ADInstruments AD8000 Series Instruction Manual page 99

AD8000 Series Spectrum Analyzer Instruction
Manual
(2) Attenuator & Amplifier
The functions of attenuator are the in spectrum sweep function. It can
reduce the signal distortion and the amplitude of input signal entering the
mixer. The value of attenuator is from 0 to 55dB with 5dB step, and the
default value is 10dB. In auto mode, the system can automatically provide a
suitable value of attenuator. If users want to change the attenuation value,
users should firstly set the 'Atten' soft key to 'Manu', and then input the
value by number keys, 'Up/Down' key or the knob. With the 'Up/Down'
cursor or the knob, the change step is 5dB. When inputting value by number
keys, the step is 1dB. If the measured signal is higher than the noise base
of the instrument, the attenuation will increase generally, which would bring
the same value increasing of the noise base.
Figure 3-66 and 3-67 show the measurement results under different
attenuator. From the channel power measurement parameters and the
blue background height of channel power, we can see the influence of
attenuator on the waveform. At the same time we can also observe the
impact of the attenuator the noise floor.
Inside the instrument there is a switch for preamplifier, when the signal
amplitude is too small to measure, you can switch on this amplifier to
increase the system test range.
Fig. 3-65 Reference Level -30dBm
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