uSwitch

The uSwitch hydroacoustic modem is a simple and affordable solution for transmitting data through the water column over short distances. Working with the device requires minimal skills, letting it be used as a simple tool while the user focuses on their own tasks — for example, testing network algorithms, prototyping, and building specialized navigation and telecontrol systems, among others.

Purpose

uSwitch is supplied as an assembly of printed circuit boards and a hydroacoustic antenna on a cable. It suits educational projects and classroom work, prototyping and self-built non-standard systems: the signal propagation time measurement function makes it possible to build navigation solutions on top of it, and the modem can act as a pinger of the WAYU system.

Specifications

The board measures 100×19×25 mm and weighs 0.03 kg. The data rate is 32 bit/s, the frequency band is 24–26 kHz and the pairing interface is UART at 9600 bit/s with data line levels of 0–3.3 V. The supply voltage is 7–13 V, and maximum output power is reached at 12 V. The maximum relative speed is ±2 m/s and the operating temperature range is −5 to +50 °C. With the RT-1.332820-1 antenna, the modem produces a sound pressure of up to 165 dB re 1 µPa at 1 m. The switch-on-in-water function uses the water detector contacts on the board.

Power modes

The maximum transmit power can be switched by soldering a jumper (a 0 Ω resistor, size 1206): for maximum range, R1 is left unsoldered and R2 is soldered; for small bodies of water such as swimming pools, the opposite — R1 is soldered and R2 is not. Never solder both jumpers at once: it damages the device and is not covered by the warranty.

Antennas and compatibility

The antenna is chosen to suit the task: RT-1.332820-1 is an affordable solution with minimal dimensions, RT-2.332820-1 is a two-element antenna with increased sensitivity for surface-side operation, and RT-1.524525-1 is a higher-sensitivity antenna. Together with the ACubes kit, uSwitch belongs to the educational products section.

Documentation

The pinout, the layout of the contact pads and a description of the power modes are given in the uSwitch specification on docs.unavlab.com.