Waveform analysis
R&S
®
RTP
298User Manual 1337.9952.02 ─ 12
7.3.4.7 Math functions: correlation
Table 7-9: Correlation (More keys)
Icon Description Usage/Comment, FormulaEdi-
tor expression
Cross correlation function of two waveforms
Measures the similarity of two waveforms as a function
of a time-lag applied to one of them.
Function limits the maximum record length to 4 MSa.
Two modes of normalization are supported: biased
and unbiased.
The length of the correlation buffer is N
0
+ N
1
–1 sam-
ples. The length of the first input signal is N
0
samples
and the length of the second signal is N
1
samples.
correlation(x1, x2, biased)
correlation(x1, x2, unbiased)
with x1 = waveform 1 and
x2 = waveform 2
correlation(x1, x2) performs an
unbiased correlation
Auto correlation
Used to find repeating patterns, for example, a peri-
odic signal obscured by noise.
The length of the auto correlation buffer is 2N –1 sam-
ples, if the length of the input signal is N samples.
Two modes of normalization are supported: biased
and unbiased.
autocorrelation(x, biased)
autocorrelation(x, unbiased)
with x = channel waveform
autocorrelation(x) performs an
unbiased autocorrelation
biased / unbiased normalization for correlation and
auto correlation
see above
Mathematic background for correlation:
The R&S RTP uses only the real part of the signal. Two modes of normalization are
supported: biased and unbiased.
Equation 7-1: Biased correlation
Equation 7-2: Unbiased correlation
Mathematics
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