Dynamic satellite systems

Military VSAT terminalDynamic networks such as SNG, outside broadcast or data acquisition usually consist of a number of remote assets and a central hub. The remotes are typically “fly-away” or “drive-away” deployable VSAT terminals. Fitting a low cost, low power CAM system in each remote provides full remote management and control of the terminal allowing them to be monitored from the central NOC. In normal operation, telemetry from the remote would be carried via the ESC (Engineering Service Channel) on the satellite link. Two features of CAM stand out in this situation: 1) CAM makes efficient use of the available bandwidth – even a 9600 baud link can provide a useable service 2) CAM can operate over one-way links — it is not necessary to provide a full duplex service. This means a remote dormant site that is listening can still receive commands and act on them, e.g. to re-enable the outbound carrier.

CAM is frequently used for the initial deployment of a terminal. In this case a secondary data path needs to be established, this is usually a cellular (GSM) or satphone (MSS) connection. The low bandwidth requirements of CAM mean that even a 2G or 7.2K Globalstar would be sufficient. Once this control channel is open, the antenna can be deployed, the BUC enabled and the carrier switched on. Once the ESC has established normal communication the GSM or MSS link can be dropped. Prior to stowing, the secondary path will be re-established to over-see the correct power-down sequence.

Central management of bandwidth using a simple load planner or more complex bandwidth allocation system means remote terminals can be dynamically loaded with different frequency plans, according to bandwidth demands in the network or scheduled changes to services.