Linrad SDR-IQ

(2020-04-29) PE1ITR

I still love my SDR-IQ from RFSpace. Not only because it was my first SDR, but also because the performance is still good. Especially when you compare it with the later and modern SDR's. In any case, I still use the SDR-IQ quite a lot.

The problem was that the SDR-IQ no longer worked in combination with linrad in modern linux distributions. I tried everything to get the SDR-IQ working until I came across gr-linrad. This is an excellent piece of software from Daniel EA4GPZ that uses GNU Radio between the SDR and Linrad. The spectrum data is then offered to linrad via a network connection.

EA4GPZ publishes this software on github. You have to compile it yourself and then add it to the GNU radio Library. He wrote this article about it on his website.

I compiled and installed this software and it works really great! Below the setup as I have used it now. In GNU Radio you can add extra functions for the frequency which are then forwarded to Linrad. Linrad itself already supports a lot of hardware. An advantage is that other hardware that does not is suppored by Linrad can now also be added via GNU Radio.

Below my setup at the moment.

GNU Radio Sketch

The two blocks "SEND RAW 16bit" and "Linrad Net Server" have been added for connection to linrad. I forward the 16bit data from the SDR-IQ over the network to the local address on port 50002. In addition, I made a choice screen to set the center frequency and the LO of a possible converter. This information is passed directly to Linrad. It is not necessary to restart the software when changing parameters.

Linrad

The screenshots show the Setup of the Network parameters, choosing the network as input. And finally the result in Linrad.

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