Totally Tubular: A History of the Development of Intercom (Part 1)

People have always needed to communicate over long distances. From the smoke signal used by Native American tribes, to the telephone, to email via the Internet, the ability to communicate at a distance is a need that goes back through the millennia.

Equally so, communicating over smaller distances has also been important. Talking from one floor to another in a single building, or within any large area (such as inside a warehouse) requires some form of internal communication. 

From "internal communication", we get the now common term of "Intercom". This term is generally used as the name of a device or system that allows people to speak to each other from one room to another, or across a large open area inside a structure.

Before electrical systems were common, the usual way to get someone's attention was by some form of signaling. As an example, communicating in a large mansion-style home from the parlor to the servant's quarters was done by pull ropes that were connected to bells that would ring - when the rope was pulled, the bells would ring, grabbing the attention of the servant. When electrical signaling devices became more commonplace, these pull ropes were replaced with wired pushbuttons that would trigger a buzzer that would sound in the servant's quarters. Whether with the pull ropes or the wired pushbuttons, the servants were only alerted that their services were needed; therefore they needed to walk from one area of the house to the other to find out what was needed.

Being able to actually talk to a person in another part of a building would be more efficient. The result of this need of efficiency was the development of an acoustical communication system, or more simply, a voice tube. A voice tube is a hollow tube or pipe that was run from one place to another, allowing people to talk back and forth to each other from different ends of a building.

The idea for the original voice tube began back in the early nineteenth century by the French scientist, Jean-Baptiste Biot. His unusual choice of laboratory in which to test his theory - the water pipes of his home city of Paris. From his experiments, Biot discovered that smaller pipes carried sounds over amazingly long distances. Larger pipes just didn't work as well for carrying sound.

In 1849, Scientific American magazine published an article describing what they called as an acoustic telegraph - a tube made of gutta percha (a latex-like material that's produced from the sap of trees that grow in Malaysia). The article claimed that a tube made of this material and of the proper size could send voices for several miles.

Later voice tube developments included work done by Antonio Meucci, an Italian immigrant scientist who built an acoustic speaking tube system in his home in New York. He later was attributed for his work on what eventually became known as the telephone.

Early aircraft models were usually of the open-cockpit design and were extremely noisy. Instructors had to scream at their flying students in order to be heard above the sound of the engine and the slipstream noise. So, in 1917, at a flying school in Gosport, England, an instructor named Robert Raymond Smith-Barry sought to overcome this problem with some rubber tubes that had a funnel on one end, and a pair of primitive headphones made of cloth and rubber on the other end. The student wore the headphones and the instructor spoke into the funnel. Smith-Barry called his invention the Gosport Tube, after the town the school was in. This became a commonly used item for flight instruction until as late as the 1930's when closed cockpits and electrical intercoms became the standard in aircraft.

In 1926, the Bureau of Standards of the United States Department of Commerce issued a paper that could be purchased by the US Government Printing Office for a pricey 15 cents, entitled "Transmission of Sound Through Voice Tubes". It is an exhaustive study of the physics of sending sound via hollow tubes, including photographs and mechanical drawings of the tubes used in the test procedures. The US Navy actually initiated the request to the Bureau of Standards for these tests to be done. The Navy is one of the prime users of acoustic voice tube technology, and that is true even to this day. Currently, modern Navy landing craft (or LCU's) use voice tubes to communicate from their upper deck to control centers below deck. Other naval vessels also use them, as well as merchant marine cargo ships.

The major advantage of a voice tube system over an electrical communication system is its simplicity and reliability. Voice tubes are impervious to the problems plaguing electronic systems, such as power failures, broken or shorted wiring, and invasion by moisture. So, despite the sophistication of modern electrical intercoms, acoustic speaking or voice tubes remain in use. Because of this, voice tubes make these a good choice for these applications.

In our next installment, we'll look at the rise of the electrical intercom systems, how they developed from the days of the invention of the telephone, and why some of the first applications of these products were for safety and security purposes.

