US5220519A — Method and apparatus for self-testing a transduce…

Claim 1

Independent Claim 123 words

An improved method of self-testing a transducer system, said transducer system having a measurand signal input for receiving a measurand signal, and a self-testing signal input for receiving a self-test signal, and a transducer system output for outputting a combined transducer system output signal, said improved method comprising the steps of: generating at least one of a random and a pseudo-random self-test signal and supplying same to said self-testing signal input to be combined with said measurand signal and supplying same to a signal processor; and simultaneously processing both the self-test signal and the combined transducer system output signal in the processor to produce the desired self-test result plus at least one noise term whose relative magnitude decreases as the test time increases.

Claim 2

Dependent Claim 123 words

An improved method of self-testing a transducer system, said transducer system having a measurand signal input for receiving a measurand signal, and a self-testing signal input for receiving a self-test signal, and a transducer system output for outputting a combined transducer system output signal, said improved method comprising the steps of: generating at least one of a random and a pseudo-random self-test signal and supplying same to said self-testing signal input to be combined with said measurand signal and supplying same to a signal processor; and simultaneously processing both the self-test signal and the combined transducer system output signal in the processor to produce the desired self-test result plus at least one noise term whose relative magnitude decreases as the test time increases.

Claim 3

Dependent Claim 17 words

The improved method of claim 1 wherein said step of generating includes generating said pseudo-random self-test signal.

Claim 4

Dependent Claim 27 words

The improved method of claim 2 wherein said generating step includes the step of generating a pseudo-random self-test signal sequence having a finite test time duration "T".

Claim 5

Dependent Claim 31 words

The improved method of claim 3 wherein said generating step further includes the step of generating said self-test signal wherein said self-test signal is restricted to switching between two fixed values.

Claim 6

Dependent Claim 39 words

The improved method of claim 4 wherein said generating step includes the step of generating said self-test signal wherein self-test signal has the property of summing to the average of the two values over the test time duration "T".

Claim 7

Dependent Claim 28 words

The improved method of claim 5 wherein said generating step includes the step of generating said self-test signal wherein said self-test signal has a relatively flat frequency spectrum.

Claim 8

Dependent Claim 26 words

The improved method of claim 5 wherein said step of generating said self-test signal includes generating a self-test signal which has the property of being unidirectional.

Claim 9

Dependent Claim 60 words

The improved method of claim 1 wherein said step of generating includes generating a pseudo-random self-test signal nf(t)+c comprising a sequence of pulses having a finite test time duration "T" wherein f(t) is restricted to two fixed values and sums to zero over the test time interval "T", and wherein "n" and "c" are arbitrary scaling and off-setting constants respectively.

Claim 10

Dependent Claim 62 words

The improved method of claim 8 wherein said measurand signal is given by "g(t)", said self-test signal is given by "nf(t)+c", and said transducer system output signal is given by H.sub.1 (nf(t)+c)+h.sub.2 g(t) where "h 1 " is the gain of the transducer system for the self-test signal nf(t)+c, and "h 2 " is the conversion gain for the measurand signal g(t).

Claim 11

Dependent Claim 103 words

The improved method of claim 9 wherein said step of processing includes the steps of: multiplying the signal f(t) times the transducer system output signal to produce the product h.sub.1 nf.sup.2 (t)+h.sub.1 cf(t)+h.sub.2 F(t)g(t); integrating said product over the test time duration period "T" to get the self-test output V(t), where: V(t)=nh.sub.1 f.sup.2 (t)dt+ch.sub.1 f(t)dt+h.sub.2 f(t)g(t)dt wherein the first term is a signal term proportional to h 1 , and the second term is zero, and the third term is an error term and the expected volume of the signal term to the noise term increases as the test time duration "T" increases.

Claim 12

Dependent Claim 32 words

The improved method of claim 10 wherein if the signal f(t) has no DC component, then the noise term will contribute no DC error even if g(t) does contain a DC component.

