HP 54620A - Glossary

Glossary
Acquisition is the process by
which the logic analyzer collects
data. The analyzer acquires data by
sampling the voltage on each input
channel and comparing it to the
threshold voltage to determine
whether the input is high or low. In
Normal trigger mode, the analyzer
begins filling the pre-trigger buffer
with data. When that buffer is full,
the analyzer will begin searching for
the trigger event. In Auto trigger
mode, the analyzer fills the pre-trig-
ger buffer, then searches for the
trigger event for a predetermined in-
terval.
Acquisition memory stores the
acquired sample. This memory is
part of the acquisition subsystem,
and is located in the sample RAM.
Acquisition memory depth is
16 bits wide and 2048 samples deep
at sweep speeds from 1 s/div to
1 µs/div. When the sweep speed be-
comes faster than 1 µs/div, the glitch
detection circuitry is disabled, and
acquisition memory is 16 bits wide
and 8192 samples deep. Acquisition
memory is located in the acquisition
subsystem sample RAM.
Advanced trigger consists of two
pattern and two edge sources com-
bined with a variety of operators to
form the complete Advanced trigger
specification. Advanced trigger is
best used when the events you want
to capture are defined by a complex
series of waveform events in the sys-
tem, and neither pattern mode nor
edge mode are capable of clearly re-
solving the necessary sequence.
Aliasing is occurring whenever
the waveform display changes more
than expected, as you expand the
time base. Aliasing is due to under
sampling.
Auto Glitch Detection is enabled
automatically when the analyzer is
powered up. The glitch detection cir-
cuitry helps prevent aliasing by
identifying additional transitions that
occur between samples. Auto Glitch
detection is disabled for time base
settings where the sampling interval
is 4 ns or faster. At these sweep
speeds, the analyzer can reliably sam-
ple all signals that are within the
bandwidth of its probing system,
thus preventing aliases. See also
Glitch mode.
Auto trigger mode causes the
analyzer to fill the pre-trigger buffer,
then searches for the trigger event
for a predetermined interval. If no
trigger is found, the analyzer forces a
trigger and displays the data as
though the trigger had occurred.
Autoscale performs a simple one-
button setup of the analyzer,
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