As per the official Website of GATE 2019, THe syllabus for Signal and system is as given below:

Representation of continuous and discrete‐time signals, Shifting and scaling operations, Linear Time-Invariant and Causal systems, Fourier series representation of continuous periodic signals, Sampling theorem, Applications of Fourier Transform, Laplace Transform and z-Transform.

For complete Syllabus visit:

https://drive.google.com/file/d/1tqnglhiggf3d5rPYATs4Mue7Tj13gU_N/view