Hi Demian,
I can confirm that the Wavecrest achieves it's ~3ps noise floor (with some
luck and getting one with a very good internal 100Mhz reference).
For full calibration of the unit, one needs the VISI software and a GPIB
connection.
It does this by having an internal resolution of
Hi Ulrich,
I think in our design the spec is limited by the ~-100dBc noise at 100Hz
offset of the 100MHz VCXO.
Please note that the ADF4002 actually improves that noise by about 15dB
from the datasheet spec (or the unit we tested was that much better than the
one shown in the datasheet).
Hi John,
we have a new 100MHz board (FireFly-IIA-100MHz) that uses an ADF4002 to
generate 100MHz from the 10MHz internal OCXO.
The VCXO we use is rated at better than 100dBc at 100Hz.
The 10MHz reference achieves typ. -148 dBc at 100Hz.
We measured -115dBc/Hz at 100MHz at 100Hz offset in
Spend a little more, and get an HP 8560B or 8560E..
You will be much happier...
In a message dated 2/19/2010 16:39:17 Pacific Standard Time,
jg...@zianet.com writes:
Since the list members are familiar with lots of test equipment, I'd
like to ask what the folks here think about the HP
It works well, and they have a wall-mount version as well.
Note that this reacts to 470MHz GMRS radios: the lamp get's brighter when
transmitting in it's vicinity, and completely shuts-off when you transmit
close to it.
It is very bright indeed.
bye,
Said
In a message dated 1/29/2010
Hi Bjoern,
you replace the capacitor inside it with a zero ohm resistor.
bye,
Said
In a message dated 1/28/2010 05:12:47 Pacific Standard Time,
b...@lysator.liu.se writes:
SMC connectors is available over the desk in my hometown - which is a
fairly remote part of our large globe.
Hi Claude,
since the SMC jack is also DC-connected to the antenna output (through an
inductor) to power the antenna, the unit also works well if you feed 4V to
5V into the unit through the antenna port!
That can be done using an L-band-capable standard Bias-T, and then leaving
the SMC
I recommend un-screwing that SMC since it is almost impossible to find the
mate, and feeding two wires from a 5V supply into the unit through the
hole, and soldering the wires to the PCB. Works well for me.
bye,
Said
In a message dated 1/26/2010 18:36:18 Pacific Standard Time,
Hi Brian,
This is a classical crystal jump.
Nothing one can do about it.
Could have been internal to the crystal (stress-relief) or external (gamma
particle hitting the crystal lattice etc).
My 58503A does it every couple of days or so. Really messes with your ADEV
performance...
Hi Mike,
the model is Extech 380950
It shows up on a Google search. It has a resolution of 1mA DC LSB.
That is the low-cost version, with lot's of features, about $130. The
high-end version costs about $350.
bye,
Said
In a message dated 1/13/2010 14:37:25 Pacific Standard Time,
No,
one is reporting in MSL, the other in GPS height.
There is about a 30m difference between the two here in Santa Clara
county, CA, similar to what you are seeing.
bye,
Said
In a message dated 1/14/2010 15:23:09 Pacific Standard Time,
r...@timing-consultants.com writes:
Depends on
Hi guys,
Extech makes a couple of very nice DC current clamp-on probes.
They have down to 1mA resolution, and one of them is very inexpensive
(around $140 if I remember correctly), and works as a standard multimeter as
well. Very rugged also.
Having a DC current clamp with 1mA resolution
On the 5334, you can get 11 digits resolution on the LED display by
subtracting 10MHz from the measurement (-10MHz offset), and setting the
mesurement intervall to 99 seconds. Both sources need to be 10MHz of course for
this
to work.
On the 5335 I seem to get one digit less with the same
Hello Jamie,
about a month ago there was a long thread that thoroughly discussed the
problems folks have been seeing when running Thunderbolts through splitters.
