5.2.12. Pulse width setting
Select pulse wave and press
【
Width
】
key, the “Width” keyboard indicator will be lighted and the generator
display current pulse width value, the users may use the numeric keys or knob to input pulse width value,
and the generator will output pulse wave with this pulse width set. The pulse width keeps unchanging while
the pulse frequency changes. Pulse width is defined as, the time value of the high level of the pulse wave.
When the frequency of the pulse wave is comparatively high, the set of pulse width will be limited by edge
time, and should accord with below formula:
Pulse width
≥
2×edge time or period-pulse width
≥
2×edge time
5.2.13. Output mode setting
Press
【
Menu
】
key and select “Mode” option to display the output mode value, use the numeric keys or knob
to input mode value. There are only two values to choose: 0 or 1, when set the value as 0, the signal from
the output port is in-phase with the sync port, and when set it as 1, the two are inverted.
5.3. CHB continuous
“CHB continuous” means CHB outputs stable and continuous signal, of which the waveform, frequency,
amplitude and phase will not change along with time.
Press
【
Shift
】【
CHA/CHB
】
key, select “CHB” option and then set parameters of CHB.
5.3.1. Phase difference between CHA and CHB setting
When the frequencies of CHA and CHB are the same, press
【
Menu
】
key and select “Phase” option, the
generator will indicate the phase difference between CHA and CHB, use the numeric keys or knob to input
phase difference value, the phase difference between signals from CHA and CHB could be set in advance. It
is meaningless to set phase difference when the frequencies of CHA and CHB are different.
The settings of other parameters of CHB is the same as the one of CHA.
Below contents give detail explanations of FM, AM, PM, PWM, FSK, frequency sweeping, burst and arbitrary
waveform functions, which are only applicable to CHA.
5.4. Frequency modulation (FM)
In Frequency modulation, the frequency of the carrier is varied by the instantaneous voltage of modulating
waveform, all the 16 kinds of waveforms listed in the waveforms table could be used as carrier waveform.
Before entering into frequency modulation, the users should set the waveform, frequency and amplitude
value of the carrier wave first under CHA continuous function.
Press
【
FM
】
key, the keyboard indicator of “FM” will be on, and CHA output frequency modulation signal.
5.4.1. Frequency deviation
Press
【
Menu
】
key and select “Devia” option, and then set frequency deviation value. Frequency deviation
represents the frequency variation of carrier wave when the modulating waveform is with full amplitude
during FM process. When the amplitude of the modulating waveform is at positive peak value, the output
frequency is equal to the frequency of the carrier plus the frequency deviation, and when it is at the negative
peak value, the output frequency is equal to the carrier frequency minus the frequency deviation. Therefore,
the frequency deviation setting must conform to the following two conditions:
(Carrier frequency
－
frequency deviation)
＞
0
(Carrier frequency
＋
frequency deviation)
＜
The upper limit of the generator
5.4.2. Modulation frequency
Press
【
Menu
】
key and select “Mod_f” option, and then set modulation frequency value. In FM, modulation
frequency is usually far lower than carrier frequency.
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