Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/23/13 10:48 PM, DaveH wrote: Something a bit similar was first published by Nick Hood in 2007. Here is a copy: http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p056. shtml Here is Nick's website: http://cullaloe.com/ Some people use marshmallows. Dave the only

Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/24/13 10:08 AM, Chris Albertson wrote: Using only "moderately" accurate equipment, like mechanical clocks and meter sticks Albert Michelson has able to measure the speed of light and determine it was a constant in all directions. It was this work the prompted Albert Einstein to think about

Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/24/13 5:21 AM, Brian Alsop wrote: The time issue was effectively eliminated by the Michaelson-Morley interferometer. One used a monochromatic light and an array of mirrors which split the light in opposite directions around the track. The two beams were recombined and an interference patte

Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/24/13 2:26 PM, Chris Albertson wrote: On Mon, Jun 24, 2013 at 1:55 PM, Jim Lux wrote: On 6/24/13 10:08 AM, Chris Albertson wrote: Isn't that the Fizeau technique, which antedates Michelson's? Michelson got the precision good enough that it finally put the question to

Re: [time-nuts] tube GPS receivers

On 6/24/13 3:01 PM, Bob Camp wrote: Hi I'm not so sure that "slow" would work. With all the sat's moving various directions all the time, I suspect you need to do a solution fairly quickly. If you don't the stale data messes up the solution. Also you need the correlators to work fast enough t

Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/24/13 4:16 PM, jmfranke wrote: The tuning fork was used with a clock. The clock was checked against astronomical measurements. http://www.schoolphysics.co.uk/age16-19/Wave%20properties/Wave%20properties/text/Speed_of%20light/index.html http://www.nhn.ou.edu/~johnson/Education/Juniorlab/C_

Re: [time-nuts] Measuring speed of light or reproducing a metre

On 6/24/13 6:48 PM, Tom Miller wrote: I wonder what the actual distance is using current GPS survey processes? Tom SLightly different, because there are some faults running across there and there have been some earthquakes with displacement. ___

Re: [time-nuts] Regulator choices

On 6/30/13 7:43 AM, Charles P. Steinmetz wrote: A three-terminal regulator (3TR) comprises (i) a voltage reference, (ii) an error amp, and (iii) a current amplifier. There is no need to duplicate the voltage reference or the error amp just because you need more current. In fact, they can only l

Re: [time-nuts] Regulator choices

On 6/30/13 8:48 AM, Brian Alsop wrote: Maybe I read the original posting wrong but I think this thread has departed greatly from the original posting. What I thought the posting said: 1) The already present transformer can produce ~20 V DC unregulated at sufficient current. 2) The desire was to

Re: [time-nuts] Regulator choices

On 6/30/13 12:35 PM, Bob Stewart wrote: "I believe the original problem was that the raw unregulated voltage may be marginally too high for a conventional three-terminal to take safely" Hi Ed, Not really. The voltage is in line with the product specs for a 7812 (35V max), as is the current I

[time-nuts] Smithsonian Time/Nav Exhibit

I had a chance to go through the Time and Navigation exhibit at the National Air and Space Museum last week. From a "time" standpoint, there's probably not much there that time-nuts don't know already, but it's kind of cool to see cleaned up examples of equipment from days gone by. (there's an

Re: [time-nuts] The "auction site"?

On 7/2/13 7:41 AM, J. Forster wrote: A few years back, some Group Owners, especially of ham lists, outlawed the mention of eBay, because the concept of selling something to the highest bidder somehow offended 'the ham ethic' that stuff should go to the 'most needy or deserving' as measured by som

Re: [time-nuts] High Accuracy Averaging Was: Speaking of Costas loops

On 7/3/13 6:58 AM, Bob Camp wrote: Hi Since the LEA6-T will do conventional RINEX dumps, I suspect that all they are doing is very long averaging on the data. I doubt the LEA6-T is the magic part of the setup. or sending the RINEX files to JPL for processing...If you don't need real time d

Re: [time-nuts] Speaking of Costas loops

On 7/3/13 12:42 PM, Azelio Boriani wrote: Sure about the "bent pipe"? If so it seems that much power is required at the transmitting ground station... Much "equivalent" power is required. If you have a 20 meter or so antenna, it doesn't take much to get a pretty high EIRP.

