Hi If you have to womp up a MCU anyway, there is no reason to put in a delay chip. It’s easier / faster / more accurate to just do it all in the MCU. You have to write and maintain custom code either way.
Bob On Aug 19, 2014, at 7:53 PM, [email protected] wrote: > I recall when the LEA-M8F was announced that they mentioned a VCTCXO and > maybe I wrongly assumed that they used it for sawtooth correction they also > mention ability to control in addition an external OCXO. I previously > suggested using saw tooth correction information to tune a TCXO but that > would > require a GPS module with sawtooth information and than it would be simpler > to just use a PIC and delay chip. Still do not understand why no one took me > up on the offer of chips and PCB. I guess time nuts like to talk about it > but not fix it. How many receivers are out there. > Bert Kehren. > > > In a message dated 8/19/2014 5:51:30 P.M. Eastern Daylight Time, > [email protected] writes: > > Hi > > They are constrained by the same basic TCXO issues that give you sawtooth > correction. They do not use EFC to get the TCXO on frequency. With sawtooth > they give you a word that lets you know what’s going on. With the NCO’s > they often are doing very crude synthesis. They don’t put a $48 DDS chip in > a $10 GPS module. If you put one on a spectrum analyzer, it’s not pretty …. > > Bob > > On Aug 19, 2014, at 5:46 PM, Said Jackson <[email protected]> wrote: > >> Tom, >> >> Btw part of my frustration with this is that we sometimes get calls from > customers asking why they need our or others' GPSDOs for a couple 100 > dollars when they can buy a CW or uBlox doing "the same thing" for a > fraction > of the cost. >> >> Most of them come back to us after evaluating these NCOs and finding > that its not the same thing. >> >> You get what you pay for I guess.. >> >> Said >> >> Sent From iPhone >> >>> On Aug 19, 2014, at 13:01, "Tom Van Baak (lab)" <[email protected]> > wrote: >>> >>> Hal, as long as you maintain long-term phase lock it's a disciplined > oscillator. So, yes, a carrier tracking WWVB receiver with sufficiently > stable flywheel LO is a WWVBDO. >>> >>> Said, too-short or too-long 100 ns cycles is one thing. Still ok for > many applications. But tell me more about extra or missing pulses in the > ublox-7. That sounds like a show stopper to me. >>> >>> /tvb (i5s) >>> >>>> On Aug 19, 2014, at 2:05 PM, Hal Murray <[email protected]> > wrote: >>>> >>>> >>>> [email protected] said: >>>>> its not a GPSDO though, not even a simple one :) >>>>> It does not discipline an oscillator. It generates the output by >>>>> mathematically calculating how many phases it has to add/drop in a > second, >>>>> then digitally adds/drops/extends/retards the phase of the output > clock to >>>>> achieve an average of number of desired clock cycles. >>>> >>>> Is there something about the term GPSDO that says I have to do the "D" > in the >>>> analog domain rather than the digital domain? >>>> >>>> I agree that current technology doesn't give results that are useful > for many >>>> applications that currently use GPSDOs. What if the clock ran at a > GHz? 10 >>>> GHz? Sure, it would have spurs, but would it be useful for some > applications? >>>> >>>> Is a GPSDO still a GPSDO if the D/A driving the VCXO only has a few > bits? >>>> How many bits does it need to be a real GPSDO? >>>> >>>> Is a battery powered wall clock listening to WWVB at 2 AM a WWVDO? > It's got >>>> a pretty good ADEV if you go out far enough. >>>> >>>> -- >>>> These are my opinions. I hate spam. >>>> >>>> >>>> >>>> _______________________________________________ >>>> 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. > > _______________________________________________ > 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.
