Skip to content

Enable GPS L5

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 L5 signals 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 L5 signal 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 the L5 signal 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 
B5 62 06 8A 09 00 00 01 00 00 01 00 32 10 01 DE ED
BBR 
B5 62 06 8A 09 00 00 02 00 00 01 00 32 10 01 DF F5
FLASH 
B5 62 06 8A 09 00 00 04 00 00 01 00 32 10 01 E1 05

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.

Configuration layer Configuration string
RAM 
B5 62 06 8A 09 00 00 01 00 00 01 00 32 10 00 DD EC
BBR 
B5 62 06 8A 09 00 00 02 00 00 01 00 32 10 00 DE F4
FLASH 
B5 62 06 8A 09 00 00 04 00 00 01 00 32 10 00 E0 04

Table 2: UBX binary strings to revert the GPS L5 signal health status monitoring to default