You may want to search the archive, and take a look..
bye,
Said
In a message dated 1/3/2010 17:42:07 Pacific Standard Time,
I have had no problem with a Gpib to RS-232 converter.
On the tau: not really an issue, just divide the number of lines in your
data file by the measurement time.
Most programs will allow you to enter any sample tau.
bye,
Said
In a message dated 12/29/2009 14:36:53 Pacific Standard
If both sources drift less than 100ns max (pk to pk) at 10MHz, then their
10MHz outputs can be used directly to start/stop the 5370B.
Choose a cable length, and a rise/fall trigger so as to measure as close to
50ns as possible, so the signals can drift up or down from that 50ns
average.
No need for that, just buy all ~18 million tickets (would cost $18 million
in the US) if the jackpot is ~$60 million or higher, which it often is...
I read someone from Australia did that in New York, and won..
In a message dated 12/23/2009 23:38:27 Pacific Standard Time,
Hi Art,
we all lost a true friend. He was always willing to lend a helping hand.
take care,
bye,
Said
In a message dated 12/22/2009 15:05:56 Pacific Standard Time,
a...@synergy-gps.com writes:
We met Randy back in 1975 when we both worked at Hydro Products, an
oceanographic and
Hi John,
but you may not be comparing apples to apples.
Tom's plots are actual performance of probably a very good sample unit.
The 5071A spec lines you drew are worst-case specs.
In reality, the 5071A probably performs much better than it's spec limits?
Also, I think the 5071A just has
Hi Alexander, Robert,
need to set the record straight: sorry, but there is no need to spend $3000
for a new GPSDO.
The FireFly-1A starts at less than $600 single piece qty, new with factory
warranty and support.
Add $80 or so for GPSCon and you will have an SNTP server. Or free when
Hi guys,
that's right, leave the old GPS in there so the firmware won't complain.
Just cut the 1PPS signal between the GPS and main-board, and feed-in an
external 1PPS with higher stability, the Z3801A will never know the difference.
Should work well.
bye,
Said
In a message dated
Just realized that if the Z3801A uses Sawtooth correction from the Oncore,
then it may slightly degrade the 1PPS from the M12+ unless there is a way
to disable sawtooth correction.
Nonetheless, I think the overall performance would improve significantly,
even if the M12+ sawtooth
Hi guys,
I wonder if anyone has ever replaced the 1PPS output of the oncore with an
external 1PPS from say an M12M receiver.
I would suspect all else being the same that the Z3801A would work much
better, and not have the problems Mike is seeing?
bye,
Said
In a message dated
Hi guys,
it turns out I achieve the best results with an E1938A driven by a Fury
board, compared to my PRS-10 Rb. I have not tried a Fury GPSDO with a
standard DOCXO yet, but suspect similar results - that test to follow next
week.
The standard deviation over 15 hours is about 2.3ns, the
Hi guys,
has anyone used a program called NMEA Time? Has this been discussed here
before?
_http://www.visualgps.net/NMEATime/Download/Download.html_
(http://www.visualgps.net/NMEATime/Download/Download.html)
It is supposed to generate IRIG-B on the Audio output, to provide an SNTP
Hi Robert,
thanks for the info. I am wondering how accurate their SNTP server with
1PPS RS-232 input is. Not sure how one would test that without specialized
equipment..
bye,
Said
In a message dated 11/25/2009 11:26:45 Pacific Standard Time,
robert8...@yahoo.co.uk writes:
Hi Said,
Hi,
I am just curious what the NMEA Time program can achieve in terms of SNTP
accuracy. Millisecond accuracy would be sufficient, and should be possible
with the accurate 1PPS input I would think.
bye,
Said
In a message dated 11/25/2009 12:58:27 Pacific Standard Time,
Hi Warren,
yes, I do think I need to insulate the unit(s) from the room heater. That
would probably help, but is a hassle to do. Double OCXO's rule!
bye,
Said
In a message dated 11/23/2009 22:10:33 Pacific Standard Time,
warrensjmail-...@yahoo.com writes:
Note the plot does not look
Hi Tom, Warren,
for now I am planning to identify the two best references I have, then go
into fine-tuning these with TC's, damping factors, etc.
