US 4,359,734 A · Signal processing system

Abstract

An improved system for processing an electrical velocity information signal in a velocity detecting system in which a detector is utilized for developing an electrical information signal, such as a Doppler signal, having a characteristic (e.g. frequency) that varies systematically with the object's velocity. A converter develops an oscillatory signal having a frequency which varies in accordance with the velocity information signal characteristic. A tracking filter having a center frequency that varies with the oscillatory signal filters all frequencies other than the center frequency. A signal generator is responsive to the frequency of the signal passed by the tracking filter for generating an output signal having a frequency which is a preset ratio relative to the center frequency, whereby the output signal of the system is relatively noise-free and has a frequency which represents the velocity of the object being detected. Another feature of the disclosed embodiment of the invention utilizes a switching network comprising a pair of flip-flops and a pair of shift registers which are responsive to the oscillatory signal passed by the tracking filter and to an oscillatory signal generated by a voltage-controlled oscillator for alternately charging and discharging a storage capacitor which is coupled to the inverting input of an operational amplifier used as a comparator. A variable resistance is placed in either the charging or discharging path and the output of the op amp is used as an error voltage to control the frequency of the VCO to thus provide a frequency locked loop.

Claims23

Dependent claims

In a velocity detecting system in which detector means are utilized for developing an electrical information signal having a characteristic that varies systematically in accordance with the velocity of an object subject to detection, an improved system for processing said electrical velocity information signal, comprising:

converter means coupled to said detector means and responsive to said velocity information signal characteristic for developing an oscillatory signal having a value which varies in accordance with said velocity information signal characteristic;
filter means, including a phase-locked loop circuit operated with a relatively long time constant to prevent said phase-locked loop circuit from locking, having a variable center value and responsive to said oscillatory signal for filtering all values other than said center value, said center value varying in accordance with said value of said oscillatory signal;
and signal generating means responsive to the value of the signal passed by said filter means for generating an output signal having a value which is a preset ratio relative to said center value, whereby the output signal of the system is relatively noise free and has a value which represents the predetermined velocity for the object being detected.

converter means coupled to said detector means and responsive to said velocity information signal characteristic for developing a first oscillatory signal having a frequency which varies in accordance with said velocity information signal characteristic;
voltage-controlled oscillator means, having an input and an output, for generating a signal at said output which has a frequency that varies in accordance with the voltage applied to said input, storage means;
reference voltage means;
comparator means having first and second inputs, with said first comparator input coupled to said storage means and said second comparator input coupled to said reference voltage means, for comparing the voltages at said first and second comparator means inputs and developing a corresponding error voltage;
means for applying said error voltage to said voltage-controlled oscillator means input;
circuit means coupled to said storage means for selectively charging and discharging said storage means;
switch means coupled to said converter means, said voltage-controlled means and to said circuit means and responsive to said first and second oscillatory signals for causing said circuit means to alternately charge and discharge said storage means, whereby the output signal of the voltage-controlled oscillator means has a frequency which is a preset ratio of the frequency of the converter output signal as controlled by the circuit means and which is essentially unaffected by environmental changes.

4 more elements

voltage-controlled oscillator means, having an input and an output, for generating an oscillatory signal at said output which has a frequency that varies in accordance with the voltage applied to said input, storage means;
reference voltage means;
comparator means having first and second inputs, with said first comparator input coupled to said storage means and said second comparator input coupled to said reference voltage means, for comparing the voltages at said first and second comparator means inputs and developing a corresponding error voltage;
means for applying said error voltage to said voltage-controlled oscillator means input;
circuit means coupled to said storage means for selectively charging and discharging said storage means;
switch means coupled to the output of said detector means, said voltage-controlled means and to said circuit means and responsive to said electrical velocity information signal and said oscillatory signal for causing said circuit means to alternately charge and discharge said storage means, whereby the output signal of the voltage-controlled oscillator means has a value that corresponds to said velocity and which is essentially unaffected by environmental changes.

3 more elements

Dependencies are inferred from the claim text.

Signal processing system

Life of this patent

Signal processing system

Life of this patent

Abstract

Claims23