| 摘要 |
<p>The monitor includes an AC signal source for transmitting a measurement signal along a measurement signal path that includes a sensor region in which grain may, or may not, be present, and an analyser for determining the attenuation of the measurement signal along the path. The analyser produces an indication of the moisture content of grain in the sensor region that is dependent on the attenuation. A simulator is provided which includes a programmable attenuator that is selectively electrically inserted in the measurement signal path and a control circuit for controlling the attenuator so that the measurement signal is attenuated and the analyser produces an indication of grain moisture content even though no grain is present in the sensor region. The attenuator may be a PIN diode or a programmable capacitor.</p> |
