John Miles wrote:
You can easily add noise to a sinewave, for example a hybrid combiner
can be used to combine the output of a sinewave generator and a noise
source.
That's just going to create AM noise, isn't it? He wants jitter (phase
modulation), I believe.
-- john, KE5FX
John Miles wrote:
Well, sure, but it also causes all kinds of secondary distortion effects
(such as potential clipping at the rails of whatever you're feeding the
signal into). I don't think AM'ing the signal when you want PM is a good
idea, when it's so easy to apply PM by itself.
-- john,
Bilal Amin wrote:
Hi John and Bruce,
Thank you for your ideas. Now I have a much better picture for the
experiment using the comparator. Now, my only concern is a noise generator.
I have searched and found out that all the commercially available now
generators are very expensive and some
Bilal Amin wrote:
Hi John and Bruce,
Thank you for your ideas. Now I have a much better picture for the
experiment using the comparator. Now, my only concern is a noise generator.
I have searched and found out that all the commercially available now
generators are very expensive and some
Stephan Sandenbergh wrote:
Hi Bruce,
Thanks for explaining - the picture is starting to become clearer. I knew
there must be a reason why commercial multipliers are so expensive.
If I understand you correctly the variation in phase (or group delay) caused
by a variation in temperature
Pete wrote:
Bruce,
Can you please provide some references to phase noise problems/performance
of the passive components you mention?
Pete Rawson
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David I. Emery wrote:
On Fri, Mar 02, 2007 at 04:02:39AM +1300, Dr Bruce Griffiths wrote:
Its not just the temperature coefficients, real inductors and capacitors
have inherent phase noise.
Silver mica capacitors can be very bad as are ferrite core inductors.
Mylar capacitors are good
Ulrich Bangert wrote:
Hi foks,
I want to put forward a similar but slightly different question:
Suppose I need an clock running at around 50 Mhz for an DDS. Because of
the DDS it need not be exactly 50 MHz, can be 52 or 54 MHz too.
Basically this clock shall be derived from a 10 MHz source
Bilal Amin wrote:
Hi Everyone,
I am working on Jitter in Analog to Digital Converters(ADCs) for GPS receiver
front-end. I am trying to setup an experiment to see the effects of jitter in
real time ADCs. I have an ADC evaluation board with external clock input for
sampling (i.e Sampling
Bilal Amin wrote:
Hi Everyone,
I am working on Jitter in Analog to Digital Converters(ADCs) for GPS receiver
front-end. I am trying to setup an experiment to see the effects of jitter in
real time ADCs. I have an ADC evaluation board with external clock input for
sampling (i.e Sampling
Larry Gadallah wrote:
Hello all:
I considering a do-it-yourself GPSDO, and I started by looking for a
good OCXO. I have been given a quote for a unit with the following
phase-noise numbers:
-120 dBc/Hz at 10 Hz
-145 dBc/Hz at 100 Hz
-155 dBc/Hz at 1 kHz
-160 dBc/Hz at 10 KHz
-160 dBc/Hz
Stephan Sandenbergh wrote:
Hi all,
How difficult is it to multiply a frequency standard from 10MHz to 100MHz?
I found the recent discussion about amplifying a 10MHz OCXO output from 5dBm
to 15dBm very interesting. Thanks Bruce for sending me that common base
circuit schematics - I
Larry Gadallah wrote:
On 2/28/07, [EMAIL PROTECTED] [EMAIL PROTECTED]
wrote:
Message: 6
Date: Thu, 01 Mar 2007 12:05:38 +1300
From: Dr Bruce Griffiths [EMAIL PROTECTED]
Subject: Re: [time-nuts] Good Phase-noise?
To: Discussion of precise time and frequency measurement
time-nuts
Larry Gadallah wrote:
Hello Bruce:
Larry
Obtaining a lower phase noise COTS OCXO in this price range is unlikely
unless Wenzel oscillators are unusually cheap.
http://www.wenzel.com/catalog.html#HF%20Oscillators
Is Wenzel the leader of the pack in this sort of technology? I know
that
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Angus wrote:
Although that's not what I was talking about doing above, I think that
it's pretty much what some of the hardware GPSDO's actually do using
various types of oscillators (and to good
Hal Murray wrote:
If I understand things correctly, when a box like the 5334 takes a sequence
of frequency measurements, each measurement has a start time and a stop time.
