gpredict VS gnuradio

I didn't watch the video but Gpredict has tracking and a map showing the orbit path and ground footprint for satellites you select.

I'm using sdrpp with Doppler correction with gPredict. I record the signal in sdrpp and then process it with noaa-apt.

look at the source of http://gpredict.oz9aec.net/

Your missing the point basically they mean upgrade your software to Gpredict satellite tracking software (GPL) which has Linux and Windoze versions. http://gpredict.oz9aec.net/   Gpredict uses hamlib to control both radios and mounts. Hamlib supports many radios and mount support includes Meade, Celestron and iOptron IEQ45 alt-az mounts via AUSCOM standard software. Once done the next part is ensuring you set up you com ports to appropriately control your devices radio and mount and making sure the appropriate devices are set-up in the software. Note if your com ports change say because you replug something, don't forget to update the port details otherwise coms will fail and the relevant device won't be usable. Check out the documentation and there are a number number of set-up videos on YouTube if needed.

LWN usually has great content but they've missed out on so much free ham software in this article that I use regularly.

My main HF rig is an older Yaesu FT-950. I tapped the IF and brought it out of the chassis where it is plugged into a cheap RTLSDR. I then access that RTLSDR (with free drivers) with GQRX (free software for visualizing anything compatible with SoapySDR or GNU radio), and the result is that I get a panadapter that is arguably better than what's available on $2000 radios. Short video here: https://photos.app.goo.gl/uP9zMMbiiiSmHYvM8

As for VHF/UHF stuff, I would be hopeless if it wasn't for GPredict on my laptop making it simple to track LEO satellites. https://github.com/csete/gpredict Short video here: https://photos.app.goo.gl/eg87BWpt2XnJdGFp7

I also run an APRS igate, which is powered by direwolf: https://sielicki.github.io/posts/radio-scanner-aprs-igate/ , https://github.com/wb2osz/direwolf

It hasn't been updated in a couple years now, but `gpredict` is a nice desktop program that will show projections of satellite orbits and predict upcoming passes.

https://github.com/csete/gpredict

GPredict

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