CrossPowerSpectrum
Advanced Analysis Library Only
AnalysisLibErrType CrossPowerSpectrum (double xArray[], double yArray[], ssize_t numberOfElements, double dt, double magnitudeSxy[], double phaseSxy[], double *df);
Purpose
Calculates the single-sided, scaled cross power spectrum of two time-domain signals. The following formula defines the cross power spectrum:
where FFT*[X] is the complex conjugate of FFT[X] and numberOfElements is the number of points in the arrays.
This function converts the cross power spectrum to single-sided magnitude and phase spectra.
Parameters
| Input | ||
| Name | Type | Description |
| xArray | double [] | Time-domain signal X. |
| yArray | double [] | Time-domain signal Y. |
| numberOfElements | ssize_t | Number of elements in the input array. Default Value: 1024. |
| dt | double | Sampling period of the time-domain signal, usually in seconds. dt = 1/fs, where fs is the sampling frequency of the time-domain signal. Default Value: 1.0. |
| Output | ||
| Name | Type | Description |
| magnitudeSxy | double [] | Single-sided magnitude cross power spectrum between signals XArray and YArray in volts rms square if the input signals are in volts. If the input signals are not in volts, the results are in input signal units rms square. This array must be at least numberOfElements/2 elements long. |
| phaseSxy | double [] | Single-sided phase cross spectrum in radians, showing the difference between the phases of signal YArray and signal XArray. This array must be at least numberOfElements/2 elements long. |
| df | double | Points to the frequency interval, in Hertz, if dt is in seconds. df = 1/(numberOfElements × dt) |
Return Value
| Name | Type | Description |
| status | AnalysisLibErrType | A value that specifies the type of error that occurred. Refer to analysis.h for definitions of these constants. |
Additional Information
Library: Advanced Analysis Library
Include file: analysis.h
LabWindows/CVI compatibility: LabWindows/CVI 3.1 and later