Re: [time-nuts] Speaking of Costas loops

On 7/3/13 2:21 PM, Dennis Ferguson wrote: On 3 Jul, 2013, at 11:47 , Bob Camp wrote: The pipe in this case is up on one frequency and down on another. The conversion oscillator on satellite that's the weak link, no matter how good the signal from the ground happens to be. That's certainly

Re: [time-nuts] Speaking of Costas loops

On 7/4/13 7:33 AM, Didier Juges wrote: That works well for transponders with o LY one signal. On commercial satellites, each transponder is shared among multiple signals, so that would not work. Ah, yes.. if it's a linear transponder/translator.. ___

Re: [time-nuts] Speaking of Costas loops

On 7/5/13 8:44 AM, Bob Stewart wrote: Wouldn't a Cs or Rb clock in orbit be slow due to relativistic effects? I'm pretty sure there is a relativistic correction to the GPS clocks. Bob - AE6RV I believe that the original WAAS repurposed transponders intended for other L-band satellite sign

Re: [time-nuts] Speaking of Costas loops

On 7/5/13 11:37 AM, Attila Kinali wrote: On Fri, 5 Jul 2013 12:14:20 -0400 Bob Camp wrote: Indeed the atomic clocks on sats are set up so they can "tune" far enough to take out the relativistic effects. That (and a bunch of other things) makes them somewhat more expensive than their ground bas

[time-nuts] WAAS/Inmarsat-3

An ION paper by Nagle, et al. Nagle, J. R., Van Dierendonck, A. J., Hua, Q. D., "INMARSAT-3 NAVIGATION SIGNAL C/A CODE SELECTION AND INTERFERENCE ANALYSIS", NAVIGATION, Journal of The Institute of Navigation, Vol. 39, No. 4, Winter 1992-1993, pp. 445-462. Inmarsat-3, the next generation of

Re: [time-nuts] Speaking of Costas loops (WAAS)

On 7/6/13 8:10 AM, jmfranke wrote: http://www.navipedia.net/index.php/WAAS_Signal_Structure Doppler Shift: The Doppler shift, as perceived by a stationary user, on the signal broadcast by WAAS GEOs is less than 40 meters per second (?210 Hz at L1) in the worst case (at the end of life of the GEO

Re: [time-nuts] Speaking of Costas loops (WAAS)

On 7/6/13 7:50 AM, Joseph Gwinn wrote: Re: time-nuts Digest, Vol 108, Issue 29 On Fri, 05 Jul 2013 19:55:42 -0400, time-nuts-requ...@febo.com wrote: OK. Given that the birds WAAS uses were built for communications purposes, not timing purposes, I'g guess that their frequency reference is a ve

Re: [time-nuts] Speaking of Costas loops (WAAS)

On 7/6/13 9:29 AM, Joseph Gwinn wrote: Code/Carrier Frequency Coherence: The lack of coherence between the broadcast carrier phase and the code phase shall be limited. The short term (<10sec) fractional frequency difference between the code phase rate and the carrier frequency shall be less than

Re: [time-nuts] HP 5370B dropping mains voltage

On 7/6/13 2:39 PM, Mark C. Stephens wrote: How Does that Work Robert? I mean why out of phase? Then the voltage on the secondary of the buck transformer is subtracted from the line voltage. This is a very common thing commercially where you have what's called a "buck/boost" transformer to a

Re: [time-nuts] HP 5370B Leds pulsing slowly, buttons selecting normally, PB LEDS scannning and appears to be reading o/k

On 7/6/13 2:46 PM, Mark C. Stephens wrote: Hopefully HP Voltage "Derated" the Cap as well so it can handle our 250V here.. We are across the road from the main transformer for the area so the voltage is highest at our place, I checked the meter box this morning - it is 255-258V on all 3 phases,

Re: [time-nuts] HP 5370B dropping mains voltage...

