Claims
- 1. A scanning sensor system for simultaneously correcting time varying view angle errors and suppressing sensor noise, comprising:
- a scanning sensor producing a sensor output signal corresponding to an actual view angle which differs from a desired view angle by a jitter angle error;
- means for detecting the jitter angle error and for generating a jitter error signal corresponding to the detected jitter angle error;
- data memory means for sequentially storing data samples of the sensor output signal;
- coefficient memory means for storing a plurality of sets of weighting coefficients, each weighting coefficient set being defined by a noise suppression filter impulse response;
- means for selecting one of the plurality of weighting coefficient sets in accordance with the jitter error signal;
- means for multiplying each of the sequentially stored data samples by a respective weighting coefficient from the selected set of weighting coefficients; and
- means for generating a corrected sensor output signal by summing results from the multiplying means.
- 2. A scanning sensor system according to claim 1, wherein the coefficient memory means comprises a read-only-memory.
- 3. A scanning sensor system according to claim 1, wherein the jitter error signal comprises a jitter time error signal including an integer portion comprising a nearest integer multiple of a sampling period for the data samples and a fractional portion less than the sampling period of the data samples.
- 4. A scanning sensor system according to claim 3, comprising:
- means for delaying respective data samples by the integer portion of the jitter time error signal; and
- wherein each weighting coefficient set corresponds to a respective fractional portion of the jitter time error signal.
- 5. A scanning sensor system according to claim 4, wherein the coefficient memory means comprises a read-only-memory (ROM) and wherein the means for selecting one of the weighting coefficient sets comprises means for addressing each weighting coefficient set in ROM in accordance with a respective fractional portion of the jitter time error signal.
- 6. A method of simultaneously correcting time varying view angle errors and suppressing sensor noise in a sensor output signal of a scanning sensor system, comprising the steps of:
- detecting a jitter error angle as the difference between an actual view angle and a desired view angle for the scanning sensor system;
- generating a jitter erro signal corresponding to the detected jitter angle error;
- storing data samples of the sensor output signal in a data memory;
- selecting one of a plurality of stored weighting coefficient sets in accordance with the jitter error signal, each weighting coefficient set corresponding to a noise suppression filter impulse response;
- multiplying each stored data sample by a respective weighting coefficient from the selected set of weighting coefficients; and
- generating a corrected sensor output signal by summing the multiplicative results.
- 7. The method of claim 6, wherein the step of selecting one of the plurality of weighting coefficient sets comprises the step of selecting a weighting coefficient set from read-only-memory (ROM).
- 8. The method of claim 7, comprising the steps of:
- defining the noise suppression filter impulse response over a predetermined time period;
- defining a sample interval as a predetermined sub-interval of the time period;
- defining a desired scan rate for the scanning sensor system as angle units per sample interval, such that the desired scan rate defines for any given time the desired view angle.
- 9. The method of claim 7, wherein the step of generating a jitter error signal comprises the step of converting the jitter angle error into a corresponding jitter time error, the jitter time error including an integer portion comprising a nearest integer multiple of a sample interval and a fractional portion as the additive complement to the integer portion required to obtain the jitter time error.
- 10. The method of claim 9, wherein the step of selecting one of the plurality of weighting coefficient sets comprises the step of addressing one of the plurality of weighting coefficient sets from ROM according to the value of the fractional portion of the jitter time error, wherein the jitter time error is constant over a predetermined number of sample intervals.
- 11. A scanning sensor system for simultaneously correcting time varying view angle errors and suppressing sensor noise, comprising:
- a scanning sensor producing a sensor output signal cor-responding to an actual view angle which differs from a desired
- view angle by a jitter angle error;
- means for sampling the sensor output signal at a predetermined sample interval n such that a plurality of data samples V.sub.1 -V.sub.i are provided for corresponding sample intervals n.sub.1 -n.sub.i ;
- a data memory for sequentially storing data samples V.sub.1 -V.sub.i ;
- means for selecting a set of k data samples from the stored data samples V - V.sub.i ;
- means for detecting the jitter angle error, and for generating a jitter time error signal M(n) corresponding to the detected jitter angle error, the jitter time error signal including an integer portion IP.sub.n, corresponding to a nearest integer multiple of the sample interval and a fractional portion FPn, less than the sample interval;
- coefficient memory means for storing a plurality of weighting coefficient sets, each weighting coefficient set being defined by a noise suppression filter impulse response;
- means for selecting a weighting coefficient W(n) from the plurality of weighting coefficient sets for each respective data sample V(n) of the selected set of k data samples;
- means for multiplying each respective data sample V(n) by the respective selected weighting coefficient W(n); and
- means for generating a corrected sensor output signal from the products of the multiplying means.
