PiBalloon III – Launch on July 1st


Launch on Wednesday, July 1st, before noon. Location TBD. Chasing encouraged.

  • APRS Primary: K5UTD-11 on 144.34MHz
  • APRS Backup: KE5GDB-11 on 144.39MHz
  • Slow Scan TV: 144.5MHz – Robot 36
  • Crossband Repeater: 446.050MHz Uplink (110.9PL); 147.5MHz Downlink

Launch Details:

This launch is part of an Intro to Space camp being hosted at UT Dallas. High school students interested in STEM will be coordinating launch aspects, and assembling the primary payload. We will be launching on Wednesday, July 1st, some time before noon. The students will chose the launch site a day or two before the launch. Upper level atmospheric conditions will dictate the launch site.

Payload Details:

The primary tracking payload will be built by the students. It will consist of a TinyTrak4, GPS, Arduino, and a handful of weather sensors. It will operate under the K5UTD-11 SSID, and beacon a position once every 15 seconds, and a telemetry packet once every 15 seconds.

The secondary tracking will be handled by a RaspberryPi and a TNC-Pi. The “signal” chain will be a USB GPS to gpsd, which is then read by a python script, and sent to the aprx daemon. The aprx daemon transmits a position every 10 seconds.

The SSTV transmitter will be driven by the RaspberryPi running the secondary tracking. The Pi will take a picture with a Pi Camera, process the .png into a .wav file, and play the audio to a radio via the soundcard. This can be run simultaneously with the APRS, as the APRS radio is controlled by the TNC-Pi, not the soundcard on the Pi.

The crossband repeater will be a Yaesu FT-530.

Power Management:

The payloads will be divided into three separate power groups: primary tracking, secondary tracking, and non-essentials. Primary tracking will consist of the TinyTrak4, GPS, Arduino, sensors, and a Baofeng UV-5R. Secondary tracking will be the RaspberryPi and another Baofeng UV-5R. The non-essentials will include the crossband repeater and the SSTV transmitter (you guessed it; another UV-5R!).

Each group will be powered by three or four Li-SO2 D cells. This will give us 10.8v or 14.4v to play with, at 9.2Ah.

Communications Plan

We will use the following frequencies depending on balloon location.

County Repeater Frequency
Collin/Rockwall UT Dallas 145.43- pl110.9
Dallas/Ellis/Kaufman Flamethrower 146.7- pl110.9
Denton/Wise Rosston 145.49- pl85.4
Tarrant K5FTW 146.94- pl110.9
Elsewhere Simplex 146.54

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