HP 8340b User Manual

A57
MARKER/BANDCROSS
ASSEMBLY
The
A57
marker/bandcross
assembly
generates
the
z-axis
signal
required
to
place intensity
markers
on
an
external
CRT.
If
enabled,
amplitude
markers are
generated
by
sending
a
marker
signal
to
the
leveling
circuits.
The
same
circuits
that
detect
markers
are
used
to
detect
band
crossings
or
the
end
of
sweep.
These
circuits
both
cause
the
sweep
to
stop
and
activate
the
instrument
processor.
Other
circuits
interface
with
the
rear
panel
connections.
During
self
test,
hardware
on
this
assembly
verifies
that
the
instrument
processor
data
bus
is
operating.
Sweep
Event
Memory
The
sweep-event
memory
stores
numbers
that
correspond
to
voltages
on
the 0-10V
sweep
signal.
Each
number
stored
in
the
memory represents
a
single
sweep
event.
Sweep
events
are
detected
by
the
sweep
comparator,
which
compares
them
against
the
0-10V
sweep
ramp.
Sweep
events
include:
•
Turning
markers on
and
off
•
Stopping
the
sweep
for
a
bandcrossing
•
Stopping
the
sweep
for
the
end-of-sweep
and
retrace
The
sweep
comparator
also
finds
the
current
sweep
position
when
you
make
changes
in
frequency
parameters
during
an
analog
sweep
longer
than
300
ms.
Manual
Sweep
DAC
The
manual
sweep
DAC
generates
the
sweep-out
signal
when
the
instrument
is
in
CW
or
manual
mode.
Sweep
Control
Block
The
sweep
control
block
allows
the
sweep
to
be
stopped
either
from
the
rear panel,
or
by
the
sweep
comparator.
With
the
CRT
Z-axis
control
circuits,
the
sweep can
be
blanked
on
a
display
for
band-
crossing
or
retrace,
and
markers
can
be
intensified.
Low
Bandcross
(LBX)
The
A57
marker/bandcross
assembly
uses
the
LBX
(low
bandcross)
signal
to
stop
the
analog
sweep
at
positions
previously
loaded
in
the
sweep event memory
by
the
instrument
processor.
When
LBX
is
low,
the
A59
digital
interface
causes
the
instrument
processor
to
run,
allowing
the
instrument
pro¬
cessor to perform
the
tasks
necessary
for
the
sweep
to
proceed.
This
happens
either at
a
bandcross¬
ing,
or
at
retrace
at
the
end
of
a
sweep.
HP 8340B/41B
Controller
Section
Theory
of
Operation F-3

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English