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Site Security: Wireless Technology to the Rescue

Job site security has become a major headache for all contractors across the country, losing both tools and materials. The CHBA Web site even has a chapter on "Site Theft" in their downloadable pamphlet How To Manage Risk, which deals mostly with the insurance side of job site security. Of course, insurance premiums are best kept under control by avoiding theft.
Part of the security problem is that most residential construction sites are not fenced in like commercial sites and, until an advanced stage of construction, there are few or no real barriers to entry. Sites are often isolated and security guards are expensive; where they are used, they are always spread thin. Even on large sites, it is not very practical to begin running security system wires all over, and trying to get things to stay in one place is like shooting at a moving target.
One of the most interesting security devices for really valuable things like the backhoe is the Boomerang type of hidden devices commonly installed in expensive cars, which report in when they are moved and tell the police where they are through satellite tracking. They are effective but expensive and limited in application.

Cell phone technology
Enter the technology of cell phones. Love them or hate them, cell phones keep us connected wherever we are. How about a security system that works with the same wireless technology? DeWalt has just brought it to market under the name SiteLock.
Let's start with a 12-foot stainless steel locking cable, which we would usually tie down with a padlock. Of course this can be cut in two seconds with a good bolt cutter. But this time, rather than using a padlock, it is locked with a transmitter that will instantly report to the base controller unit when the cable is cut, or its absence will be detected and reported if it is destroyed. This can be used to attach ladders, tools, equipment and even the steering wheel to the pedals of that backhoe or front loader.

The security cable lock serves as a control system against honest people, and a real alarm system against dishonest people.
We have lots of containers on construction sites as well as storage trailers. Once again, hardwired security is complicated and easy to damage accidentally. How about a simple little box the size of a cell phone that is either magnetically attached to the container, or bolted on through four bolt holes? Move the container more than the vibration setting you have adjusted on the Container Sensor, and it instantly reports in to the base controller unit. Equipment or products that cannot be locked down and might be lifted and towed away can be protected with this movement sensor.
Now, any decent security system would have window and door opening sensors as well as motion sensors for indoor spaces. In DeWalt's SiteLock system, these are wireless as well, as is the Key Chain Remote. In fact, you can have up to six key chain remotes so that various people can lock down or open up the site each day.
All of these devices report in to the site's Base Unit, which can control up to 48 sensors and six key chain remotes - anything within a 2,000-foot "open range" distance. In reality, few sites have "open range" conditions so the signal strength of each device must be checked as it is installed. The beauty is that the whole system is a two-way communications system, so the base will, at all times, monitor the signal strength of every sensor and let you know if something is out of range, or even has a low battery.

The base unit
The base is a relatively small unit that is mobile but can be locked down to a mounting bracket. The base unit not only has two-way communication with every one of the sensors and the activation keypads, but it uses a built-in motion sensor to protect itself.
When one of the sensors are tripped, the base unit emits a loud siren and a strobe light to chase the vandals off, but it also uses cell phone technology to send out a notice of intrusion, all in less than one second. Now there are two options. This notice can simply go out to the contractor's cell phone for self monitoring, or it can go to a central monitoring operation that specializes in the DeWalt system and they, in turn, can more efficiently run down someone responsible for the site - even send in the police where that is permitted.
Just how reliable is all the wireless communication between the sensors and the base and between the base and the monitoring support? We all know that ordinary cell phones often get into frequency problems and experience drop-out. DeWalt claims that the SiteLock system is highly reliable and virtually immune to background RF noise by using what they call "900 MHz frequency hopping spread spectrum communications with massive redundancy." This is important because reliable communications with no wires to cut is the core of their security.

DeWalt explains the technology
Spread spectrum modulation transmits RF transmitter data over many separate radio frequencies preventing interference or jamming at any one frequency.
"Frequency hopping" is a technical description of the type of Spread Spectrum where the transmitter is constantly and quickly changing its radio frequency.
The SiteLock system receivers are designed to "know" where to "hop" to find valid transmissions. Frequency-hopping spread spectrum works somewhat like sending individual words of a secret message over the entire range of an FM radio dial at very high speed.
If there is not good cell phone signal strength at the construction site, then a landline telephone line can be connected to the base controller unit for the notification signals.
When you look at this system as a whole, going wireless means you can quickly set up or continually change a complete site security system without hiring security installers. This allows you to adapt the sensor placement from day to day as site conditions change, material is delivered or even installed. Indoor motion sensors can be quickly installed inside the house every night if you wished, and moved out of the way for construction during the day. A vibration sensor could be slid into the packaging of the stack of windows not yet installed. With 48 sensors possible, you can protect a large site, or trim it down for a single renovation. It could be used to extend the coverage and efficiency of human patrollers.
For once, someone is offering a security system that is adapted for constantly changing construction needs, rather than compromising on security to avoid constantly rewiring standard security systems.

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