GPS Synchronization is the key to system scalability and system self-inteference reduction. Understanding the various sources of synchronization is important to building a reliable ePMP network.
On the AP's Configuration > Radio page, the parameter Synchronization Source indicates how receive and transmit
cycles are handled at the AP.
GPS: Synchronization timing is received via the AP’s connected GPS antenna. Co-located or in-range APs receiving synchronization via GPS or CMM transmit and receive at the same time, thereby reducing self-interference.
CMM: Synchronization timing is received via the AP’s Ethernet port via a connected Cambium Cluster Management Module (CMM). Co-located or in-range APs receiving synchronization via GPS or CMM will transmit and receive at the same time, thereby reducing self-interference. For more information on CMM configuration, refer to the PMP Synchronization Solutions User Guide.
Internal: Synchronization timing is generated by the AP and the timing is not based on GPS pulses.
Caution
If a CMM is being used, verify that the cables from the CMM to the network switch are at most 30 ft (shielded) or 10 Ft (unshielded) and that the network switch is not PoE (802.3af).
APs using Synchronization Source of Internal will not transmit and receive in sync with other co-located or in-range APs, which introduces self-interference into the system.