Is possible to measure swr with gnuradio?

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Is possible to measure swr with gnuradio?

Post by creator9724 » Fri Feb 09, 2018 8:31 am

I have been playing with gnuradio since i bought my bladerf and sometimes i think if it's possible to implement a swr meter or similar with gnuradio. I'm thinking of it because even that i make sure i'm using the proper antenna to transmit into each band, could be useful to see performance wise in what parts of the spectrum performs better certain antenna.

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Re: Is possible to measure swr with gnuradio?

Post by bglod » Wed Feb 14, 2018 10:52 am

Maybe? I wouldn't expect great performance or accuracy though, and you may have to build/buy additional components. For one, the bladeRF is not calibrated, so for the best accuracy you'd need test equipment to build a calibration table. You might be able to ignore this, but keep in mind that it could be a source of error. Also consider that SWR meters don't directly sample the transmit path. Doing so alters the characteristics of the path you want to measure (impedance mismatches, losses, that kind of thing). You could try, but one way around it is to use a directional coupler and measure the voltage on the coupled path. It might (?) be a challenge to figure out forward vs. reverse power because you only have the one ADC.

If you come up with something -- good or bad -- please report back! I am curious to hear about it.
Electrical Engineer
Nuand, LLC.

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