SOLVED: Identifying interference with oscilloscopes and software-defined radio

[djhuft]

@djhuft: You did some great work! A long time ago I did use a soundcard to check and identify different sources of noise like you did with the SDR. Worked great. It's normal to see submarine or time sync transmitters.

Thanks! It was very interesting to do this work and see what I found. Hopefully it can be useful or at least interesting to others.

[djhuft]

This is all so interesting. I'm afraid it's above my level of brain power! (So far, but I'm trying to learn!)
I do have a new guy question though. On so many stations, mine included, I always see a large 1khz spike(shown on Richo's attachments). What is that caused from, if known?
Thank you all for so much information! I do love learning about this.

Keep learning! I have a master's degree in electrical engineering, and that helps a lot with understanding certain parts  of this project. However, there are very many things I learned just by fiddling around and tinkering. There is nothing quite like actual hands-on work. And learning by doing is fun.

To answer your question about the large spike at 1 kHz to DC, I'm not exactly sure, but I think it is just an artifact of how the Fourier transform works. I see the same thing in other scenarios and don't even pay any attention to it anymore..

Edit: The lowest frequency bin in an FFT calculation is just the mean (DC) value of the signal. In our case here, it's not actually important.

[JupiterJoe]

This is all so interesting. I'm afraid it's above my level of brain power! (So far, but I'm trying to learn!)
I do have a new guy question though. On so many stations, mine included, I always see a large 1khz spike(shown on Richo's attachments). What is that caused from, if known?
Thank you all for so much information! I do love learning about this.

Keep learning! I have a master's degree in electrical engineering, and that helps a lot with understanding certain parts  of this project. However, there are very many things I learned just by fiddling around and tinkering. There is nothing quite like actual hands-on work. And learning by doing is fun.

To answer your question about the large spike at 1 kHz to DC, I'm not exactly sure, but I think it is just an artifact of how the Fourier transform works. I see the same thing in other scenarios and don't even pay any attention to it anymore..

Edit: The lowest frequency bin in an FFT calculation is just the mean (DC) value of the signal. In  our case here, it's not actually important.

Ahhhh, I understand! Thank you so much for the explanation! I find all of this fascinating. I've had a Boltek sensor going since 2009, and have always been intrigued on how it worked(even took one antenna apart once to see the insides(posted the pics on WXForum.net)), but this project shows me things I never knew about any of this, and I love it!
Thank you again for taking the time to help me understand.

[Karate_kid]

Keep learning! I have a master's degree in electrical engineering, and that helps a lot with understanding certain parts  of this project. However, there are very many things I learned just by fiddling around and tinkering. There is nothing quite like actual hands-on work. And learning by doing is fun.

How do you have this kind of time? It's incredible the amount of work this is congratulations!