Beam Switching

Beam Switching

Comtech VSAT Beam Switching feature uses OpenAMIP protocol to communicate with a mobile antenna controller to retrieve an actual geographic location and command antenna pointing, activate transmission, etc. Comtech router selects the most appropriate satellite beam according to its current geographic position and pre-defined coverage maps, dynamically adjusts frequencies, levels and changes the mode of operation to ensure compatibility with new network.

  • Preconfigured, locally-stored coverage maps and network parameters
  • Automatic round-robin and map-based switchover between satellites or beams
  • Change of mode of operation when required
  • Automatic adjustment of uplink power and Doppler effect compensation up to 1300 km/h
  • Communications with mobile antenna based on standard OpenAMIP protocol
  • COTM terminal retains the same IP address after switchover to another hosting network


  • All COTM Hubs (subnetworks) are managed by the single NMS and use a dynamic list of active terminals
  • NMS holds the global list of the terminals and authorize the roaming of these terminals between the subnetworks by adding these terminals to the respective Hub
  • Each Hub allocates some common (shared) bandwidth for authorization of new terminals

IP Routing

  • Each terminal has its own permanent IP configuration regardless of the actually-associated subnetwork and is always reachable with the same IP address
  • When terminals roam to another subnetwork, the previous and new hubs send a RIP notification to the edge router, which changes the IP routing to this terminal accordingly


  • NMS supports GXT coverage files which can be obtained from the satellite operator or created using the GXT editor
  • The user may use downlink or uplink coverages to set the most correct service area


  • All networks are preconfigured in the terminal as a priority list with coverage map (service zone).
  • On startup or after profile restart the terminal determines its current position, chooses the first of the available networks (priority list) and tries to log in to the network.
  • When the active terminal approaches the service edge, the NMS initializes its switching to the next available network in the priority list or if several networks are available and terminal allows load balancing, selects the one with minimal recent average load.