gnuradio VS multimon-ng

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

I have little experience with decoding radio signals so I don't know if any software decoders are expected to handle the clipping. I tried using multimon-ng and found that its UFSK1200 demodulator can get something out of the audio, but it also keeps repeating Error: stop bit is 0. Bad framing if verbose mode is enabled.

Sorry I gave wrong name, it is multimon https://github.com/EliasOenal/multimon-ng and is capable to decode:

It's likely that the signal is extremely strong. You can probably just pick it up with a short antenna indoors. I used MultiMonNG to decode. It's was pretty boring to be honest.

Give multimon-ng a whirl. This is CLI based, but can output what it decodes to a simple text file or hex data to do what you need with.

multimon-ng

POCSAG, FLEX (pagers), Morse, APRS and more with multimon-ng

multimon-ng for decoding various protocols.

Try this tool; https://github.com/EliasOenal/multimon-ng - It's CLI and you'll ideally want a Linux, but this can decode an awful lot more data modes like such.