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SECTION 2
Princides of ODeration
2.1
INTRODUCTION
This section covers basic operating principles of the
Model 3930A.
2.2
BLOCK DIAGRAM
Figure 2-l shows an overall block diagram of the Model
3930A. The various sections include the control section,
display and keyboard section, trigger section, synthe-
sizer section, analog section, and the power supply and
GPIE! interface sections.
2'2.1
Control Se'ctlon
The control section supervises all instrument operations.
The control section includes the 68008 microprocessor,
EPROM for program storage, and battery backed-up
RAM for working storage and memory to store operating
parameters.
This section includes a 40-character X 2-line LCD (liquid
crystal display) and a membrane keyboard. The LCD is
backlit for better visibility.
2.2.3
Trigger Skctlon
The trigger section generates trigger signals for the burst
and gate oscillation modes. Circuits in the trigger section
include the internal trigger oscillator, counter for the
burst oscillator, the I/O buffer, and various support cir-
cuits.
2.2.4
Synthesizer Section
+lYhis section is comprised of a custom LSI IC, which pro-
vides direct digital synthesis of the selected waveform.
The digital waveform data is defined by the oscillation
frequency and waveform type.
In addition to the custom LSI IC, the synthesizer section
also includes a high-accuracy crystal oscillator, a sine
wave conversion ROM, sweep I/O circuits, as well as cir-
cuits necessary to connect the Model 3930A to the op-
tional Model 3933A Phase Shifter.
2.2.5
Analog Section
The aWlogse&ion~i
a DTA converter to convert
digital waveform data produced by the synthesizer into
the analog output signal. The analog section also controls
the amplitude of the output waveform and adds the DC
offset to the output signal.
2-l
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