On Tue, Oct 20, 2015 at 8:53 PM, Bryan _ <[email protected]> wrote: > Saw this on the Hackaday site if anyone is interested. > https://hackaday.io/project/6872-gps-disciplined-tcxo
Will this design that uses the output of the DAC directly not run into problems with non-monotonicity and/or dead-zones in the DAC output? I would expect a PLL to behave very poorly if there is any non-monotonicity in the least significant bit of the DAC. My intuition would be to use TPDF dither against a higher resolution internal value (perhaps 32 bits) with noise shaping so that the dither has no power at DC (and not much near it), followed by a RC low-pass filter. With this approach the fact that available DAC parts run at speeds far faster than needed for this control helps overcome the fact that highly monotone parts are less common (last I looked). This would also help give much finer control without compromising tuning range. [Disclaimer: I've never built a GPSDO] _______________________________________________ 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.
