Hal,
For science-fair level accuracy try a $2 PTC-60 thermistor heater
one component oven for minimal complexity. I tried this with a
small box and insulating foam and it gives surprisingly good
results. Leave it to the ham radio guys to come up with a low
cost solution.
Adrian,
Take a look at Patent # US 6226231 B1 for a schematic of the
interpolator used in the Wavecrest DTS-2075. It may be similar
to what you are trying to troubleshoot and might give you some
ideas.
Richard
In the meantime I heard that Wavecrest is not distributing service
manuals. All
Hi Tom,
In the Shera design the instability of the XO timebase is
a key factor in improving the 30-second update resolution.
With the XO drift varying the sample point across the 1PPS
and 312.5 KHz edges the samples are constantly varying and
the average of the samples has a resolution much
substantial) offset in the data is also a significant issue.
Bob
On Mar 25, 2013, at 8:35 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz
wrote:
Richard H McCorkle wrote:
Hi Tom,
In the Shera design the instability of the XO timebase is
a key factor in improving the 30-second update
Ray,
Try the Trimble TimeKeeper- TSIP clock sync for windows
ftp://ftp.trimble.com/pub/sct/embedded/bin/TIMEKEEPER%20PROGRAM/
Richard
Anybody know of a PC (windoze) time synch software that works with TSIP or
SCPI
protocols.
Thanks Ray.
I have a photographic memory, its just not
Warren,
One thing Rick Karlquist pointed out is a higher thermal gain can be
realized to minimize temperature effects by optimizing the heater
transistor balance. The 10811A/B Quartz Crystal Oscillator Operating
Service Manual describes the balance circuit in section 8-40. The
two heater
Pete,
In addition to a nice box you now have a Lambda NNS15-12 12v 1.7A
power supply, a Toyocom TCO-612C OCXO and a 10M 50-Ohm buffer card.
The power supply takes up most of the case with the OCXO and buffer
card mounted inside a small aluminum box within the cabinet to
shield the OCXO and buffer
Time-Nuts,
There has been much discussion on this list about methods
of measuring short-term stability. I wanted to make the
list aware of a new paper describing a small DMTD system.
The system was developed by William Riley, author of
STABLE32, and is described in detail with schematics
and test
Fellow Time-Nuts,
When I first uploaded the Simple PICTIC interpolating time interval
counter to the K04BB site in 12/08 and presented it to the group as
a Christmas present my goal was to get amateurs building their own
interpolating time interval counters for GPS monitoring and making
Time-Nuts,
The PICTIC WIKI page has been updated to include a PDF of the
schematic and board layout as requested.
Richard
On 06/28/2010 01:46 AM, Stanley Reynolds wrote:
done
www.n4iqt.com/picticii/circuit.jpg
www.n4iqt.com/picticii/PICTICII.bmp
both above as pdf
Time-Nuts,
Thanks for your interest in checking out the PICTIC II and working
together to simplify ordering the boards and parts. My hope is by
making the code available others will find ways to improve on the
basic design and will share their modifications to make this a
better project. As
Bob,
Another option with the 16F688 is to tweak the internal oscillator
rate slightly to give the proper baud rate. The code includes the
following two lines (normally commented out) to do this.
; movlw 0x00;put the cal value in OSCTUNE
; movwf OSCTUNE ;to calibrate
The gotcha with the tune register is that it's not much help for those
without a
PIC programmer...
Bob
On Jul 2, 2010, at 8:15 PM, Richard H McCorkle wrote:
Bob,
Another option with the 16F688 is to tweak the internal oscillator
rate slightly to give the proper baud rate. The code
Bob,
Instead of the 3266 series go to the 3296 series
5K Trimmer, top adjust
652-3296W-1-502LF 7100 in stock
652-3296Y-1-502LF 590 in stock
200 Trimmer, top adjust
652-3296W-1-201LF 1090 in stock
652-3296Y-1-201LF 830 in stock
Richard
Hi
The real question somebody needs to answer is -
don't seem to be able to edit it
Bob
On Jul 8, 2010, at 7:26 PM, Richard H McCorkle wrote:
Bob,
Instead of the 3266 series go to the 3296 series
5K Trimmer, top adjust
652-3296W-1-502LF 7100 in stock
652-3296Y-1-502LF 590 in stock
200 Trimmer, top adjust
652-3296W-1-201LF 1090
Time-Nuts,
When the PICTIC was first developed a number of front-end designs were
evaluated with the 74AC175 providing the best characteristics, size,
and speed in a DIP format. When the PICTIC was released in 2008 the
74AC175PC was in full production, but by the time the PICTIC II with
the diode
little difference between this and
the DIP version (the pinouts for both versions are the same). Would this
compromise the higher frequency versions of the PICTIC II?
