ADInstruments AD8000 Series Instruction Manual page 57

AD8000 Series Spectrum Analyzer Instruction
Manual
(2) Attenuator
The input attenuator is an important part of the device. With the attenuator,
the amplitude of input signal entering the mixer could be reduced, and then
reduce the signal distortion. The range of attenuator of the device is 0dB ~
50dB with 1dB step. The default value is 10dB.
The using of attenuator should be reasonable. The increasing of the
attenuator could reduce the distortion of the mixer of the device, but
increase the noise and decrease the measurement signal range. The
attenuation value should be set reasonably to make the device work most
efficiently.
The system would offer a suitable attenuation value automatically in auto
mode. To change the attenuator, it should be set as manual with the soft-
key first. Press the up/down step key or rotate the knob to change it by 5dB
each time. If inputting with number keys, it could be changed by 1dB step.
If the measured signal is higher than the noise floor of the device, the noise
floor would increase for the same value of the increasing of the attenuator.
Fig. 3-10 Reference Level Inputting
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