I managed to transmit QPSK from my LimeSDR Mini with GNUradio. I noticed that it’s only about 5 kHz wide and the setting for “samples per symbol” has no effect on the RF bandwidth. No matter what, my signal is only about 5 kHz wide. I’ve tried various LimeSDR sample rates but it also fails to make a difference.
Any advice?
Run your random source at samples/symbol * sample rate.
Now you have a symbolrate of 10M/4samples (2.5Mhz), the 5 khz what you see is probably dc.
Try shifting your signal away from the hardware center frequency to avoid the dc spike
Last tip start using QT gui instead off the WX
Thanks @pauluzs. I seem to have working QPSK signals now, but I have other issues such as strange repeating patterns.
I ran a test by re-transmitting an 8 MHz IQ file of the 850 MHz police band at 505 MHz, fed directly into an SDRplay, of course. The LimeSDR Mini was set to 8 MHz bandwidth so the IQ file would be transmitted properly.
The trunked transmissions sounded quite distorted and I could barely hear the proper digital noise.
