Driveways form the primary perimeter for a household, and as such, they are the first line of defense against intruders. For this reason, a wireless driveway alarm is nearly indispensable for home security. Detection systems make use of driveway sensors in order to distinguish a threat. When an intruder is detected, an alarm is triggered inside the household via a driveway alarm unit, placed within hearing of a home’s residents. Detection systems have come a long way in recent times. Ultrasonic detectors and passive infrared detectors are standards in the field, but there are far more types of sensors that can be utilized to form a property’s security system.

Microwave detectors are an interesting solution for driveway intrusion detection, employed by the sensors mounted along the perimeter of a property. These devices emit microwaves from a transmitter and a separate receiver detects the reflected microwaves or any sort of microwave beam intensity reduction. Both the transmitter and receiver can be contained within a single unit, but for outdoor applications, two separate unit housings are generally utilized. By having the transmitter generate microwave energy in the electromagnetic spectrum, the sensor responds to Doppler frequency changes in energy waves, a phase shift in frequency, and motion causing a reduction in the intensity of the microwaves. When any of these conditions are satisfied, the indoor alarms is triggered, notifying the residents of the intrusion. This method of driveway detection can also be employed with passive infrared detectors to prevent false alarms, commonly known as “Dualtec” alarms.

Another solution for detection of intruders is photo-electric beams, also known as break-beam sensors. This system fires visible or infrared light beams across a monitored area where a person, vehicle, or animal can obstruct the beams, resulting in the alarm being triggered. When the beams are employed in stacks of transmitters and receivers, this security system forms a fence-like barrier, improving the odds of detection. In addition, by staggering the beams, a user can lower the possibility of an intruder managing to avoid breaking the beams. Modulated light sources are employed by most systems, thus preventing an intruder from using another light source to prevent the alarm from being set off. This type of security system is often used in movies where the criminals must avoid breaking any of the beams, but in reality, it is much more difficult to do so; therefore, users can rest easy knowing that their property is protected by photo-electric beams.