hi eric i will try that ian ----- Original Message ----- From: "Eric Lemmon" <[EMAIL PROTECTED]> To: <Repeater-Builder@yahoogroups.com>; <[EMAIL PROTECTED]> Sent: Monday, December 08, 2003 6:43 AM Subject: Re: [Repeater-Builder] Re: crystal alignment (how accurate is accurate)
> Art, > > Until I installed one of those GPS-disciplined 10 MHz oscillators on my > bench, I used my local cellular telephone site to provide an extremely > precise signal for checking my service monitor's time base. > > Each analog cell site transmits a control channel at about 880 MHz. The > exact frequency depends upon whether the cell site is Block A or Block > B. This carrier is continuous, and it is modulated with a raspy tone. > Since this control channel carries no voice, you are not violating the > FCC eavesdropping rules. The control carrier is used by mobile phones > to know what power setting to use and to know what other sites are > available. It my area, the Verizon Wireless system is Block B, which is > GPS synchronized, while AT&T uses Block A, which is not GPS > synchronized. > > I only need to tune in the control channel, and I have a rock-stable > carrier that I can zero the service monitor's carrier meter on, to about > 0.1 Hz. That's a resolution of about 0.001 parts per million. > > 73, Eric Lemmon WB6FLY > > [EMAIL PROTECTED] wrote: > > > > Perhaps I wasn't clear. I have been using this simple comparison method for > > years to align my IFR timebase to WWV. It gets you within 1 cycle or so at the > > 10 MHz. (or closer if you compare the second harmonic of the 10 MHz timebase > > with the 20 MHz WWV signal when it's strong enough.) What I was asking was, Is > > there anyone out there using another method (short of having your service > > monitor locked to the 10 MHz output of a GPS receiver) that gives you a more > > accurate measurement. I am looking for a method that would give you a visual > > indication similar to using a lissajous figure as in when comparing two audio > > frequencies. > > > > Art - KC7GF > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
