Monitoring & metering
SELECTING THE RIGHT RADIO FREQUENCY FOR TELEMETRY APPLICATIONS
In highly regulated industries where laying cables is not feasible, radio-based communication can transfer critical data from multiple locations wirelessly and effectively. When installing radio equipment and telemetry devices, such as transmitters and receivers, in an industrial facility or field-based utility applications like gas, electric and water, frequency is an important consideration. Ian Loudon, Omniflex, outlines considerations for when selecting a radio frequency (RF) to operate on.
T
he UK’s radio spectrum is more cluttered than ever. Space on bands is already at a premium and, with more and more businesses setting up radio equipment, demand will only
increase. For many businesses, the need to pay a fee for exclusive transmission rights means operating on a licensed band is undesirable. Instead, many opt for license-free bands that are open to everyone. As a result, they can transmit essential data while complying with legislation such as the new Radio Equipment Regulation (RER), which sets the standard for the UK’s radio communications. Until January 2018, there were just eight frequencies for license-free radios in the UK, ranging from 446.00625MHz to 446.09375MHz. Since then, the frequency spectrum has expanded significantly. For example, the 5 GHz band runs from 5,150 MHz to 5,850 MHz, before being broken down into three A-C bands. Two of the most common unlicensed bands in the UK are 2.4 GHz, which is the same frequency as WiFi and Bluetooth, and 868 MHz.
HIGHER FREQUENCIES When selecting higher frequencies such as 2.4 GHz, these will often have more “channels” available than lower RFs, meaning devices can be set to avoid channels that are already occupied by other equipment. The bandwidth is also greater and businesses can transmit more data faster than when operating on a lower frequency. For example, wireless SCADA systems typically use very high frequencies (VHF) and ultra-high frequencies (UHF) over a long range and rely on fast transmissions. However, the higher the frequency the shorter
the range, and the more vulnerable to interference. Ideally, businesses will select these bands for indoor applications where there are shorter distances between radio equipment. Walls, rain and even fog
52 November 2022 Instrumentation Monthly
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