On 7/6/13 5:26 PM, Mark C. Stephens wrote: The elephant in the room thing with me is SAFETY :) I mean, can this be a fire hazard, what about the insulation breakdown on the secondary winding etc.. Most transformers have a voltage rating on ALL windings that is greater than several times the

Re: [time-nuts] Speaking of Costas loops (WAAS)

On 7/6/13 7:23 PM, Bob Camp wrote: Hi Ok, lets *assume* there is some uber secret gizmo in the sat that makes the unsupervised signal absolutely perfect when transmitted from the sat. The sat still moves relative to the ground. It's speed is a vector in three dimensions (up / down , north / s

Re: [time-nuts] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?

On 7/8/13 7:55 AM, Ed Palmer wrote: In 2002, this document: THE CRYSTAL OSCILLATOR CHARACTERIZATION FACILITY AT THE AEROSPACE CORPORATION http://www.pttimeeting.org/archivemeetings/2002papers/paper32.pdf stated: "The Programmed Test Sources, Inc. PTS model #250M6NIGSX-51 low-noise frequency sy

Re: [time-nuts] The word, "Radiation" as a boogieman...

On 7/9/13 7:01 AM, Burt I. Weiner wrote: John, Unfortunately, there's a lot of money in fear. Being in broadcast engineering I learned as long time ago to never use the words, "radiation" or "radiate" a signal when referring to a station's signal. Instead, I refer to it as, "Launch" or "Launche

Re: [time-nuts] time-nuts Digest, Vol 108, Issue 55

On 7/10/13 2:15 PM, Max Robinson wrote: I think that luminous dial watches still contain a little tritium to keep them glowing for many hours after the atoms that were excited by visible photons have all decayed. Without the tritium the glow would completely go dark after most of the atoms have

Re: [time-nuts] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?

On 7/10/13 12:29 PM, Didier Juges wrote: Jim said: "It's like a HP 8663B (not the modern Agilent E8663).. very low noise," The Agilent E8663 has similar SSB phase noise spec as the older HP 8662A (-144dBc/Hz @ 10 kHz with option UNY, versus -143 for the 8662). You seem to imply they are differe

Re: [time-nuts] Very stable synthesizer, alternative to PTS(Programmed Test Sources) x10 or 040?

On 7/11/13 12:45 AM, Stefan Heinzmann wrote: Jim Lux wrote: On 7/10/13 12:29 PM, Didier Juges wrote: Jim said: Now you're confusing me. As far as I am aware, there was the 8663A which appeared in the early eighties. And much later came the E8663B, and subsequently the E8663D. I

Re: [time-nuts] Speaking of Costas loops (WAAS)

On 7/11/13 3:36 AM, Bob Camp wrote: Hi The pseudo random spreading / looks like noise / buried signal thing is the most common way people piggyback low level signals on a bent pipe. Assuming that the bent pipe isn't running saturated, which I'm not sure is a valid assumption. Running TWTAs

[time-nuts] GPS 18 behavior

I don't have a GPS-18 in front of me, and I'm modifying some software remotely, and I ran across an issue that someone on this list probably knows off the top of their head. Does the GPS-18 put out 1pps pulses even if it hasn't got a fix yet? That is, when you apply power, does it just start p

Re: [time-nuts] GPS 18 behavior

On 7/21/13 7:15 AM, David McGaw wrote: The GPS-18 does NOT output 1PPS until it acquires lock. Then the 1PPS stays on even if lock is lost, running from the internal crystal. I have not checked, but once it reacquires lock I presume it jumps to the correct second. All outputs including 1PPS ar

Re: [time-nuts] GPS 18 behavior

On 7/21/13 6:59 AM, David J Taylor wrote: My own notes on the GPS-18 LVC are here: http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm You may be able to gather something about the electrical characteristics from that note - the device will happily feed to PC "RS-232" ports connected in parallel

Re: [time-nuts] GPS 18 behavior

On 7/21/13 9:28 AM, David J Taylor wrote: From: Jim Lux [] Oh, I didn't actually think it would be 10% off.. more like a few ppm, depending on temperature. I was wondering more what would happen if you were indoors for a couple days, then went back out, what the box does. realistically, I

