Project name:

Foreign Office

Project description:


  • British Foreign and Commonwealth Office
  • Network managed by Datasat Communications

Network size

  • Two UK based earth station
  • One Australian based earth station
  • Between 80 and 120 fixed VSAT terminals throughout the world
  • UK based NOC

Case study

The network consists of a large number of remote sites situated throughout the world, linked to one of three earth stations, two in the UK covering the AOR and IOR and one in Canberra covering the POR. The earth stations themselves are linked via land lines and VPNs. Equipment at the VSAT terminals includes a pair of 1:1 redundant SSPAs, one, two or three pairs of 1:1 redundant modems and a UPS. Additional customer equipment is also present, but remote monitoring of this was not required. Control of equipment at the earth stations is also restricted to the modems only.

Each remote site is fitted with a 1U rack-mount PC running the CAM server software, control of the equipment on site is via RS232 or RS485 serial ports. One port is used to connect to the ESC overhead channel of the modem to provide the CAM telemetry link back to the hub of the network and another to a PSTN dial-up modem for fault finding in case of satellite link failure.

The earth stations consist of multiple racks of multiple 1:1 redundant pairs of modems. Because of the physical number of ASYNC and M&C connections required each rack is fitted with its own CAM server, these are then networked (via IP) to a single central data concentrator at each earth station, these machines are then linked together using the inter-site VPNs.

Engineers at the NOC and those on call are able to monitor the status of the network using a CAM GFX connection to the prime CAM server in the network, thus allowing the status and configuration of any piece of
equipment to be viewed or modified.

Alarm system: The CAM alarm system is configured to watch for significant events throughout the network – e.g. equipment faults, low eb/no, connection failures and flag these to the engineers. At the most basic level these are shown as flashing indicators on the GFX terminals, but in certain conditions the alarm system generates email and SMS text messages in order to alert the operators.

Event logging: CAM’s event logging subsystem continually records the changes in all the equipment in the network. Portions of this data are used to generate monthly reports on the availability of the modem circuits and also the performance of the UPSs at the remote sites.

Links to remote sites: The ESC link provided by the modems is a simple RS232 serial connection, CAM could use this link directly for its connection, but instead the ‘slip’ protocol to used to turn the link into IP. This means that in addition to the CAM data being carried, telnet, ftp, ssh, scp can be used to gain remote access to the machine.

Special requirement: The redundancy controller of the SSPAs does not have a computer interface, instead relying on closed contact relays for status indications and control of the RF data path. As the waveguide switches need a number of amps in order to switch, a custom piece of switching hardware had to be built in order to supply enough current. To make this general purpose, Alphawave designed and built a control board with a microprocessor, 16 digital inputs and 16 high voltage/current relays. Each remote site is fitted with one of these controllers which is also connected to the CAM machine on site.