advanced audio recording

High Precision FIR-Filter for Audio-DSP in VHDL

32k Sample RAM

32k Coefficient RAM

24 Bit

A high precision FIR filter module in VHDL for digital audio processors in FPGA

A multi channel accumulation pipeline is used to perform continous operation on the incoming audio data by applying progammable filter coefficients and smoothing the audio data with a built in window. A modified Blackman-Harris-Window is used for this. Operation mode is 4 times oversampling using complex multiplication (I x Q). The audio data ist then resynthesized with smooting filter from out of the 4 pipelines.

Thus both low deviation because of windowing and high bandwidth because of limited filter size are combined effectively.

The spectral response ranges from 6Hz ... 20 kHz (-3dB) and 16 Hz ... 16 kHz (<1dB) operating well for common audio applications.

Read about a high precision filter on a S3

96 kHz
Audio DSP


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