private mobile radio
Professional mobile radio belongs to the non-public mobile land mobile radio(nömL). It is used to transmit internal messages within a specified area of operation. This is usually the company premises. The range of company radio is limited in its spatial extent and is approx. 1 km between two radios, whereby the radio environment and the operating conditions restrict the range.
By using relay stations, the range can be extended to 10 km and more. Company radio is suitable for inexpensive communication of employees in authorities, associations or companies. Company radio systems are subject to registration and licensing and operate in specified frequency bands. Several frequency bands in the HF range, VHF range and UHF range are released for professional mobile radio.
Transmission is usually in simplex where only one subscriber can use the radio channel at a time, either to transmit or to receive. The transmission itself can be analog with Private Mobile Radio( PMR) and FDMA method or digital with Digital Mobile Radio( DMR) and TMDA method. Depending on the requirements, a distinction is made in private mobile radio (PMR), private trunked radio and trunked radio systems of network operators.
Professional mobile radio is voice radio. However, the voice radio channels may also be used for data radio. This means that company radio can be used for voice communication and also for controlling operational processes and for monitoring tasks and emergency situations. The user is assigned his or her own exclusively usable frequency. The transmission can also be encrypted.