Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Distributive type parameters
Patent
1997-08-26
1999-08-17
Brown, Glenn W.
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Distributive type parameters
324639, 324641, G01N 2204
Patent
active
059398884
ABSTRACT:
A monitor for monitoring the moisture content of grain comprises at least one programmable PIN diode attenuator connected between a microwave measurement signal source and a transmit antenna. A controller stores an addressable attenuation table, each location in the table storing an attenuation value and an associated attenuator address. A counter accesses the table locations sequentially and the attenuator addresses are applied to the attenuator to cause a step-wise decreasing attenuation of the measurement signal which is then transmitted through the grain. After the signal passes through the grain, it is detected and applied to a threshold comparator. When the magnitude of the detected signal reaches the threshold, the counter is stopped and the attenuation value at the location pointed to by the counter is taken as the attenuation of the measurement due to moisture in the grain. Once the attenuation has been determined, the moisture content and mass grain flow may be calculated. The determination of attenuation and moisture content is accomplished with digital circuitry and the determination of attenuation requires only a go no-go comparison of the measurement signal with a threshold value.
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Powell et al., "Use of a Density-Independent Function and Microwave Measurement System For Grain Moisture Measurement"; 1988 Am. Society of Agricultural Eng.; vol 31(6); pp. 1875-1881, Nov.-Dec., 1988.
King et al. "Microwave Moisture Measurement of Grains"; IEEE Transactions on Instrumentation and Measurement, vol. 41, No. 1, Feb. 1992; pp. 111-115.
McLendon et al., "Density-Independent Microwave Measurement of Moisture Content in Static and Flowing Grain"; 1993 Am. Society of Agricultural Engineers, vol. 36(3) May-Jun. 1993; pp. 827-835.
"Microwave Sensors for Process Control Part I: Transmission Sensors"; Ray J. King, KDC Technology Corp.; Sensors, Sep. 1992; pp. 68-74.
Brown Glenn W.
New Holland North America Inc.
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