Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21 SDRs and precision time
On 7/23/18 5:58 PM, Graham / KE9H wrote: It would be a lot easier if you used a GPSDO to synchronize your SDRs, since both the time and frequency derived are several orders of magnitude better than what you can get out of an LF receiver. Any systems like this, that I am aware of, use GPS, not LF. This is essentially what we are doing for SunRISE - we're going to be flying 6 small satellites in a cluster about 10-15km across to image the sun from 0.2 to 22 MHz (or thereabouts). http://www.tauceti.caltech.edu/science-at-low-frequencies-2016/slides/A/12_Lazio.pdf We have a SDR which digitizes the RF, and a GPS receiver, and we log both the GPS observables and the filtered/downconverted RF. Then, on the ground, we reconstruct the time and position when the measurements were made to do interferometry. On Earth surface, this would be somewhat easier - I've been fooling with using 4 RTL-SDR receivers, 4 beaglebone green wireless, and 4 GPS receivers to do something similar. As it happens, the challenge is in the non-determinate nature of the data path from RTL-SDR digitizer via USB (on the space version, we can arrange to use the same OCXO to drive the GPS sampler and the HF sampler, etc.), so I'm working it by generating a pilot tone that's "in-band". Some years ago, we build a breadboard to demonstrate that this kind of thing is possible for a large array at L-band. http://luxfamily.com/jimlux/rtd.htm ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21 SDRs and precision time
It would be a lot easier if you used a GPSDO to synchronize your SDRs, since both the time and frequency derived are several orders of magnitude better than what you can get out of an LF receiver. Any systems like this, that I am aware of, use GPS, not LF. --- Graham == ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21 SDRs and precision time
Hi, has anyone ever combined an SDR and Anthorn atomic clock receiver module so that they can be synchronized? the idea here is as a variant of a thinned array similar to WebSDR but using lots of smaller units to get around the thinned aray curse (tm) and combining signals with suitable offset delays so that signal increases at the expense of noise. -Andre From: time-nuts on behalf of time-nuts-requ...@lists.febo.com Sent: 23 July 2018 17:00 To: time-nuts@lists.febo.com Subject: time-nuts Digest, Vol 168, Issue 21 Send time-nuts mailing list submissions to time-nuts@lists.febo.com ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21
Hi I think it’s just the normal summertime drop-off. Everybody is on vacation….. Bob > On Jul 23, 2018, at 12:41 PM, Dan Kemppainen wrote: > > FYI, > > I would tend to agree about the drop in traffic. Not sure if it's just a > quiet period, but there are many less messages than before in the digest. > > Dan > > > On 7/23/2018 12:00 PM, time-nuts-requ...@lists.febo.com wrote: >> Could it be that the reflector drops messages? >> I did not get Ulrich's? NO-Message and also not that from msimon6808. >> It has become quite silent since the move to the new server. >> Subjectively -6 dB. >> Cheers, Gerhard > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 168, Issue 21
FYI, I would tend to agree about the drop in traffic. Not sure if it's just a quiet period, but there are many less messages than before in the digest. Dan On 7/23/2018 12:00 PM, time-nuts-requ...@lists.febo.com wrote: Could it be that the reflector drops messages? I did not get Ulrich's? NO-Message and also not that from msimon6808. It has become quite silent since the move to the new server. Subjectively -6 dB. Cheers, Gerhard ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
