Waterproof Float Logger Prototype

I want to field-test a single, fully-functioning prototype that logs freshwater temperature and depth, stores up to 256 paired readings, and beams everything to a small handheld receiver once the float surfaces.

Hardware parameters are already fixed. The float must fit roughly 195 × 25 mm, run from a CR123A cell, remain watertight, and carry both a waterproof temperature probe and a pressure sensor good for at least 35 ft. Wireless communication is via 433 MHz with an internal antenna; no external whip is acceptable.

The receiver will also be battery-powered, pocket-sized, and feature a straightforward LCD that shows current temperature and depth as live data arrives.

Firmware behaviour is equally clear-cut: sample every second or two, tag each temperature with the matching depth, keep all 256 readings even after transmission, and dump the full log automatically when the float breaks the surface. After transmission the data should still reside in non-volatile memory so I can download it again later if needed.

Deliverables
• One waterproof float unit built to the dimensions above, ready for lake testing
• One handheld LCD receiver that reliably links at typical line-of-sight boating distances
• Source code and compiled firmware for both devices, with clear instructions for reflashing
• A short build report detailing the sensors, radio module, antenna tuning approach, and enclosure sealing method

Acceptance criteria
Successful pool or dockside demo in freshwater: submerge to at least 30 ft, record for five minutes, surface, and verify that the receiver shows a scroll of all logged temperature-depth pairs with no data loss.