One to watch

The windswept roof of a 1970s tower block might seem an unlikely starting point for a state of the art security system - particularly when the building in question is a block of flats in Calderdale, West Yorkshire. But it is where Richard Sumner of consulting engineers Faber Maunsell began one of the UK's most ambitious CCTV monitoring projects.

The flats in question are managed by Pennine Housing 2000, a housing association that looks after close to 12,000 social housing properties in the region. Like most housing associations, Pennine monitors its properties using 24-hour CCTV surveillance and in the past, it has done this using standalone systems monitored via control rooms located on each of its sites. However, 18 months ago it approached Sumner with a request: how could it create a central control room from which it could monitor and manage a number of remote sites? Within a tight budget?

The logical solution would have been to link the sites using a fibre optic connection. As the industry standard, this provides reliable, good quality and fast transmission of data. The drawback for Pennine was cost. According to Sumner, the investment needed for the housing association to dig and install its own fibre optic would have run into millions of pounds. Using rented fibre costs significantly less, around £60,000-£70 000 for installation, but it would have meant an ongoing line rental of around £24,000 a year - £1000 per monitor per year, for the 24 monitors in the control room.

After an initial feasibility study, Sumner began thinking of alternative solutions. "I went onto the rooftops of each of the tower blocks the association wanted to link," he says, "and realised that from each building I had a line of sight to all the others." This was the key to his solution: with an unobstructed view between the seven sites, a wireless network became an option.

Pennine's point-to-point wireless system uses Internet Protocol technology and works by sending video and audio data from antennas mounted on the roofs of five of the sites to a central tower block in Halifax. This is relayed (along with the data from the central site) to a new 10 m mast, from where it is beamed to a purpose built control room (see over). The control room also receives audio data from the new door entry concierge system.

The installation has cost around £72,000 to put in, but as Sumner points out there are no ongoing costs and the system can easily be extended.

The challenge

All new technologies come with their problems, and this was no exception. Finding a competent installer was the first hurdle: "When we went out to tender we got a lot of non-compliances from contractors because the system we wanted to use was so modern they weren't used to it," recalls Sumner. Technology Solutions and Barrier Surveillance were eventually appointed, and have been supported throughout the scheme by systems integrators BBV and equipment supplier Dedicated Micro.

To keep costs down, the system uses the existing analogue CCTV cameras already installed on the various sites - over 130 pan, tilt and zoom units. To transmit the data using the IP network, the analogue signal is first digitised and then compressed. Although this reduces image quality, it helps the transmission. However, on some legs, the signals are travelling distances of more than 15km and being relayed up to three times. For the CCTV footage, this can accumulate a significant delay. "It's quite important to get that delay down to zero - and in an analogue solution on fibre, it would be," says Sumner. "But between the picture leaving the camera and appearing in our control room, there was a 100 millisecond delay."

Although this might sound insignificant, it causes latency - when the operator in the control room moves the joystick controlling the camera, there is enough of a delay to make it extremely difficult to follow and zoom in on moving objects.

This delay has now been reduced to 20 milliseconds. A big step forward came when they realised that Vodafone had upgraded its local masts to 3G technology, which interfered with Pennine's signal and reduced its bandwidth by more than half. Continuous, smaller improvements are gradually being introduced as new software releases, which improve the compression of the video files, come on stream and these should bring the delay down further over time.

"It's important that the operators understand the issue of latency," says Sumner. "What we've done here is good, but in a year we will have updated the software again and it'll be even better."

Room with a view

The project team created a new control room, installing an 82" front projection screen for viewing the cameras instead of the traditional bank of 21" monitors - a layout that offers much greater flexibility as it can be tailored to display up to 16 monitors at any one time.

The system uses a pick-a-point graphical user interface. From a spot monitor on the control desk, the operator can select and display any of the monitored sites simply by clicking on an aerial view of Calderdale and then drilling down to a specific camera. The image is then displayed on a second monitor as well as the main wall and can be controlled using a joystick.

According to Sumner, it was important that the operators weren't overloaded with information. To avoid this, the software operating the cameras incorporates motion detection - so called reactive monitoring, which relies on changes to the pixels being recorded by the camera: as soon as someone is detected walking onto a particular floor or into a block of flats, the camera automatically pops up on the main display. If a second camera in the same block is activated, the screen switches to a quad arrangement so it can display up to four images, and when more than four cameras have been activated in a block, it changes to a nine-way arrangement. This set-up applies to all the monitors and means the operator doesn't have to be looking at all the cameras, all of the time.

Next time around

The audio and video data is recorded onto a hard drive and archived in case it should be needed, and there are also facilities for burning it onto CDs, DVDs or more conventional video tape if necessary.

For Sumner and the project team, the last 18 months have been a steep learning curve - so, looking back, would he do anything differently? "Yes, I would try to simulate a concept link before committing to the installation - put the client's equipment on to a linked solution and let the operators play it for a week so they know exactly what they are getting," he says.

He admits that analogue transmission is still the better solution as it offers no latency and better picture quality, but it's also a lot more expensive. "The jump from analogue to digital, particularly for operators using existing equipment, can be a big one," he says. "But give it a couple more years and the IP wireless technology should be closer, if not just as good."

It's an ambitious solution and Sumner has overcome many challenges to get it up and running - but no doubt we'll be seeing more of these in years to come.