BNC 645 - Manual (Page 35)

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volatile memory.
• When you change the output function from square wave to
another, the previously-set duty cycle is remembered and will be
resumed when square wave is re-selected.
• For square waves with frequency higher than 10 MHz, the range of
the duty cycle is from 40% to 60%, and for square waves with
lower frequency, the range of the duty cycle is from 20% to 80%.
• If you change frequency to a new value with which Model 645
cannot produce the current duty cycle, it will automatically adjust
the duty cycle to the closest possible value for the new frequency.
• When square wave is selected as the modulating waveform, the
duty cycle is fixed at 50%. The duty cycle setting applies to
square wave carrier waveform for AM, FM, PM or PWM.
4.3 Ramp Wave
A ramp wave is a triangle waveform with adjustable symmetry.
Symmetry represents the percentage of time in a cycle when the ramp
wave is rising (assuming that the waveform polarity is not inverted). The
default symmetry is 100%.
How to generate a ramp wave
1. Press the Ramp button to select the output function.
2. Refer to Chapter 3 for configuring common parameters, including
frequency/period, amplitude and dc offset voltage.
3. Press the softkey under Symmetry for configuring the value.
4. Use the knob with the cursor keys to change the symmetry setting.
Or use the numeric keypad to enter a new value and then press
the softkey under % to finish the entry or the softkey under Cancel
to withdraw the changes.
5. Press the Graph button to view all the waveform parameters.
Figure 4-3