6
Special Functions
The modulation analyzer can do
more than is apparent from the
front panel. This capability is
accessed by using the data keys
and a special function key or
remotely via HP-IB. They fall into
three categories: manual control
of instrument functions, instru-
ment operation verification, and
service aids.
An example of the type of special
function found in the manual
control category is the auto
tune-track mode. This mode is
accessed by entering 4.1, then
pressing the special key. Once
the modulation analyzer has been
placed in track mode the analyzer
will continuously track the signal
as it changes frequency. This
eliminates the delays caused by
the analyzer searching for the
signal each time the signal’s
frequency changes. Using this
special function, a user could
continuously monitor modulation
accuracy on a signal generator
while tuning across the signal
generator’s frequency band.
Auto tune-track makes it possible
to tune the analyzer three ways:
automatically, manually by
entering the frequency on the
keyboard, and track mode.
Special functions can also be used
to set any measurement range or
instrument function. They can be
used to select either of two inter-
nal IF’s, the one normally used for
frequencies above 10 MHz or a
narrow IF where rates and devia-
tions are more restricted but
selectivity is increased. All instru-
ment functions not set using these
special functions remain in auto-
matic mode. This allows the user
to select any combination of
manual or automatic operation.
By depressing the special key, the
display shows an eight-digit num-
ber that indicates which functions
are in automatic and the state of
those manually set.
There are also numerous special
functions that can be used in veri-
fying that the instrument and its
various sections are operating
properly. These, along with ser-
vice functions used in diagnosing
and repairing the analyzer, make
repairs much faster and easier.
An additional service aid is the
built-in ability to use HP signature
analysis instrumentation. This
allows a technician with little
knowledge of digital circuits to
rapidly troubleshoot a failure in the
digital portion of the instrument.
Those special functions that are
most commonly used in operating
the analyzer are described on the
pullout information card under the
front panel.