Yes, the use of the PPS as a disciplining reference was discussed weeks ago. It was debated whether an analog filtering/interpolation would do or a digital one is mandatory. The question is, in my opinion, still open and, in my opinion again, it can be done in the analog domain if a high precision/low leakage circuit is designed. I have designed 4 types of digital GPSDOs in 12 years, 3 using the digital approach time_interval_measure->DAC and one using the right/left_of_reference->DAC approach. One of them is implemented in a Xilinx Spartan3 small FPGA (50Kgates) without a microprocessor. The Spartan3 based design is the last one. I recommend the digital approach because it can be changed (time constants, holdover strategy, ...) just writing software.
On Sat, Mar 10, 2012 at 2:14 PM, Bob Camp <[email protected]> wrote: > Hi > > Which module do you have? > > Bob > > > > On Mar 10, 2012, at 8:07 AM, Filip Ozimek <[email protected]> wrote: > > > Hello, > > > > > > could you recommend me a good project of GPS-DO? I've got a GPS module > with 1PPS output and a 20 MHz VCXO. > > As I understand to do a phaselock to 1 PPS signal one must build some > kind of digital PLL. But I'm not sure > > how to calculate a correction signal to the VCXO and how to test such a > disciplined oscillator. > > > > Filip. > > > > _______________________________________________ > > 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. > > _______________________________________________ > 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. > _______________________________________________ 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.
