Hytera Pseudo Trunk
Pseudo Trunk is the Hytera name for channel sharing on a single radio channel.
With conventional analogue radio each time a user transmits they occupy the whole radio channel preventing others from using it. This works fine for small radio systems with perhaps less than a dozen users or where transmissions are infrequent.
As the number of radios increases and / or the amount of traffic grows the channel becomes busier. The impact of this is that users have to wait to make calls and also their radios becoming noisier.
To account for the increased number of users two techniques can be used;
- One is to separate user into User-Groups - users that normally talk to one another. This is called Selective Calling.
- The other is to allow two or more Groups the ability to transmit at the same time.
With digital radio built to the DMR standard it is possible to split each radio channel into two ‘Slots’. This means two user Groups can both use the same channel at the same time each using a Slot. This is the principle of Hytera Pseudo Trunk. (Motorola call this Capacity plus.)
How it works
On a pseudo trunking system when a radio transmits it will look for a spare Slot. If there is free slot the radio will pick one and make the call. All the radios on the system are listening to both slots and will respond only to calls made to its own Group.