GPS synchronization

Cambium leads the wireless industry in its usage of powerful GPS synchronization capabilities in all its PMP networks. This valuable capability dramatically reduces self-interference in licensed or unlicensed frequency bands. GPS synchronization allows all sites to be set to the exact same clock so network timing is very precise. As shown in the diagram, GPS satellite timing signals reach the GPS receivers in each of the network’s access point radios establishing a common timing reference. This allows all the access point radios in the network — whether hundreds or thousands — to transmit at the same time and alter natively receive as all of the subscriber modules in the network transmit at the same time in turn. This helps prevent radio signals transmitted by an access point transceiver to interfere with reception of a user signal by another access point transceiver, perhaps the most onerous kind of self-interference in time-division duplex radio networks. With GPS synchronization, you can be certain your network can scale and grow elegantly to serve increasing numbers of users and applications.


The Navigation Satellite Timing and Ranging (NAVSTAR) and Global Navigation Satellite System (GLONASS) Global Positioning Systems (GPS) each use 24 satellites to relay information for precise derivation of position and time.

The cluster management module (CMM) contains a Cambium GPS Receiver. The CMM is a critical element in the operation of the system. At one AP cluster site or throughout an entire wireless system, the CMM provides a GPS timing pulse to each module, synchronizing the network transmission cycles.

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.
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