Claim 13

Dependent Claim 76 words

The improved method of claim 9 wherein said step of processing includes: multiplying the signal f(t) times the transducer system output signal h.sub.1 (nf(t)+c)+h.sub.2 g(t) to get the three-term product h.sub.1 nf.sup.2 (t)+h.sub.1 cf(t)+h.sub.2 f(t)g(t) and low-pass filtering the three-term product such that the first term reduces to the desired self-test result kh 1 and the other two terms constitute noise terms each tending toward zero as the corner frequency of the low-pass filter is reduced.

Claim 14

Dependent Claim 73 words

The improved method of claim 9 wherein said step of processing includes digital processing including the steps of: analog-to-digital converting the transducer system output signal to digital values equivalent thereof; providing a microprocessor; feeding the equivalent digital values into the microprocessor; supplying the signal f(t) into the microprocessor; combining said input signals; and outputting a test result which is proportional to the desired self-test result h 1 plus at least one error term.

Claim 15

Dependent Claim 42 words

The improved method of claim 13 wherein said step of generating said pseudo-random self-test signal includes providing a digital clock and a clock line and utilizing said clock line to supply said self-test signal to said self-test input of said transducer system.

Claim 16

Dependent Claim 45 words

The improved method of claim 13 wherein said step of generating said pseudo-random self-test signal includes: providing a microprocessor, a clock, and a clock line; calculating said self-test signal in said microprocessor; and feeding said self-test signal to said self-test input of said transducer system.

Claim 17

Dependent Claim 14 words

The improved method of claim 1 wherein said step of processing includes analog processing.

Claim 18

Dependent Claim 14 words

The improved method of claim 1 wherein said step of processing includes digital processing.

Claim 19

Dependent Claim 13 words

The improved transducer system of claim 1 wherein said self-testing signal is unidirectional.

Claim 20

Independent Claim 183 words

A method for self-testing a transducer system, said transducer system having an environmental signal input for receiving an environmental input signal g(t), a self-testing signal input for receiving a self-testing input signal, and a transducer system signal output for outputting a transducer system output signal, said method comprising the steps of: generating the self-testing input signal (nf(t)+c) which is a pseudo-random sequence of pulses having a finite test time duration "T", where nf(t)+c is restricted to two fixed values, f(t) sums to zero over the time interval "T", and where f(t) has a relatively flat frequency spectrum; injecting said generated self-testing input signal into the self-testing signal input of said transducer system to output said transducer system output signal; and coupling the transducer system output signal and the self-test input signal to a signal processor; and simultaneously processing said transducer system output signal and the self-testing input signal f(t) to generate a test result output signal having one term which represents the desired test result and at least one error term whose relative value decreases with the increase in the test time T.

Claim 21

Independent Claim 183 words

A method for self-testing a transducer system, said transducer system having an environmental signal input for receiving an environmental input signal g(t), a self-testing signal input for receiving a self-testing input signal, and a transducer system signal output for outputting a transducer system output signal, said method comprising the steps of: generating the self-testing input signal (nf(t)+c) which is a pseudo-random sequence of pulses having a finite test time duration "T", where nf(t)+c is restricted to two fixed values, f(t) sums to zero over the time interval "T", and where f(t) has a relatively flat frequency spectrum; injecting said generated self-testing input signal into the self-testing signal input of said transducer system to output said transducer system output signal; and coupling the transducer system output signal and the self-test input signal to a signal processor; and simultaneously processing said transducer system output signal and the self-testing input signal f(t) to generate a test result output signal having one term which represents the desired test result and at least one error term whose relative value decreases with the increase in the test time T.

Claim 22

Dependent Claim 13 words

The method of claim 19 wherein said step of processing includes digital processing.

Claim 23

Dependent Claim 7 words

The method of claim 19 wherein c=0.

Claim 24

Dependent Claim 7 words

The method of claim 19 wherein n=1.

Claim 25

Dependent Claim 118 words

The method of claim 19 wherein said step of processing includes the steps of: multiplying the self-testing signal f(t) times the transducer system output signal h.sub.2 (nf(t)+c)+h.sub.2 g(t); where h 1 is the gain of the transducer system for the self-testing input signal nf(t)+c, and where h 2 is the conversion gain of the transducer system for the environmental signal g(t) to get the resultant product h.sub.1 nf.sub.2 (t)+h.sub.1 cf(t)+h.sub.2 f(t)g(t); integrating said product with respect to time over the finite time interval "T"; to obtain V(T)=nh.sub.1 rf.sup.2 (t)dt+ch,rf(t)dt+h.sub.2 Tf(t)g(t)dt which reduced to: V(T)=kh.sub.1 +h.sub.2 f(t)g(t)dt wherein k is a known constant and kh 1 is the desired self-test result and the remaining term is said error term.

