Palomar Amateur Radio Club STEM Experimentation Lab

Satellite communications is a vast topic. There are hundreds of satellites and they use many radio bands. There are even satellites specific to amateur radio, AMSATs.

It's possible to monitor many of these satellites but the sessions tend to be fleeting as these satellites are in low Earth orbit and pass over relatively quickly, usually in just a few minutes.
Most amateur satellite communications will use the VHF and UHF bands.

Digital Modes in Satellite Comms

Beyond voice, satellite communication heavily utilizes digital modes to exchange data. Satellites often broadcast telemetry—data about the satellite's health, battery status, and orientation—using digital protocols. Commonly used protocols include:

• AX.25 Packet - the classic digital protocol for satellite BBS (Bulletin Board Systems) and APRS (Automatic Packet Reporting System).
• PSK and FSK - frequently used for telemetry downlinks, allowing ground stations to decode data automatically using a soundcard interface.
• High-Speed Data - modern cubesats often use faster digital modems to send images and larger data packets more efficiently.

You can get weather maps, listen to voice communications, and even monitor the amateur radio stations onboard the International Space Station if they are operating. If they are operating you can attempt to get a QSO from the ISS, a really cool accomplishment since you have to get through the pileups.

Satellite operation is a bit different from normal ground stations due to the extreme movement and location of the signal sources. Monitoring will often require tracking of the satellite's track across the sky either by hand or with multi-axis antenna rotators. The satellite pass is very brief, typically only lasting 10 or 15 minutes or even just a few minutes. So using a satellite prediction and tracking app is a must.

If you are transmitting to a satellite, you don't need a high-power rig. Satellite receivers are designed to be very sensitive. Satellite uplink transmission power typically should not exceed 5 watts.

Amateur Satellite Tracking Resources

A satellite tracking app or program is necessary to help locate and track satellites. They predict the satellite passes so that you can successfully track them. There are actually quite a few out there both free and paid.

• One useful (free) Apple iOS app SatSat is widely recommended
• A recommended app for Android (free) is Look4Sat
• For desktops a widely used (free) multi-platform program called GPredict is a full-featured satellite tracking application for Windows, MacOS and Linux
• For satellite tracking and predictions on the web, N2YO.com and Ham Sat Tracker can be used without installing anything.

References:

• Amateur Radio Satellites  🔗 The Radio Amateur Satellite Corporation (AMSAT)
• Space Communications Introduction  🔗 Space Communication (ARRL)
• Live Realtime Satellite Tracking and Predictions (Web)  🔗 N2YO.com
• Ham Sat Tracker (Web)  🔗 Ham Sat Tracker