Specifications

Measurement

Item	Value
Principle	GNSS interferometric reflectometry (C/N0)
Quantity	Antenna-to-water distance (reflector height, RH)
Precision	Centimetric per session (see Precision)
Typical antenna height	1–10 m above the water
Elevation window	Configurable; 5–45° recommended with the low-cost antenna (Campaign: 5–25°)
Reflector height range	Automatic (from the elevation window) or user band; typical 1–30 m; self-correcting
Arc capacity	Up to 32 concurrent arcs, 4,096 samples each
Processing	On the unit, per arc and per session

Item	Value
Board	TAHMO WLM V1: RP2350A (dual Cortex-M33), 4 MiB QSPI flash (W25Q32)
GNSS receiver	u-blox SAM-M10Q, integrated patch antenna, L1/E1/B1 single frequency
Constellations	GPS, Galileo, BeiDou, GLONASS, QZSS; SBAS optional
Measurement rate	1 Hz; C/N0 sampling interval automatic (bounded by the RH range and constellation)
Result storage	~7,300 records on flash, up to 10 arcs per record
Satellite modem	Ground Control RockBLOCK 9704 (Iridium IMT, topic 244)
Telemetry message	~22 B default (summary + health); +~13 B with position; per-arc results optional
Sending	End of session, every N hours, every N results, daily; daily maximum; automatic retry
Power	LiFePO4 26650 cell (~3,000 mAh) with solar/USB charging (BQ25176M, 500 mA, 0–60 °C)
Protection	Battery guard, internal and external watchdogs
Interfaces	USB-C (CDC serial, firmware update via RP2350 bootloader)
Power switch	Toggle switch; green LED blinks every 5 s when on
Operating temperature	−20 °C to 60 °C (TAHMO figure); solar charging stops below 0 °C
Status indication	Three LEDs (red, green, blue), readable without a computer

Item	Value
Platforms	macOS (Apple silicon), Windows x64, Linux (Ubuntu 22.04 and later)
Offline maps	Global lakes pack (optional), terrain, OpenStreetMap water
Updates	Guided firmware update with backup and checks