Jake Dodson /
06.01.2010 12:00 PM
Intercom system evolution
Cable-agnostic, mesh-networked intercom technology helps drive progress and future growth.

Since the introduction of the first analog intercom systems 40 years ago, it would be easy to think that the use of broadcast and live performance intercoms has reached an evolutionary apex. The development of point-to-point or matrix intercoms, and the more recent transition to digital wireless systems, has already had a profound effect on workflows, enabling even more complex productions. Yet the modern production environment still faces many challenges, such as increased demands to improve efficiency, reduce complexity and provide rapid setup and configuration, while bringing together additional team members with varying degrees of expertise.

That being said, this article will take a look at where intercom systems are headed next, what some of the key enabling technologies are that will be used and how they will likely be integrated in future intercom systems. New concepts such as cable-agnostic transport, mesh-networked intercoms and role-based configuration also will be discussed.

Party line and point-to-point matrix

In the early days, intercoms were exclusively based on party-line technology, where all users talked and listened to all other users. As productions grew, the need to segment became more necessary, driving party-line systems up to two, four or more channels. The emergence of point-to-point or matrix intercoms allowed individual, one-to-one communications or multiple groups to be configured for a variety of situations. This evolution has continued over the years with the addition of interruptible fold back (IFB), control logic and the multiple interconnected systems that we see in modern intercom setups.

The seemingly limitless flexibility of matrix intercoms is an advantage that should have spelled the death of the party line, yet today, party-line systems are more prevalent than ever with no signs of diminishing. Why is this? The simple answer is that party-line systems are easy to set up, easy to operate and require little operator training out of the box. Matrix systems, on the other hand, require a much higher level of user configuration, workflow mapping and system tuning to obtain the benefits afforded by the extra levels of functionality they provide.

In addition, matrix implementations tend to be characterized by hub-and-spoke cabling architectures, compared with the daisy-chained and passive Y-split cabling schemes that analog party lines are based on. This latter approach affords a much greater simplification of the cable infrastructure, with the user able to choose whether to home run or split at the end of a single cable run depending on the level of cabling redundancy required. But cable positioning has to be carefully considered for some applications to minimize noise artifacts created by crosstalk and power supply-related interference.

Instead, what is required is a new cabling paradigm that combines the flexibility of current analog cabling environments in an all-digital, noise immune environment.

Cable-agnostic transport

Cable-agnostic transport is a new concept that minimizes the dependence on different cable types by using a combination of new technologies that have a high tolerance to the impedance characteristics of a variety of cable types. Imagine being able to choose between a regular microphone, Cat 5 or coax cable, where the main consideration is the physical connector and not a costly conversion process or additional interface card. These technologies are beginning to emerge in new systems that not only allow a choice between Cat 5 or microphone cable, but also enable different impedances and cable gauges (18 to 24) without being limited to specific high-grade, AES-rated 110V cable to achieve links in the 300m to 500m range without using repeaters. Establishing such technologies over a range of intercom products opens the potential for plug-and-play intercoms in an all-digital environment, with the added advantage of passive Y-splitting and daisy-chaining capabilities.

Connectivity and mesh intercoms

Simplifying cable transport will add a large degree of freedom, but this is only useful if intercom elements can be easily connected and are able to talk to one another. Take, for example, the need to add an intercom panel at a new location. In this case, implementing a new panel typically means adding a new cable home run and, in some cases, additional interface boxes for format conversion. This can be a costly and time-consuming process. IP-based products are solving this connectivity problem, allowing intercom elements to be added to the LAN or remotely over a WAN or Internet connection.

The key question here is how to leverage the flexibility of connection without compromising audio quality. Traditional VoIP technologies are notorious for poor audio quality where architectural limitations — thanks to multiple jitter buffer stages, multiple encode/decode cycles and the subsequent reliance on narrowband codecs — create an unappealing experience. Next-generation IP technologies are solving these limitations by replacing central IP mixing architectures with fast IP routers and distribution of mixing at the extremities. This reduces jitter buffering (and its associated latency), eliminates multiple encode/decode cycles (and their associated audio corruption) and enables flexible codec choices, such as the ability to move to wideband, low-latency codecs with a corresponding improvement in overall audio bandwidth and quality.

