Digital Filter Box

Overview

With Moku:Lab’s Digital Filter Box, you can interactively design and generate different types of infinite impulse response filters with output sampling rates of 122 kHz and 15.625 MHz. Select between lowpass, highpass, bandpass and bandstop filter shapes with up to seven fully configurable types including Butterworth, Chebyshev, and Elliptical.

FAQ


Can I load my own filter coefficients?

Yes! Moku:Lab’s Digital Filter Box implements infinite impulse response (IIR) filters using 4 cascaded Direct Form I second-order stages with a final output gain stage. To specify a filter, you must supply a text file containing the filter coefficients. The file should have six coefficients per line, with each line representing a single stage. If output scaling is required, this should be given on the first line. Each coefficient must be in the range [-4.0, +4.0). Internally, these are represented as signed 48-bit fixed-point numbers, with 45 fractional bits. The output scaling can be up to 8,000,000. Filter coefficients can be computed using signal processing toolboxes in e.g. MATLAB or SciPy.


How are the filters implemented?

The Digital Filter Box implements infinite impulse response (IIR) filters using four cascaded Direct Form I second-order stages with a final output gain stage. To specify a filter, you must supply a text file containing the filter coefficients. The file should have six coefficients per line, with each line representing a single stage. If output scaling is required, this should be given on the first line.