Overview of GPS reporting methods supported in MOTOTRBO systems. Includes Regular GPS, Enhanced GPS, Enhanced GPS with CSBK, PTT triggered GPS, and Swift GPS reporting logic. Describes cadence limits, licensing requirements, throughput capabilities, and operational constraints.
GPS Data Format
•EPSG:900913 Mercator coordinates
•RSSI is measured by repeater RX antenna
•Radio sends GPS to the application through a Repeater. The repeater evaluates received signal quality
Regular GPS
•Revert channel is recommended, as voice transmissions may impact GPS delivery success rate. It is not recommended to have any non-GPS data on the GPS Revert Channel. The only exception is CPSS and CPMS where ARS data is also supported on the GPS Revert Channel
•Regular GPS utilizes a ~1 second transmission
Regular GPS capacity
| Update interval | Capacity per time-slot |
|---|---|
| 60 seconds | Up to 60 subscribers |
| 30 seconds | Up to 30 subscribers |
Enhanced GPS
•Collisions are eliminated because subscribers transmit only in reserved windows
•The repeater creates an eight minute superframe containing sixteen 30 second frames
•Each frame contains windows. A window has an announcement slot and GPS bursts
•Subscribers request a window. The repeater confirms reservation. Radios revert to the EGPS Revert Channel and transmit within their window
•Radios revert to the EGPS Revert Channel and transmit within their window
Enhanced GPS with CSBK
Capacity per slot per minute via MNIS
Window Size:
Update interval:
Windows reservation 90%≈113subscribers
Windows reservation 75%≈94subscribers
When CSBK GPS is enabled, the system supports approximately twice the number of radios at a similar delivery success rate. Revert channel for IPSC or Data Repeater for CPSS\CPMS\CapMax is required.
Requirements
• license in TRBOnet
•Window size 1 requires
•Window size 2 requires or (Control Radio does not work for CSBK in or )
For fleets exceeding 2200 radios with a 2-minute update interval, a single repeater cannot support the required number of subscribers due to memory limitations. In such deployments, it is recommended to distribute the GPS load across two scheduled repeaters by assigning separate scheduled slots, ensuring stable operation and predictable location update delivery.
Limitations
•No Basic Privacy or Enhanced Privacy
•No confirmed data delivery
•Indoor location is not supported
•MOTOTRBO Link does not support CSBK
•Allowed cadences are 7.5, 15, 30, 60, 120 seconds. Other values cause LRRP error
PTT Triggered GPS
•Operates using CSBK commands
•Requires subscriber firmware or higher
•Requires enabling CSBK data in the subscriber codeplug and Repeater GPS coordinates in MNIS
•Motorola states that inband location is sent in the first 2 to 3 bursts
•Observation: PTT must be held for about 5 seconds to activate the GPS transmission
•Recent subscriber firmware sends GPS data only through MNIS and NAI Voice and Data
Mixed Window Operation
•Each slot of a Data Repeater can be configured with a different window size
•A radio with a smaller window size fits into a larger reserved window size
•Regular GPS is compatible with EGPS Data Repeaters but sends outside the reserved windows
Swift GPS Reporting
•Swift report supports transmission of 40 to 50 coordinates per report
•Maximum packet size is 400 bytes, which holds up to 60 coordinates without extra parameters
•Typical packet size is 100 to 150 bytes
•A large report is formed only with rare trigger conditions or during server requests for stored data
Swift Store and Forward capacity (per time-slot)
| Coordinates per report | Capacity with 60-second interval | Capacity with 30-second interval |
|---|---|---|
| Up to 30 | Up to 60 subscribers | Up to 30 subscribers |
| Up to 60 | Up to 30 subscribers | Up to 15 subscribers |
Swift GPS Timing
•Swift request: about 1 second
•Swift response: about 2 seconds plus preamble
•Downloading 300 coordinates requires about 1 minute on a free channel