HP 54520 Series Service Manual page 18

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Chapter 1: General Information
Operating Characteristics
Bandwidth Limit (HF Reject) A low-pass filter with a -3 dB point at about 30 MHz for
both triggering and signal display. You can select HF reject for each front-panel input
individually, whether vertical or external trigger.
LF Reject A high-pass filter with a —3 dB point at about 400 Hz for the triggering and
vertical signal. You can select LF reject for each front-panel input individually, whether
vertical or external trigger.
ac Coupling A high-pass filter with a —-3 dB point at about 10 Hz for both triggering and
signal display. You can select ac coupling for each front-panel input individually, whether
vertical or external trigger.
ECL/TTL Presets For ECL and TTL levels, you can preset the vertical deflection factor,
coupling, offset, and trigger level independently on any vertical input channel. It is not
available for the external trigger input.
Effective Resolution The maximum sample rate and the number of bits in an
oscilloscope's digitizer are too often used for comparing oscilloscopes. These
specifications, however, do not describe performance under dynamic signal conditions.
Effective resolution is a igure of merit that describes the digitizing oscilloscope's
performance under dynamic conditions, and is measured using the sine wave curve fit
test. This method considers:
e Quantization error
e Nonlinearities (including preamp and ADC)
e System noise
e@ Frequency of input signal
All of these affect the effective resolution of the instrument. Some manufacturers specify
effective bits using half-scale sinewaves. While the effective bits performance using half-scale
testing is overstated when compared to full-scale testing, Hewlett-Packard publishes both sets
of numbers for the oscilloscope, so that when comparing effective bits performance between
digitizing oscilloscopes, a fair comparison can be made. The oscilloscope's typical
performance for a single acquisition is shown below:
Frequency S50kHz 1MHz 20MHz SOMHz 100MHz 250MHz 500 MHz
Fullscale 7.5 74 6.6 5.8 5.8 5.2 5.2
Halfscale 7.6 7.4 7.0 6.5 6.5 5.8 5.5
For more information about effective resolution, please contact your Hewlett-Packard sales
office, and ask for Product Note 5180A-2, Dynamic Performance Testing of A to D
Converters, (pub # 02-5952-7629).
Pan and Zoom Changing the Time/div and/or Delay values once acquisition is stopped
allows access to all captured data on each acquisition in the real-time sampling mode only.
The record length control sets the number of points (512 to 32,768) acquired with each
acquisition. The auto adjust softkey allows setting the sample rate independent of the time
base. The entire record length may be displayed when the oscilloscope is in the run mode.
Delay Between Channels You can null out differences in delay between channels to
compensate for differences in input cables or probe length using the probe null feature.
Reference Location You can set the reference point at the left edge, center, or right
edge of the display. The reference point is the trigger point plus the delay time.
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