My APRS broadcasts received by the ISS

This evening I managed to successfully send some APRS messages to the International Space Station that were successfully digirepeated. It might not be a major technical achievement but after monitoring and decoding many passes in the past to now actually send something myself 300 miles up to something traveling at 5 miles/second left me feeling a little chuffed!

I screen capped the evidence from the website which documents Amateur Radio data digipeated by the ISS. In order to appear on the page, a position report in a valid APRS format must be received and then digipeated through the ISS system, then be heard by an internet gateway station, which then forwards it on to the APRS Internet System.

Okay it sounds a bit more impressive when put like that 😉

The map showing received stations, M6GTG is me!
The detail of my report
List of stations with time stamps, showing me!
List of digirepeated messages

The equipment I used was very similar to that I used for the APRS IGate setup last month.

It consists of a small embedded PC running embedded XP, the sound card output was connected to the microphone input of my Baofeng UV-5R+ operating in VOX mode set to 145.825MHz. The radio was connected through my power/SWR meter in to the X-50 antenna. I used the UV-5R+ instead of the UV-3R since it has a little more power and better audio. I had a SWR of around 1:1.2 and outputting 4W.

The software I used was UISS from ON6MNU and the AGWPE packet engine. It has taken a little time to work out how to setup UISS into auto-beacon mode and putting in the time of the next decent pass (approx 45 degrees elevation) I set it to broadcast position and text data messages every 30 seconds.

The embedded PC running UISS
UV5R+ in VOX mode on 145.825MHz
The power meter showed 4W output, SWR about 1:1.2

I stood out in the dark, hoping to see the ISS pass over but the cloud cover was too thick and monitored using a handheld scanner. I heard my transmissions obviously and the ISS broadcasts as it repeated received messages, but I didn’t know if any were mine till I got back to the PC.


Well this a shameless plug for Steve Smith (G0TDJ) and his new ProjectHAB website/blog.

I met Steve last month at the International UKHAS 2013 Conference and he is embarking on his own journey into stratosphere and is busy building and programming his own payload. Steve had an exciting introduction into HAB tracking when he preformed an impromptu recovery of  Chris Stubbs (M6EDF) CHEAPO4 payload.

Steve with Chris Stubbs’s CHEAPO Pico balloon and payload after recovery

On a related note last night I attended a meeting of SKARS who themselves are looking at possible balloon projects for Gravity Fields Festival 2014

First reception of DANDE satellite

The US SpaceX company successfully launched a new upgraded version of its Falcon 9 rocket from California’s Vandenberg Air Force Base. The vehicle, carrying the Canadian Cassiope research satellite, lifted off at 16:00 UTC on Sunday, September 2013.

In addition to the main payload two satellites, DANDE and CUSat, carrying amateur radio payloads were also launched into orbit, both satellites have been reported as functional and transmitting away. Last night I had an attempt at receiving DANDE.

From Amsat-uk

DANDE stands for “Drag and Atmospheric Neutral Density Explorer.” Measuring drag and neutral particles in the lower atmosphere between 325-400 kilometers, DANDE will be measuring real time density, quantifying variations in altitude and over time, as well as providing in-situ model calibration data. The satellite is a low-cost density, wind, and composition measuring instruments that will provide data for the calibration and validation of operational models and improve our understanding of the thermosphere. Weighing approximately 45 kg, DANDE is classified as a nano-satellite that is about 18 inches in diameter.

The Colorado Space Grant Consortium (COSGC) has housed the project for approximately 7 years, in which about 150 students have been a part of the project through initial concept and design, to the current team of mission operators. There are two instruments on board which allow DANDE to make in-situ measurements rather than being passive or only carrying accelerometers. The subsystem ACC (Accelerometers) contains 6 accelerometer heads arranged in a circle which were built in-house. The NMS subsystem (Neutral Mass Spectrometer) also known as Wind and Temperature Spectrometer will survey the variety and quantity of numerous neutral particles in the Thermosphere. This data will be particularly interesting during periods of high
solar activity do to atmospheric effects seen at these times in the polar regions of Earth.

DANDE Telemetry System Information:
Beacon Downlink Frequency: 436.75 MHz FM
Callsign: dandecosgc
Data Rate: 9600 baud
Modulation: FSK
Transmit Interval: every 15 seconds
RF Power Output: 0.75 W
Antenna Polarization: linear

DANDE Beacon Portal
Bruce Davis Project Dande Blog

Using the most up to date TLE (from here) I worked out there was a nice late evening pass, so got out my homebrewed yagi, I posted a picture of it on my twitter account @nerdsville

Another evening and another home brewed antenna, must get a cheap drill press as nothing lines up properly!
— Andrew Garratt (@nerdsville) May 10, 2013

I did manage to get a signal, but it was very weak so no chance of even trying to decode it. This wasn’t helped when a connector on the coax fell apart a few minutes before the start of the pass and I was estimating where to point the antenna. I am a bit out of practice!

Below is a snapshot of the waterfall, I have highlighted the faint beacon bursts.