LimeSDR transmits noise (or maybe harmonics) at low sample rates

I wrote an application that transmits to UHD device, as well as LimeSDR (both using SoapySDR interface).

The image above shows the recorded IQ data that LimeSDR transmits over the air, if the sample rate is set to something lower than 3.500.000 sps. In this case I choose 100.000 sps.

The image above shows the received IQ data that LimeSDR transmits over the air, if the sample rate is set to 3500000 sps.

Is there a lower limit or are there special rates that LimeSDR can handle?

The datasheet says 2 MHz as the minimum bandwidth for TX and the source code says 5 MHz the minimum TX Low Pass Filter.


So I’d be inclined to change your sample rate to 5 MSPS and see if the problem persists.

I managed to upscale/downscale my data rate to/from 5 MSPS. Also I had to use the “tune argument” (SoapySDR parameter) “OFFSET=5000000” “OFFSET=1000000” to shift away the oscillator from the tuned frequency. Both steps are required to get a clean signal (as far as I can measure).

What is the status of this?

My Max SPS I like to run is 4MSPS on an Odroid-X2 USB2.0

IM thinking of Using My Lime as a Ham Radio soon … my current SDR also has an output so I already have amps that take the same input approximately .