Boots – shoes – and leggings
Patent
1981-05-26
1983-09-20
Smith, Jerry
Boots, shoes, and leggings
73708, 324140D, 364571, G06F 768, G01L 1904
Patent
active
044059906
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
This invention relates to an apparatus for producing an output signal having a pulse repetition rate which varies directly as a function of the ratio of two input signal repetition rates. The apparatus embodying the invention can be used to advantage to render measurement circuits insensitive to extraneous effects such as ambient temperature changes.
2. Background Art
It is well known to represent a varying quantity in terms of the repetition rate of a timevarying signal such as a pulse train or sinusoidal waveform. For example, an electrical component such as a variable resistor, capacitor, inductor or a combination of these may be connected into the tank circuit of an oscillator to vary the output repetition rate (frequency) of the oscillator as a function of some quantity which influences the electrical component.
In certain instances, it is desirable to ascertain the ratio between two such repetition rates. One technique for determining a ratio involves a conversion of each ratio to an analog current and causing these currents to pass through inductors, the output fields of which influence the position of a movable magnet. The ratio of rates is thus represented as the resultant of two non-parallel magnetic fields.
Another apparatus for computing repetition rate ratios is shown in U.S. Pat. No. 3,040,983 to Bigelow, "Pulse-Train Ratio Apparatus" granted June 26, 1962. In the Bigelow circuit, two rate signals are simultaneously received on separate channels, each channel including circuitry for converting its input pulse train into an analog voltage proportional to pulse rate. These two analog voltages are applied to different inputs of a DC operational amplifier such that, for a given time interval, the amplitude and polarity of the amplifier output represents the ratio of input rates.
There exists a need for relatively simple circuitry for direct determination of repetition rate ratios which does not depend upon conversion to analog signal form and which is readily compatible with digital data processing apparatus.
DISCLOSURE OF THE INVENTION
In one aspect, the invention provides a circuit for the direct and precise determination of repetition rate ratios using digital techniques which require neither magnetic field resolution nor analog voltage generation. In general, this is accomplished by alternately inputting two signals whose repetition rates are to be ratioed, generating a gating pulse which varies in length inversely with the first rate (f.sub.1) and gating a portion of the second rate (f.sub.2) onto an output terminal in accordance with the length of the gating pulse.
In another aspect, the invention provides a method and apparatus for compensating measurement circuits for the effects of extraneous influences such as temperature. In general this is accomplished by generating first and second signal quantities which vary in repetition rate similarly or in like sense in response to extraneous changes but which vary in repetition rate dissimilarly or in an opposite sense in response to measured signal quantity changes, and digitally deriving the ratio of the two component signal quantities as a stabilized indicator of changes in the measured quantity.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a detailed circuit diagram of one apparatus embodying the invention;
FIGS. 2 and 2A are charts of signal waveforms which are generated in the circuit of FIG. 1;
FIG. 3 is a simplified waveform diagram illustrating the mathematics of ratio determination according to the invention; and,
FIG. 4 is a detailed circuit diagram of an apparatus embodying an alternate form of the invention.
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 illustrates a first embodiment of the invention comprising a matched pair of inductive sensing elements 10 and 12. Sensing elements 10 and 12 are connected through complementally operated signal transmission gates G1 and G2 to an oscillator 14 where they alternately act as frequency determining elements, i.e., the sensing elements 10 and 12
REFERENCES:
patent: 2641706 (1953-06-01), Dickinson
patent: 3040983 (1962-06-01), Bigelow
patent: 3355949 (1967-12-01), Elwood et al.
patent: 3424980 (1969-01-01), Anderson
patent: 3681586 (1972-08-01), Kitaura
patent: 3739156 (1973-06-01), Gebelein, Jr. et al.
patent: 3821536 (1974-06-01), Berg
patent: 3943341 (1976-03-01), Corsi et al.
patent: 4208918 (1980-06-01), Miyamae
patent: 4244027 (1981-01-01), Shai
Pickering William
Urbanc David J.
Caterpillar Tractor Co.
Smith Jerry
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