Project description:
Client
Middle Eastern newspaper publisher
Network size
- Three main earth stations in London, Riyadh and Jeddah
- 12 printing presses in Europe and Middle East
- UK Headquarters in London
Case study
The client published a daily newspaper for the Arab speaking world. The main editorial office was in London, but with contributions from Jeddah and Riyadh. Further specialist papers and magazines were published in the Saudi offices. The final copy needed to be distributed to the 12 printing presses situated in Europe and the
Middle East. Over the duration of the project half a dozen other daily papers were added to the portfolio; the main title was updated to colour and IP-based networking added to the existing inter-office video conferencing and voice circuits. The whole network needed to be managed on a day-to-day basis to ensure equipment down-time was kept to a minimum and the paper hit the newsstands every morning.
The main earth stations consisted of *EF Data* Modems, *Miteq* up and down converters, *Andrew* dish controllers and *Varian* HPAs. All the RF equipment was in a 1:1 redundant configuration and each site typically had a dozen satellite modems to handle the customer’s traffic.
The VSAT sites were pretty much identical; all using *EF Data* modems and RFTs. Some sites had a transmit capability and some had varying numbers of modems according to what traffic needed to be received.
Every site – earth station and VSAT – had at least one CAM terminal. They performed two main functions:
Monitoring and control of all the baseband and RF equipment on site
By using the async overhead channels in the modems, a permanent network was maintained linking the sites together. Any site with uplink capability could provide a feed of CAM data. Any site receiving the primary data path was able to monitor the network of visible sites. As CAM links can work one-way, this meant that a receive-only site could still have visibility of the hub equipment also, commands *could* be issued to receive-only sites from the NOC – no acknowledgements would be received, but control was possible. To
complete the network PSTN dial-up links were installed at each site, when a call was placed, a receive-only site could be given a ‘back-channel’ into the network and thus appear to be fully connected.
In the UK, support engineers could dial in to either the UK headquarters or direct into a VSAT site.
Primary data links between the offices
To handle the unidirectional nature of the data, Alphawave designed and built high-speed synchronous serial cards which could interface between the PCs and the satellite modems. Custom software was written and integrated into CAM to provide a reliable, one-way broadcast path for the newspaper pages. A system of automatic retries and packet acknowledgements was implemented which meant that any uplink site could provide a list of ‘missing segments’ back to the transmitter where those parts of the file could be sent again. By integrating with CAM, full monitoring and control of the file transfer system was available throughout the network. Daily log files and statistics were collected and provided to the client.
To save on bandwidth, one satellite carrier between Jeddah and London was set up as a 1Mb simplex link. Using CAM’s scripting ability this link could be reversed when necessary or simply chopped into a full
duplex 512kbit/s link. This facility was available on-demand or could be programmed to automatically ‘flip’ at given times of day.
Another use of CAM’s scripting capability allowed some of the carriers between the three main offices to be swapped between newspaper transmission, video conferencing or Internet.