educational payload >o Other payload/mode ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] QRT all PCSAT transmissions!
Please QRT all transmissions to PCsat to save power for COMMANDing. PCSAT (W3ADO-1) is entering its 3 day RECOVERY window this year starting 31 Jan. Today we got logged on for commanding twice, but both times user packets killed the bird. At best PCSAT can usually only save up enough power for 2 or 3 solid packets per pass and we need 3 successfully for command and recover. One user packet in the middle of that and we lose it for the pass. MY fault for not making this announcement earlier. Not their fault. But if you see this email and you are transmitting to PCsat, please QRT for the next several days. Commanding is being done from the East and West coast of the USA and over Germany. WB4APR, Bob USNA Command Station ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Limited capabilities now on www.amsat.org
> Please let me know what you miss the most (via amsat-bb or directly) and I will attempt move it higher on the priority list. This week (thursday) I have about 30 students doing the one-day satellite tracking lab. The lab document calls for them to look at their "selected" satellite on the AMSAT SATS page and read about the satellite. So if those links could possibly be active by first period Thursday that would be GREAT! But do not use your last silver bullet. Researching the background on a satellite is not the primary focus of this lab, but just tracking it and turning a receiver to hear it is the main thing, and we do not need the AMSAT web page for that primary purpose. But the subtle nudging them to refer to the AMSAT web page is to get it in the back of their heads as a resource. So, if you can activate those links, that would help. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Bleebsats wanted
Help me delete the dead satellites. Help me add new Bleepsats. We use this list in our Comms Labs for students to try to tune in: * marks the operational ones from http://oscar.dcarr.org/index.php ? marks the unknown and need input from you. * 07530 AO7 145.950 ? 20442 LO19 Carrier? - 22825 AO27 dead * 24278 FO29 435.795 * 25544 ISS145.825 * 26931 NO44 PCsat 145.825 semi * 27607 SO50 436.795 ? 27845 Quakesat 436.675 * 27848 CO57 XIIV 436.848 * 27844 CO55 cute1 436.836 ? 27939 RS22 435.352 * 28650 VO-52 145.86 Bcon * 28895 CO58 XI-V 437.465 ? 29655 Genesat-1 437.075 * 32791 CO66SEEDS 437.485 ? 32953 RS-30 435.215 ? 33499 KKS-1437.385 ? 33493 PRISM437.250 * 32785 CO65cute17 437.275 * 32789 CO-64 D-C3 145.87 ? 32791 SO-66437.485 ? 33498 Stars437.305 ? 35870 Sumbandila 435.345 ? 35932 SwissCube 437.505 ? 35933 Beesat 436.000 ? 35934 UWE-2 437.385 * 35935 ITUpSAT1 437.325 19.2 Kbps * 36121 HO-68 435.790 ? 37224 Oreos 437.305 ? 37225 FASTsat ? 37226 Falconsat5 437.270 dead? ? 37839 JUGNU437.275 ? 37841 SRMSAT 437.425 ? 37853 RAX2 437.345 ? 37854 Aubiesat70 437.475 ? 37855 M-CUBED 437.485 ? 90021 Rax 437.505 ? 90025 Fastrack 1 437.345 ? 90025 Fastrack 2 145.825 Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Packet Contact
> where is the contact? > that just shows that both were able to copy each other. But they exchanged a QSL and both got the original exchange info from each other. On a shared single channel resource, we should be concerned with contact efficiency. This takes 16 packets for 8x8 or a total of 64 confirmed contacts. 2N for N*N contacts Compared to 256 packets for 64 confirmed contacts the analog way (4*N*N) Or compared to the impossible 2560 retries trying to do it via the ISS BBS! >> [an] aprs style contact it is usualy done like this: >> station A sends a CQ beacon with his exchange info >> station B sends a CQ beacon with his exchange info >> station B sends a bulletin message with all the calls he has >> recieved so far in the pass. Station A sends a bulletin with >> all the calls he has recieved so far in the pass. if station A is in >> the list of station B and Station B is in the list of station A, >> I would say it is a confirmed contact. >> >> in most places there are igates that will send the pass to the APRS >> internet stream and you can check back on aprs.fi or findu.com Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] TH-D72 APRS HT's
For any AMSAT folks have TH-D72’s: We are looking for as many D72 owners that live within a few hours of Mammoth Cave, KY to join in a significant cave-radio experiment on 2-3 March 2013 to demonstrate VHF/UHF cave radio “texting” and status reporting. The D72’s can automatically relay position and text data up to 7 or 14 hops from radio to radio. We want to see how well this technique can be used in caves. See http://aprs.org/cave-link.html The date corresponds to the annual Cave City hamfest and is a good excuse to come play. We have the support of the National Park service to conduct this first ever cave-radio-relay experiment. Contact me to volunteer wb4...@amsat.org Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] ISS Tracking info on your APRS Radio
