I would like to build an underwater mammal detector to take videos of seals when they get in and out of their cave (the entrance of their cave is underwater).
It will be a waterproof sealed box with a camera in it, fixed on the rocks (underwater, in front of a cave), which will record video whenever a seal is swimming in front of it, probably connected to a solar panel placed on the ground (on the shore, not underwater). The device should be autonomous for about a week.
I can think of a few solutions:
- Just use a regular smartphone with a waterproof case (connected to a solar panel), with an app which process the video and record it when something is moving,
- Same thing with a Raspberry PI and a webcam (infrared?),
- Use a Raspberry PI, a webcam and PIR sensor to trigger the video recording,
- Same thing with a laser trigger (probably not the best solution)
I would emphasize on simplicity and robustness. So I have a few questions:
- What solar panel would I need to power an iPhone processing/recording video non-stop (it will be in Greece with good sunlight conditions) (which power/specs, not which brand/model)? How will the battery evolve? Will a Raspberry PI consume less power?
- Would a PIR sensor work underwater? Which one should I get (which specs)? How will it react to ambient light changes (day/night)?
The smartphone solution is attractive because of its simplicity, the PIR sensor solution might be better because it will consume less power.
Edit: Seals are mammals, they have warm blood (37°C), but it does not mean their skin is warmed than water. "Seals keep their skin at just 34°F (1°C) when lying on ice" Mammal Anatomy: An Illustrated Guide.
I don't know if they would be detected by PIR sensor + infrared is quickly absorbed by water.