I have a PWM signal in MapleSim and want to have a spectrum analysis of it. The time domain signal should be transfomed into a frequency domain signal, to get the harmonics of this signal.

My first intention was to bring the MapleSim signal to Maple (Attachment->Worksheet->LinkModel->Simulate). Then I had a 2x1000 Matrix which i want to transform with a FFT. My problem is that it doesn´t work. How can I get a spectrum plot of this Matrix or function?