page_title: Emergency communication system
section_title: Infrastructure-dependent
hierarchical_section_title: Emergency communication system / Broadcast technologies / Infrastructure-dependent
caption_attribution_description: Deutsch: Zwei Druckkammerlautsprecher an einer Hausecke English: Two horn speakers on a corner
context_page_description: An emergency communication system is any system that is organized for the primary purpose of supporting one-way and two-way communication of emergency information between both individuals and groups of individuals. These systems are commonly designed to convey information over multiple types of devices, from signal lights to text messaging to live, streaming video, forming a unified communication system intended to optimize communications during emergencies. Contrary to emergency notification systems, which generally deliver emergency information in one direction, emergency communication systems are typically capable of both initiating and receiving information between multiple parties. These systems are often made up of both input devices, sensors, and output/communication devices. Therefore, the origination of information can occur from a variety of sources and locations, from which the system will disseminate that information to one or more target audiences.
context_section_description: Broadcast technologies that depend on man-made infrastructure to convey communication are susceptible to disruption if any part of that infrastructure is overloaded, damaged or otherwise destroyed. Some examples of infrastructure-dependent technologies are:
  Audio Public Address Systems
  A system which can provide audio (usually spoken language) messaging capability, usually consisting of microphone devices, wiring, and speakers installed in public areas of buildings. These systems are typically located indoors or in smaller outdoor areas with multiple speakers, due to their speakers' individual volume being too limited for large areas. Usually connected together by wiring requiring electricity, these systems may be vulnerable to electrical disruption or any other event which results in the wires being severed or disconnected.
  WMT Public Address Systems
  Wireless Mobile Telephony (WMT) PA Systems refers to PA paging and [intercom] systems that use any form of Wireless Mobile Telephony System such as GSM networks instead of a centralized amplifier to distribute the audio signal to paging locations across a building or campus, or other location. The GSM mobile Networks are used to provide the communication function. At the transmission end, a PSTN Telephone, mobile phone, VOIP phone or any other communication device that can access and make audio calls to a GSM based mobile SIM card can communicate with it. At the receiving end, a GSM transceiver receives these network transmissions and reproduce the analogue audio signal via a Power Amplifier and speaker. The work on this was pioneered by Stephen Robert Pearson of Lancashire, England who successfully applied for and was granted patents for the systems which incorporate control functionality in addition to the audio announcement capabilities. The use of the WMT (GSM) networks means that live announcements can be made from anywhere to anywhere in the world where there is WMT connectivity. The patents cover all forms of WMT i.e. 2G, 3G, 4G ..... xxG. A UK company called Remvox Ltd (REMote VOice eXperience) has been appointed under license to develop and manufacture products based upon this technology.
  L.E.D. Electronic Signs
  LED electronic signs use light-emitting diodes to display messages when connected over a network to an emergency communication system.  LED signs, when deployed in large numbers on a network, can be used as visual alternatives to traditional audio public address systems. LED Signs are able to communicate effectively in loud environments where audio PA systems can be ineffective. When deciding whether or not to include LED electronic signs as part of an emergency communication system, it is important to realize that a lack of hearing-impaired persons does not negate the need for visual signs. Explosions and other events can render many hearing-able people effectively deaf, necessitating the inclusion of a visual alternative to audio PA systems. LED electronic signs have multiple valuable attributes that enhance public communications:
  Some emergency communication systems can deliver, share, and prioritize the display of messages on LED signs that have been sent by multiple people and systems.
  LED signs, when connected to an emergency communication system, have the ability to project the communication in a specific direction while loud speakers generally radiate communication in many directions.
  LED signs are manufactured in a large variety of shapes and sizes, with some models designed specifically for indoor use and very bright models designed for outdoor use.
  Because LEDs consume very little electricity, power over Ethernet (PoE)  and power over RS232 can be used in conjunction with UPS power located in wiring closets to keep these devices functioning for a significant period of time during a general power outage in a building.
  Like audio PA systems, visual PA systems composed of LED signs are network-attached appliances that, unlike computer screen popup messages (more information about this technology, below), text messages, phone calls, etc., represent `
caption: Audio public address speakers
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