Two new 100MHz
oscilloscopes from HP
Hewlett Packard has done the unthinkable released its latest 100MHz digital sampling
oscilloscopes with a host of new features but
at a price which directly competes with
analog CRT readout scopes.
By LEO SIMPSON
Until now, digital sampling oscilloscopes have been neither cheap or
easy to use. Their controls have been
generally quite different from those
on conventional analog CROs and
their price has usually been a lot
higher. Now, with the release of the
54600 series oscilloscopes from Hewlett Packard, all that looks set to
change.
The immediate difference between
these new models and previous models fro m the company is that the con-
trol lineup is greatly simplified. Not
only that, it bears more than a passing
resemblance to the control layout on
a conventional analog instrument. For
example, there are knobs for vertical
attenuators, timebase, trace position
and trigger level. None of these knobs
have any calibrations though, as their
settings are shown in the comprehensive CRT display.
The knobs work in exactly the same
way as those on any analog CRO and
their response is instantaneous. This
is quite different from typical digital
sampling oscilloscopes (from HP)
which have a large number of display
modes but which require the user to
step through a number of keystrokes
and screen menus in order to get the
wanted display.
Autoscale button
The best control feature of the lot is
the AUTOSCALE button. This takes all
the frustration out of getting a useful
signal display on the screen. This can
be a time-consuming chore even on
analog scopes. On the HP 54600
series, all you have to do is connect
the probe to a signal source, push the
AUTOSCALE button and the signal is
locked on the screen, together with
the vertical attenuator and timebase
settings. Dead easy.
Unlike analog scopes, the new
100MHz scopes display their waveforms brightly and steadily regardless of sweep speed. They do not
exhibit the flicker or flare that occurs
with analog scopes when displaying
signals at very low sweep speeds.
Instead, they show a trace of constant
brightness, which is gradually retraced, to give the user a visual cue of
the low trace speed.
Also, the faint traces in highly
magnified delayed sweeps can be
viewed without the viewing hood
required with analog scopes. A peakdetect feature enables the new instruments to display complex waveforms,
such as amplitude modulation, correctly. It will catch and display any
glitch that is more than 50ns long,
regardless of the sweep speed settings.
Waveform measurement
While it is a digital sampling oscilloscope, HP's 54600 behaves very much like a
conventional analog instrument albeit with full CRT readout, electronic
graticule and good intuitive "feel".
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SILICON CHIP
The new scopes have the non-volatile storage and waveform-measurement capabilities that only a digital
sampling system can provide. With
the scopes' two trace memories, signals can be acquired and retained
Seen here is the HP54601A, the four channel version of the new 100MHz
oscilloscope. It is a very compact instrument with a large screen and easy to
use controls.
indefinitely. This allows the user to
make measurements, compare a previously captured signal with a current one, print hard copies or transfer
the data to an external computer for
further processing.
Pre-trigger viewing
Storage also allows pre-trigger
viewing by retaining waveform activity that occurs before the trigger event.
For example, after triggering the scope
on a failure mode in the device under
test, a user can look back in time to
view the events that caused the failure. This is impossible in an analog
scope.
AUTOSTORE mode displays the current waveform at full brightness,
while all previous sweeps are retained
on the display in half-bright, infinite
persistence. With this feature, the
scope can capture infrequent deviations that otherwise would require
constant observation by the user to
determine whether deviations occur.
The design of the new scopes is
based on a new digital architecture
developed by HP. Because the instruments use custom IC processors for
acquisition and display, they do not
rely on the system's CPU to perform
acquisition and display management
functions. For users , these dedicated
processors mean the new scopes have
display-update rates as fast as those
of analog instruments.
Key features of the new oscilloscopes include the following:
100MHz rep.etitive bandwidth on both
the vertical and horizontal axes;
2MHz single shot bandwidth; 2ns/
div to 5s/div range on both main and
delayed timebases; mV/div to 5V/div
vertical sensitivity; 8-bit vertical resolution; automatic setup with a single
keystroke; simple one-button display
storage operations; 16 front-panel
setup memories; two trace memories;
edge, line and TV triggering; 12 auto-
matic measurements of frequency,
time and voltage; dual cursors for
accurate manual time and voltage
measurements ; pushbutton hardcopy
output to plotters and printers via
optional parallel, RS-232 or HP-IB
(IEEE-488) interfaces.
Dimensions are 360mm wide,
180mm high and 300mm deep and
weight is 6.4kg. The 54600 series
scopes come with a 3-year standard
limited warranty with an option for a
5-year limited warranty.
Prices are as follows: HP 54600A
2-channel 100MHz oscilloscope,
$2,395; HP 54601A 4-channel
100MHz oscilloscope, $2,895; HP
54650A HP-IB interface module, $475;
HP 54651A RS-232C interface module , $475; HP 54652A parallel interface module , $275. These prices do
not include sales tax.
We hope to do a detailed review of
the 54600 series in a future issue. In
the meantime, sales information can
be obtained by calling Hewlett-Packard's customer information centre on
(008) 033 821.
SC
APRIL 1991
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