In message <[EMAIL PROTECTED]>, "Murray Greenman" writes: >Hi all, > >We have a problem at work where one of our engineers needs to measure >the start-up chirp in an oscillator destined for a GPS application. > >We are looking for ppb level frequency resolution with sample periods >around 10 - 20us (yes, that's us, not ms!). The chirp is all over well >inside 1ms. > >The measurement is on a 40MHz oscillator, which is mixed down to about >198kHz to improve resolution. We can count the down-converted frequency >in a conventional manner with no problem. The problem is of course that >at 198kHz the period is ~5us so even an interpolating counter will >struggle.
Consider getting a high-rate ADC (check the GNU-radio USRP for instance) which can sample your 40MHz directly, then do the analysis in software. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 [EMAIL PROTECTED] | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ 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.
