Chasing satellites. Part 3. FM Repeater Satellites.

There is a lot of satellites spinning around the Earth. Almost all of them have their own purpose and are useless for radio amateurs. But some of these satellites can be (and are) used by HAMs. Specifically, these are ones having FM repeaters on board. Below is a table containing information about all the satellites with FM Repeaters.



SO-50

 

SO-50 carries several experiments, including a mode J FM amateur repeater experiment. The repeater consists of a miniature VHF receiver with the sensitivity of -124dBm, having an IF bandwidth of 15 KHz. The receive antenna is a 1/4 wave vertical mounted in the top corner of the spacecraft. The receive audio is filtered and conditioned then gated in the control electronics prior to feeding it to the 250mW UHF transmitter. The downlink antenna is a 1/4 wave mounted in the bottom corner of the spacecraft and canted at 45 degrees inward.

Uplink: 145.8500 MHz FM, PL 67.0 Hz.
Downlink 436.7950 MHz FM

The satellite automatically switches off after 10 minutes of inactivity. However, this occurs rarely due to a pretty big number of amateurs willing to catch it. If you can't hear anything you might try to switch the transmitter on. In order to do this, you need to send a CTCSS tone of 74.4 Hz. The order of operation is as following

1) Transmit on 145.850 MHz with a tone of 74.4 Hz to arm the 10 minute timer on board 10-minute craft.
2) Now transmit on 145.850 MHz (FM Voice) using 67.0 Hz to PT the repeater on and off within the 10 Minute window.
3) Sending the 74.4 tone again within the 10 minute window will reset the 10 minute timer.

AO-85 (Fox-1A)

AO-85 (formerly Fox-1A) is the first of AMSAT’s Fox-1 series of 1U CubeSats. Launched as part of ELaNa XII on the October 8th, 2015 NROL 55 Atlas 5 launch from Vandenburg, California, AO-85 is in a roughly 65-degree inclination, 518x810km orbit with apogee over the northern hemisphere.

AO-85 carries a U/V FM repeater operating at up to 800mw. Uplink was planned for 435.180, but initial reports indicate it may be closer to 435.172 due to unforeseen temperature differences. Repeater access requires the satellite to receive a 67.0 Hz PL tone for two seconds. If the satellite does not receive a signal carrying a 67.0 Hz PL tone, the repeater will turn off after one minute. When the repeater is not activated by a signal carrying the PL tone, a voice beacon is transmitted every two minutes. The downlink is 145.980 and includes Data Under Voice (DUV) FSK telemetry simultaneous with repeater operation. A high-speed data downlink at 9600 bps is available for experiment and high-resolution data. In addition to the amateur operations, there are a number of scientific experiments on board the spacecraft.

AO-91 (RadFxSat / Fox-1B)

Uplink: 435.250 MHz FM, PL 67.0 Hz.
Downlink 145.960 MHz FM

AO-92 (Fox-1D)

Uplink: 435.350 MHz FM, PL 67.0 Hz.
Downlink 145.980 MHz FM

The complete table containing compressed information about uplinks and downlinks can be found HERE. Further, I provide all files with settings for all the devices I have used with satellites described in this post.