Hi Daniel, that README refers to things of the past (when you specified a decimation rather than the sampling rate you want), and "USRP" refered to what we nowadays call the USRP1.
In the version of the usrp_rx_hrpt.grc, from which the .py gets generated, the USRP source is just configured to 4MS/s. The question is whether 4MS/s is really the optimum rate; I haven't studied the HRPT signal enough to answer this. In principle, for the 100MHz devices (N210/N200), 4MS/s is a suboptimal rate, since the decimation (25) is odd, and I'd try with something less strange, like 5MS/s. Best regards, Marcus On 06/30/2015 10:49 PM, Daniel Marlow wrote: > Hello, > > In the gnuradio/gr-noaa/README file under usrp_rx_hrpt.py, there is > a comment that > reads as follows: > > "The present HRPT demodulator is only tested at decimation 16. The > only other > valid decimation rates are 24 and 32, which may work, but with more > bit errors. No > other decimation rates will work." > > My (perhaps naive) question is whether the important parameter is > the decimation > rate, or the sampling rate. For example, with 64 MHz USRP, a > decimation of 16 would > give 4 MHz sampling, whereas with a higher rate USRP, the same > decimation would > yield a higher sampling rate. > > I would appreciate it if someone could clarify this point for me. > > Sincerely, > Dan Marlow > > > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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