For each measurement, you get out the number of ticks (including fraction)
on the input signal between those times
Angus wrote:
I don't know whether the outputs on a Jupiter exhibit any granularity
or not (I've not seen anything to suggest that they do), but I think
that with receivers that do, changing from 1PPS to a faster PPS output
would normally change the granularity effects that are seen - assuming
[EMAIL PROTECTED] wrote:
Hi Bruce,
would you have some sample schematics for a more modern, faster version of
this than let's say the one used in the 5334A etc that you could share?
thanks,
Said
Said
The Attached GIF file illustrates one possible approach to a TAC using
discrete
[EMAIL PROTECTED] wrote:
Hi Bruce,
would you have some sample schematics for a more modern, faster version of
this than let's say the one used in the 5334A etc that you could share?
thanks,
Said
BRBRBR**BR AOL now offers free
email to everyone.
[EMAIL PROTECTED] wrote:
1. Same test with a Fluke 6680 yeilds 10MHz mean exactly.
2.Tried different length cables and swapping the cables. Same result.
3. Autocal was done (a few times)
- Original Message -
From: Tom Van Baak [EMAIL PROTECTED]
To: Discussion of precise time
John Miles wrote:
What do people observe on their 5370A/Bs? After warmup, I tend to see a
bias of about +0.0005 Hz, or 5E-11, when observing its own 10 MHz source.
There is some occasional random waffling on the order of about +/- 0.001 Hz
but for the most part it reads close to 10.000 000
Hal Murray wrote:
Every time I dig through the 5370 schematics, I think to myself
wouldn't it be nifty to build a replacement plug-in card with a
modern fast CPU to run the instrument, but I try and stop myself
there.
Suppose you start with an FPGA on a PCI card.
What sort of front
Hal Murray wrote:
Every time I dig through the 5370 schematics, I think to myself
wouldn't it be nifty to build a replacement plug-in card with a
modern fast CPU to run the instrument, but I try and stop myself
there.
Suppose you start with an FPGA on a PCI card.
What sort of front
Jared Morrisen wrote:
Interesting piece...
*Weak Enforcement of Corporate Governance and Lax Technical Controls Have
Enabled the Illegal Backdating of Stock Options*
*Conclusion*
The backdating fiasco demonstrates that the need for synchronized time is a
crucial business and technology
Magnus Danielson wrote:
I don't have the manuals (and particular the service manual) for the
SR620,
does anybody have them in electronics form?
Cheers,
Magnus
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[EMAIL PROTECTED] wrote:
I've done the self calibration. Nothing changes. I've let everything
warm-up and checked both channels A and B, same thing. I've swapped the
cables on the front and the back, same thing. I've tried a T-connector on
the ref input with 50ohm termination, same
Mike Fahmie wrote:
At 02:57 PM 2/21/2007, you wrote:
I have an SR620 counter that I set up with a Z3801A as an external
reference. If I put a bnc T connector at the output of the Z3801A and use
two equal length bnc cables, one to the ext. ref input on the back and the
other to channel
setup with my other counter and it read 10,000,000. or
thereabouts correctly. So rule out the GPSDO and the cables.
- Original Message -
From: Dr Bruce Griffiths [EMAIL PROTECTED]
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Wednesday
[EMAIL PROTECTED] wrote:
...if my model is correct the apparent offset in the
mean will be increased by a factor of 10 over that for a a 1 second gate
time.
Bruce
Looks like you're right Bruce. I did both 1, 0.1 and 0.01 gate times and
the error increased by a factor of 10.
And
Jared Morrisen wrote:
And just how does this prevent someone altering the files's timestamp?
Not sure what your point is.
/jared
Jared
Just ensuring that the computer clock is accurate, doesn't prevent
anyone from tampering with the file timestamps as well as the
documentation
Didier Juges wrote:
Dr Bruce Griffiths wrote:
[EMAIL PROTECTED] wrote:
...if my model is correct the apparent offset in the
mean will be increased by a factor of 10 over that for a a 1 second gate
time.
Bruce
Looks like you're right Bruce. I did both
Didier Juges wrote:
This is for a price sensitive commercial application, not a science
project and he is trying to minimize the amount of hardware at the far
end for cost and maintenance reasons.
A cleanup PLL becomes very costly when dealing with a frequency agile
system.
Thanks
for
the HP-Journal article.
