Operation Section 3
3-13
3-54. Using The Sweep Mode. When the SWEEP
key is depressed the START value is transferred to the
LEVEL or FREQ function, and the function is activated.
When the sweep is in progress the X AXIS output will
produce an incrementing voltage between 0 and 5 volts.
The START and STOP values must be compatible in
level or frequency units or an error will be displayed when
the SWEEP key is depressed. When the sweep
sequence is initiated the X axis information is presented
at the rear panel X AXIS output and after an approximate
1 sec delay the PEN output is set true. When the sweep is
terminated the PEN output is immediately set false. The
PEN output can be set independent of any sweep
operation using the PU and PD bus mnemonics.
3-55. The sweep mode will be terminated if any number
entry is attempted, any function is selected other than the
functions displayed at the start of the sweep sequence, or
either the SWEEP key or the LCL/INIT key is depressed.
Selecting filters, floating modes and display units will not
terminate the sweep mode. If a sweep has been termi-
nated, it can be resumed by selecting the appropriate
LEVEL or FREQ function and depressing the SWEEP
key. The sweep will be activated and will resume from
the displayed value until the STOP value is reached.
3-56. Generating Frequency Sweeps. The Model
1121A can generate user configurable frequency sweep
sequences up to the entire frequency range of the oscil-
lator in logarithmic or linear increments. The range of
the sweep is defined by the START and STOP values
which can be in ascending or descending order.
Logarithmic frequency increments are selected using
special function 1 through 59 and vary from 16 to 4096
steps. Linear frequency increments are selected using
special function 50 and the FREQ STEP function defines
the increment value. Linear sweep step sizes which
exceed the X axis resolution limit of 4096 steps are
allowed, however, the X AXIS output voltage will dwell at
the same level for more than one frequency increment.
3-57. Generating Level Sweeps. The Model 1121A can
generate user configurable level sweep sequences up to
the entire level range of the oscillator in logarithmic or
linear increments. The range of the sweep is defined by
the START and STOP values which can be in ascending
or descending order. Logarithmic and linear level incre-
ments are selected using the LEVEL STEP function.
Special functions 50 through 59 have no effect on level
sweep. A logarithmic level sweep is defined by a LEVEL
STEP value expressed in dB units and a linear level
sweep is defined by a LEVEL STEP value expressed in
mV or V units. Level sweep step sizes which exceed the X
axis resolution limit of 4096 steps are allowed, however,
the X AXIS output voltage will dwell at the same level for
more than one level increment.
3-58. Program Store And Recall Description. The
entire status of the Model 1121A, including all functions,
entered values and display modes, can be saved in a
program location of non-volatile memory for recall at a
later time. Up to 99 such programs (0-98) can be stored
and recalled.
3-59. Store Operation. To save the complete
frontpanel setup in the program memory, first set all the
desired instrument operating parameters to be stored.
Next depress the PRGM key and enter the desired
program location with the DATA ENTRY keypad and the
ENTER key. Finally, depress the STO key to save the
complete instrument status in program memory. Below is
a list of all the parameters which are retained in program
memory.
1. All entered values of all functions.
2. All source impedance and floating settings.
3. All display modes and selected display units.
4. All special function settings.
3-60. Recall Operation. To recall the front-panel setup in
the program memory, depress the PRGM key and enter
the desired program location with the DATA ENTRY
keypad and the ENTER key. After the memory location
has been selected, depress the RCL key. Program
location 99 is a recall-only location that restores the ini-
tialize parameters in the same manner as the LCL/INIT
key. Any panel setting may be changed after recalling a
program location.
3-61. Program Memory Initialization. In normal use the
internal memory is never erased, new programs are
simply written over the old ones. It is necessary, however,
to erase the program memory after a new firmware revi-
sion has been installed or after the CPU circuit board has
been serviced. Entering special function 25 will erase the
entire program memory. Attempting to recall an erased
program will result in Error 11 being displayed. Special
function 25 can be disabled using the internal option
switch A4S1-4.
3-62. Special Function Description. The Model 1121A
provides special modes of operation for specific applica-
tion situations. Special function modes shown in Table
3-5 can be selected using the SPCL key and the DATA
ENTRY keypad.
3-63. Option Switch Functions. Codes 1 through 8
supersede current settings of the internal option switch,
A4S1. The option switch settings are restored on
pow-er-up, by executing special function 0, or by
depressing the LCL/INIT key.
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