Knock By Decimation Coefficient Set

This block applies the supplied filter coefficients to the associated Knock System by Decimation. The decimation supports cascadable 4th order IIR filters. The selected order defines the number of coefficients exxected and must marry up with what the Knock System definition expects.

Block ID

Knock Decimation Coefficient Set

Library

motohawk_knock_by_decimation_lib

Description

Signals

Coefficients

The decimation coefficients are implemented as cascadable 4th order IIR filters. A base coefficient set is described as a 9x1 vector of int32 values. They have a fixed point representation such that 1.0 is described by the value of 83688608. The filter has the following form.

Typically the Coefficients Definition block is used to specify the coefficients as this will simplify the handling of the coefficient fixed point conversion, simplify the ordering and will also allow the coefficients to be exposed appropriately to a calibration tool.

Coefficients are physcially applied at the end of the next source window that occurs on the system so that the integral values are deterministic. This does mean that coefficients are not initially applied to the system until there is speed.

Status Output

The status port reports whether the coefficients could be applied. It should be treated as an enumeration with the following definitions

0: OK

The coefficients could be applied.

1: Error - Order Mismatch

The referenced Knock System by Decimation expected an order that was different to what was specified by this block.

2: Error - Range

Some of the coefficients exceed the value that the decimation filter system can handle.

Block Parameters

Parameter Field	Values	Comments/Description
Knock System Name	Alpha-numeric text, quote enclosed	Name of the Knock System definition that these coefficients should be applied to.
IIR Filter Order	Drop down list	Defines the filter order that this block expects.