Private Mobile Radio

Private Mobile Radio (PMR) - sometimes called Professional Mobile Radio - was developed for business users who need to keep in contact over relatively short distances with a central base station / dispatcher - a typical example is a taxi company. PMR is also widely used by emergency services. PMR networks consist of one or more base stations and a number of mobile terminals. Such a system serves a closed user group and that is normally owned and operated by the same organization as its users.

From their early designs, PMR systems have developed into 'trunked' systems, the most notable of which is TETRA, Terrestrial Trunked Radio. Trunking is a technique where the resources of the communications network are shared, thus providing both flexibility and economy in the allocation of network resources. Typically, a communication channel is allocated for the duration of a call and then automatically released to allow it to be used for another call, perhaps between different users on the same system. The technique also enables multiple base stations to be connected and to provide coverage across a wider area than with a single base station.

PMR systems generally provide facilities for closed user groups, group call and push-to-talk, and have call set-up times which are generally short compared with cellular systems. Many PMR systems allow Direct Mode Operation in which terminals can communicate with one another directly when they are out of the coverage area of a network.

PMR systems may also be developed to allow public access (by subscription), and they are then known as Public Access Mobile Radio (PAMR). The users of PAMR systems are usually not the same as the system's owner and operator. Traditionally, PMR systems have usually been based on European standards for the equipment, but operated under licence and subject to National frequency management plans. An exception is PMR 446, a consumer 'walkie-talkie' which has six analogue channels allocated in most European countries for use without a licence.

TETRA

TETRA , Terrestrial Trunked Radio, is a PMR/PAMR system developed by ETSI to respond to the increasing requirements of commercial services and emergency services, and to give the possibility for cross-border networks in Europe.

DMR

Digital Mobile Radio (DMR) is a new European standard, produced by ETSI, defining a direct digital replacement for analogue PMR.

Electromagnetic compatibility for PMR/PAMR

Electromagnetic Compatibility (EMC) requirements for PMR/PAMR are covered by EN 301 489 part 1 and part 5.

Spectrum requirements for PMR/PAMR

ETSI works with the relevant European organizations to ensure that appropriate spectrum is available for ETSI radio standards. The Institute has produced a series of System Reference Documents that define the spectrum requirements for various PMR implementations, and a range of Harmonized Standards that may be used to demonstrate compliance of equipment and components with the European Commission's R&TTE Directive (1999/5/EC).