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
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
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
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
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
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
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
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
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
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
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
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,
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
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
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
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
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
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
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
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..
___
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
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.
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
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
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
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
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
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
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.
___
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_
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
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
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
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
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
On 6/23/13 2:50 PM, Paul Berger wrote:
Hi:
The SAGE computers, which I had the pleasure of seeing the last two
operating, had an all vacuum tube array of core that consisted of 33
planes of 64 x64 cores for about 16K worth of memory.
I was wondering about the Q7.. it was all vacuum tube, but I
On 6/23/13 10:47 AM, Chris Albertson wrote:
Magnetic cores were not invented until the 1950's and realy cam into use as
tubes were beibg replaced by SS. But there isnot reason yu can't build a
tube computer with core memory. I have actually seen and used a computer
that had one megabyte of cor
On 6/22/13 5:35 PM, Bob Camp wrote:
Hi
How stable a 1.023 oscillator? How much pull range on that oscillator? H…..
Doppler is the big component..several kHz..
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On 6/22/13 4:38 PM, Magnus Danielson wrote:
electromechanical.. like omega receivers. rotary transformers can do
very high quality trig functions, but do you actually need trig
functions assuming you're just solving for X,Y,Z,T.
Oh yes. Check IS-GPS-200F, clause 20.3.3.4.3 User Algorithm for
On 6/22/13 3:28 PM, Magnus Danielson wrote:
On 06/23/2013 12:04 AM, Jim Lux wrote:
I think that doing the PN code and correlator is something that could be
done with tubes (especially if you didn't want to go P-code).
I suppose you could use a counter to record the changes in code phase a
I think that doing the PN code and correlator is something that could be
done with tubes (especially if you didn't want to go P-code).
I suppose you could use a counter to record the changes in code phase as
you scan for the correlation peak, so that gets you your numeric code phase.
Getting
On 6/20/13 4:57 PM, Gary wrote:
A common scheme in metal deposition measurement is to measure the frequency of
a crystal prior to starting the deposition process, then monitoring the
frequency shift of the crystal as the metal is sputtered.
I was told crystals are tuned this way at the factory
On 6/17/13 10:39 AM, Poul-Henning Kamp wrote:
In message <51bf15a8.40...@earthlink.net>, Jim Lux writes:
The issue also arises with fluorescent [...]
As folks transitioned to the newer ballasts, the non-sinusoidal
current problem probably got worse.
I don't know about US, but
On 6/17/13 5:33 AM, Peter Gottlieb wrote:
The current distortion from simple transformer-rectifier-capacitor power
supplies contains a lot of third harmonic content. In a 3 phase system
(as are all distribution systems for commercial and industrial) the
third harmonic ADDS in the neutral, or cre
On 6/14/13 10:55 AM, DaveH wrote:
Most RTG sources use Plutonium 238 or Strontium 90. Primary decay component
is Alpha particles which can be stopped dead by a few mm of shielding.
Good article on Wikipedia:
http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
Dave
but not ALL
On 6/9/13 8:29 PM, Bill Hawkins wrote:
Hi, Thanks in advance.
Since this is a list for precise things, could you make your questions
more precise?
What sort of test cases?
What sort of calculations? Do you mean conversions?
What do you mean by "catching" an error - where would you c
And we received signals from it on ISS at 1400Z this morning (we've got
an experimental software defined receiver doing a 48 hour test right
now). Shiny, new satellite only a few weeks old: I guess it works. At
least we were able to lock. It's still being commissioned, so it's
presumably marke
On 6/2/13 12:52 PM, WB6BNQ wrote:
Hello Mark and crowd,
I own one of these and I can guarantee that it CANNOT be moved without changing
the crystal, tweaking a
micro-minature coil value, and changing the firmware. And NO !, the company
would NOT send out the firmware
needed. However, if you
On 6/2/13 11:59 AM, Chris Albertson wrote:
Recent talk about NTP servers. It seems the limit to their accuracy is the
quality of the crystal that drives the CPU clock. Most of them make really
good thermometers. I'd like to try and replace the crystal on a Raspberry
Pi with a signal derived fr
On 6/1/13 4:52 PM, Magnus Danielson wrote:
So, what was your engineering question, really?
responding to Bob's comment that people just say "ADEV <1E-15" without
specifying a tau.
