Frequency signal conversion apparatus and method
AssigneeCaterpillar Tractor Co.
InventorJohn P. Hoffman
Life of this patent
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Abstract
A circuit (10) and method for converting a circuit input frequency signal (f.sub.i) to a circuit output frequency signal (f.sub.o) comprising a phase-locked loop (22) for multiplying the input frequency signal (f.sub.i) by a value M to produce a multiple frequency signal (f.sub.i M), and a presettable divider for dividing the frequency signal (f.sub.i M) by a settable value N to produce the output frequency signal (f.sub.o). The circuit (10) and method are used to determine engine speed by converting the signal (f.sub.i) to the signal (f.sub.o) which can be used with a counter having a one second time base to determine such speed. The conversion occurs in the frequency domain and follows smoothly any change in engine speed.
Claims6
Apparatus (10) for determining the speed of rotation of a rotating member (16) having detectable elements (18), comprising:
- (a) means (20) for detecting the elements (18) and generating a first frequency signal (f.sub.i) proportional to the speed of rotation of the member (16) in response to detecting said elements (18);
- (b) means (38) for multiplying the first frequency signal (f.sub.i) by a value M and producing a second frequency signal (f.sub.i M) in response to said multiplication;
- (c) means (42) for dividing the second signal (f.sub.i M) by the value M and producing a third frequency signal (f.sub.i o) in response to said division;
- (d) means (26) for detecting a phase difference between the first signal (f.sub.i) and the third signal (f.sub.i o);
- and,
- (e) means (44) for dividing the second frequency signal (f.sub.i M) by a value N and producing a fourth frequency signal (f.sub.o) proportional to the speed of rotation of said member (16), wherein M is proportional to a desired number of detectable elements (18) of said rotating member (16) and N is proportional to the actual number of detectable elements (18) of said member (16).
A method for determining the speed of rotation of a rotating member (16) having detectable elements (18), comprising:
- (a) detecting the elements (18);
- (b) generating a first frequency signal (f.sub.i) proportional to the speed of rotation of the member (16) in response to detecting the elements (18);
- (c) multiplying the first frequency signal (f.sub.i) by a value M and producing a second frequency signal (f.sub.i M) in response to said multiplication;
- and
- (d) dividing said second signal (f.sub.i M) by the value M and producing a third frequency signal (f.sub.i o) in response to said division;
- (e) detecting a phase difference between the first signal (f.sub.i) and the third signal (f.sub.i o);
- and,
- (f) dividing the second frequency signal (f.sub.i M) by a value N and producing a fourth frequency signal (f.sub.o) proportional to the speed of rotation of the member (16), wherein M is proportional to a desired number of detectable elements (18) of the rotating member (16) and N is proportional to the actual number of detectable elements (18) of the member (16).
Dependencies are inferred from the claim text.