A feature of some Two-Way Radios where at certain preset time intervals, the radio user is notified to press a button on the radio in order to inform a control centre that they are OK. If they does not acknowledge the periodic notifiaction by pressing the button after another defined time period, the radio sends out an alarm message. The purpose of this feature is to protect a person working on their own, so that if someone was to become ill or incapacitated their radio would send out an alarm message that can be picked up by the control centre or security office, who can then send help
A feature of some Two-Way Radios, has the inclusion of a tilt-switch. This can be programmed to automatically send an alarm signal if the radio is tipped on its side for more than a preset period. The radio usually beeps to warn the user that the alarm signal will be sent if the radio is not positioned upright again. The purpose of the “man down” feature is to protect lone workers, so that if someone was to fall, become ill, or be attacked, resulting in them falling down, their radio would send out an alarm signal that is picked up by someone in a control centre or security office, who can then send help.
OFCOM (Office of Communications)
The government organisation in the United Kingdom responsible for controlling and licencing the use of the airwaves for all types of radio use. Users wanting to apply for business radio licences can do so online at Ofcom’s web site.
All Two-Way Radio radios have a Push-To-Talk button. This is the button, usually located on the side of the radio, that must be held down to make the radio transmit and then released when the user has finished transmitting in order to listen to the response from other radios. Accessories plugged in to Two-Way Radios, such as earpiece/microphones, usually have a second PTT button on the accessory for ease of use.
This is a device that picks up radio messages and then simultaneously re-transmits them, usually with an increase in power, on a second channel. Repeaters are used to extend the area of coverage of a group or system of Two-Way Radios. The repeater antenna(s) is usually located in a high position, such as on the roof of a building or on top of a mast, to maximise the range covered.
UHF (Ultra High Frequency)
UHF radio signals frequencies between 300Mhz – 3000Mhz. In terms of UK, UHF two-way radios use frequencies between 400 – 470MHz. UHF radio signals don’t go as far as VHF signals, but are generally better for use within buildings.
VHF (Very High Frequency)
VHF radio signals frequencies between 30MHz – 300MHz. In terms of UK, VHF radios use frequencies between 136 – 174MHz. VHF radio signals travel further than UHF signals but do not travel well within and through buildings.
VHF & UHF Radios - which Is best?
VHF (136 – 174MHz) signals generally work best outdoors, providing a longer range for the same power output than UHF (400 – 470MHz).
However, VHF signals really do not work well when there are obstructions like walls & buildings.
UHF is the best all round option, unless the use of your radios is only in open countryside then VHF is better for absolute range.
Two-Way radios, range & frequency
Entry Level two-way radio systems normally just transmit directly from one radio to another. Their likely operational range can be expected to vary from a few hundred metres to a couple of miles or more.
The range is drastically reduced when Two-Way Radios are used within buildings, or in a town or city with densely-packed streets of big houses, office blocks and other buildings.
The range / coverage is extended by the addition of repeaters located in areas of low / poor signal