To actually see if it is possible to super-pressure mylar/foil balloons - this requires more balloons (of the same size) and a lighter payload. Launching would need a quicker ascent rate and an earlier launch time to make use of the solar heating.

• Lighter payload
  • Smaller battery - 1000mAh
  • Better power saving in the code
  • Smaller GPS antenna
  • Lighter wire UHF antenna
  • Use seeeduino rather than arduino pro
• More balloons - order 4 91cm balloons and see how many we need to use
• Preamble before tx'ing when in modes that have gaps
• Battery voltage monitoring
• Solar panel to charge battery during the day
• Temperature sensor

• Seeeduino film
• GPSbee
• Mini GPS antenna
• Radiometrix NTX2
• Wire 1/4 wave + radials
• 1000mAh LiPo battery - ordered
• Some insulation

• Aiming for 75g total mass.

• 36“ (91cm) Balloons ebay - £6.65

• PicoAtlas will be on 434.073Mhz RTTY ASCII-8 50 baud, 425 shift, no parity and 2 stop bits - select pico in dl-fldigi.
• Sample telem:

$$PICO,41,00:49:19,50.8156,-0.3679,207,0,0,6;2;1023;21*FE46

$$Callsign, count, time, latitude, longitude, altitude, lock, no of sats, nav status; tx mode; batt voltage; ext temp *CRC16

• There will be three transmission modes for the flight.
  • Mode 0 - for the first 500 loops will be txing continously - this is to allow preparation before launch and for people to easily find the signal.
  • Mode 1 - 'Day Mode' - between 0700 and 1900 - the payload will transmit every 20 seconds turning the radio off between to save power - there will be a preamble of UUUU to help dl-fldigi catch the transmission. The GPS will remained power through out this.
  • Mode 2 - 'Night Mode' - between 1900 and 0700 - the payload will transmit 10 strings of data with gaps of 10 seconds and then will shutdown the GPS and radio for 10 minutes. If when the GPS is restarted it has failed to achieve lock it'll continue to tx until it does before shutting down again.
• Battery Voltage
  • 1024 = 4.0v
  • 1000 = 3.9v
  • 975 = 3.8v
  • 950 = 3.7v
  • 925 = 3.6v
  • 900 = 3.5v
  • 875 = 3.4v
  • 850 = 3.3v

• rebuild 1/4 wave with lighter radials
• code to reset GPS settings if fails
• finish insulation
• Tests
  • Run battery test - 12hrs
  • Test if solar panel can charge battery (sat)
  • calculate best time for launch - launch before 10am
  • Test narcsleep
  • check radio EN