John wrote:
What's *really* interesting, though, is the idea that collectively we might develop some standard measurement protocols that would be reproducible in a number of (amateur) labs.
I agree, but I didn't dare to dream so large when I wrote:
From my perspective, the most interesting development would be an offer by someone with a very well equipped lab to test any DIY GPSDO with a consistent protocol and publish the results. That way, we could all see how the various approaches compare with respect to the characteristics that are most important to each of us.
At bottom, any such testing requires (i) a comparison standard at least as good (and hopefully at least somewhat better) than the DUT at all taus and offsets (which may, in reality, be several standards, each doing part of that job), (ii) a reliable TIC (and, potentially usefully, frequency counter) that can exploit the stability of the comparison standard, and (iii) the capability to process the raw data to produce meaningful information. [Additionally, to characterize poor-signal behavior one would presumably use attenuators and a well-situated antenna. Some may not have good antenna sites to begin with, and in any case, it would be hard to standardize the signal strength between locations.]
My thoughts were (1) for many (most?) of the people who would want to build a DIY GPSDO, it would likely be their first "really good" standard, and therefore their best; and (2) the range of TICs/frequency counters owned by the target base is so wide, and covers such a large range of capabilities (to say nothing of whether any given counter is in good repair and being used to best advantage), that obtaining comparable results from one amateur lab to another would be just as much if not more dependent on the individual counters involved than on the GPSDOs under test.
However, that is no reason not to push forward with standardized measurement protocols, which would focus all of us on what the relevant desiderata are and how to measure them.
Best regards, Charles _______________________________________________ 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.