KJ4ERJ's satserver will send you live tracking data to your APRS radio anywhere, anytime. Just send an APRS message to ISS from any APRS radio (on the national APRS channel) and if you are in range of the global APRS network (an IGate nearby), then it will respond with the time to AOS and the direction of AOS, max elevation and LOS. This also works for all satellites. For example, send a message to FO29 and get its prediciton for your location. (Of course, you have to have sent your current APRS position if it is different from when you last used that radio and callsign). You can see the types of responses as collected by APRS.FI messages page: http://aprs.fi/?c=message&limit=25&call=ISS So, if you find yourself outdoors in the mobile, with nothing to do while the wife is in the mall, just send the above message and see if anything is coming up soon. Of course, to actually work APRS via ISS, you will have to QSY to the ISS channel 145.825 and change your path to via ARISS for the pass (*instead of the usual WIDE2-2 for terrestrial APRS) For a full dscription, see: http://aprsisce.wikidot.com/doc:satsrv When I send a query, I like to use the text "pass?" this is so that others seeing the message will know what you are tyring to do. The text of the message can be anything actually... THink of APRS as your ham radio smartphone... access to data anywhere, anytime. Bob, WB4APR * Note, that the ISS will ALSO digipeat the WIDE2-2 path, but it will not insert its RS4ISS* callsign in the path for proof that you were digipeated via the ISS. So it will "work" without changing from the standard WIDE2-2 path, but you will have no proof. Also, as soon as you use that radio even a few minutes later back on the national APRS channel, the sucessfull packet via ISS will be overwritten by the next terrestrial packet in most APRS Web interfaces. SO if you want to make an APRS contact via ISS and preserve it, you should use a unique callsign SSID only for your satellite operations. Good luck. Bob Bob ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: APRS Balloon antenna tracking
And where on the planet might this "local" event be? A balloon can have a range of 400 miles or so. Lots of us can watch if we know what part of the planet this might be in... -Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of David Julian Sent: Monday, October 22, 2012 7:59 PM To: amsat-bb@amsat.org Subject: [amsat-bb] APRS Balloon antenna tracking A local University is going to do a balloon launch and release a paper airplane this Saturday. they will have APRS on both the balloon and airplane with the goal to find both when they land. I won't be able to join the chase but just for fun I would like to use my satellite antenna array to track them. Is anyone aware of a program that will steer the antenna's based on received APRS data? I am using an LVB tracker and Yaesu 5400 setup and have SATPC32 and Nova for windows if there is some sort of an interface program. Thanks//Dave WB9YIG ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] APRS for JOTA, Everywhere!
Use your APRS radio for global contacts at your JOTA station. You can use your APRS radio or HT to text message a CQ to all other JOTA stations with an APRS radio anywhere in the world. You need to remember nothing about the network, or paths, or freqs or do any set up. Just use the normal APRS frequency. Just send an APRS message to ANSRVR and make the first two words of the message be CQ JOTA . Your message will be delivered instantly to every other JOTA station in the world * that has also sent a similar ANSRVR message*. Example: Message to ANSRVR: CQ JOTA fm Four Rivers Dist, MD This Logs you into the ANSRVR which forwards the message to every other similar station instantly. NOTE. This is just a way of calling a global CQ. You should answer any incoming such message with a direct response to the CALLSIGN of the sending station, not to ANSRVR. ANSRVR is a group ANOUNCEMENT SERVER that lets you see the callsigns of everyone else that is playing. After you see the callsigns, from then on, you use normal one-on-one messages with that station to complete the contact. ANSRVR replaces the original CQSRVR because CQSRVR ignores stations using tactical callsigns and therefor impractical for general use where some stations may have tactical calls. See details on http://aprs.org/ansrvr.html Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: OH2AUE P3E transponder demo video
Wow, a narrow self centric view of the world: > a huge trend to build more and more of these shoe boxes.. > ... most of them are almost useless... > What kind of science is it,... > The wheels are re-invented again and again... > For us AMSAT'ers.. this is something we did almost 30 years ago > This is history and nothing like science anymore... Please do not speak for me. Obviously the writer above has no clue what education is all about. Guess what! Every single year, the teacher has to start EXACTLY back at square ZERO. That is what EDUCATION is all about. Teaching each new year of students the same thing over and over and over. Its not fun... but it is challenging... Now I do not defend all repeats of stupid ideas and other mistakes, but education is a repeating process every year by definition. Now, if you want a different satellite built , THEN BUILD IT. It does no credit to lambast at least those that are DOING SOMETHING... even if it is not what you want, then either build what you want, and launch it, or get out of the way I have not been following this thread at all. So if my comments are inappropriate, I apologize. But some people have no clue what it takes to educate a completely new class starting over every year. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: [APRS] Re: Red Bull Stratos Balloon