Claim 26

Dependent Claim 68 words

The method of claim 19 wherein said steps of processing includes the steps of: generating the signal f(t) with a microprocessor; converting the transducer system output signal from analog to digital; storing the digital conversion in said microprocessor; and combining the signals in said microprocessor to output a self-test output signal having one term which is proportional to the desired self-test output and at least one error term.

Claim 27

Dependent Claim 77 words

The method of claim 19 wherein said step of processing further includes the steps of: multiplying the signal f(t) times the transducer system output signal; and low pass filtering the product to output the self-test result V(t), where V(t)=avg(nh.sub.1 f.sup.2 (t))+avg(ch.sub.1 f(t))+avg(h.sub.2 f(t)g(t)) which reduces to V(t)=kh.sub.1 +avg{ch.sub.1 f(t))+avg{h.sub.2 f(t)g(t)} where k is a known constant and kh 1 is the desired self-test result and the remaining terms are error terms each of which tends to zero.

Claim 28

Dependent Claim 13 words

The method of claim 19 wherein said step of processing includes analog processing.

Claim 29

Dependent Claim 156 words

An improved transducer circuit having a first input for receiving an environmental input signal and a transducer output for outputting a transducer output signal, the improvement including a self-testing system comprising: a second input means for injecting a self-test input signal into said transducer circuit; means for generating a self-test input signal comprising a pseudo-random sequence of digital signals having a finite time duration "T", wherein said signals are restricted to two fixed values, wherein said signals sum to the average of the two values over the test time interval "T", and wherein said signals have a relatively flat frequency spectrum; means for supplying said generated sequence of signals to said second input means; and means responsive to both said self-test input signal and to said transducer output signal for producing a test result signal having one term which represents the desired self-testing result plus at least one other error term whose effect is substantially minimized.

Claim 30

Dependent Claim 156 words

An improved transducer circuit having a first input for receiving an environmental input signal and a transducer output for outputting a transducer output signal, the improvement including a self-testing system comprising: a second input means for injecting a self-test input signal into said transducer circuit; means for generating a self-test input signal comprising a pseudo-random sequence of digital signals having a finite time duration "T", wherein said signals are restricted to two fixed values, wherein said signals sum to the average of the two values over the test time interval "T", and wherein said signals have a relatively flat frequency spectrum; means for supplying said generated sequence of signals to said second input means; and means responsive to both said self-test input signal and to said transducer output signal for producing a test result signal having one term which represents the desired self-testing result plus at least one other error term whose effect is substantially minimized.

Claim 31

Dependent Claim 16 words

The improved transducer circuit of claim 27 wherein said processing means includes digital logic processing means.

Claim 32

Dependent Claim 17 words

The improved transducer circuit of claim 28 wherein said generating means includes a digital logic circuit means.

Claim 33

Dependent Claim 11 words

The improved transducer circuit of claim 29 wherein "n" is one.

Claim 34

Dependent Claim 187 words

The improved transducer circuit of claim 30 wherein said processing means comprises: analog-to-digital converter means having an input and an output for converting a sequence of analog signals into a corresponding sequence of digital signals; means for connecting said transducer circuit output to said analog-to-digital converter means input for supplying said transducer output signal thereto; microprocessor means having at least first and second inputs and a microprocessor output; means for supplying the digital representation of said transducer output signal to said first input of said microprocessor means; means for supplying said signal f(t) to said second input of said microprocessor means; and said microprocessor means for processing said inputs to output a self-testing output signal V(t), where V(t)=h.sub.1 +h.sub.1 f(t)+h.sub.2 f(t)g(t) where h 1 is the gain of the transducer circuit for the self-test input signal and h 2 is the conversion gain of the transducer circuit for the environmental signal g(t), h 1 being the desired test result and the remaining terms being error terms whose average values tend to zero over the test time period and whose magnitude decrease with increases in the test time.

