HP 54520 Series - Page 278

Panning Panning is used when the
acquisition is in the stopped mode.
Panning is moving the acquired
waveform horizontally on the dis-
play. It is controlled by the time
base delay controls in the real-time
mode. Increasing delay moves the
waveform to the left and decreasing
delay moves the waveform to the
right.
Pattern triggering Pattern trig-
gering qualifies the trigger event by
having the oscilloscope search for a
pattern across the oscilloscope in-
puts. You can define the pattern as a
combination of highs, lows, or don’t
care levels. Voltages above the trig-
ger level are a high, and voltages
below the trigger level are a low.
Peak detect Peak detect stores
the minimum and maximum values
(pairs) for each time bucket. Peak
detect can detect excursions as nar-
row as 1 ns, and it functions on
sample rates up to 250 MSa/s.
Pixel memory A pixel memory is
a volatile, screen image, storage
area. It is essentially a snap shot of
the display and has no vertical or
horizontal scaling factors associated
with it.
Glossary
Position Position (offset) moves
the waveform vertically on the dis-
play. It is similar to the vertical
position control on analog oscillo-
scopes except that it is precisely
calibrated. The position voltage is
the voltage at the center of the
graticule area.
Real-time sampling All the data
points that make up a waveform
come from a single trigger event.
The real-time sampling mode is typi-
cally used on events that occur
either once or infrequently.
Reconstruction Also known as im-
terpolation. Sampling theory
indicates that if a signal is bandwidth-
limited to less than half of the
sampling frequency (the Nyquist fre-
quency), the continuous signal can
be determined exactly from the se-
quence of samples. Two problems
exist in the real world to prevent ex-
act determination of the continuous
input. First, many signals are not
bandwidth-limited, and second, the
ideal determination requires an infi-
nite number of samples.
Reconstruction uses the assumption
that the signal has minimal fre-
quency components above the
Nyquist frequency in order to accu-
rately (but not exactly) rebuild the
continuous signal from the finite set
of discrete samples.
Glossary -3