MATLAB: Error: MATLAB cannot run this file because doppler.m shadows it in the MATLAB path.

MATLABshadows

I am trying to use a function called 'doppler.m' from a 3rd party toolkit, but whenever I run the function MatLab will default to its build-in function, which currently just returns an error. When I try to place a breakpoint in the file, I get:

MATLAB cannot run this file because C:\…2b\toolbox\comm\comm\@doppler\doppler.m shadows it in the MATLAB path.

I added my folder higher in the path than MatLab, didn't help. I even copied my doppler.m file into my current folder, didn't help. When I run "which doppler -all", I get:

C:\Program Files\MATLAB\R2012b\toolbox\comm\comm\@doppler\doppler.m % doppler constructor

Y:\Software\Test\pvt\matlab_code\doppler.m % Shadowed

C:\Users\e427259\Documents\master\Tools\MatLab Toolkits\Constell\doppler.m % Shadowed

I'm running Matlab R2012b. Thanks.

Best Answer

You can move the external toolkit to a "package". Alternatively you could rename the function, but this might concern other M-files of this toolbox also, which call doppler.m.

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MATLAB: How to get the signal strength for individual rays when I do the ray tracing

As of R2020a you can call raytrace with an output argument to programmatically access each ray's geometry and propagation characteristics. Here is an example you can run which shows one of the returned Ray objects:

% Launch Site Viewer with buildings in Chicago
viewer = siteviewer("Buildings","chicago.osm");
% Create transmitter site on a building
tx = txsite("Latitude",41.8800, ...
    "Longitude",-87.6295, ...
    "TransmitterFrequency",2.5e9);
% Create receiver site near another building
rx = rxsite("Latitude",41.881352, ...
    "Longitude",-87.629771, ...
    "AntennaHeight",30);
% Visualize propagation paths
raytrace(tx,rx,"NumReflections",[1 2]);
% Return propagation paths
rays = raytrace(tx,rx,"NumReflections",[1 2]);
disp(rays{1}(1))

The Ray object stores the path loss but not the received power. You can get an array of path loss values corresponding to the propagation paths like this:

pl = [rays{1}.PathLoss]

Now you can apply the Friis equation to compute received power along each propagation path. The code below uses antenna gains of 0, which corresponds to the default 'isotropic' antenna used above. As a result the values below match the signal strength values shown in Site Viewer when you click on each path.

fq = tx.TransmitterFrequency;
Ptx_dBm = 10 * log10(1000*tx.TransmitterPower); % Convert W to dBm
Gtx_db = 0; % Transmitter antenna gain
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MATLAB: MATLAB example not working.

Typical reasons why that function might not work:

scatteringchanmtx was introduced in R2017b. It will not work with earlier MATLAB versions. You did not tag the question with the MATLAB version you are using, but it helps us when you do.
the toolbox is not installed (check using ver).
the toolbox is not licensed (check https://www.mathworks.com/licensecenter).
the Search path has been changed so the function cannot be found.

Best Answer

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MATLAB: How to get the signal strength for individual rays when I do the ray tracing

MATLAB: MATLAB example not working.

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