Active infrared beams offer a limited form of trap type protection, but they still maintain an important position in the intruder alarm market-place. The degree of protection they offer will always be limited – essentially a single, one-dimensional beam of detection – but this is paradoxically their strength, and certainly when used externally, the transmitter and receiver based technology of an active infrared beam has the advantage of greater precision over the 'splatter' effect of passive infrared technology.
The BoundaryGard BX-100 Plus comprises an externally rated active infrared transmitter and receiver using two parallel beams (commonly known as a twin), designed for short range use in a domestic or light commercial environment. They are made by Optex in Japan, are available for around £65 + VAT from most wholesalers, and carry the European CE mark together with a manufacturer's guarantee of five years.
Both the backplate and the front cover are constructed from a rigid black polycarbonate plastic. The design is inoffensive and the small size and smooth finish mean the system would not look out of place in a domestic environment, which we believe is the intended market for the BX-100Plus.
Optex has given the product a weatherproof rating of IP54 when correctly installed on a suitable surface with the supplied sponge grommets.
The internal optics can be rotated through 180 degrees horizontally, which allows the beams to protect the surface to which they are face-fixed, for instance located on either side of an external window.
Note 1 No vertical adjustment of the beam optics is included, so the transmitter and receiver need to be fixed at more or less the same height to work effectively. Note 2 The total vertical distance between the beam pair within the receiver is 130mm, so it would take only a small object to interrupt the line of sight and create an alarm condition. Installers will need to ensure therefore, that the equipment is intelligently sited in order to prevent false alarms due to foxes, cats and birds.
In addition to the on-board piezo sounder, two separate relay outputs are provided, one normally open and the other normally closed. These are useful for actuating lighting, CCTV cameras, VCRs and the like. An anti-tamper microswitch is included to give an output when the cover is removed. The on-board piezo sounder gives annunciation when the beams are interrupted, and furthermore as an aid during the set-up procedure. The output volume is switch selectable for high or low level, or it can be disabled altogether. A second switch is used to select operational or set-up mode, making use of the on-board piezo as an audible alignment signal.
Both the receiver and the transmitter will operate between 10.5v and 28v DC. Installers could therefore use a 24v DC PSU on larger installations, thus minimising the voltage drop due to the higher resistances encountered on long cable runs.
Set-up & performance
The units have no in-built vertical alignment mechanism, so setting up the beam pair merely requires the installer to horizontally swivel the head assembly at each end to achieve the correct whistling annunciation tone in order to maximise the infrared energy arriving at the receiver. Easy stuff, but only made possible because the maximum range is relatively short, and each unit is mounted at the same height.
The unit was found to work very well within the design parameters. A range of 60m is easily achievable when used internally – in fact a far greater distance is achievable in situations where there are hard reflective surfaces running adjacent and parallel to the infrared beam. This is because the infrared energy is 'bounced' alongside the direction of travel creating a gun barrel effect, concentrating the energy into the receiver.
The opposite is true when used externally, where the infrared energy rapidly dissipates into the atmosphere thus diminishing the effective operating range by around half.
The annunciation piezo gave a reasonable volume output when selected at high level, enough to warn intruders of the presence of a detection system in operation. The piezo can operate as either a standalone type, which sounds for approximately 15 seconds then resets if the beam path has cleared, or controlled by a switched negative trigger wire connected to the 'ac' input on the receiver (applied negative to enable, negative removed to disable).
The current consumption was found to be pretty much as specified by the manufacturer, at 60mA on standby, rising to around 80mA during an alarm annunciation.
To make the product more attractive for the design-conscious domestic market, Optex can supply three separately available extra parts to fit the BX-100Plus beam pair. They are: a decorative white plastic cover (WC–1) to render the unit less conspicuous when mounted on white walls; a spacer section (SP–1) to enable the units to see past local obstructions; and a white plastic coated metal mesh guard (MG–1) to surround the units and protect them from casual vandalism.
We called Optex with some questions, and though the representative had no engineering staff on hand to respond to technical enquiries, he promised to ensure one of the Optex field engineers would return the call promptly.
This he did, and despite being unable to give us an answer there and then, the technician promised, to his eternal credit, to call the manufacturer in Japan (!) and get back to us the following day. Ten out of ten for effort.
The installation instructions are contained in an eight-page booklet, using the established Optex style of comprehensive diagrams with simplistic explanations. There are a few of the usual amusing Japanese translations, but by and large the information is all there, and experienced installers would probably not need the instructions at all.
What the manufacturer says...
The BX-100 Plus offers an alternative to traditional methods for detecting intrusion through windows, doors and roller shutters. The BoundaryGard allows detection BEFORE damage has been caused in trying to force entry. Built on the same principle and with the same dynamic features as our range of highly reliable active infrared beams, the BX-100Plus offers reliable detection. The units are small and discreet and come with a number of accessories which allow them to blend in with most architectural requirements.
There are white covers available which can be screen-printed or painted, and there are metal covers to resist vandalism. Spacers can also be provided which allow the units to be used even when windows and door-frames protrude from the building. An audible warning device will deter possible intruders in the event of activation. This feature also doubles as an alignment tool, easing installation. LED indication of correct alignment is featured, making this a very installer-friendly addition to any security system.
Separate form A and form B relays allow the units to be used with other equipment – CCTV, lighting and voice warning systems. The BoundaryGard has 99 per cent beam blocking capability, allowing the unit to cope effectively with environmental disturbances and fog. The light reduction filters make the unit highly reliable and resistant to external light sources. The BoundaryGard will operate at up to 30m outdoors and has many applications, both domestic and commercial.
Overall assessment
Many years ago, when the security industry was in its infancy, entire buildings were protected by a combination of door switches and hard wiring. The arrival of the first generation of electronic detection devices, in the form of active infrared beams, offered customers the chance to achieve effective trap protection at a reasonable cost. Decades later, there is still a place within the intruder alarm industry for the active infrared beam because essentially, what it does, it does well. The BX-100Plus is never going to set the world on fire, but Optex has refined old technology and reduced the product into an attractive package for the modern world.Source
Security Installer
