How Wireless Sensors Work

Posted by , , at 4:50 pm

Here’s another great request for information that came in through the “ASK PETER A QUESTION” link at the top of this page. I’m posting the question and my response here, since more and more smart shoppers for wireless home security want to know how it works – and why it’s better.

The Question

Does any company make a wireless sensor that is polled for assurance? Everything I’m seeing only has the sensor sending a signal during a change of state. If the wireless sensors were polled, I would expect a much shorter battery life – however the added assurance of a valid sensor would make up for that. Also, a polled sensor could report its current battery status also. In the starting days of wireless alarms it was the control box that was wireless for reporting and that radio net was polled once every 15 minutes to check for integrity of the system… that sounds like something needed here.

My Reply

Hello, Brian, and thanks for your question. It’s a good one. What you are describing is commonly known in the electronic security industry as “supervised wireless:” that means that the control panel expects to receive a signal from each wireless sensor on a regular basis. When a sensor does not “report in” during a pre-determined window, then the control unit registers this failure to communicate as a potential malfunction, and it can be reported to the monitoring center and/or alarm system user.

FrontPoint Does It Right

It just happens that the wireless sensors used by FrontPoint work in exactly the way you describe, and have done so since roughly 1980. The company that really perfected wireless sensor technology was ITI, and I started using their equipment in 1989, just after I entered the alarm industry. ITI (later operating as GE Security) really wrote the book on wireless alarm technology, and even today the other equipment companies are still trying to catch up.

How It Works

Each GE Security wireless sensor communicates over a former military frequency and has a unique “transmitter identity” that is programmed into the alarm control unit. That way your GE Security sensors are not recognized by your neighbor’s GE Security system, but only by yours, and vice versa. Each wireless sensor than has the ability to communicate an actual alarm condition, or a tamper event, or even a low battery – and also sends regular signals to the control unit. In fact, each wireless sensor sends a signal roughly every hour, and the alarm control unit logs a “malfunction” if no signal is received after a certain duration. That way you know if a sensor has been removed, or if there is some other problem – but these sensors are remarkably stable and reliable, which is one of the reasons FrontPoint chose them in the first place.

Batteries Last for Years

All this supervisory activity does affect sensor battery life, but it’s important that a wireless system be just as reliable as a hard-wired one. Wireless sensors are actually used more than hard-wired sensors, since they are easier to install, move, and troubleshoot. And, GE Security has continued to improve battery utilization, so that today many sensor batteries will last over five years – and then still send you a message so you have plenty of time to replace them, which is easy. In fact, your FrontPoint system will even announce any low sensor batteries to you.

Why Chose FrontPoint – and GE Security?

Here’s a little background on GE Security. The original company (ITI) was purchased by a larger company (Interlogix), and that larger company was in turn purchased by GE Security. Recently GE sold its security products division to United Technologies, a global manufacturer who makes Carrier air conditioners, Otis elevators, and Pratt & Whitney jet engines, to name a few of their brands. United Technologies (UTC) has changed the security products division name back to Interlogix, but still owns rights to the GE Security brand, which is why you still see GE on our web site. UTC has committed significant resources to consistent quality and new sensor enhancements, and FrontPoint is more committed than ever to this technology.

It Gets Better

You are correct that polling of the alarm control unit itself has been a part of alarm system technology – and still is. With a FrontPoint system, you have safest system you can get, since every control unit comes with a built in digital cellular radio. No phone line needed, and no phone line for a burglar to cut. And even that radio is periodically “pinged” by Alarm.com, our interactive monitoring technology partner, for the highest level of reliability you can find.

FrontPoint is all about your peace of mind, with systems that are safer, smarter, simpler, more affordable, and virtually impossible to defeat. That’s why we’re the leader in wireless home security, and the #1 ranked alarm company in the US. We’re also one the largest GE Security alarm companies you can find – and one of the fastest growing. Thanks again for your question.

 

Comments (12)

Post a Comment | View Comments
  1. shirley hudnall

    What are the comptable window sensors that work with this system?
    thanks

    • Katie Rynex

      Shirley, great question! The model numbers of the compatible door/window sensors are 60-688-95 and NX-454. We hope this answers your question and ask that you please let us know if you have any other questions going forward!

