Aha! You were correct. I was parsing the header incorrectly. However, even after parsing, and the more accurate values (now accurate to 10e-6), it appears the recorded RF data sets are still are offset from each other by an amount of nearly 2.5e-3 seconds. Any idea why this would be? It's strange, especially considering that the are synchronized to the same PPS, and I think the time is with reference to the pulse.
Michael Michael Skaggs M.S. - Computer Engineering LinkedIn <https://www.linkedin.com/in/MichaelDSkaggs> | Resume <http://goo.gl/NBEs2y> | Research Cluster <http://eclipse.umbc.edu/> University of Maryland, Baltimore County On Thu, Apr 21, 2016 at 11:57 AM, Marcus D. Leech <[email protected]> wrote: > On 04/21/2016 11:41 AM, Michael Skaggs wrote: > >> I'm trying to time/sample synchronize RF recordings with two B200minis. I >> am using the detached Metadata File Sink in GRC. Both recordings are at >> 30MSps and both B200mini boards are synchronized to the same 1PPS signal. >> >> My issue is this, when I extract the data from the Metadata header file, >> the "rx_time" value is only accurate to 10e-4 seconds (0.0001s). Which, >> with a recording at 30MSps, this will only give me a sample alignment >> accuracy to 10e-4(s)*30(MS/s) = 30,000 samples. >> >> If I'm attempting to align the two recordings by samples or time, this is >> not nearly accurate enough. Is there a way that I can get more accuracy out >> of my metadata header or a way that I can synchronize the recordings of >> these B200minis? >> >> Thanks, >> Michael >> >> The precision of the timestamps from UHD should have a precision of > whatever the master-clock is on the device--how are you interpreting > the rx_time tag? It's two parts--a uint64 with the full-seconds > portion, and a double-precision float for the fractional part. > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >
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