May not be the best way to do it, but should get me some results close to
what I am looking for.
What I am looking for is to get a similar
Hi Warren,
that is correct, I care to make best use of the environment I have, not the
one I would like to have (sounds like Rumsfeld, doesn't it?!).
It works now with the AMU changes, and I did change the TC to 500 as well.
I am comparing against my PRS-10 Rubidium (driven by an M12+
Hi Kit,
there is an easy way out:
Use a Philips Video Decoder (SAA7113 or similar), it will generate a locked
27MHz output reference pixel clock from the video stream coming out of the
STB.
Unfortunately most $49 STB's don't do proper PCR synchronization via PLL,
they just do dropped
Hi Warren, et. al,
here is a plot (about 20hrs long) of my PRS-10 (driven by a M12+) compared
against my Thunderbolt both running from the same antenna feed. Comparison
done on the 10MHz outputs, at maximum sample rate on my 5370B counter. Both
units have been running for 6+ months now,
Hi Tom,
in progress now PRS-10 against a FireFly-IIA...
The PRS-10 is set to a very long time-constant, more than 8 hours if I
remember correctly.. The Thunderbolt is set to 500s TC.
bye,
Said
In a message dated 11/23/2009 20:58:02 Pacific Standard Time,
t...@leapsecond.com writes:
Hi Warren,
checking the PRS-10 against a FireFly-IIA now, and later this month against
a Fury GPSDO.
That should clarify which unit has the best performance in my setup,
including temperature cycling, the antenna/splitter challenge, etc.. I suspect
the PRS-10 with an 8+ hour TC is going
Hi Guys,
changing the AMU thresholds to 2.0 as suggested by Warren fixed the
problem, the unit is now working properly, thanks much for the hint. And no,
this
was not obvious to me.
It is always great to get constructive help rather than the you should
know better type of comments.
In
Hi Nigel, et. al.,
I just changed the setting to C/No with the help of the instructions posted
here; learned yet something else.
With that I now get between 30 and 36dBc/Hz C/No (at night, which usually
results in higher values than during daylight).
I am impatient, and expect my
Hi Bjoern,
I respectfully disagree. I measured the loss through the GPS amp and Mini
Circuits splitter at only 10.1dB. That's really not a lot. I couldn't find
a loss-spec in the Thunderbolts' specification.
The Agilent amp has GPS filters in it that improve signal quality by
filtering
Hi Alan,
I am reading a book about the Apollo computer, they bet their life on it
not failing (everything related to spacecraft maneuvering went through the
computer, there were no mechanical or other backups whatsoever). They only
had a single computer per spacecraft!
The book states
Hi Poul-Henning,
from what I read, they a) had no tools to replace the units or even open
the computer, b) the software was different between the units (LEM had 1/2
the ROM to save weight), and c) the spacecraft attitude thrusters and the
main engines were fully computer controlled (their
Hi Bob,
I read this was done only on Block-1 systems. In Block-2 (the units that
actually carried humans) they had all attitude thrusters, and the main engine
control done by the computer itself. No spares or backup control systems
for the thrusters!
No CM computer, no return to earth. I
Hi Roy,
two of them:
Digital Apollo, Mindell, David A., MIT 2008
and:
Journey to the Moon, History of the Apollo Guidance Computer, Hall, Eldon
C., 1996
The Mindell book is really excellent, reads like a novel, no EE degree
required.
Mindell discusses the trade-offs they made such
Hi Poul,
that AGS system existed only on the LEM, and only to abort a lunar
landing. It couldn't even dock the two craft.
Mindell discusses in great detail how they went to a single-computer
digital Autopilot on pages 138 to 143, because they considered a failure so
remote as to being
Hi Bjoern,
Yes. On our FireFly series GPSDO I get up to 45dB signal to noise ratio
with a passive 1-to-4 splitter following the Agilent active splitter.