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On 6/1/13 4:50 PM, Hal Murray wrote:
jim...@earthlink.net said:
It's also the knowledge of the process yield at each step which means you
can stay in business. APL knows how many to start at the beginning to
insure they'll have 4 at the end, 2 years later.
I assume there is a distribution.
On 6/1/13 4:46 PM, Bob Camp wrote:
That is, NIST certifies publicly that WWV is "on frequency" and "on time" with
a certain precision. Do I need to go to NIST and pay them to give ma piece of paper that says
this, or can I use their published data?
Remember - the original post (and thus the
On 6/1/13 2:51 PM, Magnus Danielson wrote:
On 06/01/2013 11:27 PM, Bob Camp wrote:
Hi
On Jun 1, 2013, at 3:34 PM, Magnus
Danielson wrote:
On 06/01/2013 09:02 PM, Scott McGrath wrote:
True
However with LORAN and to a lesser extent WWVB traceability process
was well/known and documented and
On 6/1/13 12:02 PM, Scott McGrath wrote:
True
However with LORAN and to a lesser extent WWVB traceability process
was well/known and documented and had been in place for decades and
was easy to implement correctly With GPS not so much especially
with S/A. Supposedly the new satellites don't
On 6/1/13 1:46 PM, Bob Camp wrote:
Hi
For ADEV, a lot of oscillators have a sort of "floor" where the
ADEV is relatively constant, say from tau in the range10-1000
seconds, and then it rises up (from thermal effects and such), so
the shorthand is that the number quoted is that "floor value"
Y
On 6/1/13 10:35 AM, Bob Camp wrote:
Both suffer from people talking about levels (-120 dbc or 1x10^-11) without mentioning
the offset or tau. Since both are highly dependent on the offset or tau that's not a good
thing. My observation is that ADEV is much more likely to be mentioned without an
On 6/1/13 8:49 AM, Attila Kinali wrote:
On Tue, 28 May 2013 20:23:06 -0700
Jim Lux wrote:
The USO's we got for GRAIL from APL have ADEV<1E-13 from 1 to 1000
seconds, and then heads up at 1 decade/decade. The lowest ADEV is about
5E-14 at around 50 seconds, but it's pretty f
On 5/29/13 7:37 AM, Mark C. Stephens wrote:
My 3585 is like that too, Unlocked messages until it warms up.
Unless you leave it plugged in, it must keep the oven warm while on standby.
I wonder if this is the case for the 8566 too?
yes.. most of those instruments have a "standby" where the oven
On 5/28/13 9:29 AM, Bob Camp wrote:
Hi
The cost of a BVA oscillator is primarily a function of the cost of the
blank used and secondarily a function of the resonator processing. You see
numbers in the $200 to $400 range tossed around for the blank (vs < $10 for
a good SC blank). The packaged res
On 5/26/13 9:00 AM, Chris Albertson wrote:
But for many applications, the inevitable overhead
(power, heat, external components, OS, etc) simply
eliminates the gain of having a better/faster CPU.
Sometimes I end up using a 6 or 8 pin PIC with only
a few lines of code to to solve complex problems
On 5/25/13 2:10 PM, Paul wrote:
*Jim Lux*
S*at May 25 16:53:50 EDT 2013*
* 3) the "Pi" is almost PC-like and very easy to use. Costs about $40***>and
requires a HDMI or DVI monitor..
A $9 USB to 3.3V serial adapter connects to
the serial console unless you prefer ssh or VNC
On 5/25/13 10:55 AM, Chris Albertson wrote:
3) the "Pi" is almost PC-like and very easy to use. Costs about $40
and requires a HDMI or DVI monitor..
