Signal processing apparatus and method
First Claim
1. Apparatus for processing an analog input signal by integrating the analog input signal with respect to time thereof for an integration period and correcting errors in the integrated signal due to errors in the analog input signal comprising control means (26) for defining the integration period and generating a plurality of control signals, the number of control signals generated being smaller than that required by the Nyquist sampling theorem for a predetermined highest frequency component of the input signal, a sampling circuit for sampling the input signal, a gate for applying the control signals to the sampling means such that said sampling circuit derives sampled signals in response to said control signals that bear a functional relationship with errors in the input signal, means for processing the sampled signals and subjecting the sampled signals to an algorithmic process representative of said functional relationship to quantify the error in the input signal represented by the sampled signals, means for integrating the processed sample results, means for applying the control signals to the means for integrating the processed sample results to quantity the effect of errors on the integrated analog input signal and means for modifying the integrated input signal in accordance with the quantified effect to correct errors in the integrated input signal.
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Abstract
A method for correcting an integral signal representing the integral of an input signal derived from an accelerometer to eliminate the effects of errors in the input signal comprises sampling one or more signals which bear a functional relationship with the errors and subjecting the samples to a correction algorithmic process. The processed results are integrated and used to correct the input signal integral. Relatively few samples may be taken at below the Nyquist rate at random or pseudorandom intervals to provide an acceptable quantitive estimate of the error in the integrated input signal.
The samples are spaced throughout the integration period by defining window intervals and taking one or more samples randomly in each window interval. Apparatus to practice the method include an integrator for integrating the input signal and a sample and hold circuit for sampling the input signal. Sample signals are subjected to the correction algorithmic process under the control of a control circuit arranged to provide output control signals that define sampling intervals at a high frequency rate, sampling window intervals and the integration time. An accumulator receives and stores processed samples with the output of the accumulator applied to a correction circuit to correct errors in the input signal which after integration is also applied to the correction circuit, the output of the correction circuit representing the corrected signal.
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Citations
14 Claims
- 1. Apparatus for processing an analog input signal by integrating the analog input signal with respect to time thereof for an integration period and correcting errors in the integrated signal due to errors in the analog input signal comprising control means (26) for defining the integration period and generating a plurality of control signals, the number of control signals generated being smaller than that required by the Nyquist sampling theorem for a predetermined highest frequency component of the input signal, a sampling circuit for sampling the input signal, a gate for applying the control signals to the sampling means such that said sampling circuit derives sampled signals in response to said control signals that bear a functional relationship with errors in the input signal, means for processing the sampled signals and subjecting the sampled signals to an algorithmic process representative of said functional relationship to quantify the error in the input signal represented by the sampled signals, means for integrating the processed sample results, means for applying the control signals to the means for integrating the processed sample results to quantity the effect of errors on the integrated analog input signal and means for modifying the integrated input signal in accordance with the quantified effect to correct errors in the integrated input signal.
Specification