I built up the ZAZ GPSDO and like Bert have very very good performance. Whats crazy interesting is the oven I am using is a Lucent one from the cel towers. All of the stuff combined the thing draws very low power. Its been a while but I want to say 7 watts compared to may of the GPSDOs in the 30-50 watt range. Just another dimension to the timenuttieness "The green effect". Regards Paul. WB8TSL
On Tue, May 3, 2011 at 4:42 PM, Bert, VE2ZAZ <[email protected]> wrote: > Luis, > > You said: <<Furthermore the frequency counting resolution is 16 seconds, so > the ZAZ gpsdo won't lock better than 0.0625Hz.>> > > > On my GPSDO design, a single 16-second frequency sample does have a > resolution of 0.0625Hz. But the FLL firmware does averaging over as many > samples as you want before adjusting the OCXO. So I don't agree with your > statement that the ZAZ gpsdo won't lock better than 0.0625Hz. In fact, I > have never seen my design go worse than 1x10E-9. It usually sit below > 5x10E-10. This concurs with the many reports I got from other users. > > > Please elaborate. > > Thanks, > > Bert, VE2ZAZ > > > > > Message: 3 > >Date: Tue, 03 May 2011 18:14:30 +0100 > >From: Luis Cupido <[email protected]> > >To: Discussion of precise time and frequency measurement > > <[email protected]> > >Subject: Re: [time-nuts] Darn you people.... > >Message-ID: <[email protected]> > >Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > >Bob, > > > >You must be aware that the VE2ZAZ GPSDO does not lock the 10MHz phase to > >the phase of the 1pps. It is a frequency counter which uses the > >frequency error to correct the 10MHz VCXO. So it is a frequency locked > >loop FLL. > > > >By definition on a PLL you will have the phase error being used to > >compensate the 10MHz VCXO > >On a FLL a frequency error is required to compensate the 10MHzVCXO > > > >While having a permanent very very slow OCXO trend (drift or aging) > >a PLL(order 2) will exhibit a constant phase error while the frequency > >is right. With an FLL it will have a constant frequency error. > > > >Furthermore the frequency counting resolution is 16 seconds, so > >the ZAZ gpsdo won't lock better than 0.0625Hz. > >A PLL scheme, thunderbolt, the old Brook Shera's, the 10KHz James > >Miller's, or my reflock (I or II) will get you always on the ballpark. > > > > > >This PLL/FLL aspect is a subtle difference that has absolutely no > >expression whatsoever for radio-ham applications both TX and RX on HF to > >microwaves etc. application to which it was targeted and serve very well. > > > > > >But you will surely start to see these small aspects when you step into > >the next level of timenutness !!! > >Apparently you have both feet there... looking at sub Hz you're infected > >that's a fact ;-) > > > > > >Luis Cupido. > >ct1dmk. > > > > > _______________________________________________ > 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.
