On 11/05/2012 06:30 AM, Tom Van Baak wrote:
Ah, I see what you mean now. Yes, that setup can give you a rough estimate of
the counter's noise floor.
I can't give you specific numbers but one danger with this sort of test is that
the input and the timebase are artificially locked together
Thanks guys,
Like usual more complicated than I thought. I was hoping that this would
cancel any stability issues common to both the reference and the signal
thus giving me best case ability. I seem to be getting numbers too good to
be true so there must be a hitch. I get an ADEV 5x10-13 at 1
Try this setup: feed the GPSDO into A and B inputs but not to the
reference. That is, use the counter internal reference to time the
difference so that you have an uncorrelated source that can span all the
interpolator's nonlinearities.
On Mon, Nov 5, 2012 at 11:42 AM, Bill Dailey
Hi
As a practical example - a SR620 will look much better reading it's own
reference than it will looking at almost anything else. That said, it's still a
good idea to make sure the counter looks good reading it's own reference. If it
doesn't look good, then you need to fix something.
Bob
I built a GPSDO using my own power supply,
a VE2ZAZ board, a Trimble Resolution T GPS
and a surplus HP 10811 oscillator.
I'm having a bit of trouble with it. I have it set up and
it locks ok and stays in lock so far. But the recommended
long-term integration setting is not working for me.
Yes when I was measuring the noise floors of my 5370B's, the noise floor
appeared to be noticeably better when the same oscillator was used as both the
time base for the 5370B and the signal source for the test. Sorry I'm on the
road right now (in Mexico City) and can't post a plot showing
If you can measure the 10811 frequency as a function of the control
voltage with the 10811 control voltage input disconnected from
everything else, you'll have a curve that will allow you to translate
control voltage changes into frequency drift.
My impression is that the 10811 ageing is
Hi
Sounds very normal to me.
The EFC voltage can be converted directly to a frequency change. There are
enough variants of the 10811 that checking what you have is probably the
best idea. A good guess is that it tunes 0.2 ppm over the full EFC range.
To check the OCXO - break the loop, hook up
Chris:
I doubt that you have test equipment that can directly measure
the hourly aging frequency drift of the HP10811.
To get a handle on what you are dealing with, you need
to use the spec sheet on the HP10811 to calculate
the tuning sensitivity of the HP10811, in Hz per Volts.
(more likely
Chris:
I doubt that you have test equipment that can directly measure
the hourly aging frequency drift of the HP10811.
To get a handle on what you are dealing with, you need
to use the spec sheet on the HP10811 to calculate
the tuning sensitivity of the HP10811, in Hz per Volts.
(more likely
Chris
QI can measure the control voltage change over time and convert that into a
frequency drift?
Yes, no problem as long as the discipline loop is working OK.
It is very easy to plot the oscillator's long term drift per day, by just
plotting the filtered analog EFC control voltage.
Guys,
be aware, first of all, that to correctly test your new GPSDO you need an
already running GPSDO as a reference (and a 10 digits-per-second
interpolating counter). Don't forget/overlook the reference: start always
with a known, good reference.
On Mon, Nov 5, 2012 at 9:12 PM, WarrenS
Maybe need to define Correctly
True, It sure helps if one has lots of nice test equipment around to start
with, but
Then again if one already has the better test equipment needed to be able to
quickly test a new GPS,
then there would not be much reason to be building a home built thing.
I've had a Z3801A for about a year. It's always had an issue where the
number of satellites tracked will drop to zero for one or two readings
and then jump right back where it was ( often at 5 or 6 satellites ).
This often (but not always) affects the EFC and/or PPS and/or HUP. My
Tbolt is
On 11/5/2012 3:16 PM, Richard H McCorkle wrote:
The EFC specs on a 10811 are a frequency change of 1 Hz over
a –5v to +5v EFC span or a sensitivity of roughly 1e-8 per volt
(varies widely up to about 3e-8 / volt on some units) so you can
get a ballpark idea of the age rate by looking at
Hi
If you have one of the 10811's out of a Z3801, then it's EFC range is ~ 10X
a normal part. There apparently are other odd EFC ranges out there.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Chris Howard
Sent: Monday, November
Very interesting... is it using the binary protocol? Maybe a serial link
error, the binary protocol has a checksum (yes, NMEA too). Check the serial
link levels with a 'scope, maybe that the Z3801 firmware waits to see some
consecutive errors before actually reporting that something is wrong,
Yes, you're right: you need more time without a nice reference but it can
be done. You can use the PPS from the GPS receiver itself to begin with.
Anyway you may want to build your very own GPSDO even if you already have
an H-maser at hand. To start building GPSDOs you really need only a digital
Bob Camp wrote:
Hi
If you have one of the 10811's out of a Z3801, then it's EFC range is ~
10X
a normal part. There apparently are other odd EFC ranges out there.
Bob
For example, the 5071A cesium standard has 10X range (modified 10811).
I guess in the 5061 you just had to tweak the
I have three 5071 10811's all have below 1 E-12 AV from 1 to 100 seconds.
Bert Kehren
In a message dated 11/5/2012 7:07:52 P.M. Eastern Standard Time,
rich...@karlquist.com writes:
Bob Camp wrote:
Hi
If you have one of the 10811's out of a Z3801, then it's EFC range is ~
10X
a
Hi Bob,
On 11/05/2012 01:30 PM, Bob Camp wrote:
Hi
As a practical example - a SR620 will look much better reading it's own
reference than it will looking at almost anything else. That said, it's still a
good idea to make sure the counter looks good reading it's own reference. If it
doesn't
I would measure the counter both ways to characterize it, and you may
learn a little more about how it reacts.
Use its internal oscillator for the counter, apply the same 1PPS signal
to both inputs.
Use an external time base for the counter, apply the same 1 PPS to both
inputs - make sure
On Tue, 06 Nov 2012 02:14:04 +0100, Magnus Danielson
mag...@rubidium.dyndns.org wrote:
Hi Bob,
On 11/05/2012 01:30 PM, Bob Camp wrote:
Hi
As a practical example - a SR620 will look much better reading it's own
reference than it will looking at almost anything else. That said, it's
still a
Hi Azelio,
On 11/5/2012 4:09 PM, Azelio Boriani wrote:
Very interesting... is it using the binary protocol?
Yes, standard Motorola binary format.
Maybe a serial link
error, the binary protocol has a checksum (yes, NMEA too). Check the serial
link levels with a 'scope, maybe that the Z3801
azelio.bori...@screen.it said:
Very interesting... is it using the binary protocol? Maybe a serial link
error, the binary protocol has a checksum (yes, NMEA too). Check the serial
link levels with a 'scope, maybe that the Z3801 firmware waits to see some
consecutive errors before actually
On 11/5/2012 11:27 PM, Hal Murray wrote:
azelio.bori...@screen.it said:
Very interesting... is it using the binary protocol? Maybe a serial link
error, the binary protocol has a checksum (yes, NMEA too). Check the serial
link levels with a 'scope, maybe that the Z3801 firmware waits to see
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