The show is set in 500,000sq.m of dense Australian jungle. The celebrities competing are filmed in various settings and locations across the whole area making wireless belt pack microphones the obvious solution. It was down to Raycom to create sufficient RF architecture to make sure their every word was heard loud and clear even if they weren't screaming "get me out!"
Through experience with other geographically challenging applications, in the world of motorsport, Raycom turned to Italian manufacturer Wisycom, who they represent in the UK, knowing they would have the equipment and technology required to get the job done.
Wisycom's LNNA active antennas and RF matrix switches were selected as the most suitable solution. In total 40 antennas were installed around the site feeding back through a number of their new unique MAT288 eight way RF matrix combiners.
The MAT288 enables specific coverage areas to be selected on the front panel or remotely in addition to allowing gain control where required. DC power is provided for active antennas along with voltage and current measurement to provide remote diagnosis of antenna or feeder issues. For other non-permanent locations another pair of antennas feed back to the studio using a Wisycom MFL 'plug and play' RF over fibre system.
Pyers Easton, managing director of Raycom who personally assisted in the design and commissioning of the system says, "A system this large, possibly the largest of its kind in the world, requires extreme care to make sure the gain structure is correct to maintain the dynamic range throughout the system ensuring it is free from overload and does not introduce noise. The system also has a high degree of redundancy so that a failure of any antenna will not put the system at risk from dropout."
The entire system is broadband and unfiltered, the antennas cover from 470 to 870MHz. With 5 Watt walkie talkies on 515MHz that can be in close proximity to the antennas the large signal handling of the amplifiers is critical as any overload could cause serious loss of signal. In the finished system the combined noise floor was -112dBm with no overload even with levels of up to 20dBm when a walkie talkie was keyed up under an antenna!
The LNNA antennas are ideal as the gain can be set from the front panel in 1dB steps from 0 to 15dB meaning that just the correct make up gain can be applied to compensate for feeder loss. In some areas, such as the Bush Telegraph where the celebrities are very close to the antennas, gain can be easily taken out to ensure the very local antennas' contribution to the mix is at a similar average level to that from areas where the talent is located further away.
Hard wire runs between antennas and matrix combiners also had to be considered. Some of the feeders were up to 500m long so Wisycom BAW amplifiers were deployed at appropriate points, providing gain range from 0 to 22dB with very high line driving power making them ideal for the application.
Despite the tough conditions and wild nature of the location the system has proved to work flawlessly. Wisycom's products and Raycom's RF expertise worked seamlessly to provide a reliable solution. They now look forward to even more extreme projects.
(Jim Evans)