Paul Black is a freelance writer and broadcast engineer in Northern California. He holds a Certified Professional Broadcast Engineer certification from the Society of Broadcast Engineers and an FCC Lifetime General Class Operator License. He is a licensed amateur radio operator (call sign N6BBZ) and has worked for several broadcast companies, including Bonneville Broadcasting, RKO General Broadcasting, and CBS Television. Visit his website at www.paulblackcopy.com. 

Do You Need a LAN or a WAN?

When designing an IT network topology, you might want to consider a Campus Area Network (CAN), a Metropolitan Area Network (MAN) or a Tiny Area Network (TAN), but most certainly a Local Area Network (LAN) or Wide Area Network (WAN) will do the job. All of these networking schemes utilize the same switches and file transfer technologies and are used to connect computers and devices, allowing them to communicate in a specific geographical area or region.

You might be most familiar with the computer networking terms like LAN or WAN, which are thrown around a lot in conversations about setting up IT networks and collaborative environments, but what do they really mean to your organization? 

LOCAL AREA NETWORK

A Local Area Network (LAN) is a group of computers and network devices that are connected together, usually within the same building. Examples could be a small office or production facility, a single building or multiple buildings located on campus. 

WIDE AREA NETWORK

A Wide Area Network (WAN), as its name implies, connects several LANs together (whether nearby or in different parts of the world) and is typically used by an enterprise-level installation (a corporation or organization) or local governments that make civic information easily accessible to the public.

CONNECTIVITY

The technology employed - routers, servers, cabling, desktop clients for users - is high speed and relatively expensive. LANs tend to use high-speed connectivity technologies like Ethernet (CAT5/6 cabling) or Token Ring (all computers are connected in a ring or star topology). WANs most often use technologies like MPLS, ATM, Frame Relay and X.25 for connectivity over long distances.

LANs use Layer 1 devices, like hubs and repeaters, and Layer 2 devices, like network switches and bridges. WANs use Layer 3 devices, such as routers, multi-layer switches and specific devices like ATM or Frame Relay switches.

One LAN can be connected to other LANs over any distance via telephone lines and radio waves, while computers or other networked devices connected to a WAN are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites.

The major advantage of a LAN is the speed it can reach. With a LAN, it isn't uncommon to see technology that supports 1Gbps file transfers. Most agree that a LAN can operate up to 30x faster than a WAN. The further the distance, the slower the network. However, the major disadvantage with a LAN is that it is only good as far as you can reach an Ethernet cable or WiFi signal. Simply put, you cannot buy an Ethernet cable that will reach throughout an entire building, and a WiFi connection rapidly deteriorates as you get further than a few dozen miles away.

A WAN connection is generally harder to setup, but there are many creative ways to do so. One very common way is renting a line from an Internet service provider and using their network (that's already connected to the entire world) and connecting Point A to Point B. Another way to do a WAN is connecting the devices with various wireless technologies, like cellphone towers or satellites. As you can imagine, all of these are much harder to create than setting up a LAN, and almost always demands high level professional setup and maintenance.

RELIABILITY

LANs are generally more secure than WANs, but, of course, WANs enable more widespread connectivity. And, while LANs tend to be owned, controlled and managed in-house by the organization where they are deployed, WANs typically require two or more of their constituent LANs to be connected over the public Internet or via a private connection established by a third-party telecommunications provider. As for actual reliability, LANs tend to have fewer problems because there are less systems to deal with. A WAN tends to be less fault tolerant as they consist of a large number of disparately located systems that have to be reliably connected.

COST-EFFECTIVENESS

One of the big disadvantages to implementing a WAN is the cost. Having a private WAN can be expensive because of the technology required to connect two remote places together. However, WANs using public networks can be setup very cost-effectively using Virtual Private Network (VPN) hardware and software, which allows a desktop computer to transparently connect to a remote network as if you were physically attached to that network. For security, the communication link between your computer and the remote VPN hardware is encrypted while using the VPN.

The maintenance costs are often lower with a LAN because it covers a relatively small geographical area, while maintaining a WAN is difficult because of its wider geographical area.

In the end, it's clear that those implementing a network - whether a LAN or a WAN - should take a hard look at how they plan to use that network and who will use it. Each topology has its advantages and disadvantages that can affect an organization's productivity significantly. Which one you choose ultimately depends on costs and your business model.

