The 1 pps and the output frequencies are all derived from the same XO in the module. Up to 7 the difference in a T is that the saw tooth correction factor is brought out for correction purposes . 7 has a much higher XO frequency than the 5 so the saw tooth is smaller. So use a ublox 7 if you want to do a simple GPSPLL like James Miller described. If you use the cheaper M version you have to make sure you always have backup power since it does not have a flash memory like the more expensive N version to memorize the setting Also stay away from 10 MHz out better to use 200 or 400 KHz. We have done a GPSPLL with ublox7 and Morion and got very good results. I have a board if interested contact me off list. Bert Kehren In a message dated 10/9/2015 12:03:45 P.M. Eastern Daylight Time, cjaysh...@gmail.com writes:
I am still learning and want to understand, if the PPS is good then why is the programmable output bad, as I understand it thus far, the PPS is derived from the same clock source or have I got that badly wrong? On 9 October 2015 at 12:16, Bob Camp <kb...@n1k.org> wrote: > Hi > > Doing a GPSDO by locking to the awful 10 MHz output from any of these GPS > modules > is not going to work very well. Given the very long time constants > involved in a GPSDO > control loop, doing it without code is going to be pretty difficult. > > A much easier approach: > > Grab the GPS PPS and a scope. Use it to set the Lucent boxes on frequency. > Repeat the process > once a week. The direct lock will flop around by (likely many) ppb. Your > manual set will probably keep it > under 1 ppb for a week. > > Bob > > > On Oct 9, 2015, at 1:39 AM, Perry Sandeen via time-nuts < > time-nuts@febo.com> wrote: > > > > Hi, > > I have six of the older style (anodized solid aluminum case) Lucent > crystal oscillators that I’d like to turn into simple 10 MHZ output > GPSDO’s. I have some salvaged HP cases so I can have a linear PS and all > other stuff in one package. > > I’ve found two different choices of GPS relatively low cost units on > Ebay. > > One is a LUCENT M12+ GPS Timing Receiver W/100 Hz output for $19.99 > Item 171886538138. > > The other is a UBLOX LEA-5T GPS module dev board 1PPS /USB/RS232/ntp ser > with two 1 PPS outputs for $49.90. Item 251785217093. > > IIRC, one output of a Ublox can be set to a 10 MHz. > > Can this model be set to have a 10 MHz output and is it easily done from > a PC? I have no coding ability. > > For more money I’d get a simpler phase detector circuit, which is all > I’m looking for. For less money I’d have to build more circuitry. > > A factor I don’t know is if the ublox is that much better/newer to > justify the price difference. > > I already have packed away two Oncore units with either a 1 KHz or 10 > KHz output. > > Suggestions welcomed. > > Regards, > > Perrier > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Clint. *No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.* _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.