User Reference:IIRBandpass

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Synopsis

Design an IIR filter consisting of up to three parts (high-pass, low-pass and notch) and apply it as part of the signal-processing chain. To use it as a bandpass, specify the desired lower end of the band as a high-pass corner, and the desired upper end of the band as a low-pass corner.

The filters are implemented as a Butterworth filters of the specified order.

Authors

Jeremy Hill

Parameters

HighPassCorner

High-pass cutoff frequency. The default is 0, which disables the high-pass.

HighPassOrder

Filter order for the high-pass. The default is 2. A value of 0 disables the high-pass.

LowPassCorner

Low-pass cutoff frequency. The default is 0, which disables the low-pass.

LowPassOrder

Filter order for the low-pass. The default is 4. A value of 0 disables the high-pass.

NotchCenter

Notch center frequency. The default is 0, which disables the notch filter.

NotchOrder

Filter order for the notch. The default is 4. A value of 0 disables the notch filter.

Downsample

If LowPassCorner is set, downsample to a sampling rate of circa 4*LowPassCorner provided that is smaller than the current sampling rate. Downsampling is always is done by an integer factor such that the resulting sampling rate is close to (and larger than) 4*LowPassCorner.

The default is 1 (do downsampling).

Rectification

If set to 1, negative values will be replaced with zeros (Half-Wave). If set to 2, negative values will be replaced with their absolute values (Full-Wave). Set to 0 (the default) to disable rectification. Note that rectification is done after bandpass filtering, so another low pass filter is likely required to obtain an amplitude estimate.

States

None.