Pegasus VI

Launch 2nd November 2008

• Max altitude - 31,394M

• Pictures on Flickr - both construction and inflight SSTV
• Launches Images
• PegasusVILog
• Pegasus VI KML

The first of launch of Pegasus VI was overall a success, due to some adjustments to my scripts concerning the rtty sound file generator I had by a mistake reduced the shift between the two frequencies down to 85Hz. On the ground with little background noise it was easy to decode however after launching it meant that the decoder software struggled to distinguish the 2 frequencies and therefore it wasn't possible to get a good stream of data. This rolled over to affect the online tracking which meant that there weren't any updates to the maps. It got to a point that we stopped even trying to decode the rtty and instead focused on receiving the images.

As can be seen from the flickr photostream the images received worked out well, sstv is transmitted line by line which means that movements such as the payload spinning or the need to retune the receiver adds various 'noise' lines to the image hence the horizontal bands. It was also found that the coordinate overlay needed to be in a different colour so that it didn't blend in with the clouds! Hopefully with careful positioning of a yagi antenna it'll be possible to improve the quality of the images but overall we were really pleased, its really exciting watching the image come in line by line!

The weather on the day was quite unusual, when we left home it was quite clear however on reaching EARS we found that the clouds were really low and it was pretty misty. The wind direction varied depending on the level which meant that the payload after being released actually came directly over us again. After launching we remained at EARS for most of the flight and then after we detected that the balloon had burst we headed in to Cambridge. As soon as we had arrived in Cambridge the payload sent a SMS of its coordinates and so we immediately set off to collect it. It was found in a field near to the road in West Suffolk.

With the payload in good condition the plan is now to fix a few of the problems that were experienced during the first flight especially the rtty shift and also improve the antenna and then fly again probably in the new year.

• Rebuild Antenna - going to go for a linear feed slim jim, a lot lighter and flexible.
• Make the GSM LED/Switches more accessible -
• Add internal and external temperature sensors -
• Save images to usb memory stick - will require breakout of 24pin port on the verdex 24 pin breakout board (USB Hub is the other option but draws too much current and so would require its own power supply).

• Fix RTTY shift - done - now 425Hz shift (50 baud, ASCII-8)
• Change colour of data on SSTV Image - done - now magenta
• Reduce freqency of GSM messages - done - now every 5 mins
• Strip down camera for weight - done
• Switch camera to using only 3 AA batteries - done

• Gumstix Verdex
• GPSstix
• Radiometrix NTX2 434.075Mhz donated by Radiometrix
• Canon Powershot A60
• Telit GM862 + Sparkfun Breakout board
• 1 LiPo 2000mAh 3.7v cell
• 7 AA Energizer lithiums

• Uses the onboard Ublox (ttyS2)
• Code
  • gpsparser3.pl

• Radiometrix NTX-2 connected directly to the gumstixs audio out, EN pin is connected to a GPIO
• 434.075Mhz
• 3 large cycles of 10 RTTY strings

• ASCII-8
• 300 baud
• 200 Hz shift
• Format: “APU16N PEGASUS time, latitude, longitude, altitude, speed, bearing, cycle count”

• Martin 1
• 320×240 image with GPS string overlayed at the bottom

• Example ogg - 50 cycles of RTTY (300 baud, shift 200, ASCII-8) and SSTV Image Martin 1

• 3 AA Energizer Lithiums

• Components:
  • GM862 (left over from the Firefly missions)
  • Breakout board (Sparkfun)
  • 3.7v 2000mAh LiPo Cell
  • GSM antenna
• Connected to the gumstix via the BTUART serial port (ttyS1)
  • The new verdex board routes the ttyS1 (BTUART) lines down the old connex HWUART lines - therefore if you use a verdex and a GPSstix it'll come out on the pins marked HWUART rather then BTUART
  • To set up BTUART you also need to make sure that the lines are set up correctly:
  • GPIO 42 AF1 in (echo “GPIO AF1 in” >/proc/gpio/GPIO42)
  • GPIO 43 AF2 out (echo “GPIO AF2 out” >/proc/gpio/GPIO43)
• Code
  • Communication is through gnokii
  • Simple shell script on the gumstix that runs gnokii every 3 mins

• Canon Powershot A60
  • 2MP
  • 4 lithium AA batteries
  • Connected via USB to the gumstix
  • Controlled with the capture code capture
  • UV lense