  2. Duffy

    How far can wireless sensors be from the main panel? I have a shed about 100 to 150 feet from where I could put the main panel. Would the sensors still be able to connect to the panel at that distance?

    • Valerie Saponara

      Duffy, those wireless sensors need to be within 100 feet of your panel in order to communicate properly. Anything past that might cause some connection issues. We do have long-range door and window sensors so if that’s something you’re interested in give our Support Team a call!

  3. Felix

    Hi there

    I read your post with big interest since i am still looking for the best home security solution for my family.

    I would love to use a wireless solution because of its simple installation.

    But in my opinion wireless security systems can be disabled in no time with minimal effort:

    All the burglar would have to do is switch on a simple and small interference sender. The sender signal simply scrambles the signal your wireless sensor tries to send to the control unit. So the effect is that the control unit can no longer hear the sensors and therefore is not informed about a break in.

    If i was a burglar i would buy one of these standard interference senders for about 50 bucks and switch it on and therefore disable a wireless security system without touching it or having to cut any cable.

    The only solution to this natural problem of wireless systems would in my opinion be a control unit that polls the status of the sebsors about once every five seconds or so. Therefore if a burglar switches on an interference sender the control unit would not hear a response from the sensor when polling and knows that semithings is wrong (that means either sensor is destroyed or signal is scrambled via interference sender) and could therefore trigger the alarm. But of course this ony works if polling occures every some seconds and not just every hour or so.

    What is your opinion on this?

    I was first thinking that it would be too difficult for the burglar to know on which frequency the wireless sensor is sending its signal so the burglar would not know which frequencies to scramble. But i then learned that wireless security systems are only allowed to use predefined frequency bandwidth by law which makes it easy for the burglar to decide which bandwidth to sceanble.

    Thanks in advance for sharing with me your opinion on this.

    • Peter M. Rogers

      Thanks for your comment, Felix. The issue of jamming in general does come up more and more, as people get smarter about shopping for peace of mind, and gain a better understanding of the technologies offered by the alarm industry.

      There are really two issues, so let’s deal with them one by one, starting with sensor jamming (the one you brought up). In the case of the Interlogix/GE Security sensor frequency, the company uses 319.5 mhz. This is a highly encrypted former military frequency, used in all the sensors made by the company since the 80’s. There are literally millions of these GE sensors in use, each with a unique transmitter ID. The fact is that in all those years, there has not been one instance of someone successfully jamming a sensor’s communication with the control panel. That does not make it impossible, just extremely unlikely. In addition, the Interlogix panels are equipped with jam detection, so that any effort to jam the sensor frequency would be detected and processed as an alarm event, and would be sent as such to the central monitoring station. As you can imagine, with millions of sensors in use and no documented jammings having occurred, this has not been a significant concern to date. When you consider that most burglaries are opportunistic, random acts that are increasingly committed to feed a drug habit, you can see why most alarm companies are much more worried about a $3 pair of wire cutters taking out a “traditional” system that is based on a vulnerable phone line than a smart (and rare) intruder with a jammer. Of course, FrontPoint is 100% cellular, so those wire cutters don’t worry us one bit.

      That brings us to the second issue, one that other folks have mentioned: cell jamming. There are cell jamming devices that (though illegal) are not so hard to come by. However, the inexpensive ones have relatively short range, so customers following our instructions on panel placement should have little to worry about. I’m not sure how the average burglar would know that the home has a cellular system to begin with – it’s not as if the meth user who fits the standard burglar profile spends much time on our web site, or those of our competitors. Much more likely is that the burglar will have the wire cutters mentioned above, which will still take out most alarm systems in use today. The smart guy in the black outfit that we see in the movies or on TV who might have a jammer is more likely targeting specific items and much higher value properties that invariably have special security systems.

