Wireless cameras

Tireless cameras are here to stay. They have added flexibility and creative opportunities that to directors and cameramen in a way that traditional cameras with cables cannot provide. While their foremost uses lie in outside broadcast and news gathering, there are several indoor applications in studios and light entertainment which benefit from their freedom of movement and the different perspectives they offer. Wireless systems are ideal for any show coming live from a crowded place or for providing audience interaction in chat shows.

Sports broadcasting has particularly been transformed by wireless cameras with cameramen on the touchlines an everyday sight in venues from soccer stadiums and rugby pitches to basketball courts. The wireless transmitter is typically installed on a Steadycam rig, with a diversity reception system fed by antennas in several locations in the venue providing unbroken live pictures wherever the cameraman roams.

Among the most interesting applications are those where a number of wireless cameras are used alongside cabled cameras, and some of these are very complex productions. At the Asian Games, there were some impressive large scale applications where the outside races such as cycling, cycling time trials, walking, triathlon, sailing and the marathon used High Definition (HD) stabilised cameras with wireless links to get aerial shots from helicopters. They used HD RF downlinks to relay these shots back to the production suite.

In situations like these, the editor needs to co-ordinate feeds from a number of microphones and cameras, and the deciding factor in whether or not the wireless camera can be used alongside cabled cameras is the signal delay or latency. This is the delay introduced as the picture travels from the camera over the link to the receiver; it needs to be negligible if the editor is to mix live feeds from fixed and cabled cameras together in one show.

Whether the signal delay is as low as a single frame or as high as several seconds depends upon the encoding technology used and the skill of those who have implemented it. Only a few wireless systems make the grade for live broadcast, while fewer still can offer the requisite ultra low delay whilst providing contribution-quality video.

Any concerns that the picture might fade or drop out will be allayed by choosing a system that has Diversity reception capability built into it. A diversity system can use the signals from two or more antennas to produce a combined output, which takes the best of all the signals available to provide continuous unbroken coverage.

HD presents a major challenge to wireless camera system manufacturers because an HD signal has about six times as much data as a standard definition (SD) signal. To maintain the quality of the HD image, it is essential that the full resolution of the picture is maintained. This rules out down-sampling, wireless transmission and up-sampling approaches which seriously degrade picture quality.

Link Research has developed its own solution to this in the form of an FPGA-based encoding and modulation technologies that delivers full contribution quality HD video at bit rates around 18 Mbps, and broadcast quality HD images at as little as 9Mbps, all at full HD resolutions and in all HD formats. The solution uses the vendor's ultra low delay MPEG2 encoding technology with video in to video out delay of less than 50ms for seamless mixing with wired cameras, while its LMS-T modulation scheme and maximum ratio combining diversity receivers provided HD signals.

While HD wireless is going to get the money-shots for the top sports events, wireless doesn't have to be expensive.

There is a new way to use wireless cameras in news applications. The concept, Cellular Diversity, is to install a network of receive points, linked together to provide wireless camera coverage over an area as large as a city. The sites are typically towers or antennas on high buildings placed so as to cover the main news locations, such as government buildings and city landmarks. The receive points are linked back to a central location where diversity units combine the signals to provide coverage over the whole area. Once the initial rigging and setup is done the network stays in place and journalists can send a live report back any time.

A news team need consist of just a reporter and a cameraman, who can turn up at the heart of the action, switch on their camera and go live instantly. There is no longer a need for satellite trucks and the issues of getting them to their destination and then finding a parking space with a view of a satellite. The news crew can even broadcast live from their car or van. As they drive along, they could even follow a VIP car or a procession, with the journalist reporting from the car.

The BBC was the first broadcaster to adopt this idea last year, equipping their regional news teams throughout the UK with wireless systems. Since then, many sites have been set up in cities across Europe. Cellular Diversity has proved to be a very cost-effective and flexible way to cover news in cities.

Print | Email | Discuss this article |

USER COMMENTS (0 COMMENTS)

POST A COMMENT

CLICK HERE TO POST A COMMENT

Add your Comment All posts are sent to the administrator for review and are published only after approval. ArabianBusiness.com reserves the right to remove any comment at any time for any reason. Please keep your responses appropriate and on topic.
Name *
Remember me on this computer
Email *	(Your email address will not be published)
City
Country
Subject *
Comment *
Notify me of further comments
Security Code *
Please click post only once - your comment will not be published immediately.