Satellite Communications
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.
Amateur Voice Satellite Comms
Amateur satellite voice operation will predominantly be FM. Many, if not most, of these are actually cross-band repeaters traveling at high speeds across the sky. To use these a dual-band VHF/UHF transceiver will be required.
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 Operations
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.
Resources for Tracking Satellites
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 Amateur Satellite Database
- Space Communications Introduction 🔗 Space Communication (ARRL)
- Live Realtime Satellite Tracking and Predictions (Web) 🔗 N2YO.com
- Ham Sat Tracker (Web) 🔗 Ham Sat Tracker
Note: PARC does not sell or endorse any products mentioned in these pages.
Information is provided for education and instructional purposes only.