I can measure to .001hz using my scope. I thought I mentioned that the other day? It depends on frequency and how much time you want to wait, I think the low frequencies take a lot longer to stabilize.
Sent via the Samsung Galaxy Note® Edge, an AT&T 4G LTE smartphone -------- Original message -------- From: Bruce Griffiths <bruce.griffi...@xtra.co.nz> Date: 4/26/2017 2:19 PM (GMT-08:00) To: Discussion of precise time and frequency measurement <time-nuts@febo.com>, al wolfe <alw.k...@gmail.com> Subject: Re: [time-nuts] Frequency counter questions Use a USB or LSB mixer, it only requires a few more parts and a little ingenuity. Bruce > > On 27 April 2017 at 06:52 al wolfe <alw.k...@gmail.com> wrote: > > I am surprised that no one has mentioned the idea of heterodyning a > known frequency with the unknown to measure the unknown. I use a > Minicircuits doubly balanced mixer fed on one port from a PTS160 > synthesizer that is locked to 10 mhz. from a TrueTime xl-ak GPS locked > receiver. The second port is fed by the unknown though an attenuator. > The third port of the mixer gives me the sum and difference. If the > difference is an audio note then a cheep but frequency locked counter > will read out the difference or measure the period of the beat note > which can be added to the frequency of the synthesizer. A program such > as Lady Heather can also be used to determine the audio frequency to > much less then sub-cycle accuracy. The only fly in the ointment is > figuring out which side of the unknown the synthesizer is set to. > > Alternatively, the PTS160 with 0.1 cycle control can be set to nearly > zero beat with the unknown. Then watching either lissajous or dual > trace scope patterns and timing the beat notes one can get the unknown > frequency very close. > > Al, retired, mostly > AKA k9si > > _______________________________________________ > 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.