Best regards, Jeroen
Dr Bruce Griffiths wrote:
Jeroen
This means that the revised specifications apply to your oscillator, The
1976 datasheet will be applicable as will the circuit diagram that is
available.
Bruce
Didier
Additional references
http://www.nt.hs-bremen.de/peik/rof/literatur/ROF-franz-presentation.pdf
http://www.plextek.eu/brochure/rffiber.pdf
http://www.opticalzonu.com/products/oz400TR.pdf
As you may glean from the above you wont be able to achieve anything
useful unless the laser is
Didier Juges wrote:
Bruce,
The more I read the specs, the more obvious it becomes. I did not
realize how jittery these things are.
I am still trying to get more info on how clean the LO has to be, but I
am pretty sure it will be close to telecom specs.
Thanks,
Didier
Didier
One
Didier Juges wrote:
Bruce,
I have read about this, noise performance also is not good for analog
transmissions, causing very limited dynamic range.
That's probably why they use either FM or digital coding in just about
all applications.
I just did not think the jitter would be so bad,
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Bruce,
I have read about this, noise performance also is not good for analog
transmissions, causing very limited dynamic range.
That's probably why they use either FM or digital coding in just about
all
Hej Magnus
Magnus Danielson wrote:
An interesting product originating from Mitel (Mike and Terry's
lawnmowers later became MITEL - according to their local rep about 20
odd years ago)
Hehe... yeah, I know it was in the Mitel days they started this. I even
beleive
that the GPS
Magnus Danielson wrote:
From: Dr Bruce Griffiths [EMAIL PROTECTED]
Subject: Re: [time-nuts] 5370B on eBay, carrier phase tracking GPS receiver
Date: Mon, 19 Feb 2007 23:39:47 +1300
Message-ID: [EMAIL PROTECTED]
Hej Magnus
Hej Bruce,
Fuller version is that the later Mitel
Rob Kimberley wrote:
Interestingly, no one has mentioned the Augmentation systems like WAAS or
EGNOS where wide area correction data is transmitted down from INMARSAT to
improve nav accuracy. Primarily aimed at improved aircraft navigation
systems, it has a benefit for timing users. Zyfer have
Didier Juges wrote:
Magnus Danielson wrote:
You can acheive much greater speedup by a combined frequency/phase approach.
You will get a very accurate frequency error estimate, so you will very
quickly be close enought to go into phase lock. At least if your clock isn't
too noisy. So, the
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier
Typically with a good local oscillator you can do even better than that,
around 1E-11 in 1 sec is achievable and has been achieved.
Even with the on board TCXO typically 3E-11 or so in 1s is achieved.
Bruce
I don't
Didier
Didier Juges wrote:
Hi Bruce,
Dr Bruce Griffiths wrote:
Bon soir Didier
You are confusing the disciplining precision of the oscillator with
measurement of its short term stability via the GPS receiver in this case.
Bruce
Bon après midi to you, I believe, and if my
Didier Juges wrote:
This is somewhat off topic, but still a matter of precision timing.
A friend of mine wants to send a 3 GHz LO signal up a fiber optic cable.
I know there have been threads dealing with transmission of precise
timing signals over fiber optics, and I hope I can get some
Didier Juges wrote:
This is somewhat off topic, but still a matter of precision timing.
A friend of mine wants to send a 3 GHz LO signal up a fiber optic cable.
I know there have been threads dealing with transmission of precise
timing signals over fiber optics, and I hope I can get some
Didier Juges wrote:
This is somewhat off topic, but still a matter of precision timing.
A friend of mine wants to send a 3 GHz LO signal up a fiber optic cable.
I know there have been threads dealing with transmission of precise
timing signals over fiber optics, and I hope I can get some
Didier Juges wrote:
does not have an OCXO, I think.
I remember seeing a number of postings on time-nuts (must have been
Bruce) advocating the increased performance of carrier phase tracking,
but I need to educate myself about what it is and what good it can do
for me :-)
Any feedback
Didier Juges wrote:
On a different subject, I just won a Novatel Superstar 2 GPS receiver
advertised to do carrier phase tracking. It's specification lists a
timing accuracy of 50nS typical, which is not bad at all for a GPS that
does not have an OCXO, I think.
I remember seeing a number
Brooke Clarke wrote:
Hi Didier:
Many GPS receivers output carrier phase data but it's usually used in
post processing to get survey grade position accuracy. Since the code
phase position accuracy is larger than a wavelength the receiver does
not know how many integer wavelengths to add.
