Signalling a new TV era

BAE Systems has developed a wireless TV studio system which will not only allow cameramen far greater freedom of movement, but also provide the bandwidth needed for high-definition live broadcasts.

Developed at BAE’s Advanced Technology Centre in Chelmsford, the system utilises a wireless-enabled camera which sends wideband data at 60Ghz to embedded remote antenna units in the ceiling. The mushroom-shaped antennas provide overlapping coverage across the entire studio. The video signals received from the mobile transmitter are then sent along optical fibre to a base station in the control room.

Project leader Mohammad Nawaz said the system, known as ROFMOD (Radio on Fibre mobile data network demonstrator) will, for the first time, allow cameras to be moved quickly, easily and silently around a TV studio. Currently mobile live broadcast cameras require heavy, cumbersome cables that must be supported by other team members as the cameraman moves around the studio. The cables also make a slight scraping noise on the floor which can interfere with audio signal quality.

‘Using this wireless system will allow cameraman far greater freedom of movement and give them access to shots which would otherwise be impossible,’ said Nawaz.

According to the project’s chief engineer, Chris Pescod, one of the keys to the system is its use of wide band radio signals to carry the high-definition data to the antennas. Using cables to carry high definition data — as happens now — severely limits the bandwidth that can be carried at any one time.

‘Using 60Ghz gives you higher bandwidth which is crucial for carrying multiple, high-definition TV channels,’ he said.

The use of the 60Ghz band also has additional benefits for a TV studio as signals at the bandwidth are easily absorbed by oxygen in the atmosphere. This means that the signal does not travel very far, which is ideal for studios aiming to minimise disturbance across channels and interference with neighbouring studios.

The fibre-optic cable from the antennas to the base station is able to carry the data for long distances without any significant loss in signal quality. Using a conventional aluminium waveguide means that two to three decibels are lost per metre, whereas fibre-optics only lose around a quarter of a decibel per kilometre, said Pescod. To use fibre-optics the team had to develop a particular modulation scheme to carry the 60Ghz signals.

‘How you handle 60Ghz on optical fibre was one of the challenges we faced,’ he said. ‘Using just light as the signals carrier means that 60Ghz of bandwidth introduces great complexity.’

Nawaz said that the technology could also be useful in military applications as its short range would keep it relatively secure.

‘It would be ideal for naval communications, above and below deck, and could also be used to communicate easily and securely between military vehicles on the battlefield,’ he said.

In recent trials at Teddington TV studios in Middlesex the team performed simple single frequency tests to prove the technology will work, claimed Nawaz. Further trials will begin in June to test the fully-integrated system using high definition channels. The team will then work on miniaturising the wireless terminal which is to be attached the camera to make it lighter and more portable.