ALARM sensors were once the cutting edge of electronic security technology. They leveraged cool new sensing technologies like ultrasonics, active and passive infrared, multiple wavelengths of microwave and volumetric pressure detection. But somewhere along the way, things changed. Sensors morphed into ubiquitous beige housings perceived by the market as bland, interchangeable, indistinguishable and largely irrelevant to the function of capable security solutions.
As decades passed, a false dichotomy took root that was born of early PIR failures. According to this technical fallacy, passive infrared sensors only ever work reliably in completely benign internal environments. For applications where there was the merest glimmer of sunlight or an air conditioning vent, only dual technology solutions would do.
The trouble with this thinking was that it ignored ongoing development of quality PIRs whose thoughtful circuitry resolved earlier issues. It also discounted completely the evolution of high end PIR technology, which by default must be cleverer than PIR and microwave combos. Furthermore, it allowed the development of lazy dual technology designs that played the vulnerabilities of PIR and microwave off against each other to offer the mass produced $15 dollar microwave sensor.
We’ve argued in these pages for 20 years that a poor quality dual technology sensor based on off-the-shelf components is no match for a well designed and thoroughly tested PIR. The key issue is that cheap PIRs and cheap microwave sensors are equally flawed in terms of their propensity to have alarm thresholds shattered by environmental disturbances unrelated to intrusion.
Such disturbances may include RFI or EMI spikes, including popcorn noise from fluorescent lights, UHF transmissions from passing vehicles, rapid thermal changes, and movement behind glass, or even walls. When it comes to poor sensor design, it’s possible for a bad dual technology sensor to spend most its working life with half the sensor in alarm. In fact, it’s fair to say many low cost manufacturers cover up flaws in design and component quality by incorporating the second sensor technology – microwave – as a parachute.
It’s in this barren landscape of purchase-by-price and lack of education that Aritech is trying to find a balance between the best and most stable PIR sensors possible and a price point that’s amenable to the wider market.
“We’ve been doing an incredible amount of R&D in the background, leveraging all our Aritech technology to create Vector. The R&D advancement has been substantial and as a result our products are more stable and more accurate in their detection capabilities”
When it when it comes to layers of technology and depth of range and the longevity of the brand, it’s tough to find a company as committed to bringing installers and end users quality PIR sensors as Aritech is. For many years Aritech was the standard by which all other sensors were judged – while the market has changed, the company’s sensors have not lost their technological pizazz. Aritech is the highest selling sensor in Europe for very good reason.
When I visited the Melbourne office of local Aritech representative Interlogix to take a look at their sensor technology I expected to sit down and play with a single big sensor – some husky member of the VE700 family for instance. But it didn’t take long to realise the Aritech story is not about a single sensor but about the blending of a suite of capabilities into a single sensing platform that feels to me like the benchmark in PIRs.
Talking about blending ‘suites of capabilities’ sounds like marketing hype when written out loud but it’s the best way to think about what Aritech is offering installers. It’s impossible to talk about a single Aritech sensor without unstitching the underlying technology one piece at a time.
Joining me on this journey is Andrew Barron – product manager for Casi Rusco, Aritech and Sentrol at Interlogix. Barron cut his teeth in major access control systems in Canada but he has an affinity for alarm sensors that’s increasingly rare these days.
According to Barron, Aritech is not the least expensive PIR solution on the market but he maintains, correctly in my opinion, that you can save 10-15 dollars on a poor quality PIR but a single failure or a call-out for false alarm issues will cost an integrator the savings on 20 such sensors. And, of course, if you’re the end user, the impact of such a flaw may be more serious still.
While Barron concedes business is made more difficult because of the price-driven nature of the market he insists these price differences make sense when carefully considered. In fact, the more expensive solutions are better value in the long term. And he points out that things are not always as they appear.
“Everyone compares datasheets,” Barron explains. “They might all have 2-3 degree temperature compensation and the same 12m range and mirror optics but they might perform completely differently from each other in different circumstances.”
“Instead of having separated sensing ‘beams’ created by the Fresnel lens, we have this concept of gliding focus curtains – we have a continuous cascade effect of detection”
According to Barron, this difference in performance is the result of a lot of hard work.
“We’ve been doing an incredible amount of R&D in the background, leveraging all our Aritech technology to create Vector,” he explains.
“The R&D advancement has been substantial and as a result our products are more stable and more accurate in their detection capabilities.”
Barron says, rightly again, that trying to encapsulate Aritech’s technology and range is a challenge, particularly when it comes to the company’s Vector technology. To my mind Vector is a sort of real time neural workspace created when advanced mirror optics and gliding focus curtains meet advanced signal processing.
