Electronic Design

UHF Transceiver Extends Range For Telemetry And Other Wireless Applications

If your wireless applications don't require the sophisticated networking capability of Bluetooth, Wi-Fi, or ZigBee, you can always use transceivers for the unlicensed UHF industrial-scientific-medical (ISM) bands, including 315, 433, and 902-928 MHz. For simple sensor monitoring and other minimal telemetry and monitor and control operations, the ISM band transceivers provide a simple and inexpensive way to implement a wireless link.

No special protocol is needed in these applications, so data or control words can be transmitted whenever. The problem with such links is that they have limited range. Radiometrix's NiM2 transceiver solves that dilemma, offering the simplicity of ISM band UHF transceivers while providing unprecedented range.

The NiM2 is available in two versions operating on 434.65 and 434.075 MHz. Special frequencies also are available. The transmitter is a voltage-controlled crystal oscillator (VCXO) feeding a phaselocked loop (PLL) frequency multiplier that in turn drives a two-state power amplifier. The output power is +10 dBm or 10 mW. Modulation is frequency-shift keying (FSK) at up to 10 kbits/s.

The receiver is a dual-conversion superhet with IFs of 21.4 MHz and 455 kHz. Surface-acoustic-wave (SAW) filters are used to provide an image rejection of better than 50 dB. Overall receiver sensitivity is an amazing 118 dBm for 12-dB signal, noise, and distortion. Range reaches up to about 500 m in clear line-of-sight conditions. The unit operates from 2.9 to 15 V.

Applications include instrumentation, barcode scanners, data loggers, industrial telemetry and control, in-building environmental monitoring and control, security and fire alarm systems, and vehicle data collection. Contact the company for pricing information.

Radiometrix Ltd.

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