zplane

Zero-poles plots for filters

Syntax

zplane(Hq)
zplane(Hq,plotoption)
zplane(Hq,plotoption,plotoption2)
zplane(Hq,Name,Value)
[zq,pq,kq] = zplane(Hq)
[zq,pq,kq,zr,pr,kr] = zplane(Hq)

Description

zplane(Hq) plots the zeros and poles of a quantized filter Hq in the current figure window. The poles and zeros of the quantized and unquantized filters are plotted by default. The symbol o represents a zero of the unquantized reference filter, and the symbol x represents a pole of that filter. The symbols and + are used to plot the zeros and poles of the quantized filter Hq. The plot includes the unit circle for reference.

zplane(Hq,plotoption) plots the poles and zeros associated with the quantized filter Hq according to one specified plot option. The string plotoption can be either of the following reference filter display options:

  • 'on' to display the poles and zeros of both the quantized filter and the associated reference filter (default)

  • 'off' to display the poles and zeros of only the quantized filter

zplane(Hq,plotoption,plotoption2) plots the poles and zeros associated with the quantized filter Hq according to two specified plot options. The string plotoption can be selected from the reference filter display options listed in the previous syntax. The string plotoption2 can be selected from the section-by-section plotting style options described in the following list:

  • 'individual' to display the poles and zeros of each section of the filter in a separate figure window

  • 'overlay' to display the poles and zeros of all sections of the filter on the same plot

  • 'tile' to display the poles and zeros of each section of the filter in a separate plot in the same figure window

zplane(Hq,Name,Value) returns a phase response with additional options specified by one or more Name,Value pair arguments. Name-value pair arguments are only available if Hq is a filter System object™.

[zq,pq,kq] = zplane(Hq) returns the vectors of zeros zq, poles pq, and gains kq. If Hq has n sections, zq, pq, and kq are returned as 1-by-n cell arrays. If there are no zeros (or no poles), zq (or pq) is set to the empty matrix [].

[zq,pq,kq,zr,pr,kr] = zplane(Hq) returns the vectors of zeros zr, poles pr, and gains kr of the reference filter associated with the quantized filter Hq. It also returns the vectors of zeros zq, poles pq, and gains kq for the quantized filter Hq.

Input Arguments

expand all

Hq

hfilt is either:

Name-Value Pair Arguments

Specify optional comma-separated pairs of Name,Value arguments. Name is the argument name and Value is the corresponding value. Name must appear inside single quotes (' '). You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'Arithmetic' — Value types:‘double' | 'single' | 'fixed'

For filter System object inputs only, specify the arithmetic used during analysis. When you specify 'double' or 'single', the function performs double- or single-precision analysis. When you specify 'fixed' , the arithmetic changes depending on the setting of the CoefficientDataType property and whether the System object is locked or unlocked.

 Details for Fixed-Point Arithmetic

When you do not specify the arithmetic for non-CIC structures, the function uses double-precision arithmetic if the filter System object is in an unlocked state. If the System object is locked, the function performs analysis based on the locked input data type. CIC structures only support fixed-point arithmetic.

Output Arguments

zq

Zeros of quantized filter.

pq

Poles of quantized filter.

kq

Gains of quantized filter.

zr

Zeros of reference filter.

pr

Poles of reference filter.

kr

Gains of reference filter.

Examples

Create a quantized filter Hq from a fourth-order digital filter with cutoff frequency of 0.6. Plot the quantized and unquantized poles and zeros associated with this quantized filter.

[b,a] = ellip(4,.5,20,.6);
Hq = dfilt.df2(b, a);
Hq.arithmetic = 'fixed';
zplane(Hq);

See Also

|

Was this topic helpful?