Glossary of Radio Jargon

 

Baby monitor

Some radios can be set to automatically monitor a location, transmitting when sound levels go above a preset level. A very useful feature for monitoring babies, and eavesdropping it also can be used as a paging car alarm.

Base station

A remotely controlled or computer controlled receiver and transmitter located in a high place or with a high mast to relay or boost radio signals thereby enhancing the range of a radio system. These are often seen near busy roads or on hilltops.

Busy monitor and busy lockout

Others may be using the same radio channel but tone squelch will prevent you hearing them. Pressing this button disables the squelch so you can hear if the channel is busy. A feature of most radios. Busy Lockout Automatically prevents you transmitting if other users are active on your channel. If you transmit while the channel is busy your radio bleeps to alert you. Not all radios have this feature.

Cellular (mobile) Phone

A two-way radio system allowing connection to the landline telephone network. Uses a huge number of base stations organised in a cellular layout. 98% of the population in the UK is within range of this system although actual land area covered is closer to 75%. Coverage in lightly populated areas is poor. Maximum range from a base station is absolute at 35km.

Channel

A single discrete radio frequency. The radio spectrum is split into thousands of sections each of which is often called a channel. In most radio systems users only communicate on one channel at any time.

Citizens band (CB) radio

CB radio is a simple radio system operating at 27Mhz. It has no provision for tone- squelch. Interference from natural and man-made sources is a problem. see wavelength.

CTCSS (tone squelch) and DCS

Continuous Tone Controlled Squelch is a very simple and very effective way of silencing a radio until a correctly coded signal is received. When a signal is transmitted a sub-audible tone is added to the signal. The receiving radio stays silent unless the tone is the correct one. There are many tones enabling users to choose one exclusive to their group of users. DCS is a similar system using a digital pulse train instead of a tone. It functions in a very similar way to CTCSS.

Cut-Off Ear-defenders.

Cut off ear-defenders allow conversation and hearing of ambient noise (without removing the defenders) while sound levels are within safe limits . The instant noise levels approach unsafe levels internal electronics shut down the defenders into conventional noise suppression mode.

The system works with a tiny microphone built into each ear-cup feeding external stereo sound to internal speakers. This allows improving situational awareness of moving machinery by giving a direction to the sound. The electronics is very fast and opens and shuts external sounds fast enough to hold a conversation while hammering for example.

Full Duplex

Full duplex refers to communication in two direction at the same time. A conventional mobile or landline phone is full duplex. You can both speak at the same time and interrupt the person who is talking to you. Conventional two way radio is 'half duplex' or 'simplex' meaning that although you can speak both ways only one party can speak and use the voice path (channel) at a time and each person speaks by pressing PTT or triggering VOX.

Keypad lock

A simple lock to prevent accidental operation of button while the radio is in your pocket.

Microphone (mic) sensitivity

We all speak at different levels, some whisper others SHOUT. This feature allows you to adjust the radio to your style or prevailing conditions.

NIDS Compliant

Earpieces marked as NIDS compliant do not exceed noise exposure limits outlined in the Control of Noise at Work Regulations in force from April 6 2006.

Limits are:
A daily or weekly personal noise exposure of 87dB (A-Weighted) based on a steady exposure for and eight hour day. A peak sound pressure of 140dB (C weighted).

If your earpieces need to comply with NIDS please ask for a certificate as only certain products comply.

PMR 446

Private mobile radio is a general term for radio communications between two users one of which is mobile. Nearly all PMR systems are licensed by national government. PMR446 is an internationally agreed system which requires no licence. PMR users share 8 channels.

PTT

Press To Talk another name for the Transmit button. Also sometimes called pressel.

Scan and Dual watch

A scanning radio automatically listens to a number of preset channels for activity and stops when a correct signal is received, resuming scanning when activity ceases. It is a useful feature if you are part of a large group of users split across channels or just plain nosey. Dual watch is a similar system to monitor two channels usually used where one channel is reserved for emergency use while another is for routine communication. Scanning is available on some radios to scan tones as well as channels.

Scrambler

To ensure privacy from eavesdropping scrambling can be used. For example When Alice radios Bob the message is automatically chopped and shuffled according to a scheme agreed between them. Bobs radio rebuilds the message as it knows the scheme. If Eve tunes in all she will hear is the garbled message.

Time out Timer - Stuck microphone

It is possible that the transmit button could accidentally pressed or held closed. This will cause the radio to transmit preventing other users communicating on the channel or alerting the stuck-mic radio to the fault. This feature automatically stops the radio transmitting after a preset period freeing up the channel

Two-way radio

Two-way radio as its name implies is a system for communication from A to B and from B to A. distinct from broadcast radio which is a one-way medium from A to B only.

Wavelength

Frequency and wavelength are directly related. Higher frequencies have shorter wavelengths. CB is generally known as HF (high frequency) while PMR446 is known as UHF (ultra high frequency)
Shorter wavelengths as used in PMR 446 penetrate obstructions better. Longer wavelengths such as used by CB tend to be reflected by the surface of the earth and layers of the atmosphere resulting in intermittent and long distance interference. Most electrical machines generate HF so can interfere with CB radios.

VOX

Voice operated transmit. Useful in environments when you need both hands free. Talk and your radio transmits your voice automatically. Also useful for auto/security/covert monitoring of areas, baby alarm etc. This feature is inbuilt in some radios in others a VOX headset can be added.