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Technical Manual HE660 |
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Clock Control Byte The Clock Control Byte determines how fast the timer of the stopwatch measuring the time of flight of the sonic wave, ticks. If you set the Clock Control Byte 01 hex, the timer increments every 250nano Seconds or 4 million times per second. If you set the Clock Control Byte at 02 hex, the timer increments 8 times slower or once every 2 lS
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Sensor Settling Delay Byte When transmitting sonic wave the sensor is exited with high voltage. If a ceramic piezo element is used, vibration will built up as the element is continuously pulsed at it's resonance frequency. When the excitation is seized, the ceramic crystal will continue to vibrate at resonance frequency. In case a single sensor is used to both receive and transmit, it becomes necessary to wait until excitation vibration has decayed beneath the receiver sensitivity level. At this point in time, it is safe to allow the device to listen for an echo or a weak signal. In case a separate element is used to transmit and receive, settling delay may not be needed. Adequate settling delay for a single element, is usually about 2 to 5 milliseconds depending on the sensitivity level set, the lower the sensitivity the shorter settling delay is needed. The resolution the delay timer is 0.256 milliseconds, setting the Sensor Settling Delay at 10 hex then total settling delay becomes 16 * 0.256 milliseconds or approx 4 milliseconds. Sonic Transmission Period Control Byte The Period Control Byte determines the median frequency of the transmitted modulation. Unless otherwise observed, during normal operation the median should be constant. In case various elements of different resonating frequencies are being used, the following relationship should be used to alter the median.
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