MATLAB: Phase Noise on QPSK Signal

Question

I am working with MATLAB R2016a. When I attempt to execute the below code I get the following error:

Array formation and parentheses-style indexing with objects of class

'comm.QPSKModulator' is not allowed. Use objects of class

'comm.QPSKModulator' only as scalars or use a cell array.

Error in qpskemv (line 23)

x = qpskModulator(d);

CODE:

qpskModulator = comm.QPSKModulator;

phNoise = comm.PhaseNoise('Level',-55,'FrequencyOffset',20,'SampleRate',1000);

d = randi([0 3],1000,1);

x = qpskModulator(d);

y = phNoise(x);

There is a note stating of course: "Starting in R2016b, instead of using the step method to perform the operation defined by the System object™, you can call the object with arguments, as if it were a function. For example, y = step(obj,x) and y = obj(x) perform equivalent operation"

Can anyone tell me how to use this step to correct the above code?

Answer 1

As the note suggests, y = obj(x) is equivalent to y = step(obj,x) starting R2016b. In R2016a, y = step(obj,x) is the correct syntax. Replace these two lines -

x = qpskModulator(d);

y = phNoise(x);

with -

x = step(qpskModulator,d);

y = step(phNoise,x);

Thanks,

Chandresh