How XPT Expands Two-Way Radio Capacity
What is XPT Extended Pseudo Trunk, and how the system expands the capacity of DMR repeater systems.
What is XPT Trunking?
Extended Pseudo Trunk (XPT) is a patented Hytera technology to that expands on pseudo trunk technology. This exclusive technology allows the connection of several Hytera DMR Tier II repeaters in DMR mode. The XPT system allows radios in the field to access the collection of available channels at an XPT repeater site and allocating all repeater channels for greater efficiency.
A radio system has five Talk Groups: G1, G2, G3, G4, and G5.
There are two repeaters with each repeater have two voice channels, or Slots. The radio Talk Groups are programmed to use each repeater:
G1, G2, G3 – uses Repeater 1
G4, G5 – uses Repeater 2
Now if G1 and G2 are currently talking (and using Repeater 1), and G3 tries to talk, they will get a busy signal.
Even if repeater 2 is not being used. That is a challenge with conventional repeater systems.
But if the repeaters are operating in XPT mode, G3 will automatically use repeater 2, with no input or notification of the user. Also, anyone else in Group 3 will also move to repeater 2 for the duration of the call. All calls are efficiently managed with no busy signals.
The Benefits of XPT
No Tier III Trunking License Required
XPT uses beacons to distribute system information to all radios in the system. This has several benefits:
There is no need for a Dedicated Control Channel, often referred to as an FB8 FCC license or trunking license. This is a channel management frequency that must always be available, which can be very difficult to acquire in metropolitan areas. For XPT, Existing FB2 or FB6 licenses can still be used.
No need for additional FB8 licenses for “backup” control channels. In a Tier III trunking system, the Control Channel (at each site) requires an FB8 license due to the 100% transmit nature of a Control Channel. However, most Tier III trunking systems also have backup Control Channels in case the main Control Channel (repeater) fails. So, this compounds the requirement for FB8 licenses as each possible backup Control Channel (at each site) will also require an FB8 license.
Increases site resources as the absence of a control channel allows for that channel to be added to the pool of available voice channels. In a Tier III trunking system, the Control Channel does not carry voice traffic. So, you lose the resources of that repeater to be used for voice traffic. With XPT, since there is no Control Channel, you do not lose any resources for voice traffic.
An XPT trunking site can have a maximum of 16 voice channels and 16 data channels as well as support for up to 1,200 radios. That is far more than a convention repeater system.
XPT systems can also be connected for multi-site applications. Currently XPT systems can be as small as 2 sites or as large as 16 sites. All sites are connected, and roaming is built-in for those that travel between sites. All the features mentioned above are also available on XPT multi-site systems.
If there is a lost connection between sites, then the sites will automatically revert to “single site XPT trunking” status so communications within that site can continue. When the connection is restored, that site will automatically reconnect and re-join the multi-site system.
XPT is a license feature that enables fast and simple upgrades of existing Hytera repeaters to XPT repeaters. This saves on build-out costs as no new radio infrastructure hardware is required. If a system is at full capacity with two or three repeaters at a site, adding XPT licenses and a bit of reprogramming greatly increases the system voice traffic capacity.
XPT Supports all Standard DMR Calling Features
XPT supports all the flexible calling features of other DMR repeater systems
- Group Call: Probably the most often type of call
- Private Call: Calls between individual radios
- Emergency Call: A must for most users
- All Call: This special call will broadcast to every radio in your system
- Priority Calls: Emergency and All Calls have a higher priority than Private or Group Calls. During a call with lower priority, if the radio detects a call with higher priority, it will end the lower priority call to receive the higher priority call.
- Text Messaging: For quick sending, text messages can be pre-programmed to specific buttons (en route, arrived, at lunch, job finished…)
- GPS: GPS positioning is also supported for those systems that also have a GPS based dispatch center.
- Dedicated data channels: If the use case involves heavy GPS data, large fleets, XPT delivers GPS data via specific data channels so as not to interfere with voice traffic.