DualCurtain Outdoor: Know-how on the guard of the perimeter

The Ajax line of street detectors now includes a bidirectional curtain motion detector that can monitor up to 30 meters of the perimeter, efficiently protecting the approaches to windows, doors, arches, fences, and window displays.

Over the past year, we strengthened our engineering expertise to dive deeper into the outdoor security — the most complex area for security equipment manufacturers. Outdoor detectors can often be a pain for professionals. Natural disruptions, heat, rain, and snow trigger a lot of false alarms. With experience in developing our own optical systems and software false alarm filters, we started working on an outdoor motion detector with a narrow viewing angle.

And we created something special. DualCurtain Outdoor combines patented lens systems, a new digital algorithm to counter false alarms trained on millions of triggerings, a motion detection in a near area option, and highly flexible settings. All of this runs on battery power for years.

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Two detectors in one body

Each DualCurtain Outdoor element embodies the idea of engineering precision. Smooth lines, recessed lenses, and masking sensors form a streamlined rainproof body. The SmartBracket mounting panel allows you to simply and securely attach the detector to the surface while closing the setup panel.

The sides of the detector are adjusted independently. With the controls on the back panel, you can determine the detection distance for each side, detection activation in the area near a detector, and the vertical shift of the viewing sector by 3° so that sections protruding from the facade do not obstruct the view of the detector.

In the Ajax app, each side of the detector can be controlled separately: enable/disable IR or masking sensors, make them permanently active regardless of the armed mode, and adjust the sensitivity. The app allows you to flexibly adjust interaction with the detector — set entry/exit delays, link the sirens activation to a certain side, or create an automation scenario for a detector alarm.

DualCurtain Outdoor protects the most remote areas thanks to a connection range of up to 1,700 meters from the hub. And at complex sites, radio signal range extenders can help build robust perimeter protection regardless of scale.

Double filtering against false alarms

With two IR sensors on each side, DualCurtain Outdoor is effective against false alarms. The detector does not react if only one sensor has detected movement. When both sensors are triggered, the detector activates the special digital algorithm ELSA. In a fraction of a second, ELSA performs a three-step signal analysis, filtering out natural disturbances and animals, and concludes whether or not to raise an alarm.

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Three stages of the digital ELSA algorithm

1. Form analysis

ELSA compares the signal waveforms from the IR sensors. Both forms must match the movement of the object that is radiating heat in the protected area. The forms should match in any direction: either perpendicular or along the direction of the detector optics. On the same stage, the signal intensity is analyzed to consider the distance of the heat source from the sensors and its size.

2. Patterns comparison

The signal amplitudes are verified with the pattern database. To create it, we analyzed millions of test triggers of curtain-type detectors on people, animals, lights, and other natural disturbances in various weather conditions. The signals must match the patterns that are typical for humans.

3. Time verification

When signals from both IR sensors match the conditions — this is a motion, and it is typical for a human — ELSA compares the time intervals when the signals trigger, determining whether the upper and lower sensors detected the motion synchronously.

Curtain detector evolution

After analyzing the weaknesses of outdoor curtain detectors, we equipped DualCurtain Outdoor with a unique technology to extend the protected area. When the Near Area Detection is turned on, the upper IR sensor of the detector receives an additional narrow sector of view, directed at the angle of 40 degrees down. This helps to detect the motion when there is an attempted intrusion closely to the very DualCurtain Outdoor body itself, solving the problem of the blind spot (a typical problem of such detectors). This patented Ajax Systems technology is indispensable for the protection of facades and complex architectural structures.

Reliability that has become a brand

We made sure that the DualCurtain Outdoor runs for up to 4 years on bundled batteries and has comprehensive protection against sabotage. Any problems, like attempts to disable the detector or a low battery, will be immediately reported by the system to the users and the security company.

The detector is equipped with a tamper button that reacts to removal from the mount and detachment of DualCurtain Outdoor from the surface. And thanks to the configurable hub—detector polling interval, the system is able to identify a connection loss with DualCurtain Outdoor in less than a minute. The detector meets Grade 2 in accordance with the EN 50131 standard and is equipped with an anti-masking system that detects attempts to block the view or paint over the lenses.

DualCurtain Outdoor is ready for bad weather. The detector body is protected against dust and splashes, and the electronics work at temperatures from -25°C to +60°C and humidity of up to 95%.

All this combined ensures peaceful sleep of users and confidence of security companies in the equipment they work with.