Lsync (Line Cycle Synchronization) - Keithley 2701 User Manual

Model 2701 User's Manual

LSYNC (line cycle synchronization)

Synchronizing A/D conversions with the frequency of the power line increases common
mode and normal mode noise rejection. When line cycle synchronization is enabled, the
measurement is initiated at the first positive-going zero crossing of the power line cycle
after the trigger.
Figure 3-1
trigger occurs during the positive cycle of the power line (Trigger #1), the A/D conversion
starts with the positive-going zero crossing of the power line cycle. If the next trigger
(Trigger #2) occurs during the negative cycle, then the measurement process also starts
with the positive-going zero crossing.
Figure 3-1
Line cycle synchronization
Perform the following steps to enable or disable line cycle synchronization:
1.
2.
3.
NOTE
shows the measurement process that consists of two A/D conversions. If the
1 PLC
Trigger
# 1
Conversion
Press SHIFT and then LSYNC to display the present state of line synchronization
(OFF or ON).
Use the or key to display "LINESYNC ON" or "LINESYNC OFF."
Press ENTER. The instrument returns to the normal display state.
Line synchronization is not available for the AC functions (ACV, ACI, FREQ, or
PERIOD) and for integration rates <1 PLC, regardless of the LSYNC setting.
Reading
Done
Trigger
# 2
A/D
Basic DMM Operation
Reading
Done
A/D
Conversion
3-5