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FUNCTION REFERENCE 5 - 7
ALT/CHOP
Description:
In the analog mode, when two or more channels are selected, the oscilloscope
displays multiple channels in a ‘time shared’ mode. This implies that a fast
electronic switch connects each input signal to the output amplifier in turn. This
can be done at the end of every sweep, or at a high frequency. The display modes
are referred to as Alternate or Chop modes.
Alternate mode:
After each sweep of the time base has been completed, the
channel switch selects the next channel to be displayed during the next sweep.
The result is that each channel is displayed one after the other. At fast timebase
speeds this mode assures maximum intensity, while slow timebase speeds in
alternate mode result in a flickering display.
Chopped mode:
In this mode, the channel selector switch operates at a high
frequency, and is no coupled to the time base sweep. This mode is recommended
for slow timebase speeds. The display switches very fast (1 MHz) between the
channels, which results in what appears to be a simultaneous display of all
channels.
ALT/CHOP is not available with single trace display.
In the digital mode channel 1 and channel 2 each have their own digitizer for
simultaneous sampling on both channels. In this two-channel mode ALT/CHOP is
not active.
If a combination of channel 1 or 2, and channel 3 or 4 is selected, the ALT/CHOP
is active and functions in the following way:
ALT
results in a complete memory acquisition of channel 1 or 2 simultaneously
sampled, followed by a complete memory acquisition of channel 3 or 4, also
simultaneously sampled.
CHOP
results in a single sample being made on channel 1 or 2 followed by a
single sample on channel 3 or 4. This continues until the acquisition memory for
each channel is filled. This ALT/CHOP function is valid only for the real-time
sampling timebase speeds.
NOTE: For further details on three or four channel operation, also refer to the
ACQUISITION LENGTH and PEAK DETECTION functions.