I think there is something going on with the Thunderbolts such as the
antenna sense circuit not working properly etc, please also see my
Hello Magnus,
yes, interestingly enough the units I have seem to have the option to power
them through port-1 removed by brute-force: the inductor on all my units
has been ripped off the PCB by force!
This holds for the 1-2, 1-4, and 1-8 Agilent/Symmetricom splitters I have,
all of them
Hi Dave,
one nice feature is that some reasonably priced analyzers offer 1Hz
resolution bandwidths (8560E etc) which is really nice for precise work at
very
high frequencies... and for precise phase noise work which is usually
calibrated in dBc per 1 Hertz.
It allows one to clearly see
Hi Joe,
these are very simple circuits, basically just a voltage regulator from LT,
and an Agilent L1 amplifier MMIC, and a number of SAW/Cavity filters, one
for each output.
Depending on what is wrong (the voltage regulator, or the MMIC) you can
probably replace these two with a host of
Hi Joe,
I have the same problem with my Thunderbolt even though my splitter works
well. Not sure why. This is especially so if I cascade the Agilent unit
with a passive splitter, I can never get the Thunderbolt to lock up.
I think the added noise of the Amp may play funny with the
Wasn't that designed by Sun, the same company that is now strong-arming
itself against Sparkfun to try to shut them down for using their trademark?
The same company just now laying off 3000?
In a message dated 10/29/2009 09:39:15 Pacific Daylight Time,
r...@timing-consultants.com writes:
Nice part, up to 10GHz!
probably well worth the $3.50
If followed by a larger inductor/resistor, could probably be used to well
below 50MHz.
bye,
Said
In a message dated 10/9/2009 06:57:23 Pacific Daylight Time,
ijcous...@verizon.net writes:
For a broad band, surface mount biasing
Hi Joe,
I get these time-outs from GPSCon as well. On my display it says
[DATE][TIME] UTC Receiver Timeout
Or something similar. It is just a time stamp of when GPSCon is trying to
talk to the receiver, and not getting a response before GPSCon times-out.
Nothing to worry about.
bye,
Hi Bruce,
in response to the active antenna biasing discussion we had a couple of
days ago: there is a good reference I ran across with inductor part number,
schematic, and layout in the uBlox literature (hardware reference manuals)
on the uBlox website. They use a single Murata inductor
Hi Bruce,
these are very nice indeed.
I used these conical inductors in our 2004 FireFox broad-band synthesizer
prototype (working from DC to 1.64GHz), they are quite amazing.
But:
* you need a microscope and a VERY stable hand to solder them down, and
cut-off the unused wire. I
Hi Martyn,
not the M12M/M12+.
Some receivers such as those from uBlox already have the hardware, and
will only require a firmware update to work according to the manufacturer.
bye,
Said
In a message dated 10/2/2009 10:11:40 Pacific Daylight Time,
mar...@ptsyst.com writes:
Hello,
Hi guys,
some good news for our European members: the EU officially enabled the
EGNOS service as of today.
For those of you that speak German, here is a Wiki link (there are English
links on the bottom of the page too):
Hi Bruce,
but at first resonance (self resonance) the inductor has the highest
impedance that it will ever have (theoretically infinite impedance), which is
what you want in a bias-t...
bye,
Said
In a message dated 10/1/2009 19:56:03 Pacific Daylight Time,
bruce.griffi...@xtra.co.nz
That's only a small issue in my opinion.
I've designed broadband systems that run at ~50% to 150% of self resonant
frequency, and it works quite well if you put a 50 - 220 Ohm resistor in
series with the inductor as the other member noted.
It works well because it basically is a
Hi James,
In a message dated 9/24/2009 17:34:45 Pacific Daylight Time,
james.p@jpl.nasa.gov writes:
I find that hard to believe.. the use of silver in photography is rapidly
dropping.. I think it used to be about a third of the total market, and now
it's something like 10%.
