US 4,071,820 A · Measurement system

Abstract

A measuring system includes a capacitance sensor adapted to be positioned in proximity to an object to be observed, signal generating circuitry cooperating with the sensor for producing an electrical signal output indicative of a characteristic of the observed object, and signal processing circuitry for processing the signal generated by the signal generating circuitry. The signal processing circuitry has a power supply and a grounding system separate from the power supply and grounding system of the signal generating circuitry, and a receiving element coupled to but physically spaced from a transmitting element of the signal generating circuitry. The signal generating circuitry thus responds only to the electrical output signal from the signal generating circuitry as transmitted by the transmitting element and is not affected by system perturbations on the ground system adjacent the sensor or in the power supply in the signal generating circuitry.

Claims15

Dependent claims

In a measuring system that includes sensor means adapted to be positioned in proximity to but not in contact with an object to be observed, said sensor means being sensitive to variation in the sensor-to object spacing, and signal generating circuitry cooperating with said sensor means for procuding an electrical signal output indicative of the spacing of the object from said sensor means,

signal processing circuitry for processing the signal generated by said signal generating circuitry, said signal processing circuitry having a power supply and a grounding system separate from the power supply and grounding system of said signal generating circuitry, a tuned receiving circuit coupled to but physically spaced from a tuned transmitting circuit of the signal generating circuitry for receiving said electrical signal output from said signal generating circuitry and a compensation network coupled to said tuned receiving circuit for adjusting the tuning of said receiving circuit as a function of an output signal level corresponding to a condition of large spacing between said sensor means and the object to be sensed.

A measuring system for sensing the surface profile of a rapidly rotating object of complex surface configuration comprising:

snesor means adapted to be positioned in proximity to but not in contact with the surface to be observed, said sensor means being sensitive to variation in the spacing between the sensor means and the surface to be observed,
signal generating circuitry cooperating with said sensor means for producing an electrical signal output indicative of the spacing of the surface from said sensor means, said signal generating circuitry generating a carrier signal of megahertz frequency and said sensor means modulating said carrier signal, a transmitting element tuned to the carrier signal frequency for maximum RF signal transmission, and
a signal processing section including a receiving element coupled to but physically spaced from said transmitting element of the signal generating circuitry for receiving said electrical signal output from said signal generating circuitry, said receiving element being tuned to a frequency close to but offset from said carrier frequency, said signal processing section further including compensation means responsive to a reference corresponding to a condition of large spacing between said sensor and the surface to be sensed for changing the tuning of said receiving element.

A measuring system comprising:

signal generating circuitry for generating a carrier signal of megahertz frequency,
a capacitance sensor adapted to sense a condition to be monitored and to modulate said carrier signal as a function of the sensed condition,
an output circuit tuned to the frequency of said carrier signal, and
signal processing circuitry including a receiving stage tuned to a frequency offset from said carrier frequency and having a receiving element physically spaced from and inductively coupled to a transmitting element of said output circuitry,
a demodulator stage coupled to said receiving stage for producing a DC signal as a function of the modulation of said carrier signal, said DC signal having non-linear characteristics, a linearization stage responsive to said DC signal for producing a modified signal that is in essentially linear correspondence with a range of conditions sensed by said capacitor sensor,
and a compensation network responsive to predetermined values of said modified signal corresponding to a reference signal from said sensor for modifying the tuning of said receiving stage.

3 more elements

Dependencies are inferred from the claim text.

Measurement system

Life of this patent

Measurement system

Life of this patent

Abstract

Claims15