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Space-saving transmitters simplify design of license-exempt wireless links

Radiometrix has unveiled a new range of three compact RF transmitters that allow designers to build longer-range low-power radio systems in space-constrained applications that cannot accommodate a conventional 12.5 kHz/ 25kHz narrowband FM transmitter.

The MTX1, MTX2, and MTX3 are 4-channel transmitters operating on 120-180MHz, 420-470MHz and 850-950MHz respectively. RF components keep module measurements to a compact 23mm x 12.5mm x 7mm, while +10dBm transmit power allows a typical usable range of up to 500 metres with a matching narrow band receiver.

The transmitter's conformance to EN 300 220-2 (radio) and EN 301 489-3 (EMC) guarantees its performance and meets all regulatory requirements for license-exempt short-range devices. Built-in shielding enables slim-line equipment designs, while avoiding additional mechanical design complications, while careful and robust circuit design reduces susceptibility to mechanical vibrations, to ensure a clean and reliable signal under challenging operating conditions.

Each module contains the transmitter IC and baseband circuitry, with user-accessible digital and analogue inputs, which enables even analogue signals like AFSK, GMSK, DTMF tones to be transmitted. A 3V voltage regulator and brown-out reset controller are also built in. Programming is via a simple RS-232 serial interface. The wide input voltage range of 3.1V to 15V also helps simplify system design while energy conscious performance (drawing typically 20mA) maximises the lifetime of battery-powered applications.

With their small dimensions and low power operation as well as extended range, these transmitters are suitable for vehicle key fobs and other handheld devices, small-form-factor data loggers, industrial telemetry and controls, smart-building devices, high-end security systems and fire alarm sensors, and heavy-vehicle controls.

Neil Tyler

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