Thanks All for your comments and clarifications. The next OCXOs have been tested today: * Morion MV89A 10.000MHz #1 * Morion MV89A 10.000MHz #2 * Morion MV89A 10.000MHz #3 * Isotemp 131-191 10.000MHz #1 * Pilot C3Z 10.000MHz * Bliley NV26R891 100.000MHz * Giacint-M 5.000MHz
Measurement set up: * Pendulum CNT-91 with TimeBase opt.19 and 10 * Prologix GPIB-USB * TimeLab V1.2 (x64) * Windows7 Pro (x64) * PC i5 /3.4GHz / 16GB ADEV results https://dl.dropboxusercontent.com/u/21338179/hamradio/OCXO_Adev/ocxos_adev_test_20141031.jpg TimeLab configuration https://dl.dropboxusercontent.com/u/21338179/hamradio/OCXO_Adev/timelab_adev_config.jpg All OCXO's TimeLab TIM files can be download https://dl.dropboxusercontent.com/u/21338179/Hamradio/OCXO_Adev/OCXO_Adev.zip > A good MV89A can be below 1E-12. As you can see ADEV of all my tested OCXOs are not better than 4E(-10) for tau =1s. Question: can I be more or less happy with this result or something wrong in my measurement? Karen > Date: Thu, 30 Oct 2014 23:32:48 +0100 > From: Adrian <rfn...@arcor.de> > > Karen, > > as by the datasheet, the time interval resolution of your counter is 50 ps. > This translates into an ADEV value of 5E-11 at tau = 1 sec, 5E-12 at > tau = 10 sec etc, and represents the theoretical measurement limit of the > counter. > It can be measured by feeding the same signal into both inputs (start > and > stop) at the same time. A short delay (additional length of coaxial > cable) at the stop input keeps the counter from producing phase wraps > (jumping between a full input signal period and zero). > > A good MV89A can be below 1E-12. For measuring two good MV89A's > against each other, a TI resolution of 50 ps is insufficient because > up to 100 sec, to the most part of it, the actual ADEV of the > oscillators can be below the measurement limit of the counter. > > Adrian _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.