Finite Impulse Response Filter (FIR Filter)

This operator implements a finite impulse response filter.

It returns a weighted average of the current and previous pings.

Echoview accepts a single operand of the following data types as input:

See: FIR algorithm.

Settings

The Finite Impulse Response Filter Variable Properties dialog box pages include (common) Variable Properties pages and these operator pages:

Operands page

FIR Filter page

Setting

Description

Coefficient

Enter the coefficient to be used to alter signal content.

Algorithm

FIR filter

The result for any given data point may be written as:

Result(0,d) = Operand(0,d)
Result
(p,d) = C * Operand(p,d) + (1-C) * Operand(p-1,d)            where p>0

Where:

p identifies the ping
d
identifies the data point (each ping contains a number of data points)
C
is the coefficient entered on the FIR page of the Variable Properties dialog box.
Result
(p,d) is the value of the data point d in ping p in the resulting variable.
Operand
(p,d) is the value of the data point d in ping p in the operand variable.

Hence, if C = 1 the filter will make a copy of the operand variable, and if C = 0, the filter will make a copy of the operand variable shifted forward in time by one ping.

Notes:

See also

About virtual variables
Operator licensing in Echoview