Tektronix WCA200A, Руководство пользователя

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Trigger
WCA230A & WCA280A User Manual
3- 163
The trigger level to be set with IF trigger is based not on the power of the signal
in the frequency domain but on the level of the signal in the time domain. Note
that the relationship between signal power and trigger level varies with the input
signal waveform.
A waveform made by adding sine waves of 1 Hz, 3 Hz, and 5 Hz as shown in
Figure 3--111 is given as an example. Figure A shows waveforms of 1 Hz, 3 Hz,
and 5 Hz respectively, and the size is 1. Figure B shows the waveforms when the
above signals are added. You can see that the voltage at the largest peak is more
than twice the voltage of the original signals. On the frequency axis of Figure C,
only signals of size 1 are generated at 1 Hz, 3 Hz, and 5 Hz. The IF trigger
compares the waveform peak in Figure B with the trigger level set value. The
level is therefore different from the power level of each frequency component on
the spectrum (Figure C).
Amplitude
Time (s)
Add waveforms
Amplitude
Time (s)
Amplitude
Figure A: 1 Hz, 3 Hz, and 5 Hz sine waves Figure B: Added waveform of 1 Hz, 3 Hz,
and 5 Hz sine waves
Figure C: Spectrum of Figure B
Frequency (Hz)
1
0.5
0
--0.5
--1
0 0.5 1
1
0
2
--1
--2
0 0.5 1
1
0
2
0 1 2 3 4 5 6 7 8 9 10
Figure 3- 111: Waveforms in time domain and in frequency domain
Time and Frequency
Domain Waveforms