); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] From: "Richard \(Rick\) Karlquist" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Cs stability Date: Tue, 17 Jul 2007 09:52:22 -0700 Message-ID: <[EMAIL PROTECTED]>
Rick, > In case anyone still doesn't know who I am, I need to > mention that I designed the RF electronics in the > 5071A in an earlier life, circa 1990. > > Now that we have that out of the way, I will agree > with Magnus that the cited paper is severely flawed. Good, then I am not the only one seeing that. I must admitt that I didn't give it a comprehensive readthrough asI was tired as hell when I looked at it, but I did not get the necessary ques as I browsed through it and even as I dipped into certain parts in detail it left me unsatisfied. > We don't know what models of cesium were used, and > the paper seems to assume that any deviations with > respect to GPS are due solely to the cesium standards. > We also don't know anything about the GPS equipment. > Citation [3] is a 5071A product note. I guess this > is thrown in to imply that one of the cesiums is a > 5071A; but we can't be sure. There is only an indirect reference to 5071A in a. > A statement is taken > out of context from this product note to the effect > that "some cesiums don't have an independent means > of frequency setting", which might lead the casual > observer to think that this refers to the 5071A. > Actually, the 5071A does have an independent means > of frequency setting, as opposed to older cesium > clocks where you had to vary the C-field to change > the frequency. For this and other reasons, I don't > put much stock in the paper. Do note that he in the introductionary part shows the factor deviation of 2.7E-13 and that he adjusted it manually twice which can be seen in the second Fig 1. "Unfortunately, many atomic oscillators lack the possibility of non-invasive frequency tuning [3]. Using digital correction, the frequency offset of 2.7 E-13 as delivered from factory is shown in Fig.l to be reducable below 1 E-14 with only two frequency corrections at 1800 and 4O00 hours from start-up, leaving some environmental factors plus a number of unpredictable timing discrepancies lasting 50-500 horn." He actually points out that the 5071A lacks that correction, so he agrees with you. This correction can be done by him as an initial post-processing step. We just don't know, again. A little sentense or two more on how that was made would have enlighen us further on that subject. But what Cesium he actually used is not known. > I hope this clears up any confusion about the 5071A, now > made by my good friends at Symmetricom. Many, many thanks for the write-up. I greatly enjoyed it! Cheers, Magnus _______________________________________________ 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.
