ISS APRS Balloon to Launch Saturday

BLT-28 Katy to Nanjing

BLT-28 Katy to Nanjing

A group of amateur radio operators aims to establish a world record for distance by flying an unmanned, helium-filled balloon from Katy, Texas, across the Atlantic and the Mediterranean then on to Nanjing, China.

During the trans-Atlantic crossing, when out of range of shore based stations, the balloon’s APRS beacon will operate on the International Space Station (ISS) packet digipeater frequency of 145.825 MHz.

The South Texas Balloon Launch Team will release the balloon at 3 pm CST (2100 UT) Saturday, February 11.

The balloon payload package weighs only about 150 grams and contains a high altitude GPS tracking system and a 144 MHz FM APRS amateur radio transmitter. To conserve weight and battery life, no camera equipment will be on board. The maximum altitude is expected to be above 30 km, with horizontal speeds between 160 and 240 km per hour. The balloon size will increase from about 1.5 metres to about 11.8 metres at maximum elevation. Recovery of the payload package is not expected.

Individuals may follow the balloon’s progress on the Internet by logging onto APRS tracking site, filling in the “Track callsign:” field with “kt5tk-11” and changing the “Show last:” field to 24 hours.

The APRS telemetry transmitter is frequency agile to cope with different APRS standards across the globe. The frequencies used will be:
USA = 144.390 MHz FM
mid-Atlantic = 145.825 MHz (International Space Station packet digipeater frequency)
Europe = 144.800 MHz FM

APRS tracking site

Read the Katy Times story at

BLT-28 The Flight of the Orient Express

South Texas Balloon Launch Team

QRP APRS to the ISS 

Qtmm AFSK1200 soundcard modem software for decoding packet radio, APRS and telemetry from amateur radio satellites

Automatic Packet Reporting System (APRS)

Link to UZ7HO Soundmodem 1200 bps packet and other APRS software