I did a little calculation and it's a 10 digits counter. log(10,000,000,005) = 10. There is still a big gap between this one and 53132A :(
For 53132A, the time resolution is 150ps, which I think is 10digits/s with interpolator. According to the schematics the only difference between 53132A & 53131A is the ADC of interpolator. It is the reason why 53131A only has time resolution of 500ps (also 10digits/s). However, 53132A is a 12 digits/s counter. I guess the 2 more digits come from software. Linear regression maybe ? 2014-11-28 11:15 GMT+08:00 Bob Camp <[email protected]>: > Hi > > One way of looking at resolution is at the one standard deviation point. > Another way of looking at it is as a +/- 1 digit accuracy point. Each > approach has it’s advantages. It’s more common to see single shot timing > specified as one sigma and frequency specified as +/- 1 count. Often you > need to read the fine print to see just what is being spec’d. > > > > On Nov 27, 2014, at 5:30 PM, LiAng <[email protected]> wrote: > > > > Thanks for the info. > > > > What's the standard to be 11 digits/s? For real 11 digits/s, the ADEV > > needs to reach the 1e-11 level? I'm not sure if my GPSDO & Rb is stable > > enough. Maybe 2 MV89A as the refclk and signal? > > For the “easy” approach, first feed the counter’s reference back into the > input. That will usually give you a “best result no matter what” sort of > reading. It also will suppress a variety of problems coming from the > reference signal. > > A source with a <1x10^-12 ADEV at 1 second should be good enough for > testing a 10 to 11 digit counter. It’s not going to do the trick for a 12 > digit device. In the case of a 12 digit device, use a second copy of what > ever you are using for the reference for the counter …. > > —— > > Another approach, don’t measure frequency, measure period / time / phase. > Generating a pulse that is 100 ns wide is fairly easy. Doing so with < 1 ps > jitter is not impossible. If your signal source is good to a few ppm, your > pulse generation accuracy will be “plenty good enough”. Things like rise > and fall times through buffers will be a much bigger deal in the delivered > result than the absolute accuracy of the clock feeding the circuit. If the > counter measures the resulting pulse with a 10 ps one sigma error, you have > a 10 ps counter. If it says that 100 ns is 102 ns, that’s to be expected > with a simple pulse generation technique. Yes, you eventually do need to > verify that 100 ns is 100 ns, but that can be done a different way. > > Bob > > > > > > > TDC-GP22 has it problem, I will post some data/schematic/source code > > about it later. > > > > Thanks > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
