zpk
Zero-pole-gain conversion of discrete-time filter System object
Description
Examples
Highpass Filter in Zero-Pole-Gain Form
Compute the zero-pole-gain form of the highpass filter using the zpk
function.
Design a minimum order highpass FIR filter with a passband frequency of 75 kHz and passband ripple of 0.2 dB. Specify a sample rate of 200 kHz.
hFilt = dsp.HighpassFilter(PassbandFrequency=75e3,...
PassbandRipple=0.2,SampleRate=200e3)
hFilt = dsp.HighpassFilter with properties: FilterType: 'FIR' DesignForMinimumOrder: true StopbandFrequency: 8000 PassbandFrequency: 75000 StopbandAttenuation: 80 PassbandRipple: 0.2000 NormalizedFrequency: false SampleRate: 200000 Use get to show all properties
Find the zeros, poles, and the gain of the designed filter using the zpk
function.
[z,p,k] = zpk(hFilt)
z = 8×1 complex
17.2236 + 0.0000i
-3.0709 + 0.0000i
0.9732 + 0.2300i
0.9732 - 0.2300i
0.9954 + 0.0957i
0.9954 - 0.0957i
-0.3256 + 0.0000i
0.0581 + 0.0000i
p = 8×1
0
0
0
0
0
0
0
0
k = -0.0023
Input Arguments
sysobj
— Input filter
filter System object
arithType
— Arithmetic type
'double'
(default) | 'single'
| 'Fixed'
Arithmetic used in the filter analysis, specified as 'double'
,
'single'
, or 'Fixed'
. When the arithmetic
input is not specified and the filter System object is unlocked, the analysis tool assumes a double-precision filter. When the
arithmetic input is not specified and the System object is locked, the function performs the analysis based on the data type of
the locked input.
The 'Fixed'
value applies to filter System objects with fixed-point
properties only.
When the 'Arithmetic'
input argument is specified as
'Fixed'
and the filter object has the data type of the
coefficients set to 'Same word length as input'
, the arithmetic
analysis depends on whether the System object is unlocked or locked.
unlocked –– The analysis object function cannot determine the coefficients data type. The function assumes that the coefficients data type is signed, has a 16-bit word length, and is auto scaled. The function performs fixed-point analysis based on this assumption.
locked –– When the input data type is
'double'
or'single'
, the analysis object function cannot determine the coefficients data type. The function assumes that the data type of the coefficients is signed, has a 16-bit word length, and is auto scaled. The function performs fixed-point analysis based on this assumption.
To check if the System object is locked or unlocked, use the isLocked
function.
When the arithmetic input is specified as 'Fixed'
and the filter
object has the data type of the coefficients set to a custom numeric type, the object
function performs fixed-point analysis based on the custom numeric data type.
Output Arguments
z
— Zeros
column vector
Zeros of the filter, returned as a column vector.
Data Types: double
Complex Number Support: Yes
p
— Poles
column vector
Poles of the filter, returned as a column vector.
Data Types: double
Complex Number Support: Yes
k
— Gain
real scalar
Gain of the filter, returned as a real scalar.
Data Types: double
Version History
Introduced in R2011aR2024b: Support for dsp.VariableFIRDecimator
and dsp.VariableFIRInterpolator
Objects
Starting in R2024b, the zpk
analysis function supports the dsp.VariableFIRDecimator
and dsp.VariableFIRInterpolator
objects.
R2024b: dsp.BiquadFilter
object warns
The dsp.BiquadFilter
object issues a warning and will be removed in a
future release. Use the dsp.SOSFilter
object
instead. For more information on how to replace your existing code, see the
Compatibility Considerations section in the dsp.BiquadFilter
reference page.
R2024b: Support for dsp.DCBlocker
object
Starting in R2024b, this function supports the dsp.DCBlocker
object.
R2023b: Support for dsp.ParallelFilter
Object
Starting in R2023b, the zpk
analysis function supports the dsp.ParallelFilter
object.
R2023b: dsp.BiquadFilter
object will be removed
The dsp.BiquadFilter
object will be removed in a future release. Use
the dsp.SOSFilter
object
instead.
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