CubicSDR VS gnuradio

Looks like I got cubic sdr executable cubicsdr_v0_2_6a_win64 from https://github.com/cjcliffe/CubicSDR/releases/tag/0.2.4.

There is loads of software that will work such as SDR++, GQRX, CubicSDR, and SDRangel just to name a few. For HD radio reception, there is nrsc5. Nrsc5 only works with an rtl-sdr, so you will need one if you want to receive HD radio.

CubicSDR and GQRX both work on my M1 Mac. I installed GQRX using homebrew, CubicSDR was downloaded from Github (https://github.com/cjcliffe/CubicSDR/releases/tag/0.2.5). Both are the x86_64 versions and run under the emulation layer provided by Mac OS.

CubicSDR

Be aware that 3.1.5 enables EGL by default and, if your application uses GLX, you're going to have problems: https://github.com/cjcliffe/CubicSDR/issues/886

In gr-dtv transmitter examples for Gnuradio, I see some times people use a resampler block before the RF hardware sink. Say our sampling rate is ~9.14Msps which satisfies the Nyquist criterion because our samples are complex numbers.

2.1. Thanks for that tip, I forgot that I was able to check the source code of the WBFM Receive block. As you have said, there are mostly the same. There are some differences between how values are picked. The WBFM Receive block would be a synonym of Quadrature demod => Fir Filter (decimation => Low pass filter) => FM Deemphasis. 2.3. My question there is why 10 and not 20 or 100. I understand that the idea is to reduce the sample rate asap, but what I don't understand is why those values were picked and how can I understand what would be the "correct" or "best" value. 2.4. I'm not fully understanding what you said. If I check the WB FM recieve source code the values that are supplied as the cutoff freq and transition width of the Low pass filter differ from the one of the example. The webfm would apply a sample rate / decimation / 2 - sample rate / decimation / 32 as a cutoff freq and a sample rate / decimation / 32 as a transition transition width. Calculating those values would end up in different that the ones supplied in this second example. Again, is there a rule of thumb to pick these values?.

Gaussian filter is used only on the tx side, so specifying bt in the receiver makes no sense. Take a look at gfsk mod/demod blocks implementation: https://github.com/gnuradio/gnuradio/blob/master/gr-digital/python/digital/gfsk.py

GNU Radio

Here's the filter coefficients used for the GNU-Radio interpolator block to get you started. This is a 7th order interpolator (i.e., 8 FIR taps) with very good performance. Each "row" of the array sets the delay in steps of sample_time / 128.

From their README: “open-source software development toolkit that provides signal processing blocks to implement software radios.” https://github.com/gnuradio/gnuradio