sigstrength error with Satellite Toolbox example code

I'm having a problem with the tutorial "Interference from Satellite Constellation on Communications Link". https://www.mathworks.com/help/satcom/ug/interference-from-satellite-constellation-on-comms-link.html

Specifically, the function sigstrength(). It does not like the input arguments given.

% Calculate the power at receiver input corresponding to the downlink from
% the MEO satellite.
[~,downlinkPowerRxInput] = sigstrength(downlink); % In dBW

% Calculate the interference power at receiver input corresponding to each
% LEO satellite.
[~,interferencePowerRxInput] = sigstrength(lnkInterference); % In dBW

The error to these calls of sigstrength() is "Check for incorrect argument data type or missing argument in call to function 'sigstrength'." - the same error for both. For context, "downlink" and "lnkInterference" are of type "Link".

When I tried sigstrength() on its own to get more details about the error, it returned "Unrecognized function or variable 'sigstrength'." I checked the documentation, and sigstrength() is defined in both the Antenna and Communications Toolboxes, both of which I have. In the documentation, it is defined as "ss = sigstrength(rx,tx)" so I tried the following:

% [~,downlinkPowerRxInput] = sigstrength(txMEOSat,rxGs); % In dBW
% [~,downlinkPowerRxInput] = sigstrength(rxGs,txMEOSat); % In dBW

It did not work. Perhaps because both versions of the function require inputs of type "txsite" and "rxsite", rather than "transmitter" and "receiver".

Could anyone help me resolve this issue? Do you have ideas for what to try next to get this example code working?

[Walter Roberson]

For context, "downlink" and "lnkInterference" are of type "Link".

Link is an object from the third party Robotics Toolbox; https://petercorke.com/toolboxes/robotics-toolbox/ that represents robotic arm linkages. There is no hope of using those with the Antenna or Communications toolboxes.

[Lieselotte Heinrich]

No, they are of type link from the satellite communications toolbox.

If you look into the example code from the tutorial I was referencing,

downlink = link(txMEOSat,rxGs);
lnkInterference = link(txInterferingSat,rxGs);

Where:

txMEOSat = transmitter(meoSat, ...
    Frequency = txMEOFreq, ...     % In Hz
    Power = 11);        
txInterferingSat = transmitter(interferingSat, ...
    Frequency = interferenceFreq, ...                   % In Hz
    Power = 10+10*rand(1,numel(interferingSat)));       % In dBW
rxGs = receiver(gim, ...
    MountingLocation = [0;0;1]); % In m

[Walter Roberson]

Which MATLAB version are you using? The function was added in r2022b

https://www.mathworks.com/help/satcom/ref/satcom.satellitescenario.link.sigstrength.html

[LI]

I face the same problem. It also happens to the function link and ebn0 when I want to change the propagation model.

Answer 1

[Gyan Vaibhav]

Hi Lieselotte,

I understand that you are trying to follow the tutorial "Interference from Satellite Constellation on Communications Link". However, you are facing an error with the section where “sigstrength” function is used. It throws an error regarding improper input to the function.

I tried following the same example and I was not able to reproduce the error. The example runs fine, and as expected.

Here are a few tips on how to overcome this problem:

• Update to the latest release of MATLAB available to you, as the function operates without issue in R2023b. Given that the "sigstrength" function was introduced in R2022b, earlier versions may be prone to errors.
• Opening the example directly within MATLAB could be beneficial in determining whether the issue lies with the tutorial or if an unintended error has been introduced. The following command can be utilized to open the example:

openExample('satcom_antenna_phased/InterferenceFromSatConstellationOnCommunicationsLinkExample')

• Alternatively, the same example can be accessed in MATLAB Online, directly from the “Open in MATLAB Online” button on the following link.

https://www.mathworks.com/help/satcom/ug/interference-from-satellite-constellation-on-comms-link.html

• If the problem persists, I suggest you reach out to MathWorks Technical Support here: https://www.mathworks.com/support/contact_us.html

Hope this helps.

Thanks

Gyan