Re: [time-nuts] GPS 18 behavior

On 7/21/13 1:35 PM, Tom Van Baak wrote: when I'm in a GPS denied environment, it's not just because we're indoors, it's because we're somewhere that GPS isn't available, so what I'm really doing is providing a sort of flywheel to keep my little modules synced with each other. I don't need super

Re: [time-nuts] GPS 18 behavior

On 7/21/13 6:42 PM, Chris Albertson wrote: I think the way to keep the sensors in sync is to use the same method they use to keep cell towers in sync. Basically each tower has a GPS receiver and also a good local oscillator. The GPS disciplines the oscillator and the timing is taken from that o

Re: [time-nuts] GPS 18 behavior

On 7/22/13 5:48 AM, Scott McGrath wrote: You might want to look at what these guys have done for 40 years or so. Www.geophysical.com ground penetrating radar doesn't work very well in the typical disaster rubble enviroment which has uneven surfaces and a lot of random scattering in the medium

Re: [time-nuts] GPS 18 behavior

On 7/22/13 10:39 AM, Scott McGrath wrote: Moles are a bit small it would probably work better for woodchucks. who are in the process of undermining all lawns in neighborhood now. In a more serious vein most ground penetrating radar is low frequency and I was not aware that THz waves could pen

Re: [time-nuts] GPS 18 behavior

On 7/23/13 4:51 AM, Scott McGrath wrote: Thanks Jim Was not aware that <10 Ghz signals could penetrate so deeply. I work for a enterprise wifi company on the RF side and one of our key challenges is signal attenuation/distortion by building materials Any pointers to papers on this? there's

Re: [time-nuts] GPS 18 behavior

On 7/22/13 6:30 AM, Tom Van Baak wrote: For what it's worth, the application is a radar that detects buried victims in disaster rubble, so the data we are collecting is basically heartbeats and breathing. the "when was the data taken" is a "where were we when the data was collected" need. The "

[time-nuts] distirbuted sync

Starting a new thread... Brian wrote: Have you considered WWVB? Works fine within structures. Even though the carrier today is phase modulated one can probably glean 1 ms accuracy from it or the data transmitted. -- disasters occur world wide, any time day or night, so depending on WWVB won'

Re: [time-nuts] distirbuted sync

On 7/23/13 9:15 AM, Chris Albertson wrote: I don't think those requirements are hard. You can build a system that works in three cases 1) GPS is available full time 2) GPS is available intermittently. 3) there is not GPS system, world war III has destroyed it. or you're in an urban canyon or

Re: [time-nuts] distirbuted sync

On 7/23/13 11:03 PM, Chris Albertson wrote: You can prototype a system with off the shelf parts get a few computers, old notebook computers, Raspburry "pI' or repurposed routers, what ever you have. Connect a Trimble Thunderbolt GPS to each one. Each one runs NTP. Connect them all to a isolate

Re: [time-nuts] RS 232

On 7/26/13 4:41 AM, briana wrote: Ever since WINxp arrived on the scene hams who send code via computer to radios via parallel, serial or usb ports (with serial port converters following) have seen the latency issue in spades. We're talking about effective baud rates less that 50. 3-4 millise

Re: [time-nuts] was RS-232,

On 7/26/13 8:46 AM, Brian Alsop wrote: Hi Jim, You mean to imply no commercial programs ever use "quick fixes"? heavens no.. Plenty of quick fixes.. It's difference between seat-of-the-pants field engineering and a theoretical pursuit. There are no humanitarian costs associated with failur

Re: [time-nuts] RS 232

On 7/26/13 12:50 PM, Didier Juges wrote: There is a difference between managing the latency (as in ensuring that sound and video are synchronized, but latency itself is acceptable) and minimizing the latency as in a Morse code keyer where the operator has to manually control the generation of

Re: [time-nuts] GPS Spoofing

On 7/26/13 8:45 PM, J. Forster wrote: I gather from the article, the GPS position was spoofed and the autopilot, in bringing it back to where it was supposed to be, actually took it off course. There are places where a few hundred feet makes a big difference, viz. the Costa Concordia. IMO, this

