TV-BAY August 13 issue 80

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bitrates to provide acceptable picture quality. What’s the point in that? A well-engineered H.264 system should deliver at least a 30-50% efficiency improvement over a comparable MPEG-2 system. It is that level of efficiency that enables wireless camera systems to thrive. So, what should I look for in a wireless system? I’ve talked about some of the technical issues that have now been overcome, but there are practical considerations that need to be taken into account when deciding if wireless transmission is right for your operation. One of the most important is whether the selected wireless transmitter has a proven, demonstrable ability to recover quickly after loss of signal. This is what hampered so many early attempts at wireless transmission systems. They simply couldn’t be counted on when the going got tough. During any deployment a camera is bound to stray out of range or suddenly de-power to indicate the need for a battery change. Both situations are particularly acute when you are in the field covering a live event. A wireless systems must be able to recover instantly and resume operation seamlessly, which, if carefully selected, they now do. Ease of rigging is also an important factor. There are a number of wireless camera control systems on the market that take an all-in-one approach, meaning that a single unit is used to connect to a camera control panel and generate an RF control signal. This, however, can be an issue if an OB truck is parked some distance from the event (such as a car park in the basement of a stadium). This means that going wireless is difficult because you have to run long lengths of RF cable from the truck into the venue. However, it’s a given that the longer the length of cable, the greater the loss of signal, which in turn means that the RF power has to be increased to compensate. The problem with that is that it increases the overall RF noise floor, which will impair performance of other RF systems in use, such as talkback. It can even cause RF noise 60 | TV-BAY MAGAZINE: ISSUE 81 SEPTEMBER 2013 problems with the wireless camera system itself. In our case, we combat this issue by separating the RF unit from the data unit. They are connected using a standard audio circuit and can be separated by several kilometres if necessary. This ensures the RF unit is mounted at the optimum location, and RF power can be reduced as a result. IP infrastructure is now common in modern OB trucks and is often used to route camera control signals, with all-in-one master control panels gaining favour. Our latest camera control system now has Ethernet connectivity as an option and our wireless camera receiver all have IP streaming in/out capability. Frequency reuse is also very important because increasing demand for spectrum means that fewer RF channels are available. Our approach allows up to four wireless cameras to share the same 12.5 KHz bandwidth control channel, which has proven to be a substantial benefit to users. Are there still technical hurdles to making wireless links reliable? In short, no, not really. The introduction of advanced video compression standards like HEVC H.265 will inevitably benefit wireless transmission in live production. Whether the manufacturer admits it or not, all wireless systems have to trade a certain amount of bit rate to achieve extensions in range. The higher the picture quality required, the lower the achievable range. It’s as simple as that. However, improved compression will enable better picture quality to be achieved at lower bitrates, so production teams will not only benefit from increased range at current picture quality thresholds, but improved compression will also enable the use of even higher picture quality settings (such as 1080p) without requiring a tightening of what we would consider normal wireless camera coverage circles. Basically, at normal thresholds you can extend your range much, much further, but if you are transmitting at the highest image settings, you won’t have to worry about losing your signal if you cross from one side of the football pitch to the other. Another important development in terms of wireless connectivity – particularly for newsgathering – is the ongoing change in satellite technology to meet the increasing desire to utilise Ka-band. Demand for traditional Ku-band access at times outstrips capacity, which can make it expensive. However, the development and deployment of a number of large, multi- transponder Ka-band satellites and Ka- band satellite networks is increasingly offering a viable and economic alternative to Ku-band. What does the near-term future hold? Encoders specifically engineered for high capacity broadcast applications that feature IP connectivity via 3G, 4G and LAN to ensure access to super- fast wireless 3G internet connections from even the most remote locations are now on the market and will be a major game changer. The ability to set up an IP-based newsroom and enable field reporters to get on air almost instantly, and wirelessly, is a massive benefit to producers.