Waveform analysis
R&S
®
RTP
300User Manual 1337.9952.02 ─ 12
7.3.4.9 Math functions: CDR
The clock data recovery function requires at least one of the options R&S RTP-K12, or
R&S RTP-K133, or R&S RTP-K134.
Table 7-11: Clock data recovery (More keys)
Icon Description Usage/Comment, FormulaEditor expression
CDR: displays the generated clock
signal as math waveform
Software 1: CDR(sw1,x)
Software 2: CDR(sw2,x)
where x is the signal from which the clock is recov-
ered
Example:
CDR(sw1,CH2Wfm1)
See also: Chapter 18.3.2, "Displaying the recovered
clock signal", on page 1059
7.3.4.10 Transfer functions of a step-like signal
The R&S RTP provides two functions to calculate the transfer function of a system out
of its step response. These functions are not supported by the formula editor, but you
can enter them directly in the "Advanced" tab in the "Math Setup" dialog box. To enter
the formula, you need a keyboard (onscreen keyboard or a connected usual one).
Math expression Description
Step2FreqRespNormMag(x,points)
Where:
●
x is the waveform (channel, math, reference)
●
points is the number of points in the resulting
math waveform (min. 1000 points)
Normalized magnitude of transfer function in fre-
quency domain
Example:
Step2FreqRespNormMag(Ch1,2000)
Step2FreqRespNormPhi(x,points,time offset)
Where:
●
x is the waveform (channel, math, reference)
●
points is the number of points in the resulting
math waveform (min. 1000 points)
●
time offset in s
Normalized phase of transfer function in frequency
domain
Example:
Step2FreqRespNormPhi(Ch1,2000,2e-9)
The calculation of transfer functions has several steps:
●
Calculate the frequency domain representation of a step-like signal. A detailed
description is given in: A. M. Nicolson, „Forming the fast Fourier Transform of a
step response in Time-Domain Metrology,“ in Electronic letters, Bd. 9, Nr. 14, p.
317, 1973.
●
Calculate the derivative to convert the result to the transfer function.
●
Normalize the result at DC to a magnitude of 1 V and subtract specified time offset
from phase.
The step-like signal to be analyzed is a time domain waveform, and the result is a math
waveform in the frequency domain.
Mathematics
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