Ed
Richard H McCorkle wrote:
Time-Nuts,
When the PICTIC was first developed a number of front-end designs were
evaluated
The TS272CN is an acceptable substitute for the TS272ACN in the
PICTIC II but as noted has a higher input offset voltage. This
can be compensated for in the second stage by adjustment of
the offset trimmer. I selected premium parts for temperature
stability in the application. Sorry the
Paul,
Interesting you should point this out as the PICTIC was a spin-off
of a 5-year effort to modernize the Shera controller for my own use.
The 42ns TIC in the Shera was a weak point and a different TIC with
higher resolution was needed if sawtooth correction was desired.
My GPSMAX controller
FYI,
The TS272/TS274 have a slew rate of 5.5v/us at unity gain, the max
voltage on the cap is 2.7v in the new design, and the voltage is read
10us after sample complete, so the buffer should have time to
stabilize after the sample before being read.
Richard
Bruce wrote:
Not really its both
Bert,
In discussions with Brooks Shera the approach we are contemplating
is an interpolating TIC and 0-5v output add-on board for use with
his controller board. Minor modifications to the AA engineering
board will route the XO to an interpolating front end and route the
outputs back to the
on the
input signal level.
Bruce
Richard H McCorkle wrote:
FYI,
The TS272/TS274 have a slew rate of 5.5v/us at unity gain, the max
voltage on the cap is 2.7v in the new design, and the voltage is read
10us after sample complete, so the buffer should have time to
stabilize after the sample
Hi Dave,
Try www.mouser.com who list both 74ac devices in SOIC and have them in stock.
Richard
I'm looking for 74ac164 and 74ac112 in SOIC (.15 wide) as the usual
suspects (Farnell and RS Components) don't seem to stock these in UK :-(
I found most of the other 74AC logic I want.
I'm also
Hi Corby,
This is a nice collection of data and look forward to seeing how
the Motorola and -60158 variants compare. The specs on the -60111
show 1e-11 @ 1 sec although the results you obtained show they
are typically much better than this.
Thanks for the data,
Richard
Hi,
I have had the
At 12:16 PM + 10/11/08, Poul-Henning Kamp wrote:
As former sound technician...
I used to do that stuff too, being the bass player/sound guy in a
cheesy bar band. Loads of fun!
Any more time nuts with sound reinforcement experience?
--
--David Forbes, Tucson, AZ
Hi Dick,
Back in 2004 Stefan Hegnauer reverse engineered the outer oven controller
in the Z3801A and posted the schematics and a PSPICE simulation. Apparently
they are no longer on the web, but his conclusion was:
The outer oven of the Z3801A GPS disciplined crystal oscillator is used
to keep
Ho Ho Ho
Merry Christmas from the far north to all the
Time-Nuts. As a gift for the holidays I have
created a free version of the PICTIC for you
and Didier has kindly posted the files at:
http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
And to all a good night,
Richard
Bruce,
Thank You for posting a proper TAC, I'll give your circuit a try so I
improve my education in interpolator design before sharing any further
work with this list.
Richard
Richard
The attached circuit illustrates how to construct a simple high
linearity ramp TAC.
The circuit has been
Try this link for the Allstar Manual
ftp://ftp.novatel.ca/outgoing/support/Documents/Manuals/CMC/
Richard
hi i was trying to get more info on the CMC Allstar 12 GPS engines you wrote
about in 2007 as i have over 350 of them to sell but i to cant seem to find
any
info please help
Hi Samuel,
I suggest starting by downloading the component level information for
the 53131A and 53132A from tha Agilent site at the following links.
http://cp.literature.agilent.com/litweb/pdf/5989-6308EN.pdf
http://cp.literature.agilent.com/litweb/pdf/5989-6307EN.pdf
The 53132A document
Tom,
The standard configuration for our local moutain top cell sites in
Fairbanks is a VIC-100 antenna with LMR-400 feed cable to minimize
RF attenuation at very low temperatures. A Symmetricom 4-port
splitter feeds dual sets of redundant timing equipment. The ATT
guys tell me that even at -60F
John,
Output frequencies above 10 KHz with the PIC divider require separate
manipulation of the port bits within the main timing loop. A 100 KHz
output can be added this way as tvb did in his original divider code,
but if you also want the divider to work properly with both 5M and
10M input rates
John,
The specifications for AC coupled input sensitivity of the 74HC4046
from the major manufacturers are shown below. Brooks found that the
Fairchild device had lower sensitivity and recommended using devices
from TI or Phillips.
