MURS VHF vs. 868/900 MHz modems

October 7, 2017

The two watt transmit power limit across five VHF channels can make MURS appealing for long-range license-free radio systems. Alternatives for long-range data telemetry and control include 27 MHz radio modems and 868/900 MHz modems. Modems are readibly available for MURS including from Raveon. MURS data bandwidth of up to 19200 bps is sufficient for many telemetry and control applications. The longer communications range at 150 MHz is due to the free space loss advantage vs. 868/900 MHz. However, MURS modems are by definition unable to use spread spectrum to avoid interference. Warehouses, hotels, shopping malls, construction sites, hobbyists, families, etc. all use MURS frequencies.

868/900 MHz is a widely used frequency band spread over as much as 26 MHz (USA 902-928 MHz band). With appropriate antennas and line of sight between radios, the one watt transmit power allowed in the USA and numerous other countries allows kilometer+ communication range. 868/900 MHz modems typically employ a frequency hop channel list or FHSS to mitigate interference.