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Showing posts from August, 2017

HF Mini Radio - BitX40

I am an ex Army Signals officer and also built military HF radio equipment for a period of about ten years - man pack, ground and airborne, so when I saw the new BitX40 radio kit, I just had to get a couple to play with. These kits are made in India, are good quality surface mount, built up tested and aligned.  For the princely sum of $59, one can get two or three and have fun: Bread and Circuses Here is my breadboard setup.  Yup, it is a real olde skool bread cutting board.  Wood is a good insulator and some blue ticky-tacky keeps things down: BitX40 7 MHz SSB HF Radio The BitX40 is an analogue radio, with a digital synthesizer tuner - so it is a throwback to some time before the dinosaurs, circa 1985 - nice and simple. The default setup is for the 40 meter band, but one can tune it for any HF band, by using switches and coils.  They are so cheap, one could get multiple radios and configure each for a different band of interest.  However, give

Digital Slow Scan TV with gstreamer

I had a look at radio amateur Slow Scan TV and noticed that it is analogue, so I wondered whether I can create a digital version using gstreamer. Here is an example script that will play one video frame every ten seconds.  This could very well form the basis for a digital SSTV system. The first part of the script are commented tests that show how I worked my way up to the super slow method that uses the videorate plugin to drop most of the frames. Note that due to the long time between SSTV frames, everything will always be different, so motion jpeg will likely work better than h.264 compression. #! /bin/bash echo Slow Scan TV example with a laptop PC camera and gstreamer # Install all the plugins including v4l2src: # dnf install gst*plugin* # Play the laptop PC camera the simplest possible way using the system defaults: # gst-launch-0.10 v4l2src device=/dev/video0 ! autovideosink # Play the camera and scale it smaller at 30 frames per second # gst-launch-0.10 v4l2src device=