Fairchild MM74HC4046
Ac coupled input sensitivity @ 500 KHz
Lasse,
If you are getting a Message ID 1180 at power-on you are in Navman bin
mode and the EEPROM power-on default has been set to this mode. You need
to send Message ID 1331 using LabMon to set it back to Motorola protocol
before TAC32 can talk to it.
Richard
I got a Jupiter-T TU60 off eBay
Hi Dan,
If the 1938 was purchased through Fluke1 he is usually very good
about replacing bad items he sells to Time-Nuts. You might want
to contact him about a replacement unit or perhaps getting a
pre-programmed PIC from a different unit to try.
Richard
I am beginning to think that the PIC
Hi Bob,
The VE2ZAZ controller is a frequency locked loop that keeps the source
on frequency but over time the phase drifts, as past corrections are
not compensated for. When the system is stable every 16 seconds the
16-bit counter rolls over 2441 times with an extra 26624 counts (6800
HEX). The
,
but
It's hard to believe that there is enough information in a jittery 1PPS
reference
pulse to be able to recover phase errors.
Bob
- Original Message -
From: Richard H McCorkle mccor...@ptialaska.net
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency
Chis,
Over time without phase correction the analogy would be more like
zig to the right, correct to go straight, zig to the right, correct
again, and keep repeating this sequence ad infinium as the source
ages in predominantly one direction. Each time the phase shifts in
the same direction and
Jim,
Generally navigation receivers don't include survey and position hold
features so the time solution accuracy is typically about +/- 1us.
Timing receivers survey their position over a large number of samples
(typically 10,000) and go into position hold mode once the survey
completes. The
Jim,
Generally Navigation receivers
I've looked at several different manufacturer GPS datasheets now regarding
the 1
PPS output in an attempt to compare apples to apples. Some of them rate their
1 PPS
output as something on the order of PPS signals have an accuracy ranging
10ns
Bob,
The 5ns time stamper data attached shows a 500 second hang in the
1PPS phase from an M12+. A graphic example of why including
sawtooth correction in a GPSDO is a good idea. With 500 samples
having an offset even long filter times create a source control
error unless the offset is corrected
Chris,
The 10811-60165 may be similar to the HP 10811-60158
that uses using the following pin-out:
1 - BRN Oscillator Return (Com)
2 - RED Oscillator Power (+12V)
3 - ORG Oven Monitor Return (Com)
4 - YEL Oven Monitor Output
5 - GRN Oven Power (+18-24V)
6 - BLU Oven Return (Com)
The following
or
somewhere else?
CS
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]On
Behalf Of Richard H McCorkle
Sent: Tuesday, February 18, 2014 11:07 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] HP 10811-60165 Double Oven
Chris,
If you have multiple standards to monitor (or may have in the future)
you might consider building a small version of the NIST FMAS board
described in http://tf.nist.gov/general/pdf/1950.pdf to keep track
of them.
Richard
What advice does anyone have on building/finding cheap [visual?]
Chris,
A PIC requires 4 clock cycles per instruction which limits the
maximum output rate a PIC can provide as partial instruction
times can't be used. With a 10 MHz input each instruction takes
400ns and if duty cycle isn't an issue nop instructions can be
added each loop to extend the cycle
See the chart TVB produced to see the PRS10 hump in published data.
http://www.leapsecond.com/museum/prs10/
Have you observed the hump yourself or is it published data? If you made
the measure, what reference clock did you use? I have (at work, in another
department) a new PRS10, hope to get
Per the 58503B brochure:
An even-second (1 PP2S) output is available as an option to the 58503B.
The even-second output option provides one pulse every other second,
synchronized to the even seconds in GPS time. This is the reference time
used in CDMA base stations.
