I have a question about the return value of phased.Ran​geAngleRes​ponse.

In the example "Integrated Sensing and Communication II: Communication-Centric Approach Using MIMO-OFDM", the helperPositionHeatmap function is used with moving scatterers. I’m curious about what determines the color of the heatmap in this case.

Below is a portion of the code from the helperPositionHeatmap function, and I’m particularly wondering about the value rar. It seems like the heatmap colors are based on this rar value, so I’d like to know specifically what it represents.

rangeAngleResponse = phased.RangeAngleResponse('SensorArray', obj.ReceiveArray, ...
    'RangeMethod', 'FFT', ...
    'SampleRate', obj.SampleRate, ...
    'SweepSlope', obj.Bandwidth / obj.OFDMSymbolDuration, ...
    'OperatingFrequency', obj.CarrierFrequency, ...
    'ReferenceRangeCentered', false);

[rar, r, theta] = rangeAngleResponse(conj(data));

My guess is that it represents the strength of the signal reflected by moving objects, but I'm not completely sure, so I wanted to ask.

Answer 1

[Pratyush Swain]

Hi JG,

I guess you are right in your understanding. By searching for outputs for the phased.RangeAngleResponsefunction, the 'rar' or the 'RESP' seems to be range angle response data matrix containing the computed response values for different ranges and angles.

Its dimension depends upon the 'RangeMethod' and 'DechirpInput' properties passed in the function

[RESP,RANGE,ANG] = phased.RangeAngleResponse('SensorArray', obj.ReceiveArray, ...
    'RangeMethod', 'FFT', ...
    'SampleRate', obj.SampleRate, ...
    'SweepSlope', obj.Bandwidth / obj.OFDMSymbolDuration, ...
    'OperatingFrequency', obj.CarrierFrequency, ...
    'ReferenceRangeCentered', false ...
    'DechirpInput', true)

For more information, please go through the ouput arguments for the phased.RangeAngleResponse function:

https://www.mathworks.com/help/phased/ref/phased.rangeangleresponse-system-object.html#mw_3b2a0953-43ad-4130-b8c8-82563dd704c6

Hope this helps.