True,
Hi Rexa,
agree with your comments.
I happen to have a UK passport too, and now live in the US.
These kind of folks are the reason I left Europe for good.
Sometimes it is good to be reminded of just why I left..
In a message dated 9/25/2009 18:55:13 Pacific Daylight Time,
Hi,
yes, tin whiskering is a huge issue. Wikipedia has some nice (and
shocking) pics on it.
One of the best sources of information is the Nasa Tin Whisker page:
_http://nepp.nasa.gov/whisker/_ (http://nepp.nasa.gov/whisker/)
bye,
Said
In a message dated 9/24/2009 06:15:04
That's kind of part of the scam in my opinion, we now create much more
electronic trash in the name of removing miniscule amounts of environmentally
unsafe lead from products..
Forget about running your new Agilent counter for 25+ years like we used to
be able to do...
Another part of
Hi Nigel,
from what I heard from our customers (I have not had a unit to test myself,
and do not have any comparative data), many if not most of these units
have frequency jumps, and are not nearly as good as the Thunderbolt (which is
quite good, and very well documented in the Time Nuts
Hi Nigel,
since you are only concerned about a couple of sample units, I would not be
too worried about the tin-whisker problem. Probability of failure is still
quite low for a single unit, even if massively higher than with lead
solder. If you ordered 10,000 units that would be another
Hi Joe,
I think it is quite limited in the actual phase noise floor you can achieve
at carriers 1GHz. A good OCXO will far out-perform this utility due to
the noise-floor limits of the 8560 series.
To give you an idea, you get about ~90dBc/Hz up to 100Hz offset or so, then
120 - 130dBc
Hi Warren,
that's a smart idea.
It's fun to try different OCXO types out for their individual
sensitivities. I have seen some that are only sensitive in one single axis,
others that
react on several axie.
To take your concept further, one could also orient the OCXO to minimize
the
Hi James,
the kind of experience that makes one a better engineer :)
bye,
Said
In a message dated 8/15/2009 14:35:41 Pacific Daylight Time,
james.p@jpl.nasa.gov writes:
Yes.. In our case, though, I think the microphonics were from movement of
the cavity lid, which wasn't very
Hi Rick,
wonder if the operators needed their hearing calibrated after long
exposures to that :)
A long time ago I designed and built a 1KHz ultra-low-distortion signal
generator using the original H/P design (Wien bridge(?) with a small lamp for
amplitude stability).
That lamp is a
Hi there,
there are special low-g OCXO's out there. We offer one that has better than
3E-010 per g per axis, which is about 10x better than your standard
OCXO.
This is also important for stationary applications where the unit is not
tilted, for vibration-induced phase-noise is also that
Hello Ulrich,
I tested this, and it works like a charm on the FireFly units.
Thanks much again!
Said
In a message dated 7/15/2009 07:58:03 Pacific Daylight Time,
df...@ulrich-bangert.de writes:
Guys,
I have just uploaded a new version of Z38XX with the following
improvements:
1)
Hi Tom,
Two questions - Will the internal TI value still be updated against
GPS in this case (as it is with the TBolt)?
No, unfortunately not.
There is another (better?) command to manually put the Fury/FireFly units
into holdover mode:
SYNChronisation:HOLDover:INITiate
To get out
Hi guys,
I am very excited to say that Ulrich's latest Z38xx program now works quite
well on our FireFly GPSDO units.
Very impressive program Ulrich!
I haven't tried it on our Fury's yet, but I am pretty confident it will
work just as well.
Thanks much again Ulrich, great job!
Said
Hi Don,
to disable the Fury (or FireFly) GPS receiver from disciplining the unit,
send the command:
sync:sour:mode ext
That will switch the unit to external 1PPS input, and thus make it go into
holdover if there is nothing connected to the external 1PPS input.
