Fluke CombiScope PM3370B User Manual page 166

5 - 46
MAIN TIMEBASE
Description:
The Main Timebase (MAIN TB) has a wide range of time/div settings. This
enables the display of signals of various frequencies to be displayed with optimum
resolution. The time scale is adjusted with the key pair TIME/DIV (VAR).
Adjustment can be done in steps or in a continuous range (VAR). Switching
between these modes is done by pressing both keys simultaneously. For low
frequency signals, the MAIN TB speed must be slow; this is obtained by pressing
the 's' side of the key pair. For high frequency signals, the 'ns' side is pressed.
Time values of a signal can be determined as described under the 'screen
controls and graticule' function. The AUTO RANGE key activates a continuous
automatic adjustment of the TIME/DIV of the main timebase. The result is a
display of between 2 and 6 waveform periods on the screen. This functions in
digital mode. For more information, refer to the AUTO RANGE function.
If AUTO RANGE is turned on when VAR is active, the timebase is changed in
such a way that the trace on display is kept unchanged.
In the digital mode, the timebase speeds are determined by an XTal oscillator.
VARiable control of the timebase speeds in digital mode happens in bigger steps
than in analog mode
Function of key pair TIME/DIV (VAR).
Key sequence:
TIME/DIV
s ns
VAR
AUTO
RANGE
AUTO
RANGE
TIME/DIV
Key pair to adjust the MAIN TB time scale for fine or
coarse steps
Toggle key to switch the AUTO RANGE function of main
timebase.
FUNCTION REFERENCE
MANUAL + AUTOMATIC
ST6838
9312