Meteor M-N2 Images

Friday, 18 May 2018

Homebrew SDR HF Transceiver - decision time

The video below shows my Homebrew SDR rx working with the GUI on the STM32F746-Discovery board.

However, what you might notice is the presence of image products in the waterfall. The processing of the signal suppresses all but the very strongest of these so they don't appear as audio but it is mighty confusing when they are on the waterfall but actually not there (if you see what I mean)!

Herein lies a problem with using the Audio Weaver software. While it is great for prototyping I have reached the limit of what the free ST version can do. This version does not provide an FFT function so I cannot perform an FFT on the signal after the mixing of the I & Q signals after the Hilbert transforms. This means that I cannot create a waterfall display without the image products.

Consequently, I have made the decision to write the software myself instead of using Audio Weaver. I will initially use Audio Weaver to capture the I/Q from the sound port but will look to remove Audio Weaver altogether eventually.