Radiometrix has introduced a range of RF transmitters which it is offering as small-format alternatives to 12.5kHz/25kHz narrowband FM transmitters.

The MTX1, MTX2, and MTX3 are four-channel transmitters operating on 120MHz-180MHz; 420MHz-470MHz; and 850MHz-950MHz respectively. They measure 23×12.5x7mm. Their transmit power is +10dBm, which the supplier says will allow for a typical usable range of up to 500m as long as you use a matching narrowband receiver.

The transmitter’s conformance to EN 300 220-2 (radio) and EN 301 489-3 (EMC) standards will meet regulatory requirements for license exempt short-range devices. With built-in shielding, each module contains the transmitter IC and baseband circuitry, plus user-accessible digital and analogue inputs, which enables even analogue signals like AFSK, GMSK and DTMF tones to be transmitted. A 3V voltage regulator and brown-out reset controller are onboard.

Programming is via a simple RS-232 serial interface. The input voltage range of 3.1V to 15V helps to simplify system design, while energy-conscious performance (drawing typically 20mA) maximises the life of battery-powered applications

Data Sheet

The MTX2 transmitter module adds a totally new subminiature form factor to the existing range of Radiometrix ISM band devices. Using cutting edge integrated RF devices, it offers multi channel, low power narrowband operation in a previously unobtainable size. It is ideally suited to applications where existing wideband modules have insufficient range and where traditional narrowband modules would physically be too big to fit in.

Features

Conforms to EN 300 220-2 and EN 301 489-3

High performance Fractional N (Sigma-Delta) Synthesizer with TCXO

Vibration resistant (negligible microphony)

Data rates up to 10 kbps for standard module

Usable range over 500m (with suitable aerials and matching receiver)

Fully screened. Very low profile

Feature-rich interface (analogue and digital baseband)

Re-programmable via RS232 interface

Low power requirements

Applications

Keyfobs and other hand held terminals

Small form factor data loggers

Industrial telemetry and telecommand

In-building environmental monitoring and control

Covert, high-end security devices

Unobtrusive fire alarm sensors

Heavy vehicle/machinery controls

Technical Summary

Operating frequency: 433.875-434.650MHz (EU band)

458.525 – 459.1MHz (UK band)

Other custom UHF bands

850-950MHz version (MTX3) also available

4 parallel channels (also fully controllable via serial port)

Transmit power: +10dBm (10mW)

Supply range: 3.1 – 15V (will operate down to 2.9V)

Current consumption: 20mA @ 10mW

Data bit rate: 10kbps max. (standard module)

Serial configuration by inverted RS232 at 3V CMOS level

Size: 23 x 12.5 x 7 mm

Evaluation platforms: NBEK + matching carrier board