Audible altimeter part 1


As the skydiving season in Finland is nearing its end it is time to find something elso to do at weekends. As I just got the A-license I have been gathering necessary equipment for the sport. Only the audible altimeter is missing as I can not decide between Altimaster N3 and L&B Protrack (1, 2).

I have always had problems to finish electronics projects and I think that it might be related to the fact that the end result of the project would have not seen any actual use. By creating something which is useful at one of my hobbies I hope that I have enough motivation to finish the project.

Audible altimeters are used to alert skydivers with loud alarm when they pass certain altides in freefall or with the canopy. In Finland the audible altimeter can only be used as a secondary altimeter as some kind of visual (digital or analog display) altimeter is required by the regulations. As I’m going to be carrying a visual altimeter I feel it will be relatively safe to test my own electronic projects while skydiving.

I’m using Cookie G3 (3) which has two small pockets (~5cm x ~5cm) for audibles. If the electronics catches on fire I plan on installing simple cutaway system (4) for the helmet .

Even if the project fails, I hope it will create good material for some other website (5, 6).


  • Approximate size: 5cm x 5cm x 1cm
    • Neptune N3: 6.2cm x 4.3cm x 1.2cm
    • Optima II: 5.6cm x 4.1cm x 1.1cm
    • 5cm x 3.2cm x 1.6cm fits Cookie G3 nicely
    • Current PCB 50mm x 35mm
  • USB rechargeable battery
  • Audible alarm
  • Relatively good altitude accuracy (+-50m) with small lag
  • Simple logging capability

Advanced options

  • Accelerometer/attitude
  • GPS
  • Simple display
  • Led indicator for the alarms as in Optima 2 (7)


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