Agilent Technologies 8719D User Manual page 394

The analyzer has one time-to-frequency transform mode:
Forward transform mode transforms CW signals measured over time into the frequency
domain, to measure the spectral content of a signal. This mode is known as the CW time
mode.
In addition to these transform modes, this section discusses special transform concepts such as
masking, windowing, and gating.
General Theory
The relationship between the frequency domain response and the time domain response of
the analyzer is defined by the Fourier transform. Because of this transform, it is possible to
measure, in the frequency domain, the response of a linear test device and mathematically
calculate the inverse Fourier transform of the data to find the time domain response. The
analyzer's internal computer makes this calculation using the chirp-Z Fourier transform
technique. The resulting measurement is the fully error-corrected time domain reflection or
transmission response of the test device, displayed in near real-time.
Figure 6-62 illustrates the frequency and time domain reflection responses of a test device. The
frequency domain reflection measurement is the composite of all the signals reflected by the
discontinuities present in the test device over the measured frequency range.
In this section, ail points of reflection are referred to as discontinuities.
Note
Figure 6-62. Device Frequency Domain and Time Domain Reflection Responses