How Fire Alarm Communications Have Evolved Over the Decades
Fire and life-safety expert Shane Clary examines fire alarm communications’ past, present, and where he believes it will end up.
During the week that I wrote this article I spoke at the Southern California Chapter of the Society of Fire Protection Engineers Annual Fire Protection Engineering Symposium. The topic of my talk was “New Technologies for Fire Alarm Systems.”
I also discussed how I believe fire alarm systems and detection systems will evolve over the next decade and beyond. This column is a brief description of what I covered regarding communications.
I have been in the fire alarm and life safety industry since 1974, so this marks my 45th year. The systems that were installed then were for the most part a single zone system. If the system was connected to a supervising station, it was through either a directly connected dedicated phone line, a McCulloh loop or an active multiplex circuit.
The multiplex circuit would have been a voice-grade phone line. These circuits passed through a local telephone central office. It would be very rare for a protected premises that was located in Omaha, Neb., to be monitored in Los Angeles. Supervising stations were generally close to a central office.
The fire alarm transmitter may have been powered by 120VAC, but for a large number, the transmitter would have been powered by a windup spring motor. For systems at larger buildings, annunciation of the alarm may have been through a coded system, in which the cycle of the bells or horns would tell those that needed to know, where the alarm was coming from.
Through the late 1970s and up until the last decade, most alarms signals were transmitted from the protected premises to the supervising station through the use of either a digital alarm communicator transmitter (DACT) or a radio alarm transmitter (RAT).
The transmission protocols progressed from 3-1, 4-1, 4-2 to either Contact ID or SIA. This evolution allowed more information regarding the alarm to be transmitted from the protected premises to the supervising station.
Concurrently, fire alarm control units transitioned from conventional zoned to addressable and addressable/analog. The move toward addressable systems provided the means to quickly identify where an event was occurring and if the system was in a fault condition/where the fault was.
With addressable systems, the number of conductors required was reduced, so in most cases, only two conductors would be required. Wireless devices began to appear. The technology at first may have had issues, but over the years this has changed so that the wireless systems that are installed today are reliable.
Power consumption and battery life are also improving. In returning to signal transmissions, the use of phone lines is declining and even going away. The new means has been through either cellular transmitters or broadband, i.e., the Internet. The use of mesh radio is also found within a number of areas of the United States. Each of these technologies have advantages as well as some disadvantages, depending on which is being used.
For those that use cellular transmission, the move is now migrating from 3G to 5G, or Long Term Evolution (LTE). Looking into the not-too-distant future, how long will LTE be available before there is a move to 6G, 7G or even 8G? What will these even be?
Forty-five years ago, if you were a doctor or Hollywood agent, you may have had a car phone and a Page Boy pager. Now just about everyone has a smartphone that has more computing power than a Cray-2 mainframe supercomputer. Cell towers are being built left and right, and cellular areas are getting down to the size of a city block, if not smaller.
The future that I see will be in the use of cellular transmissions as it will be able to provide coverage everywhere, even in areas that there is no coverage in today. As network speeds increase, more data from a protected premises, including video will be able to be transmitted to not only supervising stations but to first responders.
Real-time information will be the norm as opposed to the exception. Within the protected premises, there will be a migration to wireless devices, sensors and even notification appliances. For this to occur, the transmitting range of these devices will need to increase and the power consumption will need to decrease.
Battery life will also need to be increased, so that one would not have to change the batteries for five to 10 years. In my next article I will discuss the evolution of detectors and sensors and cover more on notification and messaging.
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