n1...@dartmouth.edu said:
I am surprised it took them this long. A number of satellite telemetry
systems can use doppler as a matter of course for locating transmitters,
such as Iridium and Argos.
It's more complicated than just computing the Doppler. You also have to
figure out what the
In message e1wsemc-000dz8...@stenn.ntp.org, Harlan Stenn writes:
I'm actually not certain that it helps, even if you document it.
It's sort of an administrative distance and it unfairly penalizes
any GNSS in favour of terrestial if you calibrate it according to the
original intent...
I'm
In message CACYeN9zf-UO1sCTCRMHSDPN4u=ye0xb9+x71eLxBnbT=xgw...@mail.gmail.com
, Jim Miller writes:
I've spent a good part of the afternoon looking at all the plots, websites
and the few papers I could find mentioning the hanging bridge. As far as I
can tell as long as one is correcting for
Hi
Exactly correct, the sawtooth corrects for the hanging bridges.
Since that’s what it does, sawtooth correction error is not totally random.
Hanging bridges are not totally random. One looks like the other. Sawtooth
correction errors can / will have hanging bridges in them.
If you are
In message 6b362a4d-834a-4733-bed8-fcfec0ccb...@rtty.us, Bob Camp writes:
I should add here, that you _can_ do a little bit better than the
sawtooth correction.
We know, or at least assume, that the GPS's internal clock is step-less
and slowly changing, so if you put a predictive filter on this
Hi
Most of the more modern receivers don’t stop at one ns resolution on the
correction. You can go well below the ns level with them. If you are doing it
in software, it’s pretty much free.
Bob
On Mar 25, 2014, at 7:27 AM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message
The lowest cost solution is a DS chip in combination with a PIC. How ever
has any one thought about a fix by going to the source of the problem. The
TCXO. Use a DDS with internal multiplier like the AD9851 or AD 9913 and use
the sawtooth message from the GRS receiver and change the
On Mon, Mar 24, 2014 at 4:26 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote:
In message CABbxVHuQc0144==21mDa_R8ErKov=
em+9rvrbpggexnzztj...@mail.gmail.com
, Chris Albertson writes:
Yes. NTP calls it root distance [...]
And it is generally useless, because people don't calibrate it.
How
In message CAKyJ6kajBO=yvkg44s_sdo5owruzem4tzx8atvcirkmgcn8...@mail.gmail.com
, Paul writes:
On Mon, Mar 24, 2014 at 4:26 AM, Poul-Henning Kamp p...@phk.freebsd.dkwrote:
And it is generally useless, because people don't calibrate it.
How do you calibrate root distance assuming that it's
Thanks for all the helpful replies!
Lots to learn.
73
jim ab3cv
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Yes, and there was an early military positioning system, roughly 1960s /
1970s that worked on Dopplar also. The name escapes me at the moment.
-John
=
This is how ELT locating satellites work (when not relaying the newer GPS
data bursts). Several on another list I watch
Hi,
Yes, and there was an early military positioning system, roughly 1960s /
1970s that worked on Dopplar also. The name escapes me at the moment.
I think it is Transit.
See http://en.wikipedia.org/wiki/Transit_(satellite)
Greetings,
Pieter.
-John
=
This is how ELT
Could well be. I never saw the bird, of course. The portable ground
station was roughly the same size as an OD Manpak radio of the period and
read out Lat/Long on LED digital readouts. In retrospect, it may have been
in the early 1980s.
-John
==
Hi,
Yes, and there was an early
Today I spent good part of my time to figure out that my version of
Thunderbolt has some issue with the TSIP protocol definition. I am using
following document: ThunderBolt GPS Disciplined Clock User Guide,
Version 5.0, Part Number: 35326-30, November 2003
In that particular PDF file, there
Besides the header and trailer you need to unescape any embedded DLE's in the
data stream.
/tvb (i5s)
On Mar 25, 2014, at 2:43 PM, d0ct0r t...@patoka.org wrote:
Today I spent good part of my time to figure out that my version of
Thunderbolt has some issue with the TSIP protocol
On Tue, Mar 25, 2014 at 5:44 AM, ewkeh...@aol.com wrote:
The lowest cost solution is a DS chip in combination with a PIC. How ever
The lowest cost solution is to do the correct entirely in software.
After the measure the phase, simply add the correction.
All you need to know is the phase.
On 3/24/14 10:18 PM, David McGaw wrote:
I am surprised it took them this long. A number of satellite telemetry
systems can use doppler as a matter of course for locating transmitters,
such as Iridium and Argos.
Those are actually designed for measuring Doppler..
That's really the difference..
On 3/25/14 11:38 AM, J. Forster wrote:
Could well be. I never saw the bird, of course. The portable ground
station was roughly the same size as an OD Manpak radio of the period and
read out Lat/Long on LED digital readouts. In retrospect, it may have been
in the early 1980s.
Transit,
On Mon, Mar 24, 2014 at 06:15:57PM -0700, Chris Albertson wrote:
Yes, word is that they were able to determine the Doppler shift in the
plane's signal. I'm surprised this was even recorded but it must have been
in the satellite's telemetry downlink. Projecting radial velocity and
Certainly, if it's a bent-pipe repeater, that makes extracting the Dopplar
a whole lot easier. Furthermore, since it's unlikely that the missing
plane was the only signal, you can essentially do a differential Dopplar
measurement against other sorces, stationary or moving in a know
trajectory.
Yes if you want to use it only in a GPSDO and it is being done but if you
are a time nut you may want the 1 PPS..
Bert Kehren
In a message dated 3/25/2014 6:33:12 P.M. Eastern Daylight Time,
albertson.ch...@gmail.com writes:
On Tue, Mar 25, 2014 at 5:44 AM, ewkeh...@aol.com wrote:
The
On Tue, Mar 25, 2014 at 5:52 AM, Paul tic-...@bodosom.net wrote:
On Mon, Mar 24, 2014 at 4:26 AM, Poul-Henning Kamp p...@phk.freebsd.dk
wrote:
In message CABbxVHuQc0144==21mDa_R8ErKov=
em+9rvrbpggexnzztj...@mail.gmail.com
, Chris Albertson writes:
Yes. NTP calls it root distance [...]
Le 25 mars 2014 à 22:43, d0ct0r a écrit :
Today I spent good part of my time to figure out that my version of
Thunderbolt has some issue with the TSIP protocol definition. I am using
following document: ThunderBolt GPS Disciplined Clock User Guide, Version
5.0, Part Number: 35326-30,
Hi
If you are building a GPSDO, then the 1 pps out of the GPSDO should be much
better than the pps out of the GPS. Making that happen is part of the control
optimization.
Bob
On Mar 25, 2014, at 7:46 PM, ewkeh...@aol.com wrote:
Yes if you want to use it only in a GPSDO and it is being done
Much thanks Tom and Mike ! I missed that point. In another word, T-Bolt
sending DLE data wrapped by another byte ! Now I know !
On 2014-03-25 19:55, mike cook wrote:
Le 25 mars 2014 à 22:43, d0ct0r a écrit :
Today I spent good part of my time to figure out that my version of
Thunderbolt
Besides the header and trailer you need to unescape any embedded DLE's in the
data stream.
There are a number of code examples on the web showing how to decode TSIP
packets. The oldest (original source code from Trimble), is file TSIP_IFC.C
from the TSIPCHAT program. You can google for
The lowest cost solution is to do the correct entirely in software.
After the measure the phase, simply add the correction.
All you need to know is the phase. There is not point in correcting
the pulse, you don't need a corrected pulse. What you want is a
measurement of the phase.
Chris
I'm
Hi
There have been multiple posts about analog TDC’s of various designs that get
you into the sub 100 ps range without costing very much money. I believe the
cheapest posted so far adds 50 cents to a basic PIC based design.
Bob
On Mar 25, 2014, at 7:38 PM, Jim Miller j...@jtmiller.com
One thing I don't fully understand are the spot beams. If this is a bent
pipe, how do they control which beam serves the terminal? And if ground
based command, would they not have a record of which spot beam that
MH370 was utilizing, therefore know approximate location and direction ?
--
Joe
Hi Joe:
It's my understanding that the spot beams are only used for air phones where they need more gain and MH370 had no first
class, i.e. no phones.
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
Joe Leikhim wrote:
One thing I don't fully
On Tue, Mar 25, 2014 at 6:22 PM, Joe Leikhim jleik...@leikhim.com wrote:
One thing I don't fully understand are the spot beams. If this is a bent
pipe, how do they control which beam serves the terminal? And if ground
based command, would they not have a record of which spot beam that MH370
[I apologize in advance]
On Tue, Mar 25, 2014 at 7:47 PM, Chris Albertson
albertson.ch...@gmail.comwrote:
Peole here have very much mis-understood the term Root Distance.
I don't think Poul-Henning Kamp should be accused of misunderstanding NTP.
My question was answered (I wondered why I had a
Right now I'm planning to use a DS1123 driven by the PIC in my system to
provide sawtooth correction. The phase measurement is strictly binary with
a D FF. The PIC reads the value once a second and integrates with a bit of
feedforward for stability. The numerical result will be fed to a DAC which
Bob
I'm not sure who you're responding to but I have a couple of questions:
TDC = Time Delay Correlator?
Could you point me to one of these 50 cent threads? I've read a ton of this
list from 2007 forward but must have missed that.
Thanks
jim ab3cv (much to learn)
Hi
There have been multiple
If you are building a GPSDO, then the 1 pps out of the GPSDO should be much
better than the pps out of the GPS.
Bob,
That's only true for time scales less than the cross-over point. Beyond that,
the 1 PPS from the GPS receiver is actually better (more accurate). That's why
the LO is
I hadn't given any thought to correcting the linearity of the TIC I built, but
my PLL plots tell me I should do it now. Explanation: when I arrange things so
that the phase point is near the top of my TIC's range, it requires a smaller
movement than when the phase point is in the middle:
I think I figured it out. rootdisp=0 refers to Root Dispersion which
is quite different from Root Distance. They do look a little alike.
One is the distance from the local clock to the root of the NTP tree and
the other is something different, internal to NTP that is not exposed to a
user.
FYI, I've posted a few pictures of the inside of this oscillator.
Noteworthy is the tiny Dewar flask.
http://s701.photobucket.com/user/edpalmer42/library/Isotemp%20OCXO107-10%20Oscillator
If you click on the magnifying glass at the bottom of the picture and
then do it again, you'll get the
The lowest cost solution is to do the correct entirely in software.
After the measure the phase, simply add the correction.
All you need to know is the phase. There is not point in correcting
the pulse, you don't need a corrected pulse. What you want is a
measurement of the phase.
This
Bob wrote:
I hadn't given any thought to correcting the linearity of the TIC I
built, but my PLL plots tell me I should do it now.
You are using a resistor to charge the integrating capacitance, so it
charges with the classic exponential curve and you get a nonlinear
time-to-voltage
Hi,
I'm new to the list. I'm curious if anyone will be attending the NIST Time
and Frequency seminar in Boulder in June, and / or the following week's
NIST-ATIS workshop on Telco Sync in San Jose.
http://www.nist.gov/pml/div688/seminars.cfm .
Thanks...
--Brett
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