why conj is used in this example?(Scan_Radar_Using_a_Uniform_Rectangular_Array)
1 回表示 (過去 30 日間)
古いコメントを表示
when i learn example in matlab: Scan_Radar_Using_a_Uniform_Rectangular_Array.
I have a question,why conj is used in this code?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/163831/image.png)
In order to understand this question.I have tried phased.SteeringVector and phased.PhaseShiftBeamformer function. When scan_angle is 45(deg),the pattern excited by weights obtained by these functions is showned below.At the same time, it shows that when conj is used , the main lobe is directed to -45(deg).
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/163832/image.png)
In this way,why conj is used in the example to detect target?(Scan_Radar_Using_a_Uniform_Rectangular_Array)
0 件のコメント
回答 (1 件)
Honglei Chen
2017 年 5 月 8 日
The confusion probably comes from the fact that the weights in radiator and pattern plot get treated slightly different.
In a beam pattern plot, the convention is to do an inner product of the steering vector and the signal vector, therefore the conjugate is automatically applied during the inner product stage.
However, in radiator, the weights are what gets directly applied to the signal. At each element, you can think of that a weight gets multiplied to the signal, it may or may not be the steering vector. so it needs a conjugate to point to the right direction.
HTH
10 件のコメント
Honglei Chen
2017 年 5 月 17 日
This is because you passed the signal through the dechirp. If you look at the help of dechirp, it shows that the signal gets conjugated. So if you want to use dechirped signal to do the DOA estimation, you need to conjugate it again, like
xr_doa = conj(xr_doa_up);
Alternatively, you can just use the signal before the dechirp, like
[y_doa,doas] = step(hdoa,xt);
HTH
参考
カテゴリ
Help Center および File Exchange で Get Started with Phased Array System Toolbox についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!