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A Brief History of the Security Alarm

Oct 1, 1998 12:00 PM, Steve Filippini


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It is 3 a.m., and the dog is sniffing at the back sliding glass door in your dining room. This is your cue to let the dog out to relieve a little built-up pressure. As you open the door to let her out, your sleeping brain struggles to remember what it is you are forgetting to do. The bells and whistles shrieking from your security system jogs the memory. You have just created a false alarm. The first thing you worry about is waking up the family. The second thing to worry about is waking up the neighborhood. What is sometimes overlooked is worrying about your alarm company's dispatching the police to your residence. You make the call to the monitoring center, and after identifying yourself, you cancel the dispatch with a promise that you will do better next time.

It is embarrassing, but you are not alone. Everyone who uses a security system has done it, or will do it. It becomes second nature to arm and disarm your system. It is the change in the daily routine that tags you. The question will come up as to whether or not you want to have your security system monitored. It seems like such a hassle, why put yourself through it?

Having a security system monitored means that you are willing to pay a monthly fee to a monitoring center. This fee is used to hire people to sit and watch for and react to your security system in the event it calls in to report an alarm condition. Sound simple? It is.

Most of the security companies on the market today either provide or have ties to a monitoring center. Whether it is a local presence or national operation is not the issue; it is how well they provide the service that is important. But first, a little history lesson.

Way back in the days of people much older than I, people would rely on simple means to alert others of a breach in security. Little bells attached to a door that rang when it was opened, tin cans tied to a string across a pathway, that sort of thing. One day, someone placed a large bell into a metal enclosure and placed four lantern batteries (remember those?) inside of it with a relay and mounted it to the outside of the building. From the enclosure, there were two sets of wires, one for the door contacts and one for the keyswitch that turned the bell on and off. This technology is commonly referred to as a "local bell." Maintenance was a snap. Depending on the usage, these batteries could last up to a year. When the bell rang weakly, you replaced the batteries. The hardest thing I have ever had to deal with when working on one of these was the hundreds of bees and hornets that were magically drawn to them.

This simple system used the relay to monitor the door contacts. The keyswitch was located outside, and the owner would close all of the doors and turn the key at night. If the doors were open with the keyswitch on, the bell would ring. Closing the door would not stop the bell; only by turning the key could you silence it. The local bell uses a wiring scheme that latches the relay contacts into an alarm condition.

This was very popular for a while, that is until people figured out that the bell could be yanked from the wall and quickly silenced. The other flaw was the locations of some of these businesses were way out in the toolies. The bell could ring all night and bother only the local night critters.

So, someone came up with the idea that a pair of wires from the premise could be tied into the local police station through the telephone lines. These lines were dedicated to the alarm panel only. In the police station, there was a rack of modules that had dials and meters on them. The security panel back at the premise used a series of large resistors, and the police station had a room with a whole slew of car batteries that pumped voltage on the phone line to create a current source. The resistors would be tuned to send back a specific current level. This level was reflected on the dials at the police department. If the line were to be compromised (cut/bypassed), the dial would drop its reading, and the police would be dispatched. This was referred to as a DLPD (Direct Line Police Department). These systems were popular with managers of jewelry stores and high-security-minded business owners. Problem was, a lot of phone lines were being used up, and the police department was chasing tons of false alarms on a daily basis.

Next came "McCulloh." Same principle as the DLPD, but with a twist. Instead of a dedicated pair of phone wires from the premise to the police department, the phone company ran a pair of wires out to a location and allowed multiple premise units to be wired in series with the main feed. The main feed was routed to a secure location, which will be referred to as the monitoring center from here on (call it what you want, it still had a room full of car batteries) and tied into a machine with spools of paper and little probes with ink at the end. The premise units were replaced with a device that used a wheel with spokes protruding from it. As the wheel turned, it opened and closed a set of contacts that sent a series of Morse Code-like pulses to the monitoring center. At the monitoring center, each pulse would cause the probes to release ink onto a thin spool of paper. For example, if the premise unit's code wheel had two spokes followed by three spokes followed by one spoke on it, the monitoring center would see lines of ink that when counted, identified premise unit number 2-3-1.

Slick enough, but easy to compromise. If you went to an unsecured premise unit, cutting the phone line would disable all of the premise units on that feed. Another hurdle to overcome---if more than one premise unit tripped at the same time, you would see a clash of pulses that was hard to decipher. Even more of a concern, maintaining all of those car (later they were marine) batteries.

