Dear All, The B200mini does not support any board-mount GPSDO. I am wondering: would it be possible to operate one of the different Ettus GPSDO devices as a stand-alone GPS-disciplined 10 MHz reference clock generator by providing only the external power (+ GPS antenna of course)? Disclaimer: I known a better and more straightforward alternative in the Ettus catalogue would be the OctoClock-G, but the latter does not fit my SWaP constraints. Best regards, Claudio -- Claudio Cicconetti, PhD Software Engineer - MBI S.r.l. - Pisa, Italy

Being lazy, and since my Octoclock-G is already connected to a scope for triggering, I measured the 1 PPS pulse to be 200 ms wide and 2.82 V pk-pk. You can easily find GPS chips or modules that will output that level, but I am not sure about pulse width. I suspect that as long as the pulse width is on the order of 200 us or more, the B200mini will be fine. If you are not super fussy about pulse edge degradation, then a 555-based one-shot will make the pulse from the GPS module as long as you want. Obviously, it’s worth consulting the schematic where is says the 1 PPS max is -5 / +5 V and min is 0 / 2.5 V and the
SN75AUP1T57 is used to buffer the signal for FPGA input. Hope that helps. Steven Knudsen, Ph.D., P.Eng. www. techconficio.ca www.linkedin.com/in/knudstevenknudsen Der entscheidende Augenblick der menschlichen Entwicklung ist immerwährend. Darum sind die revolutionären geistigen Bewegungen, welche alles Frühere für nichtig erklären, im Recht, denn es ist noch nichts geschehen. - Franz Kafka > On Jun 15, 2016, at 08:32, Claudio Cicconetti via USRP-users <usrp-users@lists.ettus.com> wrote: > > Dear All, > The B200mini does not support any board-mount GPSDO. > > I am wondering: would it be possible to operate one of the different > Ettus GPSDO devices as a stand-alone GPS-disciplined 10 MHz reference > clock generator by providing only the external power (+ GPS antenna of > course)? > > Disclaimer: I known a better and more straightforward alternative in the > Ettus catalogue would be the OctoClock-G, but the latter does not fit my > SWaP constraints. > > Best regards, > Claudio > > -- > Claudio Cicconetti, PhD > Software Engineer - MBI S.r.l. - Pisa, Italy > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com

_send("SYST:COMM:SER:ECHO OFF\n");
_send("SYST:COMM:SER:PRO OFF\n");
_send("GPS:GPGGA 1\n");
_send("GPS:GGAST 0\n");
_send("GPS:GPRMC 1\n");
_send("SERV:TRAC 0\n");

Dear all, I have tried to power up a GPSDO and looked for a 10 MHz signal output: unfortunately there was none :( I assume some initialization is needed over the serial interface using SCPI commands. I looked to the code in gps_ctrl.cpp and the initialization sequence seems quite straightforward, with the following commands issued in an open loop: _send("SYST:COMM:SER:ECHO OFF\n"); _send("SYST:COMM:SER:PRO OFF\n"); _send("GPS:GPGGA 1\n"); _send("GPS:GGAST 0\n"); _send("GPS:GPRMC 1\n"); _send("SERV:TRAC 0\n"); Does anybody know whether this is sufficient to have the GPSDO produce 10 MHz reference signal from GPS? Best regards, Claudio On 06/15/2016 06:27 PM, Steven Knudsen wrote: > Being lazy, and since my Octoclock-G is already connected to a scope for triggering, I measured the 1 PPS pulse to be 200 ms wide and 2.82 V pk-pk. You can easily find GPS chips or modules that will output that level, but I am not sure about pulse width. I suspect that as long as the pulse width is on the order of 200 us or more, the B200mini will be fine. If you are not super fussy about pulse edge degradation, then a 555-based one-shot will make the pulse from the GPS module as long as you want. > > Obviously, it’s worth consulting the schematic where is says the 1 PPS max is -5 / +5 V and min is 0 / 2.5 V and the
SN75AUP1T57 is used to buffer the signal for FPGA input. > > Hope that helps. > > > Steven Knudsen, Ph.D., P.Eng. > www. techconficio.ca > www.linkedin.com/in/knudstevenknudsen > > Der entscheidende Augenblick der menschlichen Entwicklung ist immerwährend. Darum sind die revolutionären geistigen Bewegungen, welche alles Frühere für nichtig erklären, im Recht, denn es ist noch nichts geschehen. - Franz Kafka > >> On Jun 15, 2016, at 08:32, Claudio Cicconetti via USRP-users <usrp-users@lists.ettus.com> wrote: >> >> Dear All, >> The B200mini does not support any board-mount GPSDO. >> >> I am wondering: would it be possible to operate one of the different >> Ettus GPSDO devices as a stand-alone GPS-disciplined 10 MHz reference >> clock generator by providing only the external power (+ GPS antenna of >> course)? >> >> Disclaimer: I known a better and more straightforward alternative in the >> Ettus catalogue would be the OctoClock-G, but the latter does not fit my >> SWaP constraints. >> >> Best regards, >> Claudio >> >> -- >> Claudio Cicconetti, PhD >> Software Engineer - MBI S.r.l. - Pisa, Italy >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >