Single Site Digital Trunk Radio Systems
New digital radio systems used on single sites are normally supplied as either a conventional or a trunked radio system. With conventional radio systems, radio users are allocated a frequency to use and will always use this frequency to communicate with colleagues on the same channel. If the channel is already in use, radio users are “locked out” and have to wait until the channel is free before they can initiate their own communications. This is not very efficient when you know that another radio channel is free, has a very small amount of radio traffic, but you are prevented from using it because it belongs to a different group of radio users.
Problem: I cannot pass vital information as my channel is always busy!
Problem: I have to wait until my channel is free before I can use it!
Problem: I know there is a free channel but I cannot use it!
Solution: Digital trunked radio makes communication not only easier, but more effective, more reliable and more resilient.
With a digital trunk radio system, all available radio frequencies are “pooled” and the digital handportable radio will dynamically search for a free channel to use. The radio user simply calls a group of radios he want to communicate with and the trunk system automatically assigns any free channel so that the two-way radio conversation can take place. When the communication ends, the channel is released back into the “pool” for other radio users to make use of.
The prime advantage of a trunk radio system is that you can have many more radio talk-groups than frequencies allocated.
As an example, two digital repeater base stations working in conventional radio mode will provide four radio channels for four groups of radio users. However, in a digital trunk radio set up, two repeater base stations will provide four radio channels which are dynamically shared, enabling this system to typically support around 10 user groups.
Motorola Capacity Plus
Motorola’s single-site digital trunk radio system is referred to as Motorola Capacity Plus and uses Motorola SLR5500 or SLR8000 base station radios as the system infrastructure for their DP4000, DP3441 and SL4000 series of handportable radios.
Hytera Extended Pseudo Trunk
Hytera’s single-site digital trunk radio system is referred to as Hytera XPT and uses Hytera RD985S base station radios as the system infrastructure for their PD600, PD700 and X1 series of handportable radios.