One of the challenges for the modern broadcaster is to achieve operational flexibility, to allow technical and creative teams to co-operate in new ways. This might be direct working between multiple sites, or linking parts of a facility that were not previously connected, as we saw recently at Oman TV. An essential part of interworking […]
One of the challenges for the modern broadcaster is to achieve operational flexibility, to allow technical and creative teams to co-operate in new ways. This might be direct working between multiple sites, or linking parts of a facility that were not previously connected, as we saw recently at Oman TV.
An essential part of interworking is the ability to communicate. Broadcast intercom has developed to be carefully tuned to the needs of the industry, providing instant communication between areas, ensuring that operational decisions and requests are heard and understood by all who need to act on them.
With interworking comes the need to interconnect intercoms. Even when these are from the same vendor, there are challenges, particularly when communicating over a distance. But what happens when two parts of the facility to be connected have intercoms from different vendors, perhaps because one is using legacy equipment or it has particular operational requirements.
Just such a situation has recently arisen in the redevelopment of Oman TV, where Trilogy supplied an intercom system to the modernised radio building, but another vendor supplied the system for the adjacent television centre.
Trilogy developed a simple solution to the challenge, built around a widely recognised open telephony standard, SIP or Session Initiation Protocol. It allows users of a Trilogy Gemini intercom to call stations on another SIP-enabled device in any location to which there is a data path. In Oman, the calls are across the road, but the same technology allows the intercom to call across the world.
SIP is the standard adopted by telcos to place calls using voice over IP, which is increasingly the way that telephony is headed. It is an open standard, supported by handset and switch manufacturers serving the telecoms business. Trilogy implemented SIP in its defence communications products some years ago, to allow connection with public telephony networks and direct to SIP handsets.
It has now been adapted for use in broadcast intercoms. The SIP signalling remains firmly within the open standard, although it has required some adaptation within the intercom system.
When a normal telephone call is made, one party dials the number of another, the call is routed, the called party answers by picking up the phone, and the call is established with duplex communications both parties are able to talk and listen simultaneously.
That is not the way that broadcasters need an intercom to work. Their requirement is for an operator to push a key on a panel and talk to a remote device instantly, without the need for the operator at the called station doing anything: there is no concept of picking up an intercom message.
So the Trilogy solution treats a push to talk on a panel as an individual SIP call with simplex communication. At the called panel the device has to recognise the SIP signalling and auto-answer to hear the message. Obviously, in the pressure environment of broadcast operations this SIP signalling and auto-answering has to be instantaneous. In practice, it takes just a couple of milliseconds, so it is transparent to the user.
Originating an SIP call is performed in exactly the same way as any other intercom call. A typical Gemini panel is configured for 32 addresses, with their user names dynamically displayed on the keys (16 keys plus a shift to get to the second bank of destinations). In the standard software multiple keys can be for SIP calls to other systems or to remote locations. More destinations can be added if required through additional matrices.
So in Oman, if a user in one part of the radio facility needs to talk to another part of the radio facility, he simply presses the appropriate button. If the user needs to talk to an area in the television centre, again he simply presses a button, in exactly the same way. If a user in the television building calls a user in the radio centre then the Trilogy panel auto-answers the SIP signalling and relays the message. A two-way conversation is, in effect, a series of SIP initiations which are auto-answered by the remote panel.
Other intercom vendors are also implementing SIP for the same reason. Obviously both systems need to support SIP if they are going to talk to each other. The Trilogy system is implemented fully in software and needs no additional hardware. It is, therefore, simple to add SIP capabilities after the system has been installed, simply by unlocking them with a license key.
This also means that the system is completely flexible: any panel on the network can have access to any of the SIP addresses. And, as noted, the SIP calls need not be to another intercom system but could be to the remote devices including commercially available SIP VoIP phones and distant facilities.
The most important point is that, because SIP is a universal standard, interconnection should be standardised and needs no specific development on the part of any vendor to make the connectivity work. The result is a major productivity and economic bonus for broadcasters, who can choose intercoms on the basis of core functionality, and continue to use legacy equipment, confident that they can set up interworking wherever the systems are installed.
Malcolm Reed is Projects & Training Manager of Trilogy.
