Add diagnostic tests.

Signed-off-by: Afsheen Ghorashy <arghorashy@gmail.com>
Added test assests for quick testing.

Signed-off-by: Afsheen Ghorashy <arghorashy@gmail.com>
Massive improvement!
Realised that negative amplitudes are actually still noise (think creux of waves).

Signed-off-by: Afsheen Ghorashy <arghorashy@gmail.com>