Amateur Radio in Space

By Steve Ford, WB8IMY

Overview

Amateurs have been building satellites since the earliest days of space travel.

These satellites are known as “OSCARs”—Orbiting Satellite Carrying Amateur Radio.

The first Amateur Radio satellite was OSCAR 1 and it reached orbit in 1961.

Satellites: Relays in the Sky

Like commercial satellites, Amateur Radio satellites are primarily used to relay signals from one location to another.

From their vantage points in orbit, satellites can “see” large portions of the Earth. This is known as a satellite’s “footprint.”

Every station within the footprint can communicate through the satellite

The Footprint of OSCAR 50

In this illustration, everyone within the circular footprint of OSCAR 50, an FM repeater satelllite, can communicate with each other.

Satellite Orbits

Most Amateur Radio satellites travel in low Earth orbits at altitudes of 800 to 1500 km.

At this altitude, a satellite completes one orbit every 90 to 100 minutes.

At the same time, the Earth is turning beneath the satellite.

The result is that all stations on the ground will enjoy several 15-minute communication sessions with each satellite each day.

You can predict pass times with web tools such as www.n2yo.com or software.

OSCARs 29 and 52

OSCARs 29 and 52 relay Single Sideband (SSB) voice and CW transmissions.

Amateur Radio on the International Space Station There is also a fully equipped amateur facility

aboard the International Space Station.

APRS on the ISS

The International Space Station often functions as a digital relay for APRS packet data.

Station Equipment: FM

For OSCAR 50, all you need is a dual-band FM rig and a directional antenna.

Station Equipment: SSB/CW

For OSCARs 29 and 52, you will need a dual band SSB/CW rig. A full duplex model such as the Kenwood TS-2000 or Icom IC-9100 is best, but any will do for short contacts.

Active Satellite Frequencies Saudi-OSCAR 50 (FM Repeater, 67 Hz CTCSS) Time Transmit Receive (MHz) AOS (start) 145.840 436.805 AOS+3 Minutes 145.845 436.800 Zenith (maximum) 145.850 436.795 Zenith+1 Minute 145.855 436.790 LOS (end) 145.860 436.785 Linear Transponders (SSB/CW) Uplink Passband Downlink Passband VUSat-OSCAR 52 435.225 – 435.275 MHz 145.875 – 145.925

MHz Fuji-OSCAR 29 145.900 – 146.000 MHz 435.800 -- 435.900

MHz AMSAT-OSCAR 7 432.125 – 432.175 MHz 145.925 – 145.975

The Future

More satellites on the way. Many are FM repeaters, but there are a few SSB/CW birds on the schedule as well.

Give Ham Satellites a Try!