Bye,
Said
In a
Hi Magnus,
Agree with all your points.
On the added noise due to an accelerometer, my thoughts are that this needs
to be carefully designed so as not to add more error than we are actually
removing (due to phase shifts between crystal sensitivity and the
accelerometer response for
Hello Bjoern,
that would work well for static acceleration (tilt) but for vibration
resistance the crystal must be low-g, or complexly compensated with wide loop
bandwidths such as the FEI papers describe.
Initial Calibration would also be tricky, and having an algorithm to
measure one
Hi Ulrich,
I will try this tomorrow. In the meantime, as requested please find a
minimum list of our supported software commands for our FireFly GPSDO's here,
starting on page 7:
_http://www.jackson-labs.com/docs/FireFly_quickstart.pdf_
Hi Ulrich,
any chance you could send me a list of commands you utility uses as a
minimum command-set so I can cross-check against our Fury/FireFly GPSDO's?
There are lots of folks on this list that have our units, and it would be
great if we could get it up and running for our interface
Hi Antonio,
not an expert on space qualified crystals, but I would think that in
general Cesium and Rubidium crystals would be steered very quickly (within
seconds?) to correct for any crystal jumps that surely will happen even, or
especially in space.
In a GPSDO, we generally only have
Hi Ulrich,
since our FireFly and Fury GPSDO's support GPSCon as well, I tried your
plot program.
We use 115.200 baud by default, but when I set your program to that speed,
it defaults back to 57600 for some reason. Changing our board's baud rate
fixed that problem.
Our status output is
Hi there,
A switcher has much more stresses on the components, since it usually
switches the primary side rectified 110/220V high-voltage across a
transformer.
Thus the switching FET has to be very high voltage capable (about ~170V DC
in the US), and the second component under stress is
Hi Robert,
very good point, one more issue is the number of components used.
On switchers, this is easily 10x to 15x the number of components used on a
simple linear supply.
Every component and it's solder-joints are a statistical sources of
failure.
bye,
Said
In a message dated
Hi Pete,
your best and least expensive path may be to buy a Thunderbolt or
Thunderbolt package (power supply, antenna etc) from the GPS store in China.
Search ebay for Trimble Thunderbolt...
bye,
Said
In a message dated 5/29/2009 10:44:36 Pacific Daylight Time,
Hi guys,
the unit is gone already unfortunately :( It went really quick. Will try to
get some more specials for time-nuts in the next months.
Thanks for your interest!
bye,
Said
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe,
Thanks for the tip Magnus!
One comment on the 1938 discussion: I recently fired-up my E1938
disciplined by our Fury GPSDO. It took 3+ days for the retrace (aging) to slow
down
significantly. Now it's working really well.
Said
In a message dated 4/11/2009 13:53:41 Pacific Daylight Time,
Hi Magnus,
thanks for the info, I got to look at that 5372A again. They were too costly
when I last checked it out some time ago.
There are several Wavecrest on Ebay, starting at ~$1200 for a working unit..
I would love to get my hand on a CNT-90, but again cost and availability is
an
Hello Tom,
Not sure if someone said this already, the Wavecrest units can sample your
data. Up to 40K samples per second continuous according to their
literature, via GPIB.
Their PC application software (VISI) has a scope mode where you can make
this data visible just like on a
Hello Pete, Bruce,
I can confirm that the Wavecrest is sensitive to edge rise-time. It was not
designed to measure sine waves.
With a 10MHz sine wave from a Fury GPSDO as the source I get 8 - 10ps rms
jitter.
That exact same signal run through an NC7SZ04 buffer prior to feeding it
into
Hi There,
this is quite a good correlation I would say. I am surprised that they use
an external temp sensor, not internal to the OCXO.
4.5us drift over 24 hours is pretty good though.
bye,
Said
In a message dated 3/12/2009 12:07:43 Pacific Daylight Time,
hol...@hotmail.com writes:
Hi Tom, Holrum,
nice plots, do you have access to the Thunderbolt EFC over that day?
