R3765/67G Series Network Analyzer Operation Manual
7.7 Time Domain Function(OPT 70)
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7.7
Time Domain Function(OPT 70)
(The Time domain function is optional. This function is not available if this option has not been
installed.)
7.7.1
Time Domain Transformation Function
A measurement result in the frequency domain can be transformed into the corresponding re-
sponse in the time domain by using the Time domain transformation function. The result in the
time domain will be represented as an impulse response or step response of the DUT.
The relationship between a frequency domain response and the corresponding time domain re-
sponse of this analyzer is defined by the Fourier transformation.
The time domain result can be obtained by calculating a frequency domain measurement result
with the inverse Fourier transformation.
(1)
Transformation Mode
The bandpass and low pass modes are available for transforming the frequency domain
data into time domain data.
The bandpass mode is a general purpose mode which allows the user to set the frequency
range freely. This mode is used to measure a DUT impulse response with its limited bands.
Using the low pass mode, the user can obtain information about points of discontinuity. In
the low pass mode, the impulse mode and the step mode are available. The former is used
to obtain the response by an impulse input to a DUT ; and the latter, to obtain the response
by a step input to DUT.
In the low pass mode, however, frequency range settings are restricted. Frequency data
must be spaced equally in the range from the virtual DC point to the stop frequency:
(Start frequency) x (number of measuring points) = (stop frequency)
It is necessary that the above relation must be maintained.
The user can easily set frequency ranges to meet the condition above using {SET FREQ
LOW PASS} function.
(2)
Distance display mode
The horizontal axis is set to a time axis (sec) immediately after the time domain transfor-
mation function is turned ON. This time axis can be transformed into a distance axis (m).
At this time, however, only the annotations (values and units) on the horizontal axis are
transformed and the waveform data on the vertical axis remains unchanged.