Brooke Clarke wrote:
Hi Bruce:
Is there a paper describing the method?
Have Fun,
Brooke Clarke
Have Fun,
Brooke
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
Dr Bruce Griffiths wrote:
Brooke
Yes I
Magnus Danielson wrote:
http://tycho.usno.navy.mil/ptti/ptti99/PTTI_1999_405.PDF
There is another paper just before it. There is also a patent for a
specific
form of implementation.
Note they used an Oncore VP, the Superstar has a better carrier phase
tracking.performance.
Jeroen Bastemeijer wrote:
Dear Time-nuts,
New info on an old subject:
I opened the counter (5345A) to check what kind of oscillator was
inside. It was a 10544A instead of a 10811A!!!
I checked for a datasheet of the 10544 but I couldn't find it. Luckily I
ran across an article in HP
Rob Kimberley wrote:
Interesting paper. I agree that for nanosecond timing applications then
antenna cable and matching are important. However, for frequency sync
applications and non-critical timing, then the effects of the 75 vs. 50 ohm
cable will not be noticeable.
Rob K
Those who
Steve1 Baillargeon wrote:
Is this link correct? I don't see refrences to antenna cables?
No a slight typo should have been
http://tf.nist.gov/timefreq/general/pdf/1384.pdf
Bruce
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Those who like tinkering with their rubidium standards may find the
following paper of interest
http://tf.nist.gov/timefreq/general/pdf/1013.pdf
You can potentially drop the Allan deviation of a rubidium package by a
factor of ten using the modification detailed in the paper.
Bruce
Christopher Hoover wrote:
Those who like tinkering with their rubidium standards
may find the following paper of interest
http://tf.nist.gov/timefreq/general/pdf/1013.pdf
This is very interesting, indeed, and a very nice practical, follow-on work
from the theory paper by
For those who would like to improve the phase noise of the output of a
digital divider or who would like a good reason to using DDS instead see:
http://tf.nist.gov/timefreq/general/pdf/1380.pdf
Bruce
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Those who maintain that its OK to use 75 ohm GPS antenna cable should read:
http://tf.nist.gov/timefreq/general/pdf/1380.pdf
Bruce
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Christopher Hoover wrote:
Those who maintain that its OK to use 75 ohm GPS antenna
cable should read:
http://tf.nist.gov/timefreq/general/pdf/1380.pdf
(I think you pasted the wrong URL.)
While I provided the quote from the Thunderbolt manual that said, according
to Trimble, that 75Z
Christopher Hoover wrote:
Agreed, that that regulator doesn't have sufficient margin for the entire
TADD-1.
I was suggesting using the low-noise high PSRR linear reg only to establish
the bias level.
There are indeed better parts. This one looks pretty good for an
integration solution
://www.ko4bb.com/Test_Equipment/AvalanchePulser
Now, I just need a scope fast enough to take advantage of such a short
rise time. Back to eBay again :-)
Didier
Dr Bruce Griffiths wrote:
Didier
You can always build your own 100A avalanche transistor pulser using
several Zetex FMMT413s.
Bruce
Ulrich Bangert wrote:
Bruce,
I have seen this specs before but do you know how to find the
schematics?
Best regards
Ulric Bangert
Ulrich
NO, I'm still looking, I presume you mean the NIST amplifier schematics
and not the TADD-1 schematics at:
http://www.tapr.org/~n8ur/
Ulrich Bangert wrote:
Bruce,
I have seen this specs before but do you know how to find the
schematics?
Best regards
Ulric Bangert
Ulrich
Since the earlier NBS isolation/distribution amplifiers consisted of dc
coupled cascaded common base stages (according to Magnus who had looked
at
Christopher Hoover wrote:
The power supply noise may also limit the performance.
This is my major concern with the design.
Any noise on the supply rail goes into the first stage via the bias network,
and is transferred at whatever gain to the output.
I noticed that when I used a
Richard W. Solomon wrote:
I got a junker HP 5328A Counter and salvaged the Time Base and the
circuit board it is on. Does anyone have the schematic for it
Thanks,
73, Dick, W1KSZ
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Chris
Christopher Hoover wrote:
The TI regulators are, from my perspective extremely noisy, one can do
much better at least for higher output voltages.
They also don't have a high enough output for the TADD-1.
