If Henry Ford, having designed the Model T Ford, could have been transported forward to today to view the latest Ford Focus, he would probably be amazed at how far automotive technology has developed. Similarly we are certain that if the designers of the Racal IR772 PIR, that mainstream detector of the late 1970s, were to compare it to the Guardall V12, they too would be rather shocked, but probably delighted with the result. The IR772 featured single edge detection, meaning that the unit alarmed as soon as a target passed into or out of a single plane of the fresnel lens. This was unstable to say the least. The next generation of detectors such as the Racal Apollo incorporated dual edge detection, where the target was required to pass through two detection planes. This was an improvement, but the Apollo often appeared to be as stable as an elephant perched on a knife-edge!
Since then we have seen manufacturers develop variations on a theme, based on dual element pyro sensors and microprocessors where activity in groups of planes is necessary for an alarm condition to be signalled. This naturally has seen a great improvement in false alarm levels. A further development has been the introduction of true four element pyro sensors or quads. So it is rather fitting that Guardall, which in the past was Racal Guardall, has introduced the next generation of PIR detection, the dual-hex or 12 zone pyro sensor in the V12 detector.
Features
The V12 boasts a whole host of features, not least of which is that 12 element pyro sensor. The unit’s verification processing of the symmetrically arranged elements’ 216 detection points is said to significantly reduce the possibility of false alarms. Self-diagnostics are also built in, which can detect low voltage or component failure.
A range of detectors is available, covering standard, pet immune and anti-masking requirements. Two interchangeable lenses are also available to cover corridor and long range detection, as is an adjustable mounting bracket. A nice touch is the inclusion of onboard end-of-line resistors compatible with the Guardall PX control panel; these are selected by a DIL switch.
The off white ABS moulded housing is of rounded medium size, measuring 96 x 66 x 42mm and incorporates provision for corner or flat mounting, plus a knock-out designed to accept a swivel mount, which is an optional extra. The front cover is secured via lugs at the top and a robust captive machine screw engaging in a captive metal nut at the bottom of the rear housing. The PCB is double sided, using a mixture of surface mount and discrete component technology, and clips securely to the rear housing. In turn the sealed fresnel lens assembly clips to the front of the PCB. Immediately below the top mounted cable terminals is a six-way DILswitch assembly, controlling LED enable, pulse count, gain and EOL resistor functions.
The white light filtered fresnel lens is fitted smooth side out, to ensure that range is not impaired by dust build up, and is adjustable in the vertical plane. We liked the anti tamper switch arrangement, comprising two miniature microswitches on the PCB, one operated by the lid cover screw via a metal plate, and the other spring operated between the rear of the PCB and the unit’s case. The housing is extremely rigid, so mounting presented few problems. There is a choice of knock-outs for mounting and cable entry to suit most installation requirements. There is provision for a cable tie to prevent cable strain, and what looks like the possibility to terminate/joint additional cores at the top left of the backplate, although there were no securing screws fitted.
Vertical adjustment of detection range is taken care of by sliding the fresnel lens to align with marks on the lens mount. The single instruction sheet comprises an exploded view of the detector with all parts clearly labelled, and straightforward information on switch settings and cable entry. On the reverse side is the technical specification, plus coverage diagram and installation tips. Operation of the onboard diagnostic functions is explained, as is the operation of the onboard end-of-line resistors. We mounted the detector in a test area, and subjected it to the standard Security Installer tests, which were passed with flying colours. The unit appears slow to react at first, due to the way the signals are processed, but we found that catch rate was excellent and could not be beaten. Si
Reader Service No 101
Addendum.
After testing, Guardall added this clarification: The PIR gain switch will comfortably cover 10m at the standard setting and 15m at the high gain setting. We have changed the wording of the manual to reflect this; section 4 will now read: “For 10m range BOTH switches 3 and 4 should be in the ON position. For 15m range BOTH switches 3 and 4 should be in the OFF position. The range of the detector will depend on lens declination settings however.”
What the manufacturer says ...
One significant improvement made by manufacturers to combat false alarms has been ‘Quads’. Guardall has spent the last year researching and developing a technology that improves on the false alarm standards set by quads and high quality PIRs. The result is the V12, which offers the highest levels of false alarm immunity by making use of 12 pyro elements on the detector as opposed to the standard two – or four with quads. These are set out in a symmetrical fashion in two groups of six (Dual-Hex technology); this means that an intruder walking toward or across the coverage area gives an exactly identical signal on both amplifier channels in terms of signal pattern and timing. The ASIC in the unit is programmed specifically to alarm only in instances when an exact match is received, this rules out random signal patterns such as internal noise and also helps significantly in the battle against hot and cold air draughts. The technology used means that over a 15m coverage area there are 216 separate detection points. Together with the verification processing employed, Guardall has added diagnostics to the product by building a self-test into the unit. Should any of the electrical components fail, the unit’s LED will illuminate dimly within one hour. Further intelligence has been built into the unit through a low power supply monitor – if the supply drops below nine volts then the LED will flash slowly. Besides high immunity to false alarms and the unit’s intelligence, one of the features that has particularly impressed those installers who have had experience of the V12 to date is that the end-of-line resistors are built into the unit. When the V12 is used in conjunction with the Guardall PX control panel then there is no need to fit end-of-line resistors. This obviously saves time and effort as well as ensuring reliability.Overallassessment
Guardall has moved the goalposts for PIR detectors with this model. The test team has not seen a detector with the pyro elements arranged in this fashion before, and we believe it will prove even more reliable in its performance and low false alarm rate than quad detectors, without the price premium if dual technology detectors are used.Source
Security Installer