The Origin of TCP/IP

These days virtually everyone is talking about Internet Protocol (IP), the standard encoding scheme for sending audio and video files (as IP packets), either over the Internet directly or over an Ethernet-based CAT5/6 cabling network. The cable itself is favored because it is much smaller and lighter and therefore much easier to work with when building new A/V facilities. But where did the IP scheme as we know it today come from?

WHAT IS TCP/IP?

First, we have to look at Transmission Control Protocol/Internet Protocol (TCP/IP), which basically describes a protocol that will work on any sort of computer and operating system for transportation of packets of data across the internet or studio network between different systems.

Early concepts of packet networking were developed at several different research labs in the US and overseas, initially for military use. In the late 1970's, a set of networking protocols that allowed two or more computers to communicate, known as TCP/IP, were developed by The Defense Data Network, part of the Department of Defense, for widespread industry use across its Advanced Research Projects Agency Network (ARPANet). ARPANet was an early packet switching network and the first network to implement the protocol suite known as TCP/IP. Soon, several other TCP/IP prototypes were developed at multiple research centers between 1978 and 1983. However, the migration in the US of the ARPANet to TCP/IP was officially completed on January 1, 1983, when the new protocols were permanently activated across what has since become the World Wide Web.

Source: wikipedia.org

For production professionals, TCP/IP has become very important to audio file delivery and networking because it allows the flexibility to route resources to any part of a facility (or remote location) from a centralized position. It also facilitates the development of Audio-over-IP (AoIP) networks that allow convenient control and monitoring of equipment and systems, and the rapid transfer of audio and firmware files between components.

INFORMATION OVERLOAD

With the use of TCP/IP, the amount of information a single cable can carry has increased from a few thousand bits per second in the 1960's to a few billion bits per second today. Regular affordable connections in every day information systems now carry one or more gigabits of information in a single fiber cable over distances spanning many miles. This bandwidth is enough to transport hundreds of high quality audio channels, replacing hundreds of pounds of cabling in conventional systems. More importantly, the functional connections in a networked audio system can be designed separately from the physical connections in the network, due to the flexibility of the IP scheme.

The functionality opens up a wide array of exciting possibilities for the audio industry: any number of I/O locations can connect to the network anywhere in the system without the limitations of bulky cables, leaving the actual connections to be managed with easy-to-use software. Control signals can be included in the network without additional cabling. Computers can use the network to control and monitor audio devices, such as digital mixers and DSP engines. Video connections can also be included using affordable IP-controlled cameras. 

IP is allowing users to send high-quality audio feeds over long distances. This is also known as Audio Contribution over IP (ACIP), which enables programming contributions from outside members of the team as if they were in the next room.

CHANGING THE WAY YOU COMMUNICATE

Clearly, the Internet and IP have changed the way audio production is performed across a wide variety of applications. Time and space limitations are no longer valid. Professional productions now benefit from the ability to bring in all types of sources from a variety of disparate locations to support and control an array of devices.

The inevitable merging of computer networking technology and audio distribution has arrived. It's time to re-examine the assumptions and concerns (eg, latency, security, etc.) that are holding some professionals back from choosing Audio-over-IP solutions and just get on with it. IP packets can be easily sent and received in a variety of ways that help streamline workflows of all types. It also potentially enables more productivity with less people.

Early AoIP networks were plagued with dropouts, pops and clicks, with most devices limited to a paltry 10 Mbps bandwidth. Some thought that IP packets were never going to be fast enough to deliver real-time audio. With modern advances in networking connectivity, now we know you can.

Network speed is no longer a practical limiting factor. Gigabit speeds and modern switching technology ensure virtually zero packet loss under real life conditions in copper or fiber optic networks, while providing ample bandwidth for hundreds of channels of audio and other data at each node. Switched networks isolate traffic at each port, permitting thousands of channels to exist without conflict on a single network without dropouts or errors. 

MOVING FORWARD

The effect that the Internet Protocol has had on today's audio professional cannot be overstated. TCP/IP ensures that data will get to the correct destination and received in the correct order. We're living in a time of massive online growth. IP has helped make sense of it all and, really, saved the day by making our lives a whole lot easier. And the best part: an IP network will be relevant and easily upgradable for years to come.