Monnit Vibration Meters use an accelerometer to measure g-force on 3 axes and then determines speed and frequency from this measurement. The sensor measures vibration once every Measurement Interval, which can be set as low as 1 minute and as high the Heartbeat Interval. The sensor is designed to measure continuous vibration and be low powered so it captures vibration for less than a second during its Measurement Interval. The sensor uses a Sensitivity Threshold to filter noise or low level vibrations. If this threshold is set to 0 then any vibration captured during the Measurement Interval will contribute to the duty cycle and will be analyzed, even very low level vibrations. The Vibration Meter will also report the duty cycle, or how long the sensor was measuring vibrations throughout the heartbeat. This device operates within 900MHz and is powered by AA batteries.