Signal processing apparatus, signal processing method and non-transitory computer-readable recording medium

A signal processing apparatus comprising:

• a memory to store sampled input values and filter coefficients;
• and
• a processor configured to:
• obtain an input signal;
• sample the input signal at a sampling rate to generate a set of the sampled input values, the set of sampled input values including a number 2L+1 of sampled input values;
• generate a set of the filter coefficients for a Finite Impulse Response (FIR) filter of order 2L, wherein each of the filter coefficients is based on a corresponding sampled input value in the set of sampled input values;
• set a delay time equal to a number N divided by the sampling rate, wherein the number N is less than a number L, from which the number 2L+1 is derived, and wherein the number L determines an expected power of an output value for the FIR filter;
• select a subset of sampled input values from the set of sampled input values, the subset of sampled input values including a number N+L+1 of sampled input values that have been most recently sampled;
• select a subset of filter coefficients from the set of filter coefficients, the subset of filter coefficients including the number N+L+1 of filter coefficients corresponding to sampled input values that are not most recently sampled;
• and
• combine the subset of sampled input values with the subset of filter coefficients to generate the output value for the FIR filter, the output value for the FIR filter being delayed from the input signal by an amount of time equal to the delay time.

One or more non-transitory computer readable recording media encoded with instructions that, when executed by a processor of a computing device, cause the processor to:

• obtain an input signal;
• sample the input signal at a sampling rate to generate a set of sampled input values, the set of sampled input values including a number 2L+1 of sampled input values;
• generate a set of filter coefficients for a Finite Impulse Response (FIR) filter of order 2L, wherein each of the filter coefficients is based on a corresponding sampled input value in the set of sampled input values;
• set a delay time equal to a number N divided by the sampling rate, wherein the number N is less than a number L, from which the number 2L+1 is derived, and wherein the number L determines an expected power of an output value for the FIR filter;
• select a subset of sampled input values from the set of sampled input values, the subset of sampled input values including a number N+L+1 of sampled input values that have been most recently sampled;
• select a subset of filter coefficients from the set of filter coefficients, the subset of filter coefficients including the number N+L+1 of filter coefficients corresponding to sampled input values that are not most recently sampled;
• and
• combine the subset of sampled input values with the subset of filter coefficients to generate the output value for the FIR filter, the output value for the FIR filter being delayed from the input signal by an amount of time equal to the delay time.