Agreed, that that regulator doesn't have sufficient margin for the entire
CORRECTION
Judging from the oscillator and oven controller voltage ranges Tom's
scanned circuit is actually for the later production models of the
10544A with the improved phase noise specification. The input signal to
the oscillator buffer cascode was probably somewhat smaller than 76mV
rms
Lester Veenstra M0YCM wrote:
I have a bad 10544 (received from AST) that I am planning to look into.
No 10 MHz out and very low 12 VDC current.
Has anyone the translation from HP PN to Commercial equiv for the
semiconductors ?
Thanks
Les
Lester B Veenstra
M0YCM K1YCM
Lester Veenstra M0YCM wrote:
I have a bad 10544 (received from AST) that I am planning to look into.
No 10 MHz out and very low 12 VDC current.
Has anyone the translation from HP PN to Commercial equiv for the
semiconductors ?
Thanks
Les
Lester B Veenstra
M0YCM K1YCM
John Ackermann N8UR wrote:
I had a chance to measure a TADD-1 using an HP-3048 phase noise system
last year. I've attached a screen shot of the results; in short it was
below -140dBc/Hz from 100 Hz on out (by the way, I'm not sure I would
trust the noise floor shown in this test; I am not
Stephan Sandenbergh wrote:
Hi Bruce,
A great many thanks for all the hints and tips you gave me.
Yes, I have actually started working my way through Wenzel's hints tips
pages after I posted the first message. I remembered that you pointed me
there in a previous conversation we had.
I
Didier Juges wrote:
Dr Bruce Griffiths [EMAIL PROTECTED] wrote:
The RF amp IC's generally have inferior noise figures and reverse
isolation (20dB for RFIC, 40dB for common base stage) than a well
designed discrete common base amplifier. In fact by stacking common base
amplifiers
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Bruce,
In cases where the output signal does not need to be a sinewave, how would a
common base amplifier compare to a fast comparator and if necessary a
digital buffer as necessary to deliver the necessary power level
Ulrich Bangert wrote:
Bruce and Didier,
i had the opportunity to measure the output to output as well as the
output to input isolation of a diy MAX477 based distribution amplifier
very similar to the TADD-1 (but not identical). The output to output
isolation was in the order of 75 dB while
Howard W. Ashcraft wrote:
I am constructing a GPS disciplined OCXO using an HP10544a. If someone
has a copy of the HP manual/technical data for this oscillator, I would
appreciate getting a scan. I have already received, from a request on
the HP equipment listserv, a copy of an HP10544
Howard
I also have the July 1975, July 1976 10544A datasheets.
The phase noise floor specification is about 15dB lower in these later
datasheets.
The oven controller switching noise decoupling circuits were elaborated
to include a 10mH 0.75A inductor and a 200uf capacitor for filtring
the
Gerald Molenkamp wrote:
Hi Howard,
Please find attached a schematic of the 10544, hope it helps in anyway.
Regards
Gerald
Gerald
The connection of the 10K oven monitor resistor R12 in the schematic is
incorrect.
In this position only the very small deviations in the oven supply
Gerald
Its about 30 years since I had one of these apart for (sucessful) repair
without the aid of any circuit diagram.
At least one can calculate that the nominal crystal current is about 240
uA rms somewhat less than the 1mA in the 10811 with its SC cut crystal.
Bruce
Gerald Molenkamp wrote:
Howard
Attached GIf file depicts the recommended power supply filtering when
the oven circuit shares the same supply as the oscillator.
Bruce
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Don
Don Collie wrote:
Why not use an optocoupler as an isolation amplifier? - to the best of my
knowledge it would provide infinite isolation.
Cheers,...Don Collie
And lots of noise.
You will need a cleanup PLL on the output side.
Also optocoupler
Gerald Molenkamp wrote:
Hi Bruce,
You are right. I havn't checked my unit against the schematic at all. It is
well secured calibrated and operating in my HP 5342 operating well within
the specifications. The scanned schematic came from Leapsecond a few years
ago, and I have not had to use
Stephan Sandenbergh wrote:
Hi All,
Say for instance you have a 5dBm clean 10MHz sinusoid (such as that provided
by an OCXO). Now you want to run this signal to a device that will take a
minimum of 10dBm and maximum of 15dBm as input. How does one amplify the
5dBm?
The first thing
Stephan Sandenbergh wrote:
Hi All,
Say for instance you have a 5dBm clean 10MHz sinusoid (such as that provided
by an OCXO). Now you want to run this signal to a device that will take a
minimum of 10dBm and maximum of 15dBm as input. How does one amplify the
5dBm?