The next step Then came digital communicators. These devices used the same principle as a phone call to the police, but better. The digital communicators would be programmed to call a digital receiver at the monitoring center. The premise units were assigned a premise number that was programmed into these dialers. When the alarm tripped, the digital dialer would call the digital receiver and report the location and area of protection violated. This information would be first displayed on a small LED screen, then later printed out to a spool of paper for later reference.

No more rooms full of car batteries or dedicated phone lines. With this came an added bonus---this also allowed the monitoring center to analyze the alarm signal before dispatching the police. This reduced the number of false alarms, much to the relief of the local police officers. One further note, the digital dialer was/is able to send alarm signals that alert the monitoring center to dispatch the fire department or paramedics as well.

Since the introduction of digital dialers, the phone company has raised the cost of a dedicated phone line to the point of discouraging further requests for the line. The police departments no longer offer DLPD service, and car battery sales have dropped off significantly. At this point, you would think all was right with the world.

As the technology grew, so did the ingenuity of the burglar. All they had to do was cut the phone line. If the line is unprotected, it is just a matter of cutting the right pair that the alarm uses. Actually, they take out full banks of phone wires, hoping the right pair is included in there somewhere. Read the papers; you hear about these incidents every now and then.

Now the need for a backup communicator was needed. How do you make a phone call without phone lines? You use a cellular dialer to make the call for you if the normal line is not available. Cellular was expensive at first, but the cost has been coming down as the public embraces cellular phones. There is also a line of long-range radios that can transmit alarm signals across the country in seconds. Microwave technology is also used in some areas. If your security installer looks like he or she has a headache, you know why. As the industry develops better and faster ways to send the alarm signals, your installer needs to absorb as much of the new stuff as possible.

Enough of the history lesson. What happens to the alarm signal when it reaches the monitoring center? In today's centers, the signal is routed into an automation system that has all of your customers' information stored. The automation system looks at the signal and attaches it to the appropriate customer. From there, the customer's name, address and phone numbers are at the operator's fingertips. Special instructions requested by the customer are also displayed, and the operator can then take the necessary steps to dispatch the correct emergency agencies properly.

Why would you monitor a security system? As tight as you might be with the neighbors, they are not always home to watch the house for you. If your security system rings the bell on a daily basis, they are going to ignore it or take out the bell with a sniper's rifle. Monitoring your security system provides peace of mind. In the event of an emergency, it is nice to have one less thing to remember to do. During a fire, the priority is to get family members out of the house quickly. During a burglar alarm, getting to a phone may not be practical. Let the security system do all the work.

Now, this is when I like to pass on some lessons I have learned over the years. Let's start with local bells. I mentioned the bees and hornets. I carried two cans of Raid Insta-Kill everywhere I went. I learned if the bug spray smells like lilacs, it attracts, not repels, angry flying insects. I also learned to check the enclosure that is mounted outside of the building for a tamper switch. I once was on top of my work van with a ladder to reach the bell enclosure. As I was removing the locking screws that kept the lid secure, I had the feeling I was forgetting something. I remembered 1/10th of a second before the lid swung open on the enclosure that there was a tamper switch protecting the alarm, and the bell rang (as it should) in all of its glory. My partner swears I bounced off the hood of the van, but I remember nothing.

Direct wire was another lesson learned. Those car batteries I keep referring to are wired in series to supply roughly 90 V to 120 V to the phone line. A common practice, in the days of old, was to wire the phone line through a thin strip of window foil. This foil was glued to the glass around the outer edge (sometimes the installer would impress us by including patterns and designs) of the glass. That way, if the window was broken, the foil would tear and open the phone line to alert the police of a problem. Anyone who has worked with 24-hour foil (that's what it was called where I'm from) willagree with me when I say, you do not locate the open in the foil circuit by licking your thumb and running it along the foil to find the hairline tear. Trainees do that. Once.

McCulloh taught me that using a metal file to scrape the contacts that open and close the phone line (90 V to 120 V) during an alarm transmission is not the smartest thing I've ever done. I was working on a panel several years ago when I kept getting bitten by the phone line while I was trying to secure a circuit inside the control panel. I decided that removing the phone line from the safety of the terminals was my only course of action. I hate getting bitten by electricity. I was careful to remove the wires and extend them away from the control panel to give my hands plenty of room to work. I dropped my screwdriver and as I bent down to pick it up, the open phone line dragged across my sweaty forehead. I saw major blue streaks in my head as it snapped back at least 2 feet (0.6 m) from my shoulders.

Digital dialers are safer to work on. Although, as many of you know, you don't hold onto the ends of the phone line when a call is coming in. I hate getting bitten.



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