Raspberry Pi 4B Composite Video Output

    Raspberry Pi is a single board computing product which was developed with a focus to improving computing skills among school children's in developing countries. Its a really good platform to learn hardware, coding, Linux and much more.

    Raspberry pi board supports HDMI and VGA ports to connect to display units. In older models there is a separate RCA socket to pull composite Video output . While on Raspberry Pi4 B and later versions the RCA socket was dropped and composite video is forwarded along with audio socket on the 4 pole TRRS socket. But in Pi Zero there is an unpopulated header labelled "TV" which outputs composite video.

QRP VHF/UHF SWR meter -Reflectometer

    A SWR meter is a very basic measuring instrument which is used to measure the voltage standing wave ratio (VSWR) in a transmission media. If you are working with radio waves and antenna experiments, this is a must instrument you should have. Its not that complicated to build one and our intention here is to just get the indication of level of VSWR in a particular transmission path.

ISS SSTV- "Amateur radio on Shuttle, Mir and ISS" SSTV event - June 21-26 ,2021

    Talking about history … The Shuttle–Mir program was a mission space program between Russia and the United States that involved American low earth orbiting Space Shuttles  visiting the Russian space station Mir where Russian cosmonauts flying on the American Shuttle, and an American astronaut flying aboard a Soyuz spacecraft to engage in long-duration expeditions aboard Mir.

   SSTV event was continuous from June 21 until June 26. The images transmitted were related to some of the amateur radio activities that have occurred on the Space Shuttle, Mir space station and the International Space Station.

    Used this event to test multiple antennas. Experimented with two different antennas this time, One was QFH tuned to 136 MHz obviously for WX satellite reception and one was Slim Jim antenna tuned to 145 MHz. And another setup was with VFH-UHF Yagi antenna tuned to 145 MHz frequency in VHF range. 

    The result was as expected the tuned antenna closed to downlink frequency of ISS VHF Transponder i.e. 145.800 MHz gave better results. Managed to receive few good images using my Yagi on last days of event.

ISS SSTV - ARISS 20 years of operations on ISS December 24-31, 2020

    After a long gap of Ham activity due to busy life, Finally the world wide lockdown brought a short throwback to my hobby activities. That was the time when is saw a tweet about a special SSTV event which was being celebrated  on the occasion of 20^th anniversary of ARISS operations on the ISS. The event was scheduled from December 24 through December 31. 

There we go...!!!

    Assembled a QFH antenna on my roof and connected it to my UV5R Radio. Those who are interested can find the detailed procedure to decode SSTV signals from here. And here is the details for building interface for UV5R to connect with PC Audio input. After monitoring multiple passes got some good SSTV images. Interesting thing was the there were multiple Ham communities around globe which were issuing Diploma certificates while submitting set of quality images.

    Managed to receive some quality images from ISS with my QFH Antenna, which I built to receive WX satellite (NOAA)  images. Will post about my QFH same shortly.