The first thing
Stephan Sandenbergh wrote:
Hi Bill,
Judging by your question - that is probably something that I should do?
Considering that you'll attenuate the 5dBm signal to about 0dBm and then
amplifying it back up to about 10dBm. My gut tells me that by attenuating
the signal before amplifying it will
Stephan
Attached GIF file is the schematic for a common base amplifier with
about 12dB of gain into a 50 ohm load.
The amplifier will not saturate even if the load is open circuited.
Q102 temperature compensates Q103 which regulates the dc collector
current of the common base transistor.
Hal Murray wrote:
Of course for phase comparison with the input, one actually does not
need much filtering as one is only using the NCO digital output as an
input to a phase comparator... spurs and so forth don't count at all
here as they get filtered out in the subsequent loop filter for
Christopher Hoover wrote:
Most (except for Trimble,..) GPS receivers and antennas
are designed to use 50 ohm cable.
Trimble Bullet GPS antennas have a 50 ohm output impedance.
Trimble literature however is ambiguous in that in the
Resolution T receiver datasheets talk about using RG59
to
: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Im Auftrag von Dr Bruce Griffiths
Gesendet: Samstag, 27. Januar 2007 23:43
An: Discussion of precise time and frequency measurement
Betreff: Re: [time-nuts] Austron PRR-10 GPS discliplined Rb...
Ulrich
Since an adjustment range of a few ppm
Those of you who use multifrequency GPS antennas such as choke ring
antennas may find the following article of some interest.
The new Trimble antenna has better performance than a choke ring antenna
especially if more than 2 frequencies are required.
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Christopher Hoover wrote:
Most (except for Trimble,..) GPS receivers and antennas
are designed to use 50 ohm cable.
Trimble Bullet GPS antennas have a 50 ohm output impedance.
Trimble literature however is ambiguous
Chris
Christopher Hoover wrote:
Most (except for Trimble,..) GPS receivers and antennas
are designed to use 50 ohm cable.
Trimble Bullet GPS antennas have a 50 ohm output impedance.
Trimble literature however is ambiguous in that in the
Resolution T receiver datasheets talk
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Christopher Hoover wrote:
Most (except for Trimble,..) GPS receivers and antennas
are designed to use 50 ohm cable.
Trimble Bullet GPS
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Chris
Christopher Hoover wrote:
Most (except for Trimble,..) GPS receivers and antennas
are designed to use 50 ohm cable.
Trimble Bullet GPS antennas have a 50 ohm output impedance
Poul-Henning Kamp wrote:
In message [EMAIL PROTECTED], Dr Bruce Griffiths writes:
I can see the difference between the short 50 ohm cable terminated in 50
ohms and the short 50 ohm cable terminated in 75 ohms.
It would be instructive to repeat this with a short length of 75 ohm
cable
Didier Juges wrote:
It is true is that the impedance of a transmission line is not constant
with frequency, particularly at the low end (audio).
At the higher end, a lot of things happen, such as impedance,
attenuation and velocity factor all change (a little) with frequency.
Also, at the
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Didier Juges wrote:
Dr Bruce Griffiths wrote:
Chris
Christopher Hoover wrote:
Most (except
I think that the simplest explanation for the BIPM's recommendation that
the antenna cables be matched to the antenna output impedance and the
GPS receivers input impedance is as follows:
If one has gone to the trouble and expense of installing an antenna that
is relatively insensitive to
David I. Emery wrote:
Apparently the Austron/Datum versions (they held a patent on
this) have adjustment in the better than 10^12 area but the PRR-10 is a
pretty old design and one could certainly do better with a modern NCO
chip.
The PRR-10 and other Austron designs I am vaguely
David
David I. Emery wrote:
On Sat, Jan 27, 2007 at 01:32:40PM +0100, Ulrich Bangert wrote:
Rob,
are you absolutely sure it works this way? I experimented a lot with a
48 bit dds chip from analog devices for a GPSDO just to learn that THIS
way worked not good. What however works good is
David I. Emery wrote:
On Sun, Jan 28, 2007 at 11:43:11AM +1300, Dr Bruce Griffiths wrote:
The DDS will need to have an internal clock of at least 30MHz or so to
generate a usable 10MHz output.
Agreed, assuming the chip doesn't do clock multiplication as
several do
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