[time-nuts] question Alan deviation measured with Timelab and counters
magnus at rubidium.dyndns.org
Sun Jan 18 07:13:03 EST 2015
On 01/18/2015 04:25 AM, Bob Camp wrote:
> I’m a little concerned about the measurement setup here. Based on the quoted text, there have been a few messages in the thread that have not showed up here.
The messages got accidentally posted in the wrong thread.
> The “start” input on the counter is defined below. The “stop” input is not defined. Is the counter running in time interval mode or in frequency mode?
> IF it’s in time mode - what is the stop hooked to?
> IF it’s in frequent mode - what is the gate time set to ?
> Is the “standard input” the missing front panel input or is it the external reference input on the back panel?
I was also considering the setup strange in this regard. Common switched in?
> I’m looking at the data on the link:
> In both cases the slope is roughly 1/tau. Both plots end up in the 3 to 4 x 10^-13 range at 100 to 300 seconds. That’s suspiciously good performance for a rubidium or a GPSDO. Which is what makes me wonder about the setup.
> The Blue plot (1 pps?) ran for 18 minutes and has 1,114 points in it. The Pink plot ran for about 9 minutes and has a bit over 500 points in it. Both seem reasonable for a 1 pps to 10 MHz sort of setup. That may explain part of my confusion above.
> Again - I apologize if this all got explained in a post that went missing here.
Not really. The plots looks to me like measurement setup baseline plots,
with some sine noise in them.
More information about the time-nuts