This feature helps to offload GPS messages away from the selected channel with increased reliability and throughput compared to the current GPS revert feature by scheduling the GPS transmissions of the radios. The Enhanced GPS Revert channel supports GPS data only. Voice and non-GPS data are not supported on a channel when this feature is enabled.
The primary difference between the GPS Revert Channel and Enhanced GPS Revert Channel lies in the method a subscriber accesses the channel. In the GPS Revert channel feature, subscribers access a channel in a desynchronized manner and may therefore cause transmission collisions.
The probability of collision increases with the number of transmissions made over the channel and collisions adversely affect the reliability of transmissions.
This enhanced feature enables subscribers to access a channel in a synchronized manner, which eliminate collisions and allow them to use the channel efficiently. The synchronization between subscribers is achieved by a repeater that divides a logical channel into groups of contiguous bursts defined as “windows”. This allows subscribers to make reservations for these windows in which GPS data can be transmitted.
This feature is applicable in Digital Single Site, IP Site Connect, and Capacity Plus modes.
1. Select check box(es) Slot 1 or (and) Slot 2 to enable Enhanced GPS featurein codeplug of Repeater in MOTOTRBO CPS. When this feature is enabled on the Repeater slot, then the slot is responsible for scheduling the GPS updates of all the subscribers. This is a slot-wide feature so each slot can be configured independently.
2. Select Window size = 8. Set the parameter Periodic Window Reservation.
Periodic Window Reservation specifies the percentage of windows that can be reserved for periodic updates for the Enhanced GPS Slot 1. The available choices are None, 45%, 60%, 75% and 90%. If the user chooses 90%, it means that 90% of the total available windows are reserved for periodic updates and the remaining 10% are reserved for a one-time updates. If there is a high call volume on the selected channel, the user should not run at 90% capacity, instead use 60% or 45% capacity.
Select IP Site Connect Slot 1 и Slot 2 when working with IP Site Connect Network.
SmartPTT are using the following parameters in LRRP request:
RequestId, TimeStamp, Latitude, Longitude, Accuracy, Speed(Velocity)
Real experiments proves that window size should be 7, it does not work with less than 7.
We recommend Window Size = 8 because in case privacy is used in the radio system, you need to increase window size up to 8. So Window Size = 8 will work for any radio sysem.
1. Enable GPS functionality in the General Settings of the subscriber radio in MOTOTRBO CPS.
a) When working with IP Site Connect Network select check box Enhanced GPS and specify Window Size = 8 on the Enhanced GPS Revert Channel.
b) When working with Capacity Plus system on the Capacity Plus Data Channel select check box Enhanced GPS.
In our example Slot 1 - Enhanced GPS Channel, Slot 2 - Voice Channel. The main (voice) channel must have Enhanced GPS feature disabled and Enhanced GPS channel should be selected as GPS Revert channel.
SmartPTT Software Settings
Location Update Intervals can be 30 seconds, 1 minute, 2 minutes, 4 minutes or 8 minute.
Specify one of the listed location update intervals in Subscriber Properties Window (Location tab).
If Dispatcher has no permissions to change Update Interval, then specify this Interval in SmartPTT Radioserver Configurator for each subscriber group (SmartPTT Server Configuration window / Radio Network Services / Location).
The Enhanced GPS feature can be configured in the following manner in:
1. Conventional single-site and IP Site Connect modes:
- One slot for voice, one slot for Enhanced GPS Revert
- One slot for GPS Revert, one slot for Enhanced GPS Revert
- Both slots for Enhanced GPS Revert
2. Capacity Plus mode:
- One slot of data revert repeater for GPS/ARS, one slot for all other data
- Both slots for Enhanced GPS Revert
If you don't see coordinates displayed in subscriber Call Window, or Radio is not displayed on the map, then please check if radio settings and GPS settings meet all requirements.