>> Does Anyone know what the APRS tracking ID for the Red Bull Stratos Balloon > Track STRTOS and STRTOS-11 I was surprised that no one else was inputting objects, so I fired up my old 486 laptop which has not been used in years and initially enetered the STRTOS object. Then killed it to change to STRTOS-11 which would be more recognizable as a balloon. Then made some bad entries with the PC clock being off, then had the time zone off. Then accidentallly entered two posits with a capital Z instead of "z" and APRS.FI ignored those. Finally got it all OK. Entered another object JUMPD using the HUMAN symbol when he jumped and gave it a CSE of 180 and 729 MPH. But when he got to the ground, I changed the velocity of both to 0 so they would stay put on the map.. Remember, APRS was made to track ANYTHING and distribute that info to everyone. Does not need GPS. It just takes someone to enter the object. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Skydiving Mission in Progress Now
> the record breaking skydive mission is currently in > progress. tune to: http://www.redbullstratos.com Also tracking an object on APRS called STRTOS-11. See http://aprs.fi/strtos-11 ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Ideal AMSAT FM Transponder
> I presume the reason for UHF downlink rather than > 145 MHz, with it's lower Doppler shift, is due to > other mission constraints ? Yes, avoid QRM to the 145.825 APRS transponder. > BTW is the uplink in the amateur satellite segment > of 10m (29.3-29.5) or down at the bottom of the band ? Bottom segement. Think of it as a UHF linked band monitor for existing PSK31 operation on 10m usually between 28.120 and 28.123 MHz. The entire band is authorized by the ITU for satcom, though most band plans protect downlinks above 29.3 MHz. > This might also be a great project for balloon launches... > to be able to test all the ground station setups. > Any idea if these transponders will be made available > to others after this project is completed ? It will be up to Brno University and Mirek.. > It appears that the Small Wonder Labs' PSK device > is no longer available, pending a replacement that's in the works. Yes, we used a Brno module for the first flight back in 2006 on PCSAT2 but then used a Small Wonder Labs PSK transceiver on the RAFT satellite in 2007. The #1 hardest thing on making this system work, is getting the antenna tuned and resonant. This is a real challenge, because you cannot get inside the 4" cubesat with any instrumentation to tune for resonance. ANYTHING you connect to the spacecraft and antennas completely messes up the affect of the counterpoise. The best method we have found is to just build the transponder, and then tweak a tuning element via a hole in the spacecraft until you can hear the best signal from the transponder listening to normal signals on 10m. Oh, and having the whole set up FAR away from the ground and ANYTHING else... It is a long and tedioius process. We just did a preliminary EZNEC analysis, and the antenna impedance is something like Z = 2 - J1100 using a 6 foot wire. Bob, WB4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Ideal AMSAT FM Transponder
The ideal AMSAT FM transponder for a cubesat is the PSK-31 transponder being developed for the Naval Academy PSAT mission. With an FM downlink, anyone can receive it with an HT and a laptop with PSK-31 software. And anyone with a 10m PSK-31 uplink can transmit to it. The reason it is ideal is that it is a multi-user transponder supporting up to 30 users at the same time. Everyone can transmit horizon-to-horizon and see everyone else. A big QSO party in the sky: http://aprs.org/psat/PSK31-DESIGN-NOTES.html And since it is FM, Everyone tuned into the downlink SEES THE SAME WATERFALL and sees EXACTLY where they are in the downlink. A small uplink doppler adjustment can keep each station locked to his chosen channel in the passband. Everyone can talk to everyone if they want, or go one-on-one too. The SSB uplink and UHF downlink transponder fits on a smaller than 3"x3" circuit board being developed by Mirek Kasal at Brno University. If we could just get more Cubeats to fly these things, we would have all the joys of multi-user transponders, and yet they fit well in any cubesat. The ONLY problem is the HF wire antenna. Ours is going to be a 4 or 6' whip of Nitinol Wire. In addition to thes PSK-31 transponder, PSAT also supports the usual APRS AX.25 transponder on 145.825 too. Launch is planned for Summer 2013. Bob, WB4aPR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Chasing NWS Balloons with APRS
Although there are a few APRS type Balloon launches every few months to serve as educational tools and short-duration small-satellite simulations, there is often not one available when you happen to need to show some students a class. Now, a Ham in Brazil has written a sound-card decoder for the DAILY National Weather Serice balloons that then takes the balloon data (the fancy ones with GPS) and converts the downlink into APRS format on the ground and then you can feed that into any APRS system or the global APRS internet feed and track these balloons just as if they were APRS balloons. Since they are throw-aways by the NWS, they are fun to go chase and try to find. The ham just told me about this, and I encouraged him to package it up, since it has excellent educational value. When he has it all together and posted on line, Ill let everyont know. This sounds like more fun.. Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
