Re: [Discuss-gnuradio] HRPT receiver

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

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