comm.PhaseFrequencyOffset
Apply phase and frequency offsets to input signal
Description
The PhaseFrequencyOffset object applies phase
and frequency offsets to an incoming signal.
To apply phase and frequency offsets to the input signal:
Define and set up your phase frequency offset object. See Construction.
Call
stepto apply phase and frequency offsets to the input signal according to the properties ofcomm.PhaseFrequencyOffset. The behavior ofstepis specific to each object in the toolbox.
Note
Starting in R2016b, instead of using the step method
to perform the operation defined by the System object™, you can
call the object with arguments, as if it were a function. For example, y
= step(obj,x) and y = obj(x) perform
equivalent operations.
Construction
H = comm.PhaseFrequencyOffset creates a
phase and frequency offset System object, H.
This object applies phase and frequency offsets to an input signal.
H = comm.PhaseFrequencyOffset( creates
a phase and frequency offset object, Name,Value)H, with each
specified property set to the specified value. You can specify additional
name-value pair arguments in any order as (Name1,Value1,...,NameN,ValueN).
Properties
|
Phase offset Specify the phase offset in degrees. The default is When you set the When you set this property to an M-by-1 vector,
the object applies time varying phase offsets, specified in the vector
of this property, to each column of the input to the When you set this property to a 1-by-N vector,
the object applies the i-th constant phase offset
of this property to the i-th column of the input
to the When you set this property to an M-by-N matrix,
the object applies the i-th time varying phase
offsets, specified in the i-th column of this property,
to the i-th column of the input to the |
|
Source of frequency offset Specify the source of the frequency offset as one of |
|
Frequency offset Specify the frequency offset in Hertz. The default is This property applies when you set the When you set this property to a scalar value, the object applies
the constant specified frequency offset to each column of the input
to the When you set this property to an M-by-1 vector,
the object applies time-varying frequency offsets. These offsets are
specified in the property, to each column of the input to the When you set this property to a 1-by-N vector,
the object applies the i-th constant frequency
offset in this property to the i-th column of the
input to the When you set this property to an M-by-N matrix,
the object applies the i-th time varying frequency
offset. This offset is specified in the i-th column
of this property and to the i-th column of input
to the |
|
Sample rate Specify the sample rate of the input samples in seconds as a
double-precision, real, positive scalar value. The default is
|
Methods
| step | Apply phase and frequency offsets to input signal |
| Common to All System Objects | |
|---|---|
release | Allow System object property value changes |
Examples
Introduce Phase Offset to 16-QAM Signal
Introduce a phase offset to a 16-QAM signal and view its effect on the constellation.
Create a phase frequency offset System object™. Set the phase offset to 30 degrees.
pfo = comm.PhaseFrequencyOffset('PhaseOffset',30);Generate random symbols and apply 16-QAM modulation.
M = 16; data = (0:M-1)'; modData = qammod(data,M);
Plot the 16-QAM constellation.
scatterplot(modData);
title(' Original Constellation')
xlim([-5 5])
ylim([-5 5])
Introduce a phase offset using pfo and plot the offset constellation. Note that it has been shifted 30 degrees.
impairedData = pfo(modData);
scatterplot(impairedData);
title('Constellation after phase offset')
xlim([-5 5])
ylim([-5 5])
Algorithms
This object implements the algorithm, inputs, and outputs described on the Phase/Frequency Offset block reference page. The object properties correspond to the block parameters, except:
The object provides a SampleRate property, which you must specify. The block
senses the sample time of the signal and therefore does not have a corresponding
parameter. |