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plotResponse

System object: phased.RangeDopplerResponse
Package: phased

Plot range-Doppler response

Syntax

plotResponse(H,x)
plotResponse(H,x,xref)
plotResponse(H,x,coeff)
plotResponse(___,Name,Value)
hPlot = plotResponse(___)

Description

plotResponse(H,x) plots the range-Doppler response of the input signal, x, in decibels. This syntax is available when you set the RangeMethod property to 'FFT' and the DechirpInput property to false.

plotResponse(H,x,xref) plots the range-Doppler response after performing a dechirp operation on x using the reference signal, xref. This syntax is available when you set the RangeMethod property to 'FFT' and the DechirpInput property to true.

plotResponse(H,x,coeff) plots the range-Doppler response after performing a matched filter operation on x using the matched filter coefficients in coeff. This syntax is available when you set the RangeMethod property to 'Matched filter'.

plotResponse(___,Name,Value) plots the angle-Doppler response with additional options specified by one or more Name,Value pair arguments.

hPlot = plotResponse(___) returns the handle of the image in the figure window, using any of the input arguments in the previous syntaxes.

Input Arguments

H

Range-Doppler response object.

x

Input data. Specific requirements depend on the syntax:

  • In the syntax plotResponse(H,x), each column of the matrix x represents a dechirped signal from one frequency sweep. The function assumes all sweeps in x are consecutive.

  • In the syntax plotResponse(H,x,xref), each column of the matrix x represents a signal from one frequency sweep. The function assumes all sweeps in x are consecutive and have not been dechirped yet.

  • In the syntax plotResponse(H,x,coeff), each column of the matrix x represents a signal from one pulse. The function assumes all pulses in x are consecutive.

In the case of an FMCW waveform with a triangle sweep, the sweeps alternate between positive and negative slopes. However, phased.RangeDopplerResponse is designed to process consecutive sweeps of the same slope. To apply phased.RangeDopplerResponse for a triangle-sweep system, use one of the following approaches:

  • Specify a positive SweepSlope property value, with x corresponding to upsweeps only. In the plot, change the tick mark labels on the horizontal axis to reflect that the Doppler or speed values are half of what the plot shows by default.

  • Specify a negative SweepSlope property value, with x corresponding to downsweeps only. In the plot, change the tick mark labels on the horizontal axis to reflect that the Doppler or speed values are half of what the plot shows by default.

You can specify this argument as single or double precision.

xref

Reference signal, specified as a column vector having the same number of rows as x. You can specify this argument as single or double precision.

coeff

Matched filter coefficients, specified as a column vector. You can specify this argument as single or double precision.

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 quotes. You can specify several name and value pair arguments in any order as Name1,Value1,...,NameN,ValueN.

'NormalizeDoppler'

Set this value to true to normalize the Doppler frequency. Set this value to false to plot the range-Doppler response without normalizing the Doppler frequency. This parameter applies when you set the DopplerOutput property of H to 'Frequency'.

Default: false

'Unit'

The unit of the plot. Valid values are 'db', 'mag', and 'pow'.

Default: 'db'

Examples

expand all

Compute the range-Doppler response of an FMCW signal using an FFT.

Load data for an FMCW signal that has not been dechirped. The signal contains the return from a target about 2200 m away. The signal has a normalized Doppler frequency of approximately -0.36 relative to the radar.

load RangeDopplerExampleData;

Create a range-Doppler response object.

hrdresp = phased.RangeDopplerResponse(...
   'RangeMethod','FFT',...
   'PropagationSpeed',RangeDopplerEx_Dechirp_PropSpeed,...
   'SampleRate',RangeDopplerEx_Dechirp_Fs,...
   'DechirpInput',true,...
   'SweepSlope',RangeDopplerEx_Dechirp_SweepSlope);

Plot the range-Doppler response.

plotResponse(hrdresp,...
   RangeDopplerEx_Dechirp_X,RangeDopplerEx_Dechirp_Xref,...
   'Unit','db','NormalizeDoppler',true)