From: John Ackermann N8UR <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Some long-term data Date: Sat, 23 Dec 2006 17:53:50 -0500 Message-ID: <[EMAIL PROTECTED]>
Hi John! > Magnus Danielson said the following on 12/23/2006 05:22 PM: > > > Such as temperature and humidity. One of the Cesiums seemed to have a rather > > large frequency offset. Did you drift-compensate your ADEV measures or not? > > No, I ran the ADEV in Stable32 without removing drift. My understanding > is that linear drift shouldn't affect the calculation. I was also a > little concerned whether drift removal would work very well given that > both Cesiums had periods where the offset changed for quite a long > period (CS1 near the end of the data, CS2 at the beginning) and I wasn't > sure what impact that might have. I know next to nothing about Stable32, so I don't know what that black box actually is doing. >From a theory standpoint, it is trivial to show (I've done the exercise to convince myself, but it is already covered in literature) that linear frequency drift does affect the result. Time/phase offset and frequency offset cancels. >From a practical standpoint, linear frequency drift may or may not be small enought not to interfere with the measure of the noise power. To be sure, measure the drift rate. > > (Actually, if you hand me the raw data I would love to do some exercises on > > them.) > > I'll be happy to ship the data to anyone who's interested. Each file is > about 600kb before compression, and it compresses well. No problem! Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
