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Ask the experts Intercoms for outside broadcasts I just assume outside broadcast trucks come with an intercom. Why do I need to even think about it? The first big point is that an outside broadcast is not just a control room on wheels. It is an event. And that means communications beyond the truck. Within the production you probably have more than one control room. If you are covering sports you will have what some of us still quaintly call the VTR truck, full of servers and excitable server operators. If it is a music event there will probably be a separate vehicle dedicated to sound recording. Barry Spencer, Trilogy Communications There is the event itself, which may have its own communications network. You do not want the teams running onto the pitch while you are on a commercial break, but trying to call the tunnel on a mobile phone to get the players to wait is not going to be practical. At Glastonbury you do not want the headline act to rock into their opening number until you have got the servers into record. That is what floor managers are for. Why does it affect the choice of intercom? Talking to your own floor manager is great for those go/no go moments. But sometimes you need to know more than that, and understanding what the event is doing makes covering it easier. If you are broadcasting live – sport, for instance – then the broadcast playout centre is a part of our outside broadcast. Timings are bound to be unpredictable and plans change, both at the event and in the broadcast schedule. It is easier to discuss these rather than send text messages or put up a cue dot to warn a break is coming. So you are saying that the broadcaster, the OB truck and the sports stadium should all be on one giant intercom? No, definitely not. But you should be able to link the intercoms simply. The transmission controller should find, for the duration of 46 | TV-BAY MAGAZINE the live event, one or more buttons on the intercom panel which go direct into the OB network. Similarly, the director in the truck should be able to access the event network. Give the people that need it the ability to talk to each other, clearly and instantly. Sounds good. How? The latest generation of intercoms, like Trilogy’s Gemini, use IP for connectivity and communication. The internet protocol is universal, and will go down any data circuit and ethernet switch that has enough bandwidth. Thanks to the might of the telecoms industry audio codecs are standardised. The G.722 codec gives a nice 7kHz bandwidth with an encoding delay of just 3ms (so effectively no latency) and fits in 64kb/s which should not be a problem for any data circuit today. Another useful standard, the session initiation protocol or SIP, defines how a call from point to point is set up. IP intercoms are peer-to-peer systems: they do not need a central matrix, just a network connection between all stations and a server-based look-up table for IP addresses. Recently the EBU determined these standards as the recommended practice for broadcast intercoms. Coming from the telecoms world they are already widely supported. Making connections between, say, multiple Gemini installations – however far apart they are – is a breeze. Connections between different vendors’ IP intercoms will become simpler as the standards are implemented. An IP intercom sounds complicated. Is it going to be tough to rig and operate? No and no. It is much easier to rig, because all you are doing is using ethernet bandwidth. No need to pull in special multi-core cables for the intercom. Just plug in RJ-45s. With rig times cut as short as possible, that is good news. Operationally, we have to accept that there are a lot of different users who have different