The humble intercom has now evolved into a more sophisticated solution that links large communication networks and installations across various sites. This paper looks at the role of the modern intercom application and where this technology is headed The face of the humble intercom has changed dramatically over the last couple of years. What was […]
The humble intercom has now evolved into a more sophisticated solution that links large communication networks and installations across various sites. This paper looks at the role of the modern intercom application and where this technology is headed
The face of the humble intercom has changed dramatically over the last couple of years. What was a simple point-to-point voice communications device has now grown to accommodate major communication networks and large installations.
This evolution also brought about a change in our expectations of this technology. While it was good enough to provide a simple communications link between two or more users in the past, today several different data and signal types need to be integrated into an overall network.
Furthermore, such installations are getting more and more complex, demanding new approaches and new solutions that do not only include communications within one production site but also link together multiple production sites simultaneously.
What, therefore, are the requirements of the modern intercom system? What solutions are already available and what ideas should be further expanded?
This paper from Riedel explores the current trends in intercom design and offers an outlook on possible future developments and ideas.
Requirements for modern intercom systems
The demands for contemporary intercom systems are as diverse as the installations, where they are used.
Sometimes large productions facilities with hundreds of users need to be equipped and sometimes its just a couple of control panels at a theater production. To provide a solution for all of these different applications, a modern communication infrastructure needs to be scalable from a small single-matrix system up to very large networked intercom system with more than 1,000 ports, all using the same technology.
Without such a high level of scale-ability, the planning, installation and maintenance of any system would require larger volumes of work than necessary and would not be cost effective. However, with scalable systems, already established solutions can easily be 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.
Todays intercom systems are doing a lot more than just providing a communications link between two people. Analogue 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 how it integrates them, is an extremely accurate indicator of its usability.
The seamless integration of analogue 4-wires, AES3, MADI, Ethernet, VoIP data and GPIs should be a given set in todays systems.
Different network approaches to intercom
To understand modern intercom systems, its important to understand their different technological approaches. Four main paradigms are apparent in current intercom installations.
Star Topology: Here, 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 cabling.
Bus networks: Bus or trunking networks are quite 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.
Meshed system: In this model, all mainframes are interconnected with one another. This ensures the continuing operation of the complete installation if one node stops working. With larger systems, the cabling requirements grow exponentially making this topology the most demanding in terms of cabling and set up.
Ring Topology: In a ring topology, all available mainframes are connected in a dual fibre ring. Even in large systems, the effort needed for cabling is reduced to a minimum.
Each of these four approaches shows different characteristics 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 with 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, where reliable performance is always needed.
With regards to operational reliability, both the star topology and the bus networks systems are prone to single points of failure. The failure of one node within a trunked system, or even just a connection failure between two nodes, can bring the whole system down. Redundant ring topologies and meshed systems are secured against these problems. Because there is no master mainframe and every link is set up redundantly, the entire infrastructure will stay online even if a node or a link stops working.
Intercom applications in todays field operations
Beyond topology and network concerns, connectivity is one of the most important considerations for an intercom installation. Two aspects matter the most. One factors to consider is what type of signals are used. Secondly, how does the intercom system transmit the integrated signals and what kind of transmission protocol is used?
Three considerations should be taken into account with regards to signal integration. First of all, modern intercom installations deal with much more than just speech transmission. Secondly, this requires a greater variety of signal formats. Thirdly, this means that a higher signal density needs to be handled by the network. It is, therefore, no surprise that all of these new signals are based in the digital domain. The way an intercom handles digital signals, and especially the combination of analogue plus digital signals, is a good indicator of its usability and the degree to which it is prepared for future applications.
The most common digital signals that are utilised are AES3 for ordinary audio and MADI for multi-channel audio transmission. This allows system designers to integrate digital audio routers seamlessly with the intercom system. Using digital audio formats offers several advantages such as easy integration of broadcast quality commentator audio at the panel or feeding multiple IFB sources to the matrix. This minimises the installation requirements and reduces costs significantly. In addition, this adds a lot of flexibility, especially when it comes to integrating other equipment into the infrastructure. Relying on non-proprietary standard conform data types like AES3 and MADI significantly expands the installations versatility.
The other crucial factor for modern intercom systems is the way the signals are handled within the network itself and in combination with the outside communications world, including remote installations. On the one hand, there is on-site communication, which needs to be handled in real-time for obvious reasons like the general need to avoid latency and the use of commentator audio. Also, networking over greater distances is best handled via IP signals because its the most cost-effective way. Connections in real-time are not a priority in these cases for example, when connecting to distant studios. Merged TDM/IP solutions that combine real-time TDM-based communications and IP-based communications into one integrated network are the answer to this demand. Relying on one approach only would limit the possibilities of the given installation. Its apparent that former long distance communications solutions such as ISDN and analogue hybrids are going to be sooner or later replaced by completely digital IP-based solutions.
These days intercom systems rely to a large extent on hardware components such as matrices with processor and client cards, control panels and interfaces to provide all the functionality that is needed. To expand the flexibility of future systems, intercom infrastructures will need to begin incorporating software-based functionality. This will ultimately result in hardware components only providing the basic infrastructure, upon which the software-based intercom features will run.
Following this development, it is apparent that the usability of those software features will play a major role in the success of a specific intercom system. Features such as easy-to-configure IFB tables, extensive audio routing capabilities, GPI integration or real-time system monitoring and remote control are indispensible for contemporary intercom applications.
Integration of various signal types and transmission methods is the only way that modern intercom systems based on standard components can be adapted specifically to the individual needs of every installation without costly adaptations and special developments for each project. Any intercom can only be as effective as it is reliable and flexible in terms of connectivity, data types and network architecture.
