An explanation of the Z transform part 2 – the H(z) surface by
David Dorran
https://www.youtube.com/watch?v=WCxM4SYsg1w&fbclid=IwAR2IkkDiG7VjIHpkWKJIebS5Bk-P33za73fbVjfFeM3SQlpXAm1JJUBBbss