Received: by 10.236.170.1 with SMTP id o1mr11204770yhl.42.1344999395388; Tue, 14 Aug 2012 19:56:35 -0700 (PDT) Path: c6ni115652349qas.0!nntp.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!nrc-news.nrc.ca!goblin1!goblin.stu.neva.ru!news.astraweb.com!border5.a.newsrouter.astraweb.com!not-for-mail From: josephkk Newsgroups: sci.electronics.design Subject: Re: Phase detection of RF carriers Date: Fri, 10 Aug 2012 19:59:01 -0700 Message-ID: <9dib281an5q9oeek6un2vn63us7g9rna9i@4ax.com> References: <18ee644f-a722-4346-b517-cbb1d2119cc6@googlegroups.com> X-Newsreader: Forte Agent 6.00/32.1186 MIME-Version: 1.0 Lines: 31 Organization: Unlimited download news at news.astraweb.com NNTP-Posting-Host: 7b28ed00.news.astraweb.com X-Trace: DXC=V78@m^@TnaFmRUYobjn7jFL?0kYOcDh@JYXA4R\P[DPG>3<:Wm\C]QOJMhG?lE6deMEcG5O9_c[NOh1:?D;M88mNE]hH32>Ag5GQN[`Qf^;WSE Bytes: 2295 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable On Tue, 7 Aug 2012 12:32:42 -0700 (PDT), George wrote: >Is it practical to do this directly at the RF receive frequency? I = expect to sub-contract the design work but looking for an opinion first = about practicality.=20 > >Requirement: Receive two CW carriers off the air in the 1.8 to 2.5 MHz = range, and report their relative phase with at least 50 nsec accuracy. > >Assumptions: The CW carriers' frequencies are precisely known in = advance and are assumed to be perfectly stable. Nominal C/No >50 dB/Hz = each carrier.=20 > >"Phase:" The carriers are at different frequencies. What we really = want to know is how much one leads or lags the other in time, like = measuring the relative zero-crossing times of the two sinusoids. For = measurement accuracy it is acceptable to time-average each measurement = over as long as 100 msec. > >Regarding implementation, we'd like to start work by 1 September = assuming this concept is practical. Any recommendations for someone to = do the design are appreciated. We are located in Southern Calif. Well, whether anybody else says so or not i have say that phase is a null concept for different carrier frequencies. Perhaps there can be a definition iff they are rationally related frequencies and you can = provide some definition of phase for different frequencies. ??-)