The Amateur Radio on the International Space Station (ARISS) packet digipeater aboard the ISS has been active for several days now on 437.550 MHz. The UHF frequency means users will have to make adjustments for Doppler on both uplink and downlink.

The change to 70 centimeters comes in the wake of a problem that has sidelined the Ericsson VHF transceiver, so the UHF model has been put into service. The digipeater operates just as it did when it was on its former 145.825 MHz frequency.

AMSAT suggests that users program a group of five memory pairs to permit an operating range that will compensate for Doppler, with transmit frequencies from 437.560 to 437.540 MHz, and receive frequencies from 437.540 to 437.560 MHz, in 5 kHz increments (i.e., the transceiver would be in simplex for 437.555 MHz).

More information is available from the AMSAT Station and Operating Hints page. Scheduled ARISS contacts and APRS operations will also utilize the Ericsson UHF transceiver in the Columbia module. — Thanks to AMSAT News Service