Section 3 Operation
3-12
3-42. Step Size and Step Key Operation. The keys
marked with up and down arrows are used to increment
and decrement source and program function values in the
active window designated by the KYBD legend. If an
arrow key is constantly depressed, the stepping will
repeat. Functions which can be stepped are PRGM,
FREQ, START, STOP, and LEVEL. Stepping any other
function has no effect.
3-43. Increment/Decrement Program Number. The
Program number can be stepped in single increments. A
special Auto-recall function is provided which auto-
matically executes the recall operation after the program
location function has been incremented or decremented
with the step keys. This function allows rapid recall of
sequential program setups by using a single key or bus
mnemonic. The auto-recall function can be enabled or
disabled using the internal option switch A4S1-5 or
special functions 7 and 8.
3-44. Increment/Decrement Frequency Values. Fre-
quency values in the FREQ, START, and STOP functions
can be stepped by the value in the FREQ STEP function.
Available frequency step sizes are listed in Table 3-3. If
the step size is smaller than the resolution of the selected
function, the function will be stepped by the resolution
value. The frequency step size also functions as the step
size for the linear frequency sweep mode.
3-45. Increment/Decrement Level Values. Amplitude
values in the LEVEL, START, and STOP functions can be
stepped by the value in the LEVEL STEP function. Level
step sizes can be linear or logarithmic values. Available
level step sizes are listed in Table 3-3. If the step size is
smaller than the resolution of the selected function, the
function will be stepped by the resolution value. Table
3-6 lists the output level ranges and resolution. The level
step size also functions as the step size for the linear and
logarithmic level sweep modes.
3-46. Sweep Mode General Description. The Model
1121A provides a user programmable sweep capability
which simplifies time consuming measurements such as
flatness, distortion vs. power output and compression/
expansion linearity. In the sweep mode the source of the
Model 1121A is used as the stimulus and can be
configured to sweep frequency or level in linear or
logarithmic steps. The source provides the X axis and pen
control signals for an external plotter/recorder. The
analyzer measurement provides the Y axis information.
The Y axis scale can be set using the HIGH and LOW plot
limit functions.
3-47. SWEEP Key Description. The SWEEP key is an
alternate action key which initiates and terminates the
sweep. The key’s LED indicates a sweep is in progress
and will be illuminated for the period of one sweep.
3-48. START Key Description. The START key allows
entry of either the frequency or level START value. The
START value defines the origin of the X axis which
corresponds to 0 volts at the X AXIS output connector.
When the START key is depressed the SOURCE display
will contain the START value and 0 volts is presented at
the X AXIS output connector as an aid in setting the offset
adjustment on most X-Y plotters.
3-49. STOP Key Description. The STOP key allows
entry of either the frequency or level STOP value. The
STOP value defines the end of the X axis which corre-
sponds to 5 volts at the X AXIS output connector. When
the STOP key is depressed the SOURCE display will
contain the STOP value and 5 volts is presented at the X
AXIS output connector as an aid in setting the sensitivity
adjustment on most X-Y plotters.
3-50. X AXIS Output Description. The X AXIS output of
the Model 1121A is the scaled result of the sweep fre-
quency or level relative to the START and STOP values.
The Model 1121A can be swept in level or frequency with
4096 points of resolution on the X axis. Selection of a
level or frequency sweep is determined by the type of
START and STOP values entered: START and STOP
level entries designate a level sweep and START and
STOP frequency entries designate a frequency sweep.
3-51. Y AXIS Output Description. The Y AXIS output of
the Model 1121A is the scaled result of the analyzer
measurement value relative to the HIGH and LOW val-
ues. There are 4096 points of resolution between 0 and 5
volts on the Y axis. Any measurement mode can be used
for sweeping. Various measurement modes and
applications require greater measurement settling before
a data point is generated. The Model 1121A allows for
user configurable settling times using special functions 61
through 69. The settling time is based on the number of
consecutive measurement cycles achieved before a data
point is plotted. Special function 60 disables the analyzer
measurement and the YAXIS output and allows the
source to be used as a rapid incremental sweep
generator with X AXIS and PEN control.
3-52. The HIGH and LOW plot limits are always displayed
in the same units as the analyzer measurement mode.
The Y AXIS output will be scaled linearly or loga-
rithmically depending on the display units. For example,
if the distortion measurement is displayed in % units the
result will be plotted linearly between the LOW and HIGH
plot limits and if displayed in dB units the result will be a
logarithmic plot. Analyzer measurements displayed in
mV or V units will be plotted linearly and those displayed
in dBV or dBm will be plotted logarithmically.
3-53. PEN Output Description. The Model 1121A gen-
erates a TTL compatible pen control output for use with a
plotter/recorder. The active state of the PEN output is
selected using option switch A4S1-3 or special functions
5 and 6.
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