On 10/02/2012 07:19 PM, Mark Spencer wrote:
On a somewhat related note over the weekend I spent a few hours characterizing
the performance of two of my HP5370B's for making ADEV measurements by feeding
the stop and start inputs with identical 10 Mhz signals from a HP5087a
distribution amp. Not surprisingly they perform somewhat differently. More
surprisingly the results vary depending on the oscillators used for the clock
source for the HP5370B's. (I was under the impression the built in 10811's
were more than adequate enough for this application.)
Did you disable the wide-band 5 MHz comb-generator of the 5370s?
I did it to mine.
Cheers,
Magnus
I've also found that when trying to characterize the performance of an
oscillator (in this case a disciplined PRS10 Rb unit) making two simultaneous
measurements using different references and overlaying the results can provide
some additional confidence as to their accuracy. (I suppose if I had an H
maser I probably wouldn't need to use both an OCXO and GPSDO at the same time
to have confidence in the measurements (: )
Looking at the phase differences in this case gives me a reasonable degree of
confidence that the OCXO has not significantly drifted during the first 20,000
seconds or so and that the HP5370B's are providing valid data.
--- On Tue, 10/2/12, [email protected]<[email protected]>
wrote:
Message: 1
Date: Tue, 02 Oct 2012 13:29:11 +0200
From: Timeok<[email protected]>
To:<[email protected]>
Subject: Re: [time-nuts] Best counter setting for ADEV?
Message-ID:<[email protected]>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
test using HP53123A:
The pink line is the noise floor using the TI mode
The blue line is the noise floor using the Frequency mode
(gate 2 sec)
The other two line are the same oscillator, an HP105B tested
with both
the modes.
As you can see the range between 1 and 200 sec is "totally
compromised" by the system noise floor using the TI method.
The approximation using the freq mode can be anyway usefull
to make a
comparatinon between two source.
I suppose to have right measurements, without any
restriction we have
to use the Timepod or other high level instruments than this
kind of
counters.
Luciano
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