Wow you invested a lot of time and effort to create this very interesting video. Like so many of these older devices the accuracy is outstanding. Really impressive for the age and very comparable to the modern Chinese GPSDO's. Before I started watching your video's 2 years ago I knew nothing about GPSDO's. Now I feel very informed. Thanks
Thank you Ian! Yes it took some time and enjoyed every minute. Yes amazing how the Rapco performs still. My first GPSDO was also magic for me.. during the video i learned al lot.. thanks for sill watching also my progress on this matter.
Unlike GPS use for positioning, for a frequency reference the best satellite arrangement is actually the reception of a single strong satellite signal, not a constellation of them, since you are not trying to triangulate a location, but to clearly receive the signal of one of the cesium clocks aboard a satellite. The more satellites you receive, especially if they are from 2 different systems the more it confuses the receiver, slightly reducing the accuracy. I believe the GPS receivers designed for timing will automatically try to select a single strong satellite signal to work from.
Hi Tony,Love your videos.You are coming close to my area of test & measurement.Phase /stability analysis will give much better results of the UUT.The BG7 's i have show very good 1 second and 10 second precision. I use a Rohde & Schwarz XRM rubidium (has been running for 15 years /with external battery back-up) as my primary timebase source and 3 BG7's (3 years running time)as secondary sources . Phase stability in the order of 5 x10-14 comparing these units with timepod.These BG7's are a wonder of affordability to cost ratio.let us know of your results of the Rapco with some long term running.
Nice video Tony. I would love to see a setup where you put this gpsdo and the Chinese in to an oscilloscope ans see how stable the two sinuses are to each otter. If you trigger on one the should both be stable :)
I think it would be much better to compare that two GPSDO using phase (same phase requires same frequency) comparation method like connecting them both to the two channels of the oscilloscope in the X-Y mode. The result should be one point that does not move on the screen. When phase of that two signals change, that point would move on the eliptic curve. So if you put the oscilloscope into a infinite persistence, then you should obtain some part of an eliptic curve, where angular length is proportional to maximal phase difference of that signals. I think this would be a nice experiment. Similar thing did CuriousMarc comparing the GPSDO to the cesium standard and he found, that theese things are little bit wobbly in a phase each other, but nobody knows if this came from the cesium standard or from the GPSDO. So I think, that repeating this experiment with two completely different GPSDOs could bring a little more light into this issue. Resoultion of that X-Y image is proportional to the sample rate of the oscilloscope, so higher is always better :3.
Wow you invested a lot of time and effort to create this very interesting video. Like so many of these older devices the accuracy is outstanding. Really impressive for the age and very comparable to the modern Chinese GPSDO's. Before I started watching your video's 2 years ago I knew nothing about GPSDO's. Now I feel very informed. Thanks
Thank you Ian! Yes it took some time and enjoyed every minute. Yes amazing how the Rapco performs still. My first GPSDO was also magic for me.. during the video i learned al lot.. thanks for sill watching also my progress on this matter.
LOL, I love when I put the location into google it comes up with a picture of your bench.
LOL yes google watches too :))
Hi Tony, it's great to have one of these GPSDOs on the test bench, very interesting... Greetings from Buenos Aires...!!
Thank you!
Unlike GPS use for positioning, for a frequency reference the best satellite arrangement is actually the reception of a single strong satellite signal, not a constellation of them, since you are not trying to triangulate a location, but to clearly receive the signal of one of the cesium clocks aboard a satellite. The more satellites you receive, especially if they are from 2 different systems the more it confuses the receiver, slightly reducing the accuracy. I believe the GPS receivers designed for timing will automatically try to select a single strong satellite signal to work from.
Thank you, yes lot to learn still for me about this.
Nice work! Try comparing both 1 sec pulses (one edge) with your scope as suggested (infinite persistence).
And nice place to live beside the channel!
Thanks! .. yes a better test indeed.
Hi Tony,Love your videos.You are coming close to my area of test & measurement.Phase /stability analysis will give much better results of the UUT.The BG7 's i have show very good 1 second and 10 second precision. I use a Rohde & Schwarz XRM rubidium (has been running for 15 years /with external battery back-up) as my primary timebase source and 3 BG7's (3 years running time)as secondary sources . Phase stability in the order of 5 x10-14 comparing these units with timepod.These BG7's are a wonder of affordability to cost ratio.let us know of your results of the Rapco with some long term running.
Thank you David, yes it was very interesting to do. Wow you are very serious about this with so many GPSDO's Cool!.. thank will try that.
Nice video Tony. I would love to see a setup where you put this gpsdo and the Chinese in to an oscilloscope ans see how stable the two sinuses are to each otter. If you trigger on one the should both be stable :)
Great idea!
I think it would be much better to compare that two GPSDO using phase (same phase requires same frequency) comparation method like connecting them both to the two channels of the oscilloscope in the X-Y mode. The result should be one point that does not move on the screen. When phase of that two signals change, that point would move on the eliptic curve. So if you put the oscilloscope into a infinite persistence, then you should obtain some part of an eliptic curve, where angular length is proportional to maximal phase difference of that signals.
I think this would be a nice experiment. Similar thing did CuriousMarc comparing the GPSDO to the cesium standard and he found, that theese things are little bit wobbly in a phase each other, but nobody knows if this came from the cesium standard or from the GPSDO. So I think, that repeating this experiment with two completely different GPSDOs could bring a little more light into this issue.
Resoultion of that X-Y image is proportional to the sample rate of the oscilloscope, so higher is always better :3.
Thank you, yes that would be a nice test indeed...
Nice!
Thanks!
🙂👍
Thank you