PMP Synchronization Solutions User Guide
Neutralizing interference
PMP-0297 007v001 (January, 2017)
1-5
The Oncore GPS Receiver tracks eight or more NAVSTAR or GLONASS satellites. The CMM
uses the signal from at least four of these satellites to generate a one-second interval clock
that has a rise time of 100 nsec. This clock directly synchronizes APs and which, in turn,
synchronize the SMs in the network.
The Oncore GPS Receiver also provides
•
the latitude and longitude of the GPS antenna (co-located with the CMM)
•
the number of satellites that are being tracked
•
the number of satellites that are available
•
the date
•
the time in Universal Coordinated Time (UCT)
•
the altitude of the GPS antenna
•
other information that can be used to diagnose network problems.
Configuration options for TDD synchronization
Cambium PMP systems use Time Division Duplexing (TDD) - one channel alternately
transmits and receives - rather than using one channel for transmitting and a second
channel for receiving. To accomplish TDD, the AP must provide sync to its SMs – it must
keep them in sync. Furthermore, co-located APs must be synced together - an
unsynchronized AP that transmits during the receive cycle of a co-located AP can prevent
that second AP from being able to decode the signals from its SMs. In addition, across a
geographical area, APs that can “hear” each other benefit from using a common sync to
further reduce self-interference within the network.
For more information on each product series’ synchronization configuration options, refer
to the corresponding user guide, available here:
