Push to Talk private mobile radio (PMR)

by Colin Bryant, TelecomsAdvice

If you mainly use your mobile phone to communicate within your own workforce, a private mobile radio (PMR) system could be a cost effective solution.

The ubiquitous mobile phone, also known as cellular mobile communications, continues to soar in popularity, but cost remains a crucial factor. Every call is metered and charged for, either by pre-payment or a regular network subscription.

To use a phone for communications and connections between personnel within a single organisation or a small geographical area is rather like spending money on postage to send a message to a colleague in the same building. PMR offers a two-way communications service that permits users to talk over a short distance on a simple local system or wide-area, even nationwide on a more complex system, without incurring any costs on the calls made - no matter how many or for how long.

Who uses PMR?

PMR is the oldest form of mobile communications - it has been in use for over 70 years. It is used by many taxi and courier firms, security guards and utility companies. Many rural businesses choose the PMR option, because they find that they simply do not have mobile phone coverage, or they are in an area where the network frequently goes down.

PMR is particularly well suited to operations requiring the passing of frequent short voice or data messages from a central point to individuals or groups of personnel.

A radio frequency licence from the Radiocommunications Agency is usually needed to operate PMR in the UK. Voice, data or mixed voice and data can be supported, with system management usually the responsibility of the licensee. However a new, short-range two-way radio protocol called PMR 446 is completely registration and licence free.

How much does it cost?

The costs of two-way radio are fixed. There are generally no on-going line rental charges or airtime costs -users communicate free of charge within the range of the radio. The signal is broadcast to all users within range - anyone with a radio switched on can hear messages, hands free, together with everyone else on the frequency. In an emergency, instant communication with several people can be vital, and in everyday working situations it can be very useful and save a lot of time.

The entry costs for PMR 446 is simply the cost of the units required - buy the handsets, charge up the batteries and start transmitting. No base station or antenna is needed.

Kenwood produces a PMR 446 radio that has 15 channels - there is little chance of them being congested. It is built to US Army specifications and has impressive resistance to extreme conditions such as damp, temperature, dust exposure and vibration.

Motorola is launching a scheme to make it easier for PMR dealers to loan out high-value accessories for demonstration purposes, and will offer PMR equipment on trial for 30 days free of charge.

PMR in action

BP International uses a PMR set-up at its London headquarters, operated by 2CL Communications. Security personnel need to be able to communicate throughout the entire eight storey building, operating discreetly so as not to disturb office personnel.

To provide coverage on all the floors 2CL installed an antenna system, split by means of a phasing harness between floors to obtain high quality voice coverage throughout the entire building. To keep noise to a minimum, the operatives wear earpieces fitted with acoustic tube extensions, while consoles in the security and maintenance departments monitor the radios on a 24-hour basis. There are two channels in use, one used by security staff, and the second by facilities management personnel.

After 7pm, a “lone worker” feature comes into automatic operation - an invaluable feature for checking night patrol staff every hour. Each security person has to respond - any failure to do so alerts the system to investigate.

There are also PMR systems utilising trunking technology, the most popular being a universal standard known as MPT1327. This technique is ideal for private single-site systems, such as those needed in shopping centres, sports stadiums and factories. Inexpensive products are also available to enable coverage over a small area such as an airport, factory or university, through to regional coverage for a utility or public service provider.

The key benefits of trunked PMR are radio spectrum efficiency and the ability to assign a communication channel even when others are using the system. This is ideal for a small company operating groups of personnel within a specific area who need to communicate strictly between themselves or their base office.

Not all PMR systems are voice-based. Anyone who has travelled in a taxi will have experienced the constant crackle of voices on the radio, but this gives a false impression of PMR. Many modern taxi systems are voiceless, using a system known as data despatch. Quite simply, calls to the taxi company are sorted, a taxi selected, and pick-up addresses and other details sent to the vehicles automatically and silently. In fact, you can now book a car without speaking to an operator, and with the assistance of global positioning systems, the cab office can locate the nearest car to you.

What is the future of PMR?

The PMR industry is reviewing its future strategy in the light of the development of 3G cellular licences. At the beginning of the 21st century we need to look back at the impact of mobile radio and evaluate what the trends will be. The signs are good. Certainly over the past 40 years, different mobile communications sectors have evolved along with improved technologies and that is set to accelerate into the digital age - PMR is no exception.

The Federation of Communication Services is the trade association for the mobile communication industry and maintains a database of FCS registered suppliers.

Reviewed January 2011

last updated : 21/01/2011

See also our UK ICT Directory for supplier lists and links

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