Claim 35

Dependent Claim 157 words

The improved transducer circuit of claim 30 wherein said processing means comprises of: an analog multiplying means having first and second input and a multiplier output; means for supplying said self-test input signal f(t) to said first input of said analog multiplying means; means for supplying said transducer output signal to said second input of said analog multiplying means; said analog multiplying means for multiplying said self-testing input signal times said transducer output signal and producing the product h.sub.1 f.sup.2 (t)+h.sub.2 f(t)g(t); where h 1 is the gain of the transducer circuit for the signal f(t) and h 2 is the conversion gain of the transducer circuit for the measurand signal g(t); and means for dividing the integrated product by the time "T" to produce the self-test output signal V(T), where ##EQU12## where h 1 is the desired self-test result and the remaining term represents a noise term whose value decreases as the test time "T" increases.

Claim 36

Dependent Claim 20 words

The improved transducer circuit of claim 29 wherein n=1, c=0, and wherein said self-test input signal is given by f(t).

Claim 37

Dependent Claim 23 words

The improved transducer circuit of claim 29 wherein one of the fixed values is zero, and wherein said self-test input signal is unidirectional.

Claim 38

Dependent Claim 16 words

The improved transducer circuit of claim 27 wherein said processing means includes analog circuit processing means.

Claim 39

Dependent Claim 71 words

The improved transducer circuit of claim 27 wherein said environmental input signal is given by g(t), and said self-test input signal is given by [[](nf(t)+c)[]] where "n" and "c" are constants and wherein f(t) is a pseudo-random sequence of digital pulses having a finite time duration "T", where f(t) is restricted to values of +1, sums to zero over the test time interval "T", and has a relatively flat frequency spectrum.

Claim 40

Dependent Claim 39 words

The improved transducer circuit of claim 27 wherein said transducer circuit is operably disposed on an integrated circuit chip and wherein at least a substantial portion of said self-testing system is operably disposed on said same integrated circuit chip.

Claim 41

Dependent Claim 191 words

An improved transducer system on an integrated circuit chip and including a transducer, transducer signal conditioning means, a first transducer system input for receiving at least one of a testing and a monitoring signal g(t), a second transducer system input for receiving a self-testing signal, and a transducer system output for supplying a transducer system output signal, said improvement comprising: a self-testing subsystem operatively disposed at least partially on said integrated circuit chip, said self-testing system including: means for producing a self-test signal (nf(t)+c), where "n" and "c" are abitrary constants and where the signal f(t) is a pseudo-random sequence of signals having a finite time duration "T", and being restricted to the values of ±1, summing to zero over the test time period "T", and having a relatively flat frequency response; means for feeding said self-testing signal to said second transducer system input; and signal analyzing means responsive to said signal f(t) and to said transducer system output signal for producing a self-test output signal having one term representing the desired self-test output result and at least one error term whose value decreases as the test time interval "T" increases.

Claim 42

Dependent Claim 191 words

An improved transducer system on an integrated circuit chip and including a transducer, transducer signal conditioning means, a first transducer system input for receiving at least one of a testing and a monitoring signal g(t), a second transducer system input for receiving a self-testing signal, and a transducer system output for supplying a transducer system output signal, said improvement comprising: a self-testing subsystem operatively disposed at least partially on said integrated circuit chip, said self-testing system including: means for producing a self-test signal (nf(t)+c), where "n" and "c" are abitrary constants and where the signal f(t) is a pseudo-random sequence of signals having a finite time duration "T", and being restricted to the values of ±1, summing to zero over the test time period "T", and having a relatively flat frequency response; means for feeding said self-testing signal to said second transducer system input; and signal analyzing means responsive to said signal f(t) and to said transducer system output signal for producing a self-test output signal having one term representing the desired self-test output result and at least one error term whose value decreases as the test time interval "T" increases.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-06-14	1996-12-14	1997-06-15	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-06-14	2000-12-14	2001-06-15	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-06-14	2004-12-14	2005-06-15	$7700.00	Window Closed / Lapsed

Method and apparatus for self-testing a transducer system

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag