Cross Band Repeater Quick Start Guide

The CubeSatSim v2.1 software has a Repeater mode that simulates a UHF up, VHF down FM satellite repeater often known as “Mode U/V” similar to AO-91 (RadFxSat / Fox-1B).

Software

To see if your CubeSatSim has this software, you can type this command after logging into your Pi Zero:

CubeSatSim/config

and see if the version is v2.1. If it is, you can try this mode by typing the command:

CubeSatSim/config -e

Alternatively, if you press and hold the pushbutton, the v2.1 software cycles through seven operating modes instead of the five modes in the v2.0 and earlier software (modes 1 – 5 are APRS, FSK, BPSK, SSTV, and CW, while the additional two modes are FunCube and Repeater).

If your pushbutton allows you to set mode 6, then you can try out Repeater mode by releasing the pushbutton during the 6 blinks.

Updating to Version v2.1

If you aren't running v2.1, you can update it by logging into your Pi Zero typing these commands:

cd

cd CubeSatSim

git pull

git checkout fc

./update

If the update script does not automatically reboot, you can manually reboot by typing:

sudo reboot now

You can then switch to Repeater mode by logging back into the Pi Zero and typing:

CubeSatSim/config -e

Repeater Mode

Once in Repeater mode, the CubeSatSim will be in receive mode, listening to either the default receive frequency of 435 MHz, or another frequency set by the CubeSatSim/config -F command. The green LED will be on, but the blue transmit LED will be off. If you transmit on that frequency and the squelch is broken, the CubeSatSim will retransmit the FM signal received at the default frequency of 146 MHz and turn on the blue transmit LED. Or, if another transmit frequency is set by the CubeSatSim/config -F command, the transmit frequency will be the set transmit frequency minus 290 MHz (e.g the default 434.9 MHz – 290 MHz gives the default 144.9 MHz).

The blue transmit LED will stay illuminated as long as the squelch is broken. There is about a one second timeout.

You should initially listen for the repeated signal with no squelch on your receiver as the signal will be weak. Also, there will be a small random frequency offset from expected frequency, so you may need to tune a few kHz either side of the expected frequency. An SDR with a waterfall is helpful to find the signal.

Advanced Settings

You can try different squelch level settings using the CubeSatSim/config -q command.

To prevent false triggers, you can set a CTCSS PL code on the CubeSatSim that will need to be set on the transmitting HT in order to break the squelch. For example, you could set a 67 Hz CTCSS tone just like AO-91 (RadFxSat / Fox-1B). For information see https://github.com/alanbjohnston/CubeSatSim/wiki/Command-and-Control#private-line-pl-for-transmit-and-receive