Radio communication involves the transmission and reception of messages on various frequencies. These frequencies are measured in Hertz (Hz), which represents the number of cycles per second. The commonly used units for expressing radio frequencies are kilohertz (kHz) and megahertz (MHz).
The Very High Frequency (VHF) band encompasses frequencies ranging from 30MHz to 300MHz. In the United Kingdom, Business VHF Radios operate within the range of 136MHz to 174MHz. On ships and for communication between vessels, harbors, bridges, and locks, "Marine band" VHF radios utilize frequencies between 156MHz and 162MHz. Specific channels within these frequency ranges are allocated for different purposes, such as emergencies and ship-to-shore communications.
The Ultra High Frequency (UHF) band covers frequencies from 300MHz to 3000MHz. UK Business UHF Radios operate within the range of 400MHz to 470MHz. Within the UHF band, there are also eight "licence-free" channels known as PMR446. These channels operate at the following frequencies in MHz: 446.00625, 446.01875, 446.03125, 446.04375, 446.05625, 446.06875, 446.08125, and 446.09375.
In the United States, there are specific radio frequencies for Family Radio Service (FRS) and General Mobile Radio Service (GMRS). FRS has 14 channels numbered 1-14, while GMRS uses the same channels as FRS 1-7 and adds an additional seven channels numbered 15-22. The frequencies for these channels are as follows in MHz: 462.5625, 462.5875, 462.6125, 462.6375, 462.6625, 462.6875, 462.7125, 467.5625, 467.5875, 467.6125, 467.6375, 467.6625, 467.6875, 467.7125, 462.550, 462.575, 462.600, 462.625, 462.650, 462.675, 462.700, and 462.725.
It is important to note that the use of American FRS and GMRS walkie-talkies in the United Kingdom is illegal and can cause interference to licensed radio users. Despite this, some British holidaymakers purchase these radios abroad and unknowingly break the law by using them in the UK.
In the United Kingdom, there are also specific frequencies allocated for radio communication. These include VHF LOW BAND frequencies such as 77.6875, 86.3375, 86.3500, 86.3625, and 86.3750. VHF MID & HIGH BAND frequencies include 164.0500, 164.0625, 169.0875, 169.3125, 173.0500, 173.0625, and 173.0875. The UHF BAND frequencies are 449.3125, 449.4000, 449.4750, 458.7875, 458.8000, 458.8125, and 458.8250.
In summary, radio communication utilizes various frequencies expressed in Hertz. Different frequency bands such as VHF and UHF are used for specific purposes, and specific channels within these bands are allocated for different types of communication. It is essential to adhere to legal regulations and avoid using radios on unauthorized frequencies to prevent interference and ensure efficient communication.