Re: [time-nuts] Story in the Economist about GPS jamming

Yes.. You put a gain antenna on the space craft, so for the same tx power, you get the same flux density on the ground. The gps height was chosen for a variety of reasons. It is out of the debris band, for one. There's also a tradeoffs on launch costs, etc. GPS world magazine had a great mu

Re: [time-nuts] Low cost GPS for model aircraft

Design so that when that module is no longer available, you've got pins and software switches to use something else. Lots of one off projects depend on something surplus or cheap, and rapidly become non-duplicate-able when the parts supply ends. On Aug 5, 2013, at 1:18, "M. Simon" wrote: >

Re: [time-nuts] NTP/1-PPS/RS232 question

On 8/20/13 8:20 AM, Brian Inglis wrote: On 2013-08-20 02:45, "Björn" wrote: b...@lysator.liu.se said: The PTTI 1PPS is defined in http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf It is 20us long and common in some applications. However the voltage levels are a bit high... The sectio

Re: [time-nuts] de Witte's Experiment

On 8/28/13 9:00 AM, Steven Kluck wrote: It might appear that the Torr-Kolen Experiment, which had similar results to de Witte, had similar temperature compensation and control problems. I think it would be interesting to run for a year with an east-west coax run, and a separate north-south coa

Re: [time-nuts] sub-minute time-precision in court-case

On 9/3/13 7:07 AM, Poul-Henning Kamp wrote: It is very rare to see courts deal with time precisions less than minutes, but it seems to have happened in this case: Interesting (and of course, this case has been in the news recently).. In this case, all the messages were presumably handled by

Re: [time-nuts] Synthesizers

On 9/2/13 7:50 PM, Bill Hawkins wrote: Why do we hardly ever talk about synthesizers - those boxes that turn 10 MHz into other frequencies? We do.. there's a fair amount of talk about boxes like the PTS synthesizers. And there's been talk about 866x series synths, and perhaps the 3325, alt

Re: [time-nuts] Jackson Labs' Web-Site

On 9/3/13 10:20 AM, Said Jackson wrote: Hi guys, Thanks for the heads up, all should be well now. The auto-renew did not work because we moved and they had an old CC address. Domains that expire stay locked for 36+ days to the old owner, so no risk there.. This brings up a good point, we have

Re: [time-nuts] sub-minute time-precision in court-case

On 9/3/13 11:21 AM, Poul-Henning Kamp wrote: In message <5225f8af.60...@earthlink.net>, Jim Lux writes: In this case, all the messages were presumably handled by the same carrier, so the issue of skew in timestamps is negligible; Anything but. The text-messages are likely stamped by t

Re: [time-nuts] sub-minute time-precision in court-case

On 9/3/13 2:47 PM, Tom Van Baak wrote: Nowhere does the opinion mention if the timestamps were taken on the same clock or if the two clocks were synchronized. PHK, Correct. This is an age-old problem, whether its minutes or nanoseconds. Time-stamps are inherently relative to a local oscillator

[time-nuts] GPS-18, Windows, NTP & Lat Lon

I'm looking for an easy way to get current lat lon, when you've got a GPS-18 hooked up for NTP. That is, the GPS receiver is there doing it's NTP thing, so presumably it knows where it is. If NTP is decoding the GPRMC message, it has the lat/lon in it, so how can I get that info out (in a co

Re: [time-nuts] GPS-18, Windows, NTP & Lat Lon

On 9/3/13 5:35 PM, Jim Lux wrote: I'm looking for an easy way to get current lat lon, when you've got a GPS-18 hooked up for NTP. That is, the GPS receiver is there doing it's NTP thing, so presumably it knows where it is. If NTP is decoding the GPRMC message, it has the lat/lo

Re: [time-nuts] GPS-18, Windows, NTP & Lat Lon

On 9/3/13 6:47 PM, brent evers wrote: Wouldn't turning off ntp drive it nuts? At the risk of throwing out the bone head answer and assuming this isn't going on your next space craft, you could just split the GPS serial (my quick google showed the 18 to be the serial unit vs usb) signal and run a

