What makes it unique

	BREVA reflexa micro	Typical GNSS-IR station	Radar / pressure gauge
Hardware	Low-cost board with an integrated patch antenna; solar + LiFePO4	Geodetic receiver and antenna, mains or large solar	Dedicated sensor, often in or over the water
Processing	On the unit: results, not raw data	Raw data uploaded, processed on a server	On the sensor
Telemetry	~22-byte Iridium message per session, global coverage	Mobile/Internet link, megabytes per day	Mobile link or logger
Contact with water	None	None	Pressure: in the water; radar: over the water
Footprint	Tens of metres of water surface (averages waves)	Same	A point
Set-up	Field console: map, terrain, live verification on site	Expert configuration	Survey and mounting

The unit is a reflectometry gauge cheap enough for dense networks, that processes on the board and needs only a few bytes per day of satellite airtime: hardware by TU Delft and TAHMO, developed with GReD in the TEMBO Africa project (see Hardware). reflexa micro is GReD’s software for it: on-board processing with a quality check on every arc and a self-correcting search range, a field console that plans the site on a map with terrain and verifies it live before you leave, compact versioned Iridium reports, and a path to continuous, redundant monitoring with reflexa on GeoGuard.

A flexible measurement window

The same TAHMO WLM board can also run TAHMO’s own firmware. reflexa micro sets where and how the unit measures with wider, more flexible limits:

	reflexa micro	TAHMO WLM firmware
Azimuth	1 to 8 separate sectors, each with its own start and end, drawn toward the water on a map	One window, between a minimum and a maximum azimuth
Elevation	Any minimum below the maximum, up to 90°; 5°–45° recommended with this antenna; the Station page can suggest it from the mapped water	One window, between a minimum and a maximum elevation
Water-distance search	Auto (around the antenna-height estimate, or the widest range the elevation window resolves), widened by the unit when reflections land on its edge; or set by hand within 0.05–50 m	Reports heights in 0–20 m
Antenna height	Optional estimate, 0.05–250 m, or left empty: the unit measures it	—

Several sectors follow an irregular shoreline, skip a jetty or a building, and use every stretch of open water around the unit (site requirements).

reflexa micro and continuous monitoring

A reflexa micro unit measures water level only, by reflectometry. It works in sessions and reports a summary; it is not a real-time alarm and it does not measure displacement. Where water and structures must be watched continuously, GReD runs reflexa, its reflectometry service, together with GeoGuard GNSS displacement monitoring, on larger units built for harsh environments that support up to two antennas each and carry other integrated sensors.

On a monitored site, every GeoGuard antenna that sees the water also measures its level. A dam with several stations on the crest or the shore gets several independent level series, each from its own point of view and its own stretch of water, with no extra hardware: they cross-check each other, a station that drifts or is obstructed stands out, and the level keeps coming when one station is down. Level and displacement come from the same receivers, in the same reference frame and on the same timeline.

	reflexa micro unit	reflexa on GeoGuard
Best for	Remote lakes, rivers, surveys; places without power or network	Dams, reservoirs, bridges, coastal and critical infrastructure
Measurement	Sessions; a summary per session	Continuous, every satellite pass, multi-receiver
Hardware	Compact single-antenna unit, solar	Larger units for harsh environments, up to 2 antennas per unit
Redundancy	One point of view per unit; add units for more	Every station that sees the water measures it: several independent, cross-checked level series
Data link	Iridium, a few bytes per day	Continuous upload, full raw data
Processing	On the unit	BREVA processing chain, validated time series
Measures	Water level only (reflectometry)	Millimetre 3D displacement, water level by reflectometry, other integrated sensors, correlations, alerts, dashboard and API

Start with a reflexa micro unit, scale to continuous monitoring on the same site. The home page shows a year of reservoir level and dam displacement from a monitored dam (anonymised), and an interactive 3D view.