Ceyear 4051 Series, User Manual

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4. Operating Instruction
4.2 Advanced operation guide
122
 Press Span/X Axis] and [Zero Span].

Press 【 Sweep 】 , [Sweep Time] and enter 5 ms.
Step 7. use video trigger function to stabilize display trace:
 Press
【
Trig
】
and [Video
▶
].
Since the modulation is stable, sweep operation can be triggered on the waveform via video trigger to stabilize
trace, which process is similar to the oscilloscope, as shown in Fig. 4.35. If the video trigger level is set too
high or too low in video trigger mode, the sweep will stop. In this case, the knob on the front panel can be
used to adjust the video trigger level until the sweep resumes.
Step 8. close all markers and set the analyzer as free trigger mode:
 Press
【
Marker
】
and [OFF].

Press 【 Trig 】 and [Free Run].
Step 9. increase sweep time and reduce video bandwidth to display the waveform as a horizontal signal:
 Press
【
Sweep
】
, [Sweep Time] and enter 5 s.

Press 【 BW 】 , [Video BW Auto
Man
] and enter 30 Hz.
Step 10. place the horizontal signal at the center of Y axis, increase video bandwidth and reduce sweep
time to display the waveform in a sine wave:
 Press 【 Amplitude/Y Axis 】 and [RefLevel], turn the knob to adjust the reference level and place the
horizontal signal at the center of Y Axis.
 Press
【
BW
】
, [Video BW Auto
Man
] and enter 100kHz.
 Press 【 Sweep 】 , [Sweep Time Auto
Man
] and enter 5 ms.
Step 11. measure AM signal modulation depth:

To obtain a modulation depth in percentage, the following method can be used to read the trace: 100%
AM modulation depth takes up all the grids from top to bottom, while 80% AM (as shown in this
example) takes up grids from second from the top to second from the bottom. The number of grids taken
up by Y axis can be counted to determine signal modulation depth percentage, as shown in Fig. 4.36.