Re: [time-nuts] Synthesizers

On 9/3/13 7:14 PM, Pete Lancashire wrote: Ah the 8660's Image 22 8660A's in two racks, was an fun tax payer, paid project :-) We where never told what the master clock was. Have S/N suffix 0009 in the garage. For you time nuts, a side hobby should be frequency nuts. How to produce the cleane

Re: [time-nuts] sub-minute time-precision in court-case

On 9/3/13 10:11 PM, Sanjeev Gupta wrote: On Wed, Sep 4, 2013 at 6:19 AM, Tom Van Baak wrote: Does it help if we both have GPS? Both have cesium(s) in the back seat? Since the GPS "communicates over Radio Frequencies", please ensure it is capable of "hands-free" operation while you are opera

Re: [time-nuts] Raw GPS signal samples

On 9/2/13 7:21 PM, John Seamons wrote: Somewhat off-topic but it might help someone out: I've had a tough time finding, and using, files on the net containing raw GPS signal samples to be used with the various software-only (or software-mostly) GPS receivers out there. I finally got a file of

Re: [time-nuts] GPS-18, Windows, NTP & Lat Lon

On 9/4/13 7:35 AM, Didier Juges wrote: Jim, You should be able to piggyback a second serial port in parallel with the one used by NTP (just the Rx line and ground) and use any NMEA decoder. It does not even have to be the same computer. I have a quick NMEA decoder for Windows I wrote some time

Re: [time-nuts] Raw GPS signal samples

On 9/4/13 2:05 PM, Tom Van Baak wrote: Hi John, It's not off-topic at all. Thanks for posting. Someday it would be cool if an amateur precise time project emerged from this effort. What is not clear from your link is the accuracy or stability of the LO that was used. It seems to me, for timing

Re: [time-nuts] GPS outage?

On 9/6/13 4:00 AM, Bob Camp wrote: Hi A "truck jammer" isn't what you would use to take out a large area, you would need > 100,000 of that sort of jammer. Since the truckers that use them get fired, there's a limited number of them in use…. Considering they cost $30, and they're not that easy

Re: [time-nuts] GPS outage?

On 9/6/13 8:36 PM, John C. Westmoreland, P.E. wrote: Fellow Time Nuts: Is this a site to be trusted?: http://adn.agi.com/SatelliteOutageCalendar/SOFCalendar.aspx Regards, John W. AGI are the folks who make and sell STK (Satellite Took Kit, I believe) which has a dominant position in the ma

Re: [time-nuts] Lightning Strike Site

On 9/9/13 5:59 AM, J. Forster wrote: FYI: -John the underlying National Lightning Detection Network distributes the data with a timing precision of 1 microsecond RMS. I assume their sensors are GPS synchronized. The location is done by a co

Re: [time-nuts] GPS choices.

On 9/9/13 8:08 AM, Paul wrote: Although the inexpensive yet high sensitivity units are nice I'm not sure why someone would choose a positioning MTK (e.g. Adafruit) over a timing Ublox (or even an old Motorola style timing receiver). Sometimes, continuing availability is a bigger design driver.

Re: [time-nuts] Lightning Strike Site

On 9/9/13 8:36 AM, Bob Smither wrote: On 09/09/2013 07:59 AM, J. Forster wrote: FYI: Here is another one: http://www.strikestarus.com/ That uses an ad-hoc network of Boltek detectors, which work ok. I had one in 1999-2000 at work..

Re: [time-nuts] Lightning Strike Site

On 9/9/13 1:20 PM, Mark Sims wrote: A cute little lightning detector based upon the AS3935 lightning detector chip: http://www.embeddedadventures.com/as3935_lightning_sensor_module_mod-1016.html ___ time-nuts mai

Re: [time-nuts] Wavecrest DTS 2070

On 9/9/13 2:21 PM, Mark C. Stephens wrote: Is 200 amperes @ 2v not lethal? Not particularly.. any more than putting your fingers across a 1.5 or 3V battery is lethal. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://w

Re: [time-nuts] Wavecrest DTS 2070

On 9/9/13 2:38 PM, Mark C. Stephens wrote: I have seen a 12v car battery and a wire frame bed to torture victims on television twice now. Are you telling me that's bunk?! (pardon the pun) As someone who used to make their living doing just such physical effects for film and TV.. It's a spec

Re: [time-nuts] Lightning Strike Site (Jim Lux)

On 9/9/13 3:52 PM, Mark Sims wrote: The AS3935 has an INT output pin that signals a detection. You could monitor that. The AS3935 is based upon an internal DSP processing the receiver output. No telling how long between when the strike occurs and when INT is activated.

