Its actually Tau with a subscript 0.
This is the the time interval between successive measurements.
e.g. if a measurement is taken every second then Tau0 is 1 sec.
Bruce
Edgardo Molina wrote:
Dear John Ackermann,
I find your reply to my request to be very interesting. Without fear of asking.
May I know how do I achieve a Tau 0 measurement in a 1 second interval with my
setup? (HP-53132A + TimeLab).
Please tell me if I am wrong. I assume I would take the 10 MHz output from the
53132A and plug it into the Channel 1 input, while the external reference of 10
MHz is disconnected.
As far as I am concerned, TimeLab does not allow a value of 0 for Tau. If I
enter zero as the measurement time duration I get an error and actual
acceptable Tau range. The smaller value is in the order of 1E-6s. Am I getting
it right? I am sorry for my confusion.
Regards,
Edgardo Molina
Dirección IPTEL
www.iptel.net.mx
T : 55 55 55202444
M : 04455 10045822
Piensa en Bits SA de CV
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On Nov 14, 2012, at 8:13 PM, John Ackermann N8UR<[email protected]> wrote:
Edgardo, the minimum sample rate in practice is determined by the noise floor
of the measurement system. I would suggest that you do a baseline test by
measuring the counter reference against itself with a tau0 (sample rate) of 1
second. You'll see a best-case result and from it you can determine at which
sample rate your noise floor is better than the predicted performance of the
oscillator under test. You'll probably find that you are measurement-noise
limited below several hundred seconds.
Also, you'll generally get a lower noise floor doing time interval rather than frequency
measurements, so you might experiment with that, which normally involves using a low-rate signal
such as PPS for "start" and "stop" channels.
John
On Nov 14, 2012, at 8:43 PM, Edgardo Molina<[email protected]> wrote:
Dear Group,
Now that I have setup TimeLab along with the Prologix GPIB to USB adapter and
the HP-53132A frecuency counter, I am starting to get some data from my
frequency standards. Still I think I have a long way to go in front of me.
One of the main concerns that cross my mind at this point are:
a. What is the recommended sampling duration to consider for Quartz, Rubidium
and other types of oscillators?
b. What are the recommended sampling intervals for the above mentioned
oscillator types?
c. I am using a 10 MHz Rb FE-5806A frequency standard as an external reference
for the HP-53132A.
d. I am connecting my DUT at the frequency counter channel 1
e. I am setting Timelab for Data Type = Frequency
f. My graphs somehow have the same geometry of classical ADEV examples, I can
differentiate the ADEV noise types quite easily.
g. Should I use sub-second sampling intervals for my graphs to start closer to
the vertical axis of the graph? Or should I use a conservative 1s sampling rate?
With the previous questions I am looking for consistency in my ADEV studies.
Are there any typical ADEV conditions to be considered when analysing this way?
Am I missing something? My apologies to everybody if I am missing something or
doing it the wrong way. In the end I want to learn more than anything else.
Your kind comments are welcome. Thank you.
Best regards,
Edgardo Molina
Dirección IPTEL
www.iptel.net.mx
T : 55 55 55202444
M : 04455 10045822
Piensa en Bits SA de CV
Información anexa:
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