CODEWITHSUNDEEP
gnuradiortl-sdr
SteveJP
SteveJP

Reputation: 261

GNU Radio RTL-SDR command syntax

I would like to be able to control the RTL_SDR GNU Radio block via its "command" port, but I'm unable to find a reference to the protocol this input accepts. In particular I would like to control the centre frequency and also whether the output is "Quadrature Sampling" or "Direct sampling (Q branch)" in order to cope with frequencies above and below 24 MHz. I'd be grateful if someone could point me at a suitable reference.

I've assumed that it would be a PMT pair, so I've tried (guessed) various keys etc, but they all result in errors, so either I've got the wrong key, or my assumption is false.

Upvotes: 0

Views: 479

Answers (1)

SteveJP
SteveJP

Reputation: 261

As Marcus pointed out, there are actually two RTLSDR sources available in the GNU Radio Companion, one under the OsmoSDR tab which I was using, and one under the Core/Soapy/Source. I'm not aware of the relevant merits of the two options, but they certainly both work fine. I haven't been able to find the documentation for the OsmoSDR version, but the Soapy RTLSDR module is well documented via the wiki. See https://wiki.gnuradio.org/index.php/Soapy#Messages I have not tried it yet, but the frequency can apparently be changed as described. There is no obvious mechanism for selecting between the Direct Sampling Q branch and Quadrature sampling, however, both the RTLSDR modules change automatically depending on which side of 24MHz you happen to select.

Upvotes: 0

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