Time Frequency problems



Hello, I am trying to conduct a time frequency analysis but it is producing the attached plot.
I am not filtering the data at 3Hz, and its not just 0s about 3 Hz but very small values. Has anyone had this before and know what is likely to be causing the issue? I am new to the analysis so probably making an obvious mistake.



I see a symmetric spectrum on your picture. That is a normal property of FFT but you do not need both.
Focus this picture on the range 0 - 50 Hz.
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