Holrum mentioned:
Also, by looking at the DAC and TEMP plots the temp sensor chip readings
ARE used in generating the DAC voltage in GPS locked mode...
Is there any chance to post these plots?
Hi Holrum,
thanks for sending the plot. It's tough to see on this plot with all that
noise.
To see how the relationship really works, the unit should be in holdover..
Would you have a plot of EFC versus temp in holdover?
thanks,
Said
In a message dated 3/8/2009 13:42:41 Pacific
Hi,
while this is good news for Trimble's competition and may open up the avenue
for an amateur mod, I think we would have to be fair to Trimble and do the
double-blind test:
1) Put the original temp sensor back into the unit, let it run one week, and
do the drift tests exactly the same
Hi there,
Would you have the EFC plots while in holdover for us?
You can try to place the unit into your refrigerator. That will drop it down
to 3C or so from ambient. That will give you enough of a change so that you
can see how the EFC changes with the two sensors.. It will also give you
Hi Bruce,
the PRS-10 datasheet is pretty smart in not showing the data below 10s
through, it would make their 10s performance not shine as much. There
certainly
could not be any measurement reason for not showing 10s ADEV.
As someone has mentioned, they also used a very bad GPS receiver
Good stuff coming down the pipe,
I looked at the Mems/Si technology and the phase noise, thermal stability,
and jitter specs are orders of magnitude higher than what we would like to see
here on Time Nuts.
I think Quartz is going to be the king of the hill for some time to come due
to
Hi Bruce,
seems that would be in line with extending the 10s plot down to 1s in a
linear fashion.
Not that great. Tom's GPSDO measurements show some GPSDO's go down to ~E-013
at 1s.
bye,
Said
In a message dated 2/25/2009 12:33:22 Pacific Standard Time,
bruce.griffi...@xtra.co.nz
Hi there,
my Watts Up? power meter showed a reading of 130V+ one day coming from PGE
here in NorCal. I confirmed this with another meter.
_https://www.wattsupmeters.com/secure/products.php_
(https://www.wattsupmeters.com/secure/products.php)
I called PGE, and they were surprised that
Hi Alf,
if you can get an M12+ from iLotus, that's not too shabby either. M12M is
the king of the crop though as Bruce said.
Now you got two answers :)
bye,
Said
In a message dated 2/17/2009 13:50:54 Pacific Standard Time,
alf.pou...@surffi.net writes:
Thanks Bruce for your answer,
Hi there,
I did see that in the recent GPS World receiver survey, but Javad for
example only claims 3ns rms accuracy...
The m12+ claim 2ns rms in the old Motorola literature, but that only with a
properly surveyed antenna, sawtooth compensation, and good antenna-delay
calibration of
Hi,
in the previous edition of the magazine GPS WORLD there is a GPS receiver
survey, in the table they state 3ns rms timing, but there is no clear
definition
what the measurement details are.
bye,
Said
In a message dated 2/17/2009 15:51:15 Pacific Standard Time,
b...@lysator.liu.se
Hello Tom,
over the last week we've been doing a test on a double oven Fury GPSDO in
response to our discussion.
The first part of the test was running the unit on the lab bench without
modifications. A couple of days ago, we removed the OCXO Supply regulator
feedback sense resistor, and
Hello Tom,
it's pretty straight forward to calculate the effects of ground-loop due to
cable loss; we can calculate this based on the impedance of the wire.
From Wiki (search for AWG table) we get 16.14 Ohms/1000Ft, or 16.14mOhms/
foot for a 22 Gage wire. We have seen that the OCXO
Hi Tom,
yes, they are all GPS locked.
here is the same OCXO type without proper temp compensation:
_http://www.jackson-labs.com/images/gpsstat.htm_
(http://www.jackson-labs.com/images/gpsstat.htm)
You can see that now the phase has to change considerably to compensate for
the EFC
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