Have a look at BS 7647, the standard for radio controlled electricity meters.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Vince Sent: 05 April 2007 12:21 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Droitwich Note specifically that the 198 KHz signal is phase modulated by low-speed data. John's link below reproduces an old BBC information sheet with details. I have just had a quick play with the "Spectran" audio spectrum analysis and waterfall display program (http://www.weaksignals.com/), and that clearly shows close-in sidebands at ± 12.5 Hz etc. Compare that with the French station on 162 KHz, which has "noise" (well, OK, audio modulation) all the way down to the carrier - the "BBC Radio 4" signal on 198 KHz clearly has a high-pass filter on the audio modulator so the audio doesn't interfere with the slow phase-mod data. I'll try and find out if there is any later information about the data that is phase modulated. Peter Vince (Snr.Engr., BBC TV, London) >Neville Michie wrote: >> Hello all, >> I have a HP 5090A fixed frequency receiver which I believe was made >> to recover precision frequency signals from Droitwich radio station. >> I can not find any technical information on this receiver, can anyone >> tell me is Droitwich still active as a stable frequency reference, >> and where can I find a manual for the receiver? >> cheers, Neville Michie >> >> _______________________________________________ >> time-nuts mailing list >> time-nuts@febo.com >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> >See http://tx.mb21.co.uk/gallery/droitwich/droitwich-lf-data.asp - half >a megawatt now on 198kHz > >John > >_______________________________________________ >time-nuts mailing list >time-nuts@febo.com >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