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On 5/25/13 7:22 AM, Bob Camp wrote:
Hi
PIC's have been around for a *long* time. The PIC16's came early on and were
followed by the PIC18's. Both are a bit dated at this point. The PIC24's and
dsPIC33's are actually very similar parts. The PIC33's form a third family
pretty much on their own.
On 5/21/13 8:29 AM, Chris Albertson wrote:
The question here, I think was about the day-to-day shaking, not a once in
a lifetime event. Seriously if there was a 1+g acceleration who'd care if
their OCXO was still running under that pile of rubble that used to be a
house. It is the days-to-day
On 5/20/13 2:43 AM, Attila Kinali wrote:
Oh.. and connect the whole thing to a port on the PC that does _not_
have an internal USB hub.
That's a bit of challenge, I suspect.. A casual look at the PCs I have
around here running windows all seem to have on-mobo hubs when you
check Device Manag
On 5/17/13 5:07 AM, Grant Hodgson wrote:
A client company has sourced a quantity of 'New in Box' iSBC series
memory modules manufactured by Intel in the 1980s for a MULTIBUS based
computer system. These are still in their original, sealed packaging and
have been stored (for 25 years) in controlle
On 5/14/13 9:27 AM, Richard Solomon wrote:
You can buy the Adapter and Antenna over on the "evil empire" for a lot
less money.
yeah.. but you have to find it.
What I was wondering if someone sells an antenna that you just "stick on"..
Say you want a functional equivalent of the GPS18, but perh
On 5/14/13 9:02 AM, Chris Albertson wrote:
The adafruit GPS has a built in antenna. But you can add an external one.
it doesn't say that it has an antenna, and all the pictures show it
connected to an external antenna.
But why use this for timing? They don't even give a spec for timing
acc
On 5/14/13 8:54 AM, Chris Albertson wrote:
The problem is the PPS needs to be referenced to the same clock the PC
is using as a basis for system time. Yes, you could send the
counter's value periodically but that has the same problem of sending
the PPS, that is an un knowable delay.
The good
Interesting product.. too bad they don't have a small antenna that could
be integrated with it. (or maybe they do, and my browsing around didn't
find it).
I've got a bunch of applications coming up for something which needs
synchronization at 1us to 1ms level for distributed data collection. T
r. The
new board is only about 10W. You can see a payback on only 6 months
and you make $100 in the next 6 months. The power savings can also
pay for replacing the GPS receivers with serial units.
On Mon, May 13, 2013 at 7:43 AM, Jim Lux wrote:
rummaged through archives and couldn't find
rummaged through archives and couldn't find anything..
I've got some GPS-18's with the RS232 and 1pps output. BUT, I'm
wondering if anyone has tried to get timing with the USB version (Linux
or Windows..), and if so, is getting 1 millisecond absolute accuracy
feasible.
The underlying USB th
On 5/12/13 12:38 PM, Al Wolfe wrote:
Years ago we were taught that it was poor engineering practice to use
pots to trim a DC value, especially if any appreciable current was to be
drawn from the wiper. (Probably true for any kind of signal on a pot) It
seems that current through the wiper would e
On 5/11/13 9:29 AM, Ed Palmer wrote:
On 5/11/2013 5:32 AM, Magnus Danielson wrote:
On 11/05/13 06:48, Jim Lux wrote:
On 5/10/13 6:52 PM, Ed Palmer wrote:
Part of me thinks it's cute, part of me wants to kill it. :-)
https://www.tindie.com/products/akafugu/vetinari-clock
Looking fo
On 5/10/13 6:52 PM, Ed Palmer wrote:
Part of me thinks it's cute, part of me wants to kill it. :-)
https://www.tindie.com/products/akafugu/vetinari-clock
Ed
but.. what is the actual distribution? Is it white phase or white
frequency?
