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myriadrf / libxtrx

High-level XTRX API library
Apache License 2.0
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XTRX (tx) flips the signal #3

Closed freqmod closed 5 years ago

freqmod commented 5 years ago

XTRX flips the signal in the frequency domain during TX.

The easiest way to check this is to open sdrangel and do an ssb transmission. Then you will need to use USB to listen to LSB or visa versa.

I also see this in my own app that uses soapy directly, there i have to mix my signal (using a zadoff chu sequence as a preamble) with a complex mixer, and use the difference product for it to be received correctly.

(This was tested by receiving with a LimeSDR, it might be that that flips the signal, but i think that is unlikely since that driver has been out for a few years).

mgw93 commented 5 years ago

I did notice this issue too. I was just transmitting a sine wave, and it showed up on the wrong side of the center frequency when receiving with a USRP. So it probably isn’t the LimeSDRs fault.

sergforce commented 5 years ago

That was due to an uninitialized variable in gr-osmosdr. Fixex in the new release.