The result is a sensor with perspective. What Vector gives a sensor is a detailed comprehension of its target area as a default, as well as the ability to objectively place intrusions in order to establish speed and direction of movement – both vital for an Aritech PIR.
Vector provides information allowing the sensor to distinguish a person that is moving compared to other nuisance sources of infrared (Air Conditioning, heaters, white light) We’ll come back to Vector a bit later on – first let’s get a taste of the contributing technologies. Barron starts off the discussion by running me through slides showing how a Fresnel or standard mirror PIR works.
“The algorithms in the background of a standard sensor making sure there’s an accurate detection decision are quite convoluted,” he explains. “This means they are often on the periphery of whether or not there’s going to be an alarm or not. Depending on sensitivity settings the program will err on the side of caution if you don’t want false alarms or give alarms if you want higher security.
“Another issue for standard sensors is perspective – objects that are closer appear much larger than they are and appear to move faster than they are moving. This can be compensated for but as a result of this compensation, if an intruder is at the ideal sensing distance, then you get under-sensitivity.
“Another issue for standard lenses is near obstructions which blind whole areas of detection in the target area. Let’s just say there’s some obstruction in the way of a typical Fresnel lens PIR – you lose all that detection space behind it. Simply, standard technology works but it doesn’t give them the granularity of detection we can achieve.
“Our solutions can actually handle variables that make competitors much less effective and they do it with no adjustment at all,” Barron explains.
“Instead of having separated sensing ‘beams’ created by the Fresnel lens, we have this concept of gliding focus curtains – we have a continuous cascade effect of detection,” he says.
According to Barron, no adjustment is ever necessary.
“You can take a 16m Aritech PIR and put it in a much smaller room and it knows the room stops right there,” he says. “All these detection points are aware of each other’s sensitivity levels and the detector adjusts itself and is as stable as it would be in a 16m deep room.
“Try to achieve the same thing with a competitor’s technology and the sensor would have no sense of the size of the target area and that has lots of different ramifications. Aritech sensors know the size of the image wherever it is in the target area. Our sensor sees one continuous object across the gliding focus curtain. If there’s a sign in the way of the sensor you only lose the slice of space directly behind it. And our algorithms are much more logical.”
Gliding mirrors
Aritech’s patented Step and Gliding mirror optics is at the core of its PIR technology. While this word ‘gliding’ denotes actual physical movement, this is not the way the process works. Instead, the mirrored surface is designed to create a continuous curtain of detection coverage regardless of the focal point location in the sensor’s range.
The gliding mirror design gives complete coverage of an entire scene – there are none of the holes you get with low cost PIRs whose lenses are designed to split pyro sensitivity into zones or beams of detection. Sure, pyroelectric elements don’t send out physical beams – instead they convert infrared energy to electrical waveforms which when amplified may or may not breach alarm thresholds in sensor circuitry. But from a conceptual point of view, lenses serve to create lanes of sensitivity that on the basis of pulse counts are used to generate alarm events.
Standard PIR lenses can create lanes of sensitivity that might be just a few inches wide but many metres apart at the extremities of a sensor’s detection range. In comparison, Aritech’s mirror optics covers every single part of the scene in view with such accuracy that it’s possible to use supplied masks to cover particular areas.
The design of Aritech’s mirrored lenses also allows the reflected IR in the target area to be compensated for on the basis of range. That means the voltage generated at the pyro by an intruder is identical whether the person is standing 2 metres from the sensor or 12 metres from it. And this sense of perspective allows speed of movement to be compensated for with perfect accuracy, too. You can forget about getting this performance from Fresnel lenses.
“And competitors will often have a separate pyro as a lookdown sensor for tamper attempts but if you compare with our design we cater for lookdown in a single projection based on the design of the mirror,” Barron tells me.
“Part of the benefit of this design is the amount of power we use – our anti-masking sensors use only one third the power of competitor’s anti-masking sensors. When you’re installing one hundred of them, this adds up.”
Another key property of Aritech’s gliding mirror technology is that it gives a sensor the ability to ‘autofocus’ on an IR source in the target area perfectly and with no need for adjustment of sensitivity. Typically with other PIR’s, in smaller room the pulse count will be turned down to reduce sensitivity and avoid false alarms. Trouble is, this makes the sensor much easier to defeat by crawling or creeping, especially on warm days.