Some GPSDO have both a 1PPS
Ray,
For a simple solution with WinDoze machines take a look at Tardis 2000
at http://www.kaska.demon.co.uk as a possible approach. Tardis can get NTP
time from the internet or use a GPS NEMA message to sync the time server
and reboadcast NTP on your local LAN. The K9 client can be used on the
John,
I have asked Alaska's representitives to reinstate LORAN funding due to the
large number of private pilots and small fishing boat operators that rely
on LORAN in Alaska. During periods of high aurora activity in the arctic
the interference with GPS makes it unusable and LORAN is the only
Dick,
Schematics can be found on Brooke Clarke's site at
http://www.prc68.com/I/HPE1938.shtml.
Richard
I finally got to hooking up the E1938A I got. When
compared to my GPS based reference, I find it is
6.6 Hz low.
Is there a frequency adjust trimmer on the board ?
I don't have a
Bene [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, October 23, 2005 7:30 AM
Subject: [time-nuts] RE: phase locking Rb to GPS
Richard H McCorkle wrote:
[snip]
In interfacing an Isotemp mil spec version of the HP 10811B
the rubidium
very fast.
I use to joke that the best, simplest way to make a
GPSDO with an Rb is to just change the EFC once
a day. There is some truth to this.
/tvb
- Original Message -
From: Richard H McCorkle [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
The board you are describing is used in the Lucent RFG-M-XO reference
frequency generator. It takes in 10 MHz on J2 from a Rubidium oscillator and
disciplines the Efratom SC cut OCXO on the main board from the 10 MHz input.
The output from the OCXO is converted to 15 MHz and supplied as the
For a schematic of the Z3801A outer oven controller try here:
http://homepage.sunrise.ch/mysunrise/shegnauer/Z3801A/Outer%20Oven%20Controller/z3801a_outer_oven_description.htm
Hope this helps.
-- Original Message -
From: Magnus Danielson [EMAIL PROTECTED]
To: time-nuts@febo.com
Sent:
A very low cost way to test your GPSDO is to generate 1Hz from the GPSDO
with the TVB divider compare it to the GPS 1PPS with the Simple Time
Interval Counter with RS-232
Output(http://www.piclist.com/tehref/member/RHM-SSS-SC4/TIC232.htm), log the
difference readings over time on a computer, and
. And yes, both Simple Commands and
TIC232 are now public domain, so feel free to cut and paste to your heart's
content.
Enjoy!.
- Original Message -
From: Brooke Clarke
To: Richard H McCorkle
Sent: Friday, August 11, 2006 12:35 PM
Subject: Re: Fw: [time-nuts] TIC232
Hi
at the selected
averaging time.
By making these modifications to the Simple Time Interval Counter
the modified TIC can provide cleaner data capable of analysis in the
sub nanosecond range for use in serious timing work.
.
Enjoy!
Richard H McCorkle
Here is a detailed description of the operation of the
Simple Time Interval Counter.
1. A sample counter is loaded with the selected number
of samples
2. TMR1 is enabled, interrupts are enabled, GPS 1PPS
hasn't arrived yet so the 4046 output is low, TMR1G
is low, and TMR1
jitter
if it's not done at the right time. Since the counter is read from an
ISR, there may be issues of latency.
I am very interested as I am considering using a small proto Silabs PWB
with an C8051F300 chip for the experiment.
Didier KO4BB
Richard H McCorkle wrote:
Here is an insider
Richard H McCorkle wrote:
I have posted a detailed operation of the TIC to help
clear up most of the questions you asked.
As far as overflow tests, a 16 MHz XO over a full
second would not completely fill a 24-bit register
(16777216) and 256 times that will not completely
fill a 32-bit
I am indeed using a TVB style divider for my DUT 1PPS
and since it has a square wave 1Hz output, I programmed
an inverted 1Hz output for my TIC test box DUT 1Hz.
That way any drift over time keeps the phase detector and
TIC well away from the zero crossing during long-term testing.
I remove the
between the two at best overall stability. (about horizontal)
Enjoy!
Richard
- Original Message -
From: Brooke Clarke [EMAIL PROTECTED]
To: Richard H McCorkle [EMAIL PROTECTED]
Sent: Sunday, August 13, 2006 9:02 AM
Subject: Re: Enhancing the TIC232 code for better data
Hi Richard:
I
Enjoy!
Richard
- Original Message -
From: Glenn [EMAIL PROTECTED]
To: Richard H McCorkle [EMAIL PROTECTED]; Discussion of precise
time and frequency measurement time-nuts@febo.com
Sent: Sunday, August 13, 2006 10:58 AM
Subject: Re: [time-nuts] TIC232 Detailed Operation
I've never
Has anyone on the list had an opportunity to work with the SigNav
TM3-02 GPS receiver (http://www.signav.com.au/index_files/PDF_Files/
New_Brochures/SigNav%20TM3-02%20Brochure%20V1.2.pdf)
and test the stability of their sawtooth eliminated 1PPS output?
