MATLAB Coder: Undefined function or Variable, the first assignment to a local variable determines its class

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mounika 2019-9-20

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评论： mounika 2019-9-20

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Hi,

I am using MATLAB Coder to convert a simple FSK Modem to C Code. Following are my codes:

Modulator Function:

function modSignal = my4FSKmod(data)
M = 4;
freqSep = 200;
fskMod = comm.FSKModulator(M,freqSep,'BitInput',1);
modSignal = step(fskMod,data);
end

Demodulator Function:

function demodData = my4FSKdemod(receivedSignal)
M = 4;
freqSep = 200;
fskDemod = comm.FSKDemodulator(M,freqSep,'BitOutput',1);
demodData = zeros(100,1);
demodData = step(fskDemod,receivedSignal);
end

My Test Code:

data = randi([0 1],100,1);
mod_out = my4FSKmod(data);
demod_out = my4FSKdemod(mod_out);
isequal(data,demod_out);

I went through few MATLAB Answer links and introduced the intialization of the 'demodData', but I still get this issue. Am I missing anything? kindly advice

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Walter Roberson 2019-9-20

You should probably not be building your modulator and demodulator every step. You should be building them at the time you initialize your system, save the variable somewhere handy, and recall it each time you need it. This is especially important for carrying on processing of a partially-used buffer (your packets are probably going to be varying size, due to data compression and error correction that you insert.)

mounika 2019-9-20

Thank you Walter for your respone. So is it okay if I create another function (as I have to convert it to c) where I initialise the modulator and demodulator and later use the for modulation and demodulation.

It will be greatly helpful, if you can provide an example on how to

Thanks in Advance

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