NF WF1946B, Instruction Manual

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WF1946B
1-3
1.2 Operating principles
„
Block diagram
Sweep
input/output
Displ
ay a
nd
p
a
n
el ke
y
Isolation
occurrence
Others
Digital output
Overlevel
Detector
A
m
pli
tude
contr
o
l
Clock
Synchronous operation
input/output
Offset D/A
M
u
ltipl
ier
M
u
ltip
lier
z The CPU conducts analog control for display, panel keys, remote control (GPIB, USB), DDS,
amplitude and DC offset. Sweep input/output is also controlled for sweep internal/external
modulation.
z
The clock generator produces DDS reference and CPU clock signals.
z Two sets of circuits for DDS and analog compose two channels.
z
An isolation circuit between the CPU and DDS provides floating functions.
z The DDS (Direct Digital Synthesizer) uses an original LSI device and generates digital data of
the setting frequency.
z The waveform memory converts digital data from the DDS into standard or arbitrary waveform
data. Waveform data are set from the CPU.
z The digital to analog (D/A) converter produces an analog signal from the resulting waveform
data.
z
The lowpass filter (LPF) smoothes the stepped D/A output signal.
z Amplitude control is set by the gain control. DC offset is produced by the offset D/A converter
and the output amplifier adds and amplifies the output signal.
z The attenuator (ATT) selects the output range by 1/10 attenuation on/off.