Intercom

An intercom, also Intercom ( from Latin communicate between Inter and Latin communicare ) called, is a means of communication for the transmission of speech by means of electric signals - similar to the phone. It is used in safety-relevant areas for internal communication in particular. For the speech connection no listener has to be removed, the communication takes place as with hands-free " talking loudly ". Therefore, the intercom is often used to create an independent additional level of discussion.

Intercoms are generally such as telephone systems from a central body to which a plurality of terminals, in this case, the microphone units are connected. But there are also decentralized systems that do not require central facility.

History

The origin of the intercom is in Scandinavia. There it was originally designed for office communication, as the local post office also on internal (internal ) calls raised fees in the 1930s. The development of the intercom was the attempt to create a more favorable internal communication tool basically.

However, earlier intercom systems have been developed for home use: In 1899, the Berlin company warhorse Paul & Co. brought her three rooms and kitchen connecting phone system on the market. Under the No 146763 of phone factory Actiengesellschaft, formerly Joseph Berliner "in Hannover, patented the Imperial Patent Office, the first " Linienwählschaltung for handsfree talking. " In 1919 followed by the first intercom of the company S. Siedle und Söhne. , The intercoms of that time, however, were more likely call systems and not what is today understood by this term.

The first "modern " intercom was brought in 1935 by the company AB Gylling on the German market. The plant was often called " Hundehüttchenmodell " and consisted largely of telephone technology.

In intercoms, only one participant to talk (which must to switch to its direction ), with intercom systems both at the same time (such as on the phone ).

The biggest problem with intercom is the volume loss. Until 1951 was an intercom without volume loss as impossible. Engineers experimented with volume controls on Glimmstrecken, damping boxes and with the automatic speech direction changing means of frequency shift.

In G. Petzold's book "Against and intercoms " of 1951 voice-controlled systems are first mentioned. Voice Controlled here means that no simultaneous listening and speaking (such as the telephone ) is possible, but is always enabled only one language direction. The switching of the speech direction is controlled by an echo suppressor. This automatically detects who is speaking and switches the channel from the speaker to the listener free. Speeches both at the same time, the Louder the speaker and the Quieter can only hear.

It was in this era many intercom manufacturers, who developed the systems in different directions. From these development directions resulted According to Peter Kerger a division into different industries:

• Office intercoms
• Industrial intercoms
• Hospital Communications
• Home / House elocution

The Ericsson Group was the first of an electronic call control einbaute in a switching center in 1956. This allowed for the first time will be accommodated in a common housing microphone and speaker of the station. Shortly thereafter, Philips presented the first fully electronic system with decentralized parallel cabling.

Since then, the intercom systems have evolved and are now being used far beyond their original functions also. The development of the intercom was the phone ahead at times. For example, integrated circuits and microprocessors were used in intercom systems much earlier than with the phones. Some of today introduced on phones functions are in intercom systems for decades standard.

Modern Intercom systems can transport not only language, but also data and information ( for example on security control ) to perform complex control mechanisms.

Intercoms today

Intercom systems can be used in almost any environment today. The manufacturers provide a wide range of different stations available (for example, cleanroom, industrial, emergency call stations ). Intercoms can with full-duplex and DSP support ( for quiet environments ) or with a modern language scale ( for loud, harsh environments ) are operated today. The connection to the microphone units via copper cable, fiber optic, IP networks or wireless.

Since intercom systems are now often used in control stations safety- relevant areas, they usually offer many different interfaces to other systems such as CCTV, telephone, radio, paging systems, personal computers, personal emergency systems and building management systems.

Furthermore, it is often used in the event industry as a " Intercom " designated intercom system that supports the communication between the different areas. The intercom usually consists of several, via XLR cable-connected and equipped with headsets transceivers, called " beltpack ". A beltpack features usually have a call function, which is equivalent to the ringing of a telephone, and an intercom function, which is used in the first place.

For motorcyclists, the use of special motorcycle intercom systems suitable.