      While it’s important to discuss what could happen, it’s equally important to discuss what has happened, and what is happening today. Cell jamming must be extremely rare, because if it is occurring, we are not aware of it. Same for sensor jamming. In fact, after more than 20 years in this industry, I have never heard of either kind of jamming resulting in a burglary that was not detected. But I have heard of many cut phone lines – and more all the time. And when it comes to traditional phone lines, they are going away at a remarkable rate. The major carriers (including AT&T) have even petitioned the FCC for a “sunset” provision that will allow the carriers to stop supporting these “hard copper” phone lines. Internet alarm communication is not sufficiently reliable, as is generally agreed by the alarm industry: even ADT does not use it. And the companies who use Internet monitoring (such as Comcast) as the primary channel don’t report the loss of Internet connectivity outside the home, either through interactive monitoring or to the central station, since this loss happens all too frequently.

      That leaves cellular monitoring as the safest and most reliable method – and FrontPoint is 100% for alarm signal transmission. The exposure of cellular to being defeated is minimal, as proven by actual experience, and is expected to remain that way for the foreseeable future. Thanks again for your question.

  4. Felix

    Hi there

    I read your post with big interest since i am still looking for the best home security solution for my family.

    I would love to use a wireless solution because of its simple installation.

    But in my opinion wireless security systems can be disabled in no time with minimal effort:

    All the burglar would have to do is switch on a simple and small interference sender. The sender signal simply scrambles the signal your wireless sensor tries to send to the control unit. So the effect is that the control unit can no longer hear the sensors and therefore is not informed about a break in.

    If i was a burglar i would buy one of these standard interference senders for about 50 bucks and switch it on and therefore disable a wireless security system without touching it or having to cut any cable.

    The only solution to this natural problem of wireless systems would in my opinion be a control unit that polls the status of the sebsors about once every five seconds or so. Therefore if a burglar switches on an interference sender the control unit would not hear a response from the sensor when polling and knows that semithings is wrong (that means either sensor is destroyed or signal is scrambled via interference sender) and could therefore trigger the alarm. But of course this ony works if polling occures every some seconds and not just every hour or so.

    What is your opinion on this?

    I was first thinking that it would be too difficult for the burglar to know on which frequency the wireless sensor is sending its signal so the burglar would not know which frequencies to scramble. But i then learned that wireless security systems are only allowed to use predefined frequency bandwidth by law which makes it easy for the burglar to decide which bandwidth to sceanble.

    Thanks in advance for sharing with me your opinion on this.

    • Peter M. Rogers

      Thanks for your comment, Felix. The issue of jamming in general does come up more and more, as people get smarter about shopping for peace of mind, and gain a better understanding of the technologies offered by the alarm industry.

      There are really two issues, so let’s deal with them one by one, starting with sensor jamming (the one you brought up). In the case of the Interlogix/GE Security sensor frequency, the company uses 319.5 mhz. This is a highly encrypted former military frequency, used in all the sensors made by the company since the 80’s. There are literally millions of these GE sensors in use, each with a unique transmitter ID. The fact is that in all those years, there has not been one instance of someone successfully jamming a sensor’s communication with the control panel. That does not make it impossible, just extremely unlikely. In addition, the Interlogix panels are equipped with jam detection, so that any effort to jam the sensor frequency would be detected and processed as an alarm event, and would be sent as such to the central monitoring station. As you can imagine, with millions of sensors in use and no documented jammings having occurred, this has not been a significant concern to date. When you consider that most burglaries are opportunistic, random acts that are increasingly committed to feed a drug habit, you can see why most alarm companies are much more worried about a $3 pair of wire cutters taking out a “traditional” system that is based on a vulnerable phone line than a smart (and rare) intruder with a jammer. Of course, FrontPoint is 100% cellular, so those wire cutters don’t worry us one bit.

      That brings us to the second issue, one that other folks have mentioned: cell jamming. There are cell jamming devices that (though illegal) are not so hard to come by. However, the inexpensive ones have relatively short range, so customers following our instructions on panel placement should have little to worry about. I’m not sure how the average burglar would know that the home has a cellular system to begin with – it’s not as if the meth user who fits the standard burglar profile spends much time on our web site, or those of our competitors. Much more likely is that the burglar will have the wire cutters mentioned above, which will still take out most alarm systems in use today. The smart guy in the black outfit that we see in the movies or on TV who might have a jammer is more likely targeting specific items and much higher value properties that invariably have special security systems.

