Maybe it's the 2nd LO for a dual conversion receiver with IF's at 10.7 MHz and 455 kHz. 10.238 + 0.455 = 10.693
Rick Karlquist N6RK Jim Lux wrote: > At 10:37 AM 5/30/2008, you wrote: >>I have two PIEZO 10.230 MHz crystal oscillators in the same style package >> as >>the 10811. But the oscillator in question is for 10.238 MHz. > > > interesting.. is the 8kHz a deliberate offset? Is the manual tuning > off to one end? Maybe they were using them in a scheme where instead > of I/Q they did offset IF sampling. > > > > >>John WA4WDL >> >>----- Original Message ----- >>From: "Jim Lux" <[EMAIL PROTECTED]> >>To: "Discussion of precise time and frequency measurement" >><time-nuts@febo.com> >>Sent: Friday, May 30, 2008 12:47 PM >>Subject: Re: [time-nuts] "Piezo Little Wonder" OCXO >> >> >> > At 08:33 AM 5/30/2008, you wrote: >> >>Early GPS receivers used a 10.23 MHz time base. >> >>Probably related to 2^10-1. >> > >> > >> > yep.. the chip rate for the C/A code is 1.023 Megachips/second, the P >> > code is 10.23 Megachips/second, and the L1 frequency (1575.42) is >> > exactly 154 times the 10.23 MHz, the L2 is 120 times. >> > So you can see that having a 10.23 MHz oscillator is a handy thing in >> > a GPS receiver, especially if you can discipline it with the received >> > signal. >> > >> > These days, one might choose a reference oscillator somewhat higher, >> > so that when you do your 1bit A/D of the signal, you get many >> > samples/chip, and so that the signal directly aliases to somewhere >> > convenient. A lot of receivers use a sampling clock such that you get >> > 1 bit I and Q samples at a convenient sample rate. 4*10.23 would >> > work nicely, eh? 40.92 MHz >> > >> > >> > >> >>Some GPS manufacturers approached HP about making >> >>a 10811 on 10.23 MHz. There is a circuit modification >> >>for 10.23 MHz and some crystals were made (I >> >>have some somewhere). However, I don't believe >> >>any 10.23 MHz 10811's were sold. This unit was >> >>probably intended to meet the need not filled by HP. >> > >> > >> > >> > _______________________________________________ >> > time-nuts mailing list -- time-nuts@febo.com >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> > and follow the instructions there. >> > >> >> >>_______________________________________________ >>time-nuts mailing list -- time-nuts@febo.com >>To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.