The missing link in the live HD production chain has been a handheld wireless camera system with the required bandwidth and high reliability to transmit full HD images.

For several years broadcasters producing live events in HD have had to settle for SD wireless systems whose images had to be upconverted before being added to the broadcast. Besides being of lower quality , these SD systems were plagued by video latency problems- the compressed video signal would be transmitted back to the production truck on site and arrive several frames later than the audio signal. This resulted in lip-sync problems and sometimes dropped pictures.

[For its live HD golf events in 2007, CBS will delay the audio signal three frames as it comes into the video switcher to keep handheld segments in sync.]

Several new HD systems use either MPEG-2 or JPEG 2000 (wavelet) compression algorithms, which appear to have successfully addressed these shortcomings. Ikegami, Link Research, RF Central and Grass Valley now all offer HD wireless systems with as little as three frames of delay (and getting better all the time). These systems must have line-of-sight in order to work most reliably.

For example, RF Central’s new HD Camera Mount Transmitter (RFX-CMT-HD), which debuted last month at the HD World Conference in New York City, uses an NEL encoder and high-quality linear RF amplification technology from Gigawave.

Weighing 4.5 pounds, the transmitter is available in various frequency bands (1 to 6 GHz). The HD transmission system includes built-in wireless camera control, which is useful for remote operation at sporting events. It comes with interface plates to fit most common professional batteries, or can use an 18W power source via a 4-pin XLR socket interface plate.

For more information on these wireless systems, visit http://www.pjwdesign.co.uk, http://www.rfcentral.com/, http://www.ikegami.co.jp/, and
http://www.thomsongrassvalley.com/ [PDF].