- 12. A scanning sensor system according to claim 11, wherein the means for selecting a set of k data samples comprises;
- means for selecting a set of data samples proximate the subject data sample defined by V[q+IP.sub.q +r ], where r is defined by the range of from -(k-1)/2 to +(k-1)/2.
- 13. A scanning sensor system according to claim 12, wherein the coefficient memory means comprises a read-only-memory (ROM) and the means for selecting a weighting coefficient comprises means for addressing the respective selected weighting coefficient W(n), for each corresponding data sample V(n) in the set of k data samples, in ROM according to an address corresponding to a value calculated as [(k-IP.sub.q)+M(q+k-IP.sub.q)].
- 14. A scanning sensor system according to claim 12, wherein the means for generating a corrected sensor output signal comprises means for summing the products of the multiplying means.
- 15. A scanning sensor system according to claim 14, wherein the means for generating a corrected sensor output signal comprises means for scaling the summed products of the multiplying means by a scaling factor F.sub.s, defined as
- F.sub.s ={1+0.25[M(q+2)-M(q-2)]}
- 16. A method of simultaneously correcting time varying view angle errors and suppressing sensor noise in a sensor output signal of a scanning sensor system, comprising the steps of:
- sampling the sensor output signal at the sample interval n, such that a plurality of data samples V.sub.1 -V.sub.i are provided for corresponding sample intervals n.sub.1 -n.sub.i ;
- storing data samples V.sub.1 -V.sub.i in a data memory;
- selecting a set of k data samples from the stored data samples V.sub.1 -V.sub.i ;
- detecting a jitter angle error as the difference between an actual view angle and a desired view angle;
- generating a jitter time error signal M(n) corresponding to the detected jitter angle error, the jitter time error signal including an integer portion IP.sub.n corresponding to a nearest integer multiple of the sample interval and a fractional portion FP.sub.n less than the sample interval;
- selecting a weighting coefficient, W(n), from a plurality of stored weighting coefficient sets for each respective data sample V(n) of the selected set of k data samples, each weighting coefficient set being defined by a noise suppression filter impulse response;
- multiplying each respective data sample, V(n), of the selected set of k data samples by the respective selected weight-ing coefficient W(n); and
- generating a corrected sensor output signal from the multiplicative results.
- 17. The method of claim 16, wherein the step of selecting a set of k data samples from the stored data samples V.sub.1 -V.sub.i, comprises the steps of:
- selecting a subject data sample V(q); and
- selecting a set of data samples proximate the subject data sample defined by V[q+IP.sub.q +r], where r is defined by the range of from -(k-1)/2 to +(k-1)/2.
- 18. The method of claim 16, comprising the steps of:
- defining the noise suppression filter impulse response over a predetermined time period;
- defining a sample interval as a predetermined sub-interval of the time period; and
- defining a desired scan rate for the scanning sensor system as angle units per sample interval, such that the desired scan rate defines for any given time the desired view angle.
- 19. The method of claim 17, wherein the step of selecting weighting coefficients comprises the step of selecting the respective weighting coefficient W(n), for each corresponding data sample V(n) in the set of k data samples, by addressing in ROM according to the formula:
- Address=[(k-IP.sub.q)+M(q+k-IP.sub.q)].
- 20. The method of claim 19, wherein the step of generating a corrected sensor output signal comprises the step of:
- summing the multiplicative results.
- 21. The method of claim 20, wherein the step of generating a corrected sensor output signal comprises the step of:
- scaling the summed multiplicative results by a scaling factor,
- F.sub.s, defined as F.sub.s ={1+0.25[M(q+2)-M(q-2)]}.
Parent Case Info
This application is a continuation of application Ser. No. 07/791,221, filed Nov. 13, 1991, now abandoned.
US Referenced Citations (14)
Continuations (1)
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791221 |
Nov 1991 |
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