Analog / Digital
In two way radio systems, Analog radios are the first level of radios with frequency modulation type. It has clear voice transmission, but cannot filter the nearby noises. Analog radios are inexpensive and easy to use. Analog radios use frequency modulation (FM) to encode a voice signal within a carrier wave. The difference between the modulated frequency and the baseline channel frequency can then be demodulated by the receiving radio and turned back into a comprehensible voice message.
Digital Mobile Radio, DMR, is a new standard that has been developed by ETSI defining digital standard for PMR. With the growing need to improve the efficiency of radio communications systems and add new facilities, the move to a digital system is of great importance. Accordingly the new Digital Mobile Radio communications system has been developed to provide affordable digital systems with low complexity with facilities for voice, data and other supplementary services. Digital radios are two types TDMA (Time Division Multiple Access) and FDMA (frequency-division multiple access). A TDMA radio uses the full 12.5 kHz channel and splits it into two time slots, using 6.25 kHz each. By splitting the band, more users can transmit on one channel, sending and receiving messages in succession based on time. TDMA radios have a higher battery life than FDMA, have reduced interference and many more voice and data channel options than FDMA radios.The voice message is encoded into binary packets (ones and zeroes). A digital radio has the capabilities such as text messaging, group calling, and privacy during calls, higher battery life and increased reliability .Emergency calls, priority calls, full duplex communications, short data messages and IP-packet data transmissions are also supported. DMR developed in three Tiers
- Tier 1 is the low-cost, license-exempt 'digital PMR446'
- Tier 2 is for the professional market offering peer-to-peer mode and repeater mode (licensed)
- Tier 3 is for trunked operation (licensed)
TETRA
TETRA (Terrestrial Trunked Radio or Trans European Trunked Radio) is a digital trunk standard uses time-division multiple access (TDMA) with four user channels on one radio carrier and 25 kHz spacing between carriers. TETRA radio offers many new and valuable features and in this way it is a major step forwards over previous private mobile radio communications systems. These include a fast call set-up time, which is a particularly important requirement for the emergency services.
TETRA (Terrestrial Trunked Radio or Trans European Trunked Radio) is a digital trunk standard uses time-division multiple access (TDMA) with four user channels on one radio carrier and 25 kHz spacing between carriers. TETRA radio offers many new and valuable features and in this way it is a major step forwards over previous private mobile radio communications systems. These include a fast call set-up time, which is a particularly important requirement for the emergency services.
- Public Safety
- Transportation
- Utilities
- Government
- Military
- Commercial & Industry
- Commercial & Industry
- Oil & Gas
- It has wide features like
- Wide area fast call set-up "all informed net" group calls
- Direct Mode Operation (DMO) allowing "back to back" communications between radio terminals independent of the network
- High level voice encryption to meet the security needs of public safety organizations
- An Emergency Call facility that gets through even if the system is busy
- Full duplex voice for PABX and PSTN telephony communications
License free Radios
- License free radios are Analog and digital type which is very cost effective .It has very less output power when compared to other radios.Mainly applicable for
- Short range in building communications – especially if mobile phone reception is poor
- Parking assistance or other communications for events
- Car to car communications when travelling in convoy
- General short range communications
- Communications for walkers, bicycle riders, runners etc
- Short range communications for use with running audio visual at plays, music events and other shows