54 System Feature Overview
April 2011 68007024085
• Support for up to 360 location responses per minute per repeater using both slots, while
running at 90% capacity, and decrease in the number of channels and associated
hardware needed for GPS data transmission.
• Increased GPS reliability due to the drastic reduction of collision among subscribers
sending GPS data. For more details on reliability based on voice loading on primary
channel, refer to Section 4.4.5.6 “Enhanced GPS Revert – Loading & Reliability”.
• More control over system throughput, by allowing users to choose the most appropriate
window size, based on the location response characteristics needed.
This feature is supported in repeater mode only and works in single-site, Capacity Plus and IP Site
Connect modes of operation. Only GPS data (unconfirmed only) is supported on the Enhanced
GPS Revert channel in conventional mode (both single-site and IPSC). In Capacity Plus mode,
ARS Registration Message is also supported on the Enhanced GPS Revert channel. There is no
support for voice or other non-GPS data on the Enhanced GPS Revert channel. Data from option
board interface is also not supported over an Enhanced GPS Revert channel.
A window size ranges from 5 to 10. The size depend on the following factors:
• The parameters that the application has requested in a location response, such as
longitude, latitude, time, altitude, velocity, direction, and so on.
• Whether IP/UDP headers compression is enabled.
The table below shows the calculation for the window size with enhanced privacy enabled.
The following calculations assume GPS data is unconfirmed and “Compressed UDP Data Header”
is selected in the CPS.
For No Privacy,
Requested Element
LRRP Response
Size (bytes)
Latitude + Longitude 11
Time 6
Request ID ** 3
Speed_hor * 3
Direction_hor 2
Altitude * 3
Radius * 2
* Variable sized fields
** Assume that Request ID value is smaller than 256.
WindowSize LRRPResponseSize 1+()12÷()3+=
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