[time-nuts] Misuse of word "decimate" (was Re: Short term 10MHz source)

[Tom Van Baak]

> I don't think case A makes sense.  You are throwing away information.  You 
> will get aliasing.

Hal,

Ah, but we do this all the time. Your GPSDO or your cesium standard outputs 10 MHz. There are many cases where throwing 9,999,999 of every 10,000,000 is useful. The result is ... 1PPS.

Yes, this is throwing away information. But most of it is useless information. For example, if your Cs is ahead of GPS by 123 ns, you don't need 10 million measurements to tell you that. One will do. So 1PPS is useful here.

And about aliasing, right, 1PPS is not immune to that. If your Cs clock secretly speed up by 5x for 200 milliseconds you would not see this crime in your 1PPS data. If you're worried about that happening, one solution is simply to measure at 10 PPS instead.

/tvb