      While it’s important to discuss what could happen, it’s equally important to discuss what has happened, and what is happening today. Cell jamming must be extremely rare, because if it is occurring, we are not aware of it. Same for sensor jamming. In fact, after more than 20 years in this industry, I have never heard of either kind of jamming resulting in a burglary that was not detected. But I have heard of many cut phone lines – and more all the time. And when it comes to traditional phone lines, they are going away at a remarkable rate. The major carriers (including AT&T) have even petitioned the FCC for a “sunset” provision that will allow the carriers to stop supporting these “hard copper” phone lines. Internet alarm communication is not sufficiently reliable, as is generally agreed by the alarm industry: even ADT does not use it. And the companies who use Internet monitoring (such as Comcast) as the primary channel don’t report the loss of Internet connectivity outside the home, either through interactive monitoring or to the central station, since this loss happens all too frequently.

      That leaves cellular monitoring as the safest and most reliable method – and FrontPoint is 100% for alarm signal transmission. The exposure of cellular to being defeated is minimal, as proven by actual experience, and is expected to remain that way for the foreseeable future. Thanks again for your question.

  5. Alan

    This is a great post Peter.

    I can attest that whenever I take a sensor offline, I will always get text messages informing me of a sensor malfunction, and when I put it back online, it reports an end of malfunction for that sensor the same way. As you note, it also reports any sensor tamper. In almost 5 years, I have yet to have any batteries run out on any of my sensors, so cannot report on that… That is a good problem to have. I never would have imagined those little cell batteries could last so long, especially for the sensors that see A LOT of activity, like our access door to the garage.

    And a little bit unrelated, but I really like the text message reports when the AC power goes out and also when it comes back on. Nice to know in case one needs to make arrangements for the frozen foods or something while away. And with the control panel’s 24 hour backup battery, I can rely on it to outlast pretty much all power outages we are likely to ever get here, which is really really nice.

    Nice backstory history reminder. Also good to bring it full circle and even not the control panel itself is essentially “supervised” as well… Most important of all one wants to make sure the central brain of the system is A-OK.

    • Peter M. Rogers

      Thanks, Alan – I was thinking of some of our more inquiring and discriminating users when I wrote this post, and you are clearly on that list! Glad to know your system is working just that way it should, and that it’s giving you the peace of mind you deserve. I hear you on the batteries – we are having similar longevity at our house. And when they do need to be changed, the system, will tell (with plenty of warning). All the various batteries are easy to find at places like Staples, CVS, etc. Thanks again.

  6. Alan

    This is a great post Peter.

    I can attest that whenever I take a sensor offline, I will always get text messages informing me of a sensor malfunction, and when I put it back online, it reports an end of malfunction for that sensor the same way. As you note, it also reports any sensor tamper. In almost 5 years, I have yet to have any batteries run out on any of my sensors, so cannot report on that… That is a good problem to have. I never would have imagined those little cell batteries could last so long, especially for the sensors that see A LOT of activity, like our access door to the garage.

    And a little bit unrelated, but I really like the text message reports when the AC power goes out and also when it comes back on. Nice to know in case one needs to make arrangements for the frozen foods or something while away. And with the control panel’s 24 hour backup battery, I can rely on it to outlast pretty much all power outages we are likely to ever get here, which is really really nice.

    Nice backstory history reminder. Also good to bring it full circle and even not the control panel itself is essentially “supervised” as well… Most important of all one wants to make sure the central brain of the system is A-OK.

    • Peter M. Rogers

      Thanks, Alan – I was thinking of some of our more inquiring and discriminating users when I wrote this post, and you are clearly on that list! Glad to know your system is working just that way it should, and that it’s giving you the peace of mind you deserve. I hear you on the batteries – we are having similar longevity at our house. And when they do need to be changed, the system, will tell (with plenty of warning). All the various batteries are easy to find at places like Staples, CVS, etc. Thanks again.

Leave a Comment