Best of all, from an installer’s point of view, there’s no calibration with an Aritech gliding mirror sensor. The signal received at the pyro is consistent regardless of the distance the intruder is from the sensor.
The next piece of the puzzle is signal processing. Aritech breaks its analytics up thus: 1D is shape, 2D is duration, 3D is speed, 4D is size and 5D is environment. Aritech sensors like the EV1000 have 5D processing – 5D is the latest generation and it can differentiate between fast and slow moving signals.
This means that when a slow moving thermal source is detected – let’s say it’s a creeping intruder or the sun reflecting off the floor – signal processing switches to 5D which activates additional pattern recognition so as to try to compare the signal being received with the signal generated by a slow moving person. Should these signals match, there’s an alarm and if they don’t match, there’s not. It’s very smart work from Aritech. Sensitivity is maintained at all times but false alarms are rejected.
Vector technology
Barron says the newest thing Aritech has is Vector technology.
“We’ve taken all the really cool stuff that we have – the gliding focus curtains, the mirror optics and the signal processing and exponentially grown how sophisticated it is and how accurate it is. Vector is a composite of all these features.
“Vector’s direct target is addressing the frustration relating to the usage of dual technology sensors. The thinking is if there’s a dodgy little area then you just put a dual technology sensor in but that’s not an ideal solution at all,” he explains.
“With Vector you get one excellent sensor instead of 2 poor sensors. The technology is stable and installers can rest assured they won’t have to go back to a job – that’s been the primary concern. To explain the nature of this Vector processing technology in more detail, Andrew pulls up a series of graphics to show me.
“In each 2D pane here on screen you can see electrical ‘images’, which we call x positive and x negative,’ he explains. “Using these, the sensor can establish how large the object is and how fast it is moving based on the time it takes to move through a scene.
“Now, because we have so much control over these different axes thanks to the mirror optics, we’ve created Vector which is x and y – positive and negative at the same time. It sounds confusing but it means that instead of having just an x positive and an x negative to drive signal processing you also have a y positive and a y negative and you can control these so finely we have reached a point where we have interlaced them.
“What happens is that when an object moves from one side to another of one of these curtain lenses, is that the sensor gets movement on the x positive – and while that movement is occurring the sensor is also getting movement on the y negative and the same thing on the other side.
“If you plot that over a real time signal plot graph you get a beautiful shape of continuous movement across that plane – it’s these signals that Aritech sensors equipped with Vector use to generate alarm events.”
According to Barron, another thing Vector does is double the width of the curtain so you have fewer blind spots throughout the target area.
“It means there’s no physical separation of detection beams of the type you get with quad pyro detection. With Vector you get all the activity happening at the same time and this means we have incredibly detailed knowledge of events. Because of the extra wide coverage area we can see sunlight moving slowly through x or y and know it’s a false alarm.”
Then there’s spatial discrimination and unit time discrimination.
“Because the 4 points; x and y, positive and negative; are spaced apart we can actually prove motion – competitors can see movement in a target area but they can’t see which direction it’s coming from. With Vector we see movement in this curtain, there’s a space and then there’s the next curtain – they’re separated by a time delta,” Barron explains.
“Now we can prove what direction an intruder is moving and how fast they’re moving. This technology is exercised in the VE700 series by providing a selectable dry-contact that can be trigged upon either left-to-right or right-to-left motion.”
There are a host of applications that would benefit from this capability in areas like retail, customs – even around the home if parents want to keep an eye on runaway toddlers.
“The amount of data that we actually get is profound and no other detector can do this and it’s all PIR-based,” says Barron. “We know from work in simulations that what happens is that you get a distinct output for each different typical interference. This allows detection to be distinct and ensures Vector can distinguish between common nuisance infrared sources and true infrared movement.”
Conclusion
According to Barron, the markets Interlogix is targeting with Aritech sensors are the commercial segment and the mid-tier security segment with entry level mirror optics and the high security market with products like the mighty VE700 series.
“The price for the entry level VE1000, which includes our Vector technology, is $40-50 dollars. When you go through the amount of technology you are getting, it’s a very good deal for a very capable sensor.
“From the point of view of installers and integrators, the benefit for them is that all this technology just makes a job easier for them. They don’t have to worry about the various nuisance IR sources, obstructions in the room, wall angle deviations, room size, power consumption – it makes choice and installation straightforward. “They install the sensor and let Aritech do the rest.”
Vector is a nice development from Aritech. It’s smart and it’s affordable. As ever, it’s pleasing to see a manufacturer that continues to work hard at enhancing the performance and reliability of the unsung heroes of intrusion detection.