___
time-nu
On 5/5/13 2:49 PM, Magnus Danielson wrote:
I have all the Hg-199 and Hg-202 I need for a few clocks, but in it's
natural mixture. Don't feel like building a separation facility...
Use the quadrupole system you're using as a trap as a mass-spec to do
the separation.
__
On 5/5/13 11:45 AM, Magnus Danielson wrote:
Hi Jim,
On 05/05/2013 07:33 PM, Jim Lux wrote:
On 5/5/13 10:05 AM, Magnus Danielson wrote:
They have been targeting this goal for a very long time. Several
interesting papers is to be found at PTTI, NIST etc.
Yeah.. some years (6 or 7?) ago, John
On 5/5/13 10:01 AM, Magnus Danielson wrote:
Hi Jim,
On 05/05/2013 03:59 PM, Jim Lux wrote:
On 5/5/13 1:48 AM, Magnus Danielson wrote:
The above is a summary of things collected from a variety of sources,
but I think this coarse walk-through of issues gives some insight as to
what issues pops
On 5/5/13 10:05 AM, Magnus Danielson wrote:
On 05/05/2013 06:50 PM, Jim Lux wrote:
On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is
On 5/5/13 8:42 AM, Richard (Rick) Karlquist wrote:
At HP in the 1990's, Len Cutler's group built some experimental
mercury ion standards for USNO (IIRC). They were of the
trapped ion type. BTW, it is important to understand that
the architecture is the key factor, not the flavor of atom.
When p
On 5/5/13 1:48 AM, Magnus Danielson wrote:
On 05/05/2013 10:05 AM, Attila Kinali wrote:
On Sat, 4 May 2013 12:36:20 -0700
"Tom Van Baak (lab)" wrote:
Rule of thumb: quartz is best short term, Rb or H-maser mid-term,
and Cs by far the best long-term.
Ah.. so it's a fundamental limitation. An
On 5/2/13 5:18 AM, Poul-Henning Kamp wrote:
In message <5182325e.4020...@t-online.de>, Volker Esper writes:
Rummor has it that the single piece price in the US is $1475 for just the
CSAC. Weather that's with or without the demo board
And for that price a SRS PRS10 is a better buy, unless you
On 4/30/13 4:18 PM, li...@lazygranch.com wrote:
A bit OT, but back in the day there was what amounted to an X-prize for a real
accurate chronometer for navigation.
Make that way back in the day.
http://en.m.wikipedia.org/wiki/John_Harrison
And he had a heck of a time collecting. I suspect co
On 4/27/13 9:40 AM, Gregory Muir wrote:
On Fri, 26 Apr 2013 17:59:21 -0700, Jim Lux wrote:
Total dose will be very small (after all astronauts live in LEO)
So you'd worry about cosmic rays and single event effects.
They fly a lot of unmodified commercial equipment on ISS (a
On 4/26/13 9:18 AM, Chuck Forsberg WA7KGX N2469R wrote:
On 04/26/2013 06:01 AM, Bob Smither wrote:
As many on this list are amateur radio operators the following might
be of interest:
to track the satellites in real time."
Will radiation fry the cell phones before thy burn up on re-entry?
Th
On 4/26/13 6:01 AM, Bob Smither wrote:
As many on this list are amateur radio operators the following might be of
interest:
http://www.phonesat.org/
The project asks amateurs to monitor transmissions from cell phones that have
been placed in orbit.
Except that the transmissions are from
On 4/23/13 6:54 PM, li...@lazygranch.com wrote:
http://www.aorusa.com/receivers/ar2300.html
Just a FYI.
Interesting..
