The XL-MaxSonar® line of MaxBotix® Inc., ultrasonic range sensors has arrived. This low cost, high performance sensor is available in both indoor and outdoor versions. The XL-MaxSonar® sensor line maintains the same look and feel of the existing LV-MaxSonar® sensor line; with small size, low power, stable range readings, object detection to the front sensor face, and more, but now has even more reliable distance readings. The XL-MaxSonar® line has fully automatic real-time background calibration, much higher acoustic output power, greatly improved real-time noise rejection, centimeter resolution, longer distance range measurement, and for some models real-time analog envelope output and various analog hardware gains from 250 to 4000. These features result in virtually noise free distance readings for most users. The XL-MaxSonar® sensor line is available with factory calibrated beam patterns.
Real-Time Automatic Calibration
For the XL-MaxSonar® products, the real-time fully automatic calibration happens in the background, so that for every range reading, the sensor is calibrated to operate properly for that individual reading. Even if the sensor is powered up with an object pressing against the front sensor face, the presence of the object will be reported correctly. Or if during operation, the power supply voltage droops (range of *3.3V to 5V), or if the temperature changes (range of *–40°C to +65°C), the automatic calibration runs in the background and sets the parameters for the sensor to operate correctly. *Operation at 3.3V while at temperatures below –10°C might not be suitable for all sensors and installations.
High Acoustic Power
For the XL-MaxSonar® products, the high acoustic power allows for the ultrasonic energy to effectively overpower many outside acoustic noise sources. This allows for proper operation in many environments such as micro UAV vehicles, where a lower powered sensor would be unusable.
Real-Time Noise Filtering
The XL-MaxSonar® products now reject noise with equal effectiveness, independent of hardware or software gain. For the XL-MaxSonar® products, the real-time filtering of the analog envelope is held to a new standard. For all the products in this sensor line, for regular continuous noise sources such as motors and vibrations found on robots and UAVs, the sensor learns and then removes the noise, allowing reliable readings. In addition, when the engine noise increases, or an additional noise source comes into play, the filtering learns and changes to compensate.
Increased Resolution and Range
The XL-MaxSonar® products with increased acoustic power, auto calibration, and better noise filtering allows for stable distance readings with centimeter resolution. In addition, the higher power allows for longer-range measurements.
Real-Time Analog Envelope and Various Gains
The real time analog envelope provided to the user is taken directly from the end of the analog chain of the XL-MaxSonar® product. The output is the log compressed voltage output of the acoustic return signal. When powered with five volts, the sensors compress the waveform into an analog output range of about three volts. Most users will only use this to verify product installation and operation, but other users may desire to perform there own signal processing. Hence, users wanting fine details of the waveforms may deliberately select a lower gain product. Conversely, users wanting long-range or details outside the central field of view will choose a higher gain product.
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