In December 2018, I passed the Class B (General Class) Amateur Radio License. I was awarded the call sign 4I1AWN (I started as Class C in 2017, with call sign 4G1AWN). I intend to document my progress as I explore the various areas of interest in amateur radio, particularly, satellite communications. One day, I will build my own radio equipment setup and antenna system capable of reaching and talking to the astronauts in the International Space Station (ISS).
Recently, I have been engaged with what is called SSTV, or Slow Scan Television. SSTV is a radio communication technique wherein images are transmitted through radio frequencies, that can be received directly by a proper radio equipment. This is the same technique used in sending and receiving images from the moon during the Apollo mission (the missing Apollo tapes are recorded SSTV transmissions).
Receiving SSTV images transmitted by the International Space Station during flyby (as the satellite passes in your location) is a popular hobby among amateur radio enthusiasts. The idea is to setup an equipment—such as an antenna, a radio receiver, and a decoder like as a PC or a mobile phone—that will allow you to receive and decode SSTV transmissions. Receiving SSTV images is just one of the many activities under the program called the Amateur Radio International Space Station or ARISS. This program is managed by various space and radio agencies around the world such as the NASA, Rosaviakosmos, CSA, JAXA, and ESA.
I have attempted to receive SSTV images from the ISS. The images below were continuously transmitted (in a loop) by the ISS from June 30 to July 2, 2018, and I was able to receive and decode 3 images in two flybys, at 2:30 am and 12:30 pm on July 1, 2018, from the Philippines.
At the moment, my setup is a mobile station—a vehicle with a radio equipment. I was in a parking lot when I received these images from the ISS!
To receive SSTV images from the ISS, you need a radio that can be tuned to 145.800 MHz, the frequency at which ISS transmits SSTV images and voice communications. This is also the frequency you will listen to if you wish to hear astronauts talking with fellow radio enthusiasts on the ground. Should you wish to engage in ARISS, please do not transmit at 145.800 MHz as it is a dedicated downlink frequency. For more information on various ISS frequency assignments, click here.
My current radio equipment are as follows:
- Motorola CP1660 VHF 5-watt handheld transceiver (2 units)
- Yaesu 2900R VHF 75-watt base radio
- Diamond M285 mobile antenna (converted a 1/4-wave)
- Diamond SG7000 dual band mobile antenna (1/4-wave VHF, 6/8-wave UHF)
- Diamond K33 antenna mount
- Diamond SX200 SWR meter
- 4 meters of RG8 cable
Here’s a demo on how SSTV images can be received (at 145.8 MHz) with a radio and a decoder such as a smart phone.
Through amateur radio, you can engage in various activities such as receiving images from the ISS, use various satellites as relay stations, bounce a signal off the moon, or talk to the astronauts on the ISS (as it orbits 400 kilometers above)!
© Anthony Urbano (Manila, Philippines)