I see they use the OEM GPS from Garmin. I wonder what kind of DO
performance they get, and whether they actually discipline the
oscillator or just measure it. Since they'
On 4/22/13 3:15 PM, Hal Murray wrote:
dginsb...@gmail.com said:
First, the frequency offset of the microcontroller. I use a built-in
counting timer in the uC which runs at 84MHz to measure the duration between
2 PPS. What I get is ~84008000 timer ticks between two pulses, which
corresponds to a
On 4/22/13 12:26 PM, Eric Fort wrote:
Thanks, figured someone who reads this list may be connected there...
not like precision timekeeping is a huge community.
Eric
On Sun, Mar 17, 2013 at 2:53 PM, Magnus Danielson
wrote:
On 03/17/2013 10:47 PM, Eric Fort wrote:
Would anyone on this list kn
On 4/21/13 10:37 PM, Stewart Cobb wrote:
Date: Sat, 20 Apr 2013 12:52:03 -0700
From: "Tom Van Baak"
To: "Discussion of precise time and frequency measurement"
Subject: Re: [time-nuts] pin-wheel antenna
Message-ID:
Content-Type: text/plain; charset="iso-8859-1"
There's a very
On 4/21/13 5:18 AM, Attila Kinali wrote:
On Sat, 20 Apr 2013 12:52:03 -0700
"Tom Van Baak" wrote:
For the rest of you:
http://www.leapsecond.com/images/gps-pinwheel-1.jpg
http://www.leapsecond.com/images/gps-pinwheel-2.jpg
Thanks a lot...
So the design changed slightly from what Kunysz r
On 4/19/13 11:47 AM, Peter Monta wrote:
Hi Hal,
Why are X-Ray pulsars better than radio pulsars for navigation?
My impression is that it's easier to manage all-sky coverage at x-ray with
a small spacecraft package (I think millisecond pulsars generally emit at
both microwave and x-ray).
On 4/19/13 7:30 AM, Attila Kinali wrote:
On Wed, 17 Apr 2013 20:16:24 -0700
Jim Lux wrote:
There's a very nice picture of a pinwheel from Novatel on the back cover
of the March issue of GPS world..
Has anyone a digital (or scanned) copy of that picture?
It's kind of diff
On 4/18/13 1:40 PM, b...@lysator.liu.se wrote:
All of the "high quality" GNSS receiver manufacturers have their own
version of correlator that try to mitigate multipath. See for example
this Ashtech-document (for a ca 10 year old L1 only receiver (DG14/16)).
ftp://ftp.ashtech.com/OEM,%20Sen
On 4/18/13 12:15 PM, Peter Monta wrote:
I wonder if there's any advantage in combining far-away GPS with X-ray
pulsar navigation (XNAV), which is said to be good to a few kilometers,
though long integration times are needed. For example, the rough system
time from XNAV could enable very long (a
On 4/18/13 11:02 AM, Magnus Danielson wrote:
On 04/18/2013 04:01 PM, Jim Lux wrote:
On 4/18/13 4:01 AM, David J Taylor wrote:
An interesting novel use of GPS "stray" signals
"ESA’s retired GIOVE-A navigation mission has become the first civilian
satellite to perform GPS
On 4/18/13 4:01 AM, David J Taylor wrote:
An interesting novel use of GPS "stray" signals
"ESA’s retired GIOVE-A navigation mission has become the first civilian
satellite to perform GPS position fixes from high orbit. Its results
demonstrate that current satnav signals could guide missions
On 4/18/13 12:01 AM, Chris Albertson wrote:
If I read the paper correctly you can skip the choke ring if you mount the
antenna on top of a 2 meter or longer mast. Iron pipe comes on 10 foot
lengths. The choke ring is for portable survey antenna that can't be
placed on tall rooftop masts. I th
There's a very nice picture of a pinwheel from Novatel on the back cover
of the March issue of GPS world..
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On 4/17/13 12:18 PM, Chris Albertson wrote:
Another way to ask this question is "what is the effect of a small
deviation form the ideal dimensions?"
If we assume deviations of about 1/20th of a wavelength are OK then we can
allow about 1cm of dimensional error. Almost anyone using simple hand
t
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