Oscilloscope Reference Spectral analyzer window types
Coefficients
These are used to generate the windows that are constructed from a cosine series. For the Gaussia n window,
the value of "a" is given instead of a set of coefficients. You can find descriptions of cosine series windows
in the Handbook of Digital Signal Processing Engineering Applications by Elliot. ISBN 0-12-237075-9.
What do you want to do next?
Go to a list of all spectral math controls. (see page 760)
Learn about using spectral analyzer windows. (see page 771)
Go to a step-by-step procedure for defining a spectral math waveform. (see page 623)
Spectral analyzer window types
In the time domain, a window is a bell-shaped function equal
in length to the gate duration.
For most windows, this functi on tapers to zero at both ends
of the gate region. Before computation of the spectral
transformation, the window is multiplied, sample by sample,
times the input data in the gated region. The w indow
function affects the shape of the spectral analyzer response
in the frequency domain.
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The window functions affect the ability to resolve frequency in the output spectrum and can affect the
accuracy of the magnitude and phase measurements. The previous figure shows how the time domain
record is processed.
Accurate magnitude measurements require that the input source waveform be stationary within the gated
region. This means that waveform parameters, such as frequency and amplitude, should not change
significantly as a function of time within the g ate region that is input to the spectral analyzer. Also, the gate
width must be greater than or equal to the period of the start frequency of the span of the spectral analyzer.
That is, there must be at least one cycle of the harmonic being measured within the gated region.
There are eight different spectral analyzer windows:
Rectangular (see page 778)
Gaussian (see page 775)
Hamming (see page 776)
DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series 771
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