Hi Said, The Miller design doesn't support holdover. You can either run it free (using JP1, see earlier mail) or run it GPS-locked. I think the PLL is all of one gate and an RC filter so there's nothing to "hold" the EFC. See his web site for details.
Right, if you pull the GPS antenna the unit quickly goes way off frequency. This is a side-effect of its minimalist design. Remember he calls it the "10 MHz Simple GPSDO". So it's not a GPSDO one would sell to telecom. But it works fine for non-critical use. Yes, the performance is nice. I've tested two earlier simple GPSDO prototypes from Miller and they each get better. I'll have a better understanding when I make the measurements Bruce suggested. /tvb ----- Original Message ----- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] ; [email protected] Sent: Wednesday, February 13, 2008 11:03 AM Subject: Re: [time-nuts] GPS Locked and Unlocked Performance Comparison Hi Tom, I wonder how the Miller unit would perform if the GPS is kept alive during holdover. If the Jupiter continues to generate the 10KHz and 1PPS from it's internal TCXO even without GPS reception then I would expect the holdover performance to degrade to that of the TCXO if the unit goes into antenna-related holdover? Unless the Miller design removes the 10KHz reference from the PLL if there are less than a certain number of sat's received etc. Should be possible to add that feature by monitoring the RS232 output, gating the 10KHz, and clamping the EFC control voltage - if that feature is not already there. That's a nice behavior trait of the Motorola receiver: it shuts off it's 1PPS when there are less than 4 Sats etc (in TRAIM mode). It's surprising what kind of performance can be achieved with the 10KHz locking the OCXO through an Exor gate. Then again that design get's to compare phase 10.000 times more often per second than all of the other 1PPS based PLL's :) bye, Said In a message dated 2/13/2008 10:47:44 Pacific Standard Time, [EMAIL PROTECTED] writes: The other is to remove the power/data connector to the Jupiter board (which is what I did). _______________________________________________ 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.
