Re: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Hi, I have another Thunderbolt cousin, a NTGS50AA. For a long time I desired to have 1PPS from it and even I asked this list for a cue, the responses were negative, some thought that there were no 1PPS outside the big chips. My unit developed a problem and troubleshooting it I found the wanted 1 PPS at TP-33 coming from U2-76. Given that this GPSDO has two outputs whose usefulness is dubious, 1/2 PPS and 9.8304 MHz (we don't have a CDMA tower, do we?), my plan is to use one of these outputs for the 1PPS signal. Both outputs have drivers that are identical so probably I will cut the 9.83404 signal just before the driver and solder a piece of wire wrapping wire from TP-33 to the driver input. In that way I will have 1/2 PPS and 1 PPS on the output connectors. I have checked that the 1PPS is totally synchronous with the 1/2 PPS, I don't have means of properly check the jitter between both signals but a scope shows no jitter at all. The above mentioned problem became worse and finally I had to replace the whole thing. Fortunately a member of this list kindly offered to sell me one of this spare units and now my reference is working fine. As soon I have a time gap I'll do the modification and publish the pictures. Regards, Ignacio El 26/05/2015 a las 14:09, Tom Van Baak wrote: Hi Nate, Nice page. Thanks for sharing your work. The Nortel units are a reasonable and slightly cheaper alternative to a TBolt, if you don't mind the much larger size, mass, and non-standard connector issues. The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here: http://www.leapsecond.com/pages/nortel/ For NTP none of these plots matter (most GPSDO are a thousand to a million times more stable than NTP or a PC can handle). /tvb - Original Message - From: Nathaniel Bezanson mys...@telcodata.us To: time-nuts@febo.com Sent: Monday, May 25, 2015 7:08 PM Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM! As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an even second output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software. However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here: https://www.i3detroit.org/wiki/Nortel_GPSTM This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there. Enjoy!-Nate B- ___ 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.
[time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an even second output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software. However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here: https://www.i3detroit.org/wiki/Nortel_GPSTM This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there. Enjoy!-Nate B- ___ 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.
Re: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Hi Nate, Nice page. Thanks for sharing your work. The Nortel units are a reasonable and slightly cheaper alternative to a TBolt, if you don't mind the much larger size, mass, and non-standard connector issues. The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here: http://www.leapsecond.com/pages/nortel/ For NTP none of these plots matter (most GPSDO are a thousand to a million times more stable than NTP or a PC can handle). /tvb - Original Message - From: Nathaniel Bezanson mys...@telcodata.us To: time-nuts@febo.com Sent: Monday, May 25, 2015 7:08 PM Subject: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM! As anyone with a Nortel GPSTM knows, it's a close cousin to the Thunderbolt but not exactly identical. Notably, coming from a CDMA environment, the unit has an even second output, aka PP2S, aka 0.5pps, aka 0.5Hz, etc. (Hoping to make this searchable...) There are software commands to configure this on the Thunderbolt too, but the GPSTM appears to have this function hard-coded into the PAL, and it can't be set back to PPS in software. However, there exists a PPS signal on the PCB, at TP13 between the Trimble chip and the PAL, discovered by some folks at the hackerspace here, during some noodling-around with an oscilloscope this afternoon. It's all documented here: https://www.i3detroit.org/wiki/Nortel_GPSTM This is for a NTBW50AA-11 module (single long board), other parts may have the signal in different places but I bet it's in there. Enjoy!-Nate B- ___ 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.
Re: [time-nuts] pp2s? No, 1pps from a Nortel GPSTM!
Moin Tom, On Tue, 26 May 2015 05:09:05 -0700 Tom Van Baak t...@leapsecond.com wrote: The performance depends somewhat on which vendor's oscillator was used. I tested a bunch here: http://www.leapsecond.com/pages/nortel/ The phase noise plots look a bit peculiar for unit 2 and 4. Do you have any guess where the humb at 4kHz comes from? Also the much higher amount of harmonics(?)/spikes of these two units raises some questions. Might it be that they use a different PLL structure as well? Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ 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.