I am curious how the 1PPS stability
Hi Bill,
You can find all the details on the Simple Time Interval Counter at
http://www.piclist.com/techref/member/RHM-SSS-SC4/TIC232.htm.
It was developed as a simple way to get phase data from an OCXO
and a GPS into a computer for analysis at minimal ($20) cost.
Enjoy!
Richard
in the August
There are Motorola Oncore VP GPS receivers currently
for sale on e-bay (Search Oncore VP) in case someone
on the list is looking for a spare GPS for their Z3801A.
The price looks reasonable for these vintage GPS
receivers. (The 8-channel VP works in the Z3801A as it
can emulate the original
Am I the only one who can't find the PTTI_2006.pdf file at the address
listed in this note? The PowerPoint file is there, but no paper.
Wondering,
Richard
- Original Message -
From: Tom Clark, K3IO [EMAIL PROTECTED]
To: Time Nuts time-nuts@febo.com
Sent: Sunday, December 10, 2006 6:31
Back when these Lucent units were first appearing GPS had not yet been
implemented at the cell sites here in Alaska. The rubidium was too noisy for
direct frequency synthesis, so the XO unit was phase locked to the rubidium
to provide the long-term stability needed, and the XO output was
I'm sure Lucent engineers spent quite a bit of effort designing that metal
box to keep the rubidium temperature as low as possible for extended life.
If the rubidium is used in a different enclosure pay special attention to
thermal
conditions as the life of the rubidium is reduced with increasing
Jason,
What divider output are you using? The typical input to the phase detector
should be between 312.5KHz and 625KHz and an appropriate jumper has to be
installed on the divider header on the [EMAIL PROTECTED] board to tie the
selected divider
output to the phase detector. Sounds like you
Had,
While I have been unsuccessful in finding a description of the Z3801
internal diagnostic LED's the 55300A GPS Telecom PRS Users Guide
(http://www.symmetricom.com/media/pdf/manuals/097-55300-01.pdf)
has a section in the manual (starting on page 6-28) on the Diagnostic
LED's that may prove
Fellow Time Nuts,
The PICTIC II is a spin-off of a low cost front end developed for a
GPSDO to compare the oscillator to GPS 1PPS over very short ( 20us)
time intervals. In that application all that was required was 1ns
TIC resolution to match the resolution of the GPS sawtooth correction
to get
Time-Nuts,
New members to the Time-Nuts list may wonder if the Time-Nut disease
has infected them just by joining the list. A clear indication that
someone has been infected with the Time-Nut disease is they own a
reference that provides accurate time to better than 1us and
frequency to better
Ho Ho Ho,
Tis the season once again for giving and I wrote this up to give some
suggestions to the discussion. The PICTIC II was a spin-off of a GPSDO
front end designed specifically for low cost, low parts count, amateur
construction, and 1ns resolution to equal the performance of a modern
GPS
the divider and can find uses for similar
code in other specialized divider applications.
Good Job!
Richard
I got some of the cheap Pletronics OHM40480526 26MHz OCXO parts for
experiments (couldn't resist $2 each :-). For this purpose I modified the
Richard H McCorkle/Tom Van Baak code for generating
Hi Said,
I hope Jackson Labs will provide better documentation and support
for this product than what is typically available from Symmetricom.
Especially maintaining support and documentation availability later
in product life when the units go surplus to second-hand users at a
price that an
Brooke,
I believe he is referring to the Efratom FRS-C Rb oscillator which
was very popular in telecom applications. I looked at the specs for
one on eBay (140128295361) and in my FRS-C manual and came up with:
FRS-C Electrical Specifications:
Long-term Drift: or = to 5x10-11/mo*, or =
Can any one tell me what the full Hint Box' text is for the message
one gets when mousing over the logging on/off box?
The text starts'When green, logging is active: when yellow,data
logged that seco.. but I can't see any more text as the box
is not long enough.
