- 60 -
Vtop:
Voltage of the waveform's flat top, useful for square/pulse waveforms.
Vbase:
Voltage of the waveform's flat base, useful for square/pulse waveforms.
Vamp:
Voltage between Vtop and Vbase of a waveform.
Overshoot:
Defined as (Vmax-Vtop)/Vamp, useful for square and pulse waveforms.
Preshoot:
Defined as (Vmin-Vbase)/Vamp, useful for square and pulse waveforms.
Cycle RMS:
The true Root Mean Square voltage over the first entire period of the waveform.
Cursor RMS:
The true Root Mean Square voltage over the range of two cursors.
9.1.3 Automatic measurements of the time parameters
The oscilloscopes provide time parameters auto-measurements include Period, Frequency, Rise
Time, Fall Time, +D width, -D width, +Duty, -Duty,
Delay A→B , Delay A→B , Screen Duty,
Phase
A→B , and Phase
A→B , FRR, FRF, FFR, FFF, LRR, LRF, LFR, LFF.
Figure 4.13 shows a pulse with some of the time measurement points:
Fig. 4.13 Explanation of the parameters
Rise Time:
Time that the leading edge of the first pulse in the waveform takes to rise from 10% to
90% of its amplitude.
Fall Time:
Time that the falling edge of the first pulse in the waveform takes to fall from 90% to
10% of its amplitude.
+D width:
The width of the first positive pulse in 50% amplitude points.
-D width:
The width of the first negative pulse in the 50% amplitude points.
+Duty:
+Duty Cycle, defined as +Width/Period.
-Duty:
-Duty Cycle, defined as -Width/Period.
Delay
A→B
:
The delay between the two channels at the rising edge.
Delay
A→B
:
The delay between the two channels at the falling edge.
Screen Duty:
Defines as (the width of the positive pulse)/(Entire period)
Phase
A→B
:
Phase difference calculated according to " Delay
A→B " and the period of
source A, expressed in degree. The calculation formula is as shown below:
Phase
A→B = (Delay A→B ÷ Period of source A) × 360°
Phase
A→B
:
Phase difference calculated according to " Delay
A→B " and the period of source
A, expressed in degree. The calculation formula is as shown below:
Phase
A→B = (Delay A→B ÷ Period of source A) × 360°
Rise Time
Fall Time
+Width
-Width
