Template Class MultiChannelTransferFunctionFilter

Inheritance Relationships

Base Type

Class Documentation

template<typename T>
class MultiChannelTransferFunctionFilter : public filters::MultiChannelFilterBase<T>

One-dimensional digital filter class.

This class calculates the output for \(N\) one-dimensional digital filters. Where the input, \(x\), is a ( \(N\) x 1) vector of inputs and the output, \(y\), is a ( \(N\) x 1) vector of outputs. The filter is described by vectors \(a\) and \(b\) and implemented using the standard difference equation:

\[\begin{eqnarray*} a[0]*y[n] = b[0]*x[n] &+& b[1]*x[n-1]+ ... + b[n_b]*x[n-n_b]\ \ &-& a[1]*y[n-1]- ... - a[n_a]*y[n-n_a] \end{eqnarray*}\]

If \(a[0]\) is not equal to 1, the coefficients are normalized by \(a[0]\).

Example xml config:

<filter type=”MultiChannelTransferFunctionFilter” name=”filter_name”>

<params a=”1.0 0.5” b=”0.2 0.2”>

</filter>

Public Functions

MultiChannelTransferFunctionFilter()

Construct the filter.

~MultiChannelTransferFunctionFilter() override

Destructor to clean up.

virtual bool configure() override

Configure the filter with the correct number of channels and params.

Parameters:

  • number_of_channels – The number of inputs filtered.

  • config – The xml that is parsed to configure the filter.

virtual bool update(const std::vector<T> &data_in, std::vector<T> &data_out) override

Update the filter and return the data seperately.

Parameters:

  • data_in – vector<T> with number_of_channels elements

  • data_out – vector<T> with number_of_channels elements

Protected Attributes

std::unique_ptr<RealtimeCircularBuffer<std::vector<T>>> input_buffer_

The input sample history.

std::unique_ptr<RealtimeCircularBuffer<std::vector<T>>> output_buffer_

The output sample history.

std::vector<T> temp_
std::vector<double> a_

Transfer functon coefficients (output).

std::vector<double> b_

Transfer functon coefficients (input).