ADVANCE NOTICE – Horus 48 – Telemetry Test Flight & Test Transmission

On the weekend of the 10-12th of March (exact day TBD), Project Horus will be performing a small (not-so-)high-altitude balloon launch from Mt Barker. The flight will be a short one (~1.5 hrs), with a maximum expected altitude of only 13km. All the payloads have been custom-built to be very lightweight – the total payload mass for this launch is < 300 grams!

The aim of this flight is to evaluate the performance of a new telemetry payload, which uses ‘THOR16‘ modulation. While about half the speed of the current RTTY payload, the THOR modes utilise forward error correction and interleaving. This promises to reduce or remove issues with mobile flutter and multi-path fading that we encounter with RTTY. In short, while we may not be getting telemetry sentences quite as often, we will have a much higher chance of the telemetry that is received being useful to us!

THOR Receiver Tune & Test Day – Sunday 4th March ~10:30AM CDST

To help stations adapt to the new THOR16 signal, this coming Sunday (a week prior to the launch) there will be the opportunity for stations in the Adelaide metropolitan area to set up dl-fldigi as per the linked guide below and have a go receiving a higher-power version of the THOR16 signal. This will be broadcast from Mt Lofty Summit by Mark VK5QI. Mark will be on the VK5RSB 70cm repeater (439.900 -5MHz / 91.5Hz CTCSS) as ‘technical support’, to help assist setting up the software. The signal should be easily receivable from the Adelaide Metro area and some surrounds.

Look for the test signal on 434.640MHz

Horus 48 Launch Campaign – Tentative 10-12th March

For the actual launch the following weekend, the telemetry frequencies for the flight are as follows:

  • RTTY – ‘HORUS’ – 434.650 MHz
  • THOR16 – ‘THORUS’ – 434.640 MHz

Both payloads are running 10mW transmit power, and have essentially identical antennas.

DL-FLDIgi Setup for THOR16

As usual, use dl-fldigi to decode telemetry, but in the case of the THOR16 payload, you will have to manually select the operating mode from the drop-down list as follows:

If you have the capability of running two 70cm receivers, please consider running two instances of dl-fldigi to decode both payloads. This may require either multiple PCs, or multiple sound cards. If you can only run a single receiver, please try and alternate between the different telemetry payloads.

We would very much appreciate reports as to your experiences decoding the different telemetry payloads – please e-mail these through to

Tracking for the launch will be available on the HabHub online tracker. We hope to see you as part of the tracking nets!


73 de Mark VK5QI