Requirement
Provide a reliable, flexible CCTV network capable of deliver high FPS and telemetry control to two control centres at the same time.
Solution
Utilised Wavesight’s high performance OFDM wireless bridges to deliver the performance, output and flexibility the client needed.
At the end of 2004 leading Dutch system integrators QCAT were asked to design a wireless network to support surveillance cameras surrounding Amsterdam Central Railway Station.
The requirement was to deliver analogue camera pictures to the Central Supervision Unit of the Dutch Railway (CTR) and digital camera pictures to the Police Station at the Nieuwerzijds Voorburgwal (NZVW), over half a kilometre away from the Station. To be able to deliver reliable connections and encode technology, Q-CAT combined the equipment of two different suppliers: Wavesight and Indigo Vision. Q-CAT already had a lot of experience as a system integrator for wireless video transmission for both companies.
Choosing a Wireless Solution
The system they chose was based on radio communication with high performance Wavesight OFDM radio bridges, which in this case had two key benefits. First, they offered near line of sight (NLOS) capability, which meant that even where free line of sight was not available, a link could be established and sufficient bandwidth would be available even if there were obstructions. This provided greater flexibility and reducing the number of radios required (and the time it took to install them) over other systems.
The second benefit was the range of frequencies available, one of the widest on the market from a single product. In this case it was vital that to use frequencies outside the public domain. WaveMAX provided sufficient non-overlapping channels to avoid interference with neighbouring channels.
Designed for future growth
Q-Cat’s solution for the Central Station surveillance area used 20 strategically placed cameras, divided into 5 sectors, using 90° or 120° sector antennas. By doing this only 5 free frequencies were required, providing flexibility for future growth in the system. For further flexibility, the bandwidth control utilised
IndigoVision’s VideoBridge 8000 Codec to deliver 2,5 M/bits per video streams in MPEG4 2CIFquality. In this configuration, an upgrade to a greater amount of cameras or 4CIF quality was built in for future expansion.
Real time feeds to both locations
The feeds initially went back to the CTR for onwards transmission to the Police Station, but there needed to be no delay. To ensure a reliable, simultaneous connection for the NZVW police station, Q-CAT again used WaveMAX wireless Ethernet bridges for point between the two sites. The result was that all dome camera-pictures were available at the police station at the same time with 25 fps video. Apart from providing real-time images, WaveMAX’s high throughput allowed remote control of the cameras from the Police Station as required.
For the client, they now have the ability to monitor the Central Station Area with the minimum of manpower, 24/7, with the added benefit of easy expansion or redeployment as required. For Q-CAT this has been a very successful project and a clear demonstration of their capability to integrate wireless technology to provide the reliability, performance and flexibility their client needed.
