Software Defined Radio with HackRF by Michael Ossmann, Lesson 10: Filters

[@joelmiller246]

What a great way to start learning about this stuff.

[@GreatScottGadgets]

Glad you think so!

[@wetter4293]

Note for 10:20 - It looks like they've disabled the spectrum width display on the QT Frequency Sink. If you're seeing negative frequencies after changing your datatypes to Floats from complex, don't panic like I did - Simply go: Right Click QT Freq Sink --> Properties --> Spectrum Width --> Half Apply, and okei!

[@CallousCoder]

Fascinating! Never really thought about filtering as adding a delay but that’s exactly what a capacitor on an RC filter does too. It takes time to charge or decharge the capacitor. So in hindsight it makes sense in DSP, but I wouldn’t have instinctively thought that it actually is implemented by add delayed samples.

[@WillowUfgood]

Mind=blown! Actually feel that I understand this now. Btw the GNU radio I have shows the double peak for all floats, without needing to convert to complex.

[@WillowUfgood]

I mean the Freq sink shows the +/- spikes, with float specified

[@bradfordjones71]

Sir, This is great information, and I appreciate all your time that you put into this training. With this particular training, I have found that I do not get the same results as what you did. I'm not sure if it is because I don't have the WX series GUIs, only the QT, or not. My filter looked like a very large BPSK signal, vice the slanted look, with the null you had Also, I was very curious on how to use these filters on live signals like your key fob example in this video. Is it possible to create another video (when you have free time of course), detailing live collection, (with your GUI setup, and that cool record button) either with your key fob, or something like a GFSK signal from a Radio Control car / plane controller, which is my main interest at this time. There is very little training out there, to explain the parameters that are needed in GFSK demod, or to explain why my Quadrature Demod doesn't appear to be working. The only thing I can find, is simulations, which of course, works, but doesn't help me with unknown signals. 🙂 Again, I do appreciate this filter training, as it has explained a lot. Thank you.

[@GreatScottGadgets]

Thank you for watching the series! If you need specific help we suggest joining our Discord server (discord.gg/rsfMw3rsU8). Most of the Great Scott Gadgets staff and many of our community members hang out there and someone will be happy to chat. As for your video recommendations, I've added them to my list. Thank you for the suggestions!

[@bradfordjones71]

@@GreatScottGadgets Thanks so much for your reply sir, I'll check out the server. As a signals analyst, I'm having a hard time using my training to understand Gnuradio. So, all the help I can get, the better. 😀 Thanks again.