add solar panel
try out cell phone call
>> works, but currently not at same time as data
add hydrophone (covered i2s mic?)
add omni mic
get one klangnetze object in case we want to try higher quality sound
add temperature sensor (neuhold DS18B20)
Sensors
hydrophone (i2s mic?)
Power management
add uC for power management: signal pi to sleep, then cut off power, and wake up after timer. it could also monitor battery voltage and only wake up if time passed AND battery level ok.
since the pi will be sleeping sometimes, we should have a separate monitoring server which can say 'sleeping until 9am, check back then' or so.
given the power consumption of the pi+modem up and running: 2W (5V 400mA), an 11Wh (3000mAh 3.7V) Li-Ion battery only provides around 5.5 operating hours. of course we can use a bigger battery, e.g. a 10000mAh 3.7V lipo (37Wh) should provide around 18 hours of uptime. but it's a balancing act that depends on our charge rate. As our charge rate depends on sun and river power, this will be variable.