GPS L5 Signal
Health Status Configuration
The ZED-X20P supports GPS L5 signals. Broadcasting of Civil Navigation (CNAV) messages on the L5 signal began in April 2014. At the time of writing, the GPS L5 signals remain pre-operational and they are set unhealthy until sufficient monitoring capability is established. To evaluate GPS L5 signals before they become fully operational, the receiver can be configured to ignore the GPS L5 health status by overriding it with the respective GPS L1 C/A signal status.
- Do not use unhealthy, pre-operational GPS
L5signals for safety-of-life or other critical purposes. This is an operational issue concerning the satellites/space segment; not a limitation or specific configuration of u-blox products. - Users who choose to ignore the GPS
L5signal health status in their production system do so at their own risk and must be fully aware of the implications. The system should also include a mechanism to revert to the mode where theL5signal health status is respected.
Enable GPS L5 Signal
The receiver does not use unhealthy signals for navigation by default. To ignore the GPS L5 signal health status and override it with the respective GPS L1 signal health status, the following UBX binary strings can be used. To confirm that the above UBX messages are sent successfully to the receiver, check that a UBX-ACK-ACK message is received afterwards. The configuration can be stored in RAM, BBR (battery-backed RAM), and/or flash layers.
- Writing to RAM ensures the UBX messages are taken into use immediately.
- Writing to BBR allows the UBX message to be carried out at next power-on if battery backup is maintained.
- Writing to flash ensures the UBX message is taken into use at every startup until the firmware is replaced in flash.
| Configuration layer | Configuration string |
|---|---|
| RAM | |
| BBR | |
| FLASH |
Table 1: UBX binary string to override GPS L5 signal health status with GPS L1 health status
Disable GPS L5 Signal
To revert back to the default configuration, send the configuration string given in Table 2. The device returns the UBX-ACK-ACK message if the configuration is sent successfully.