What is the appropriate level of proof for showing a valid miranda waiver?

A substantial Miranda Waiver must be: 
(1) knowing and clever (suspect comprehends his rights and the results of forsaking them); 
(2) intentional (not the result of police compulsion) 
A Miranda waiver might be express or suggested by a course of lead that shows the want to talk with police questioners. In the event that an individual gets Miranda cautioning and after that puts forth an uncoerced expression to the police he has deferred the privilege to stay noiseless