Intercom design trends
Dec 1, 2009 12:00 PM, By Andreas Hilmer
Current systems integrate systemwide communications.
Figure 1
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What were once just simple point-to-point voice communications devices have grown over the last two decades into major communications networks and large installations. This evolution of intercom systems also brought about a change in perspective. While it used to be good enough to just provide a simple communications link between two or more users, nowadays, several different data and signal types need to be integrated into an overall network. Furthermore, installations are getting increasingly complex, demanding new approaches and new solutions that do not only include communications within one production site, but also link together multiple production locations simultaneously.
What are the requirements for modern intercom systems? What solutions are already available, and what ideas should be further expanded? This article gives a brief overview of the current trends in intercom design and offers an outlook on possible future developments and ideas.
Requirements for modern systems
The demands on contemporary intercom systems are as diverse as the installations where they are used. Sometimes large production facilities with hundreds of users need to be equipped, and other times, it's just a couple of control panels at a theater production.
Figure 2
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To provide a solution for all of these different applications, a modern communications infrastructure needs to be scalable from small, single-matrix systems up to very large, networked intercom systems with more than 1000 ports. In this way, the same technology platform can be easily used in large studio facilities, as well as in small trucks or event installations. Without such a high level of scalability, the planning, installation and maintenance of any system would require more work than necessary and would not be cost-effective. However, with scalable systems, established solutions can be easily adapted to new environments, securing prior investments.
As much as scalability is important, modern intercom systems also need to be able to handle a large number of different signal formats. Today's intercom systems are doing more than just providing a communications link between two people; analog and digital audio signals, IP data, control data and GPI signals are all interfaced in contemporary digital intercom applications. How an intercom system handles different signal types and integrates them is an extremely accurate indicator of its usability. The seamless integration of four-wire analog, AES3, MADI, Ethernet, VoIP and GPIs should be a given in today's systems.
Reflecting the importance of intercoms in today's production processes, reliability remains an important issue for intercom installations. For example, redundancy provides maximum reliability in modern intercom systems. Hot-swappable components, redundant CPU and PSU units plus redundant network topologies have proven to be the most successful solutions in protecting installations against failures and dropouts.
One aspect that is often neglected is the usability of the intercom system itself. The way it is configured, operated and maintained plays a major role in determining how well it will perform in day-to-day field operations. Shorter production cycles require greater system configuration flexibility and the option for a higher degree of automation. Optional control via external router control systems is also a feature that increases the degree of studio technology integration.
Different network approaches
Figure 3
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To understand modern intercom systems, it's important to comprehend their different technological approaches. In intercom system architecture, four main paradigms are apparent in current thinking:
- Star topology
In star topologies, all control panels are connected to one central mainframe. Although this makes planning the system quite easy, the effort of setting up larger systems is extremely high, especially regarding cabling. (See Figure 1 on page 8.)
- Bus network
Bus, or trunk, networks are similar to star topologies. The network consists of several star topologies with nodes that are connected, or trunked, together. Additional four-wire cabling expands the bandwidth between the various mainframes. (See Figure 2 on page 8.)
- Meshed system
In meshed systems, all mainframes are interconnected with one another. This ensures the continuous operation of the complete installation if one node stops working. With larger systems, the cabling requirements grow exponentially, and this topology is the most demanding in terms of cabling and setup. (See Figure 3.)
- Ring topology
In a ring topology, all available mainframes are connected in a dual fiber ring. Even in large systems, the effort needed for cabling is reduced to a minimum. (See Figure 4.)
Each of these four approaches is different in terms of performance and reliability. Ring topologies and meshed systems are able to handle a high amount of bandwidth. In particular, ring topologies, with their non-blocking network approach, are able to provide maximum network and communications performance. Star topologies and bus/trunked systems, on the other hand, suffer from significant bottleneck issues. Especially when there are a high number of calls or significant data transmission, the whole system will be throttled down or calls will not make it through due to a lack of bandwidth. Therefore, it is not recommended to rely on systems based on a star topology when reliable performance is always needed.
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