[time-nuts] Lightning detectors

On 9/9/13 4:08 PM, Jim Lux wrote: On 9/9/13 3:52 PM, Mark Sims wrote: The AS3935 has an INT output pin that signals a detection. You could In an interesting coincidence, Charles Wenzel (yes, that Wenzel) has a design for a lightning detector: http://www.techlib.com/electronics

Re: [time-nuts] 82357B GPIB USB from China

On 9/10/13 7:23 AM, J. L. Trantham wrote: There also appears to be a ton of 'genuine' Agilent 82357B's from China some selling for under $155 with free shipping (to US and UK). Quite the 'dump' of technology. I wonder if there is a USB 3.0 version coming out soon? more likely that most Agile

Re: [time-nuts] 82357B GPIB USB from China

On 9/10/13 8:36 AM, Gerhard Hoffmann wrote: Am 10.09.2013 16:23, schrieb J. L. Trantham: Quite the 'dump' of technology. I wonder if there is a USB 3.0 version coming out soon? What should that be good for? Using a 350MB/s port to transfer 1MB/s over the GPIB? But it looks ever so much coo

Re: [time-nuts] Example of clocks interlocking with each other

On 9/14/13 6:20 AM, Tim Shoppa wrote: The math I am familiar with, seems to have mostly developed around master-slave arrangements associated with radar pulses and (as you point out) TV. In the MIT Rad Lab series there are some single-purpose treatments but a good summary is Millman & Taub, "Puls

Re: [time-nuts] Example of clocks interlocking with each other

On 9/14/13 11:22 AM, Joe Leikhim wrote: Microwave injection locking of Magnetrons with beam steering phased array. Lots of math! http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDkQFjAD&url=http%3A%2F%2Fwww2.iee.or.jp%2Fver2%2Fhonbu%2F14-magazine%2Flog%2F2008%2F2008pdf-b%2F20

Re: [time-nuts] Example of clocks interlocking with each other

On 9/14/13 5:19 PM, Joe Leikhim wrote: Funny when I go to the links and read about the subject, time seems to slowww down "By the way, googling "microwave weed burner" to find this article turned up another application of microwave heating for a very different kind of weed." Oh wow..

Re: [time-nuts] Req: Decent GPS Antenna Active/PassiveRecommendation

On 9/15/13 2:27 AM, Anthony Stirk wrote: Hi John, I've found as long as the module has lock the level of timing isn't going to change so you can use anything really (heck we even us ceramic chip antennas on some boards). For outside use any active automotive patch should be fine but keep the lea

Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation

On 9/15/13 1:36 PM, Hal Murray wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can liv

Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation

On 9/15/13 4:33 PM, Bob Camp wrote: Hi All of the ones I've opened up or seen dis-assembled have had the ceramic plate antennas in them. That very much surprised me early on, since I *assumed* they had something fancy inside based on their shape. I don't know that the thermal expansion effect

Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation

On 9/15/13 10:24 PM, David J Taylor wrote: From: Bob Camp Hi All of the ones I've opened up or seen dis-assembled have had the ceramic plate antennas in them. That very much surprised me early on, since I *assumed* they had something fancy inside based on their shape. No argument about the fil

Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation

On 9/16/13 6:03 AM, David J Taylor wrote: I am thinking about exact time measurement - getting your PPS edge exactly on the nanosecond. People can add in the length of the cable as an offset, so they must also need to enter any delay through any filters, mustn't they? Agreed that for position

Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation

On 9/16/13 12:48 PM, Charles Steinmetz wrote: Jim wrote: Spectrum regulators know this, of course, and assign adjacent services accordingly. They do? Remember, it was the FCC that came up with the idea of using the Mobile Satellite Service L-band downlink spectrum for terrestrial broadband s

Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation

On 9/16/13 6:43 PM, John C. Westmoreland, P.E. wrote: Hello Everyone, While we're on the subject - not to get too far off on a tangent - I have been doing 'web-research' on this - but can someone recommend a great site or reference for the specifications of the GPS signaling sent down by a GPS s

Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation

On 9/16/13 9:13 AM, David J Taylor wrote: From: Jim Lux Of course they would factor all this in. That's why the UNAVCO site has all the phase center locations and delay behavior for the various antennas. === Didn't know about: http://www.ngs.noaa.gov/ANTCAL/

Re: [time-nuts] DIY Choke Ring Antennas?

On 9/16/13 6:51 PM, Bob Stewart wrote: With all the talk about choke rings, and having spent all my pennies elsewhere, I looked around to see if there were any do-it-yourself versions. I found this one: "http://www.mauve.gr/var/DIY_Choke_Ring_GPS_Antenna.htm";. Is it worth the effort, other

Re: [time-nuts] Space mission comes to an end because of a "computer time tagging" problem

On 9/21/13 2:30 AM, Rob Kimberley wrote: David, The satellite has probably got a Rb as its clock (hopefully more than one). Very, very few deep space probes carry a Rb ( I can't think of any off hand). Regular old quartz, usually some sort of tcxo. If they are doing radio science, then it

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/20/13 5:12 PM, Bob Camp wrote: Hi Low bid wrist watch used as time base? - I'd bet there is some form of master time tick in their RTOS that keeps everything pumping. Loose the time tick (or the time tick count) and it all goes away… yes and no. Most spa

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

from JPL http://www.jpl.nasa.gov/news/news.php?release=2013-275 "Mission controllers postulate that there was an anomaly generated by the spacecraft's software which left the vehicle's computers in a condition where they are continuously rebooting themselves. If this is the case, the computers

Re: [time-nuts] Space mission comes to an end because of a "computer time tagging" problem

On 9/21/13 5:41 AM, Bob Camp wrote: Hi I'd be a bit surprised if they were running anything as power hungry as an Rb all the time when a quartz based device would be smaller / lower power / lower volume. Of course they may have had mission requirements that drive them to a hydrogen maser ...

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/21/13 5:52 AM, Bob Camp wrote: Hi So it's a pretty good AT cut crystal without any compensation of heating. Not quite a cheap wrist watch, but not a BVA in a dewar flask either. Yep. The AuxOsc is what is used if you don't want to have the downlink locked to the uplink.

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/21/13 6:03 AM, Magnus Danielson wrote: On 09/21/2013 02:52 PM, Bob Camp wrote: Hi So it's a pretty good AT cut crystal without any compensation of heating. Not quite a cheap wrist watch, but not a BVA in a dewar flask either. The environmental perturbations should go quite slow most of t

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/21/13 6:40 PM, Hal Murray wrote: jim...@earthlink.net said: If it gets cold enough (without power from solar cells, it won't generate enough internal heat to keep warm), it will die. That's probably what happened to Spirit on Mars. It got cold enough during the Martian winter, and with

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/21/13 11:03 PM, Hal Murray wrote: albertson.ch...@gmail.com said: What stops working when things get cold? > On Mars, the solar cells are pointed in the right direction. Why doesn't it recover when the sun comes back in the Spring? They run out of power for running the battery heater

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

rame, or every N frames. The question is whether they have all the bits of sclk all the time, or just the LSBs all the time, and the MSBs occasionally. DI is a fairly old design, so the telemetry format probably isn't very complex (e.g. it's not like they have dynamically allocat

Re: [time-nuts] Space mission comes to an end becuase of a "computer time tagging" problem

On 9/22/13 4:48 PM, Mark Sims wrote: And my favorites: Nickel-Hyrdogen cells and their silvery cousins. You have to work REALLY hard to kill them. Yes, forgot the NiMH too.. although they self discharge --- for rechargeable? NiCd (in the past) Lithium Ion (now)

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