RedGTR code communication modem

The RedGTR modem provides point-to-point network operation. It stands out for its compact size, operating range and low power consumption. It is indispensable for controlling underwater actuators and for building acoustic release devices where highly reliable signal transmission is required.

Reliable. A specially designed signal and its processing methods ensure stable communication under interference, multipath propagation and partial signal loss.

Rugged and convenient, thanks to its patented monoblock design.

Suited to applications with strict weight and size requirements. The modem measures just 64 × 62 mm and weighs 0.36 kg.

Requires no setup or calibration. Immediately after power-on, the user gets a transparent channel that requires no knowledge of the modem's control protocol. Simply connect the device.

How it works

RedGTR uses a fixed-length signal with code division. This makes it possible to build a point-to-point network of 25 devices in the same water area: each modem has its own isolating code channel (address), and any of them can be sent one of 40 code commands with very high reliability. The modem can also be used in wireless underwater sensor networks.

Key specifications

According to the specification, the modem operates in the 5–15 kHz frequency band, the signal duration is 400 ms, the supply voltage is 12 V, and the pairing interface is UART at 9600 bit/s (0–3.3 V levels) with the open NMEA 0183 PTNT protocol. The built-in depth and temperature sensor is rated for a maximum depth of 300 m; on request the modem can be supplied without a pressure sensor, in which case the permitted depth is 400 m. The operating temperature range is −5 to +50 °C, the maximum relative speed is ±3 m/s and the default cable is 0.5 m (the length can be changed). The bit error rate is 10⁻⁶ at a limiting signal-to-noise ratio of −6 dB (the value was obtained in a laboratory static experiment, without multipath effects).

Compatibility

In size (64×62 mm) RedGTR matches the RedLine modem and the RedNode navigation receiver. RedGTR fits when you need short code commands for several devices; for longer-range data transmission the range has RedLine, and for networks with Internet access, the Amphibious Access Point.

Documentation

Besides the specification, docs.unavlab.com provides the RedGTR pairing protocol description.