matlab phasewrapping,Saturation and Wrapping

Saturation and Wrapping

Consider an 8-bit unsigned word with binary-point-only scaling of

2-5. Suppose this data type must represent a sine

wave that ranges from -4 to 4. For values between 0 and 4, the word can represent

these numbers without regard to overflow. This is not the case with negative

numbers. If overflows saturate, all negative values are set to zero, which is the

smallest number representable by the data type. The saturation of overflows is shown

in the following figure.

If overflows wrap, all negative values are set to the appropriate positive value.

The wrapping of overflows is shown in the following figure.

Note

For most control applications, saturation is the safer way of dealing with

fixed-point overflow. However, some processor architectures allow automatic

saturation by hardware. If hardware saturation is not available, then extra

software is required, resulting in larger, slower programs. This cost is

justified in some designs — perhaps for safety reasons. Other designs

accept wrapping to obtain the smallest, fastest software.

The Simulink® software supports saturation and wrapping for all fixed-point data

types. You can select saturation or wrapping for fixed-point Simulink blocks with the Saturate on integer overflow

check box.