crosspower spectrum
PrintThe spectrum containing the product of the power of correlated frequency vectors of two channels. Consists of both a real and imaginary part, that is, a complex spectrum.
The cross spectrum is the power between the input and the output, and hence is computed by multiplying and averaging (denoted by the hat) the instantaneous spectrum of the input (
) and output (
). Note that these spectra are complex, i.e. they can be viewed as vectors.
The crosspower spectrum is particularly useful in the measurement of frequency response in that it removes the influence of system noise. The “noise reduction” assuming uncorrelated Gaussian noise is
where
is the noise reduction in dB for N averages.See frequency response to see how the cross spectrum is used to make high quality frequency response measurements.
Units:
V2 and rad
Additional References
Helpful Web Sites:
Reader Comments | Submit a comment »
Legal
This tutorial (this "tutorial") was developed by National Instruments ("NI"). Although technical support of this tutorial may be made available by National Instruments, the content in this tutorial may not be completely tested and verified, and NI does not guarantee its quality in any way or that NI will continue to support this content with each new revision of related products and drivers. THIS TUTORIAL IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND AND SUBJECT TO CERTAIN RESTRICTIONS AS MORE SPECIFICALLY SET FORTH IN NI.COM'S TERMS OF USE (http://ni.com/legal/termsofuse/unitedstates/us/).