Hi There is another route to getting where you want to go.
Buy an atomic clock. If you spend some time shopping, telcom rubidium atomic clocks are out there for sub $50 prices. For $100 you can get one quite quickly. An Efratom LPRO is one example. There are many others. They normally put out 10 MHz and some put out 1 pps. I'd avoid the 1 pps only versions for what you are trying to do. To be absolutely perfect, you do need to calibrate an Rb. I have never seen one that was off by more than 0.5 ppb (0.0005 ppm). Their tune range is rarely more than a few ppb. More or less - if they fire up and lock, they will do what you need to do. Of course if you have both the GPS *and* the Rb then you can calibrate the Rb against the GPS and get it real close. Welcome to time nuts .... Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of John Beale Sent: Thursday, February 17, 2011 1:10 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Freq cal to 1ppm without GPSDO Hi Murray, Thanks to you and the others for your replies. After some more HF reception problems here, I have come to the same conclusion as you. I found an Oncore M12+ timing GPS is available pretty cheap from Hong Kong, so that's my plan. best regards, John Beale > 1. My best advice is to get hold of a cheap GPS module with a 1pps (seconds pulse) output. Connect it up, and when you have a fix, use the 1pps to trigger your digital oscilloscope. Set the timebase to 1us/div to start with, and ultimately 100ns, and observe the 10MHz output of your TCXO. You will see the waveform drifting slowly. Counting how long it takes to slip one cycle will tell you how far off the TCXO is. If you have a counter with Time Interval mode capability, you could use that, using the GPS to start and 10MHz to stop, again observing the drift. _______________________________________________ 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.