Last Modified: January 12, 2018

Unwraps an array of phases by eliminating discontinuities whose absolute values exceed either pi or 180.

Input array of phases to unwrap.

This input accepts a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

Units for the input phases and unwrapped phases.

Name | Value | Description |
---|---|---|

radian in, radian out | 0 | Radian in, radian out |

radian in, degree out | 1 | Radian in, degree out |

degree in, degree out | 2 | Degree in, degree out |

degree in, radian out | 3 | Degree in, radian out |

**Default: **radian in, radian out

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an **error in** input and an **error out** output so that the node can respond to and communicate errors that occur while code is running. The value of **error in** specifies whether an error occurred before the node runs. Most nodes respond to values of **error in** in a standard, predictable way.

**Default: **No error

Unwrapped phases.

This output can return a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

**error in** input and an **error out** output so that the node can respond to and communicate errors that occur while code is running. The value of **error in** specifies whether an error occurred before the node runs. Most nodes respond to values of **error in** in a standard, predictable way.

When the difference between two adjacent values in **input phase** exceeds
$\pi $, and **phase unit** is radian in, radian out, this node uses the following equation to calculate **unwrapped phase**:

$P\_Out\left[i\right]=\{\begin{array}{cc}P\left[i\right]-\lfloor \frac{P\left[i\right]-P[i-1]}{2\pi}+0.5\rfloor *2\pi & i=1,\dots ,\text{\hspace{0.17em}}N-1\\ P\left[i\right]& i=0\end{array}$

where

*P_out*is**unwrapped phase***P*is**input phase***N*is the length of**input phase**- $\lfloor \rfloor $ is the floor operation

This node uses similar equations to calculate **unwrapped phase** for the other units you specify in **phase unit**.

The following two graphs show the effects of unwrapping the phase. The first graph shows the original phase before unwrapping, and the second graph shows the phase after unwrapping.

You can apply this node to the computed phase response of a linear time-invariant system. The phase response is defined as the complex angle of the frequency response of a system. You compute the phase response as angles within [- $\pi $, $\pi $], or, in other words, as angles within one circle of 2* $\pi $ radians. Because multiples of 2* $\pi $ wrap when you compute the phase response, often there are discontinuities in the phase response from one frequency bin to the next.

**Where This Node Can Run: **

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application