Thanks
DaveB, NZ
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED]
In my Brooks Shera style LPRO rubidium controller I am using
the same HC4046 input conditioner and divide down counter on
the oscillator and HC4046 phase detector interrupting the PIC
as used in the original design. The phase
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED]
Thanks guys for the input,
I wanted to clarify that the time interval being measured at each
GPS 1PPS is typically 2/5 of a 1.6us window (Rb/16) or 640ns at
setpoint. The filter input value is built by accumulating (not
averaging)
) apply
a negative sawtooth correction with 1 ns resolution, then
average 120 of those sums, and then expect a 84 ps
resolution result? Something doesn't sound quite right.
/tvb
- Original Message -
From: Richard H McCorkle [EMAIL PROTECTED]
Thanks guys for the input,
I wanted
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED]
Gentlemen,
I would like to pose a theory question and see if my thinking is
faulty. My original design used a 50 MHz TIC clock and the TMR0
prescaler as the phase counter giving 20ns single sample resolution
in the prototype system.
-
From: Richard H McCorkle [EMAIL PROTECTED]
Tom,
I did most of the software development work using just the
uncorrected 1PPS into TMR0 and two scaled and summed PWM
outputs instead of a DAC, and the results were surprizingly
good. It made a very low cost, small footprint design without
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY
Jared,
Symmetricom has a Stratum definition page at:
http://www.ntp-systems.com/think_sync_view_article.asp?ID=42NewsletterID=1month=4year=2005
This is what they have to say;
Dr. David Mills from the University of Delaware,
); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY
In the telecommunications world, stratum refers to the holdover
performance of an oscillator in the event of loss of synchronization.
Stratum 1, Stratum 2, Stratum 3, and Stratum 4 are the most typical. A
Stratum 1 clock
Hi Brooke,
The transmitter coordinates are
62 deg 23.5 min North Latitude
145 deg 8.8 min West Longitude
or 8 mi north of Gakona, Alaska
in case you were interested.
Richard
Hi:
This is not a frequency measuring test.
I wonder if there would be doppler on the return signal.
The transmit
Tom,
My UT+ is showing PRN32 at 35 degrees elevation and status OK
here in Alaska.
Richard
PRN32 is heading towards the USA, so should be heard there soon!
PRN32 (=SVN23 =SATID 20959) should be above 30 degrees
elevation from Seattle, but so far none of my GPS receivers
are picking it up.
Tom,
PRN32 is now at 50 degrees elevation in Alaska according
to the UT+ and not visible using either of my Jupiter-T
receivers! :-(
Richard
PRN32 is heading towards the USA, so should be heard there soon!
PRN32 (=SVN23 =SATID 20959) should be above 30 degrees
elevation from Seattle, but
Tom,
At 51 degrees elevation PRN32 just disappeared from the UT+ satelite list.
Could they have changed its status again?
Richard
PRN32 is heading towards the USA, so should be heard there soon!
PRN32 (=SVN23 =SATID 20959) should be above 30 degrees
elevation from Seattle, but so far none of
Brooke Clarke wrote:
Hi Richard:
I neat idea.
I would think there are three key measurements:
TI1 = GPS-A
TI2 = GPS-B
TI3 = A-B
Of these A-B is the most precise and the other two with GPS involved are much
lower stability. In your proposed method only the poor time intervals are
being
Hello,
I looked at the dual standard data from yesterdays run, and
once again the predominance of the short-term variations in
phase occur simultaneously in both systems. As pointed out
earlier a 3-corner hat is the wrong methodology as what I
am doing is closer to a common view comparison. If I
Bruce,
The data I am trying to determine is the GPS short-term phase error
based on the results from comparing the same receiver to multiple
higher short-term stability sources. If that could be determined
then you would have an idea of the short-term noise being added
by the receiver and
Bruce Griffiths wrote:
Bruce,
Thanks for verifying that a common OCXO for the TIC clocks will work.
I wasn't looking forward to downgrading to individual XOs.
Richard
That only works if either:
1) The TIC OCXO isnt locked to the GPS (or either of the oscillators
being disciplined).
OR
Richard,
One more thing, maybe I missed this earlier in the thread, but
can you really call it sawtooth correction when you apply a
receiver reported correction (with 1 ns granularity) to a 1PPS
signal (with 9 ns RMS or +/- 15 p-p jitter) as coarsely measured
by a 100 MHz TIC (with 10 ns
David and Patrick,
Check out the following two sites to get an idea of the
current costs to have a custom made board produced.
http://www.pcb123.com/
http://www.expresspcb.com/index.htm
Richard
Hi David and list
I am quite interested in this post too.
I have wanted to fabricate my own PCBs
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