By embedding IP technologies across multiple devices, a common, flexible communication transport system begins to emerge in which previously disparate intercom elements, such as matrix frames, party-line main stations and intercom panels, can become nodes on the same network. This new paradigm of mesh intercom networking will allow the development of highly flexible intercom environments with each node able to provide specific local functions, yet still be part of an overarching intercom environment that can be managed remotely. This reduces configuration and administration costs and allows rapid changes to configurations anywhere in the network.

The “read the manual” challenge

How many iPhone users do you think have ever read the product manual? Does a product manual even exist? In today's intercom environment, we expect users to do just that (read the product manual) to train themselves to understand the complexities of manually configuring hardware, but this process takes up their valuable time that could be better spent elsewhere.

How much easier would it be to plug a number of intercom elements (frames, interfaces, panels, etc.) together and have the system discover and configure them accordingly? The concept of plug-and-play operation, while prevalent in other industries, is only now finding its way into the intercom domain.

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Role-based architectures

As we solve today's configuration, connectivity and cabling issues and move toward the reality of a mesh intercom architecture, further opportunities to increase usability will become available.

One such concept is role-based operation. Today's intercom systems essentially are location-based, meaning a user is fixed to a physical panel or beltpack location in a particular part of the studio or venue. Role-based architectures change this dynamic by allowing specific attributes such as key settings, labels, audio level preferences and security levels to be linked to a user or role rather than a location. If the user moves location or changes hardware, a simple act of logging in to the new hardware via a keypad entry or hardware dongle will enable his or her personal characteristics to be implemented on the new hardware.

This type of approach promises a highly flexible environment for the end user while at the same time offering a personalized approach tailored to the specific individual. A much more dynamic system is created by enabling the intercom environment to tune itself to the needs of the individual yet remain flexible enough to allow easy hardware swap-outs or user movement to different parts of the network. As teams become more fluid and mobile, such concepts will allow the intercom infrastructure to move with the users, not restrict them to a fixed workspace.

Wireless intercom systems

Traditionally, wireless intercom systems have been designed to provide mobility to key personnel, such as directors and producers, who need full-duplex and multichannel access to the main intercom system, and lighting crews, cameramen and other support crews, who rely on wireless intercoms for cues and safety.

In the 1970s, VHF wireless was king, but the emergence of wireless microphone technology caused crowding in the VHF space toward the end of that decade and drove the evolution of new wireless products in the UHF bands in the early 1980s. We now face similar crowding in the UHF space as new legislation takes hold. While UHF technology typically provides good coverage across a variety of venues, the recent changes in UHF spectrum licensing are promoting the development of narrower-band UHF. This increases capacity at the expense of voice quality and, therefore, may be of limited value to the end user.

As party-line systems have evolved to point-to-point matrix intercoms, the desire for more wireless channels has increased. The emergence of digital wireless intercoms is a direct result of the need to overcome frequency crowding while at the same time increasing the level of channel flexibility offered to the individual user.

New license-free digital systems in the 2.4GHz frequency range have the advantage that they can be used anywhere globally with the ability to mitigate noise and audio artifacts to produce a solid user experience. But as greater percentages of production teams evolve toward wireless connectivity, a new conflict emerges, namely the pressure to devolve current point-to-point wireless systems back into party-line-based operations. Point-to-point wireless systems require multiple RF channels, thereby limiting the maximum number of users on any given system due to limited RF spectrum. Future wireless developments will need to trade between a variety of modulation schemes, such as orthogonal frequency-division multiplexing (OFDM), which offers more bandwidth and higher audio quality, and quadrature amplitude modulation (QAM), which provides more channels.

Today the ideal solution is not clear, but the ability to address a high number of individual beltpacks and maintain good audio quality may require a hybrid approach spread across multiple wavelengths. Such an environment could include the ability to partition wireless users based on QoS criteria and combine both party-line broadcast and selective point-to-point schemes in a single network for optimum efficiency.

The future

Intercom systems form the backbone of today's production environment, and the continuing evolution to reduce setup time and configuration costs, improve connectivity, and enhance workflows through added user mobility is fundamental to helping the modern production environment achieve the necessary efficiencies to be successful. While there have been great strides made in the advancement of intercom systems, there is still a long way to go. Intercom developers will continue to be challenged to bring next-generation technologies to market as rapidly as possible, ushering in a new era of communications flexibility.


Jake Dodson is vice president of product management at Clear-Com.



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