Digital Microwaves
Digital Processing
Other microwave sensors operate in analog mode. They simply look for a significant disturbance in the microwave signal to create an alarm.
The MWxPRO digital microwave protection sensors only start their work when a disturbance is noticed. By analyzing the wave pattern generated during the disturbance, they determine if it is a real alarm or a nuisance event that can be ignored. How do they do that? Using “fuzzy logic,” the size, shape, and rate of change of the observed signal are compared to hundreds of stored patterns corresponding to known alarm types. If there is a close match, an alarm is generated. Intruders walking, running, or rolling will be detected. All disturbances, whether or not they are recognized as alarms, are date and time stamped and stored in the receiver for later analysis.
What kinds of things don’t cause nuisance alarms when you use these sensors, even though their sensitivity is set high? Small animals, birds, fog, and reflections off pooled water. All of these can create alarms with old analog-style sensors until you lower their sensitivity to a dangerously low level.
Clean Strong Signal
The MW482 digital microwave protection sensor uses a parabolic antenna with linear polarization. This parabolic antenna allows the head to be rotated through 90º in very demanding installations to avoid sources of interference at crossover points. Older microwave sensors typically have elliptical or planar antennas with circular polarization and see no change if the antenna is rotated in this way. Furthermore, the parabolic antenna allows for a stronger, cleaner received signal compared to analog microwave systems.
Relying on this clean, strong signal, the MW482 detectors have outstanding anti-masking capability. Placing a false transmitter in front of the receiver in an attempt to shield an intruder will be immediately detected as a change in signal strength.
Narrowing the detection field
The MWxPRO digital microwave protection detectors can operate in tight confines that would render older microwave sensors useless due to nuisance alarms. Typical scenarios include running the sensors between fence lines, along roadways, or near tree lines. The MWxPRO can overcome this problem in two ways. First, alternate antennas can be used to physically narrow the field of microwave radiation. Second, “fuzzy logic side target discrimination” analyzes signal strength to recognize disturbances occurring only at the edge of the field of view, such as a waving tree branch or a loose, moving chain-link fence, without triggering an alarm.
Fuzzy Side Target Detection Pattern
Detection Pattern Typical of Older Sensors
Between Fence Lines
Signal Interface
The MW482xPRO digital microwave protection is not affected by interference from airport radars or environments with powerful military microwave frequency transmissions. Installations using MW482xPRO microwaves in civil aviation and at military airports attest to this statement. The MW482xPRO operates in the X-band, providing improved volumetric range and protection of the detection zone.
At crossover points, the potential for interference is reduced by having four pre-settable modulation codes or channels available. In complex environments, the sensors can operate at any of sixteen different frequencies, which can effectively be doubled by rotating the parabolic antennas 90° to take advantage of the linear polarization.
At An Airfield
Crossover Point
Automatic Adjustment to Environment
Temperature is continuously monitored to detect faults. Additionally, temperature changes over time are monitored, and compensation is made for signal differences created by those changes.
Set Up and Adjustment
The MW482xPRO incorporates built-in audio and visual setup aids. It also includes a walk test function that identifies the actual protection zone and provides the installer with a true feel of the detection area.
For more sophisticated control and analysis, we offer MW Manager software. The receiver head has an RS-485 link for connection to either a portable computer brought to the sensor or, via the appropriate network connections, to a computer anywhere in the world.
