Agilent Technologies 8935 Series, Руководство пользователя

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294 Chapter 10
Block Diagrams
Audio Analyzer Section
Audio Analyzer Section
Input Level Control
Switchable gain amplifiers on the A2A80 Audio Analyzer #1 (see Figure
10-7 on page 295 ) and A2A40 Audio Analyzer #2 (see Figure 10-8 on
page 296 ) assemblies keep the audio input signal within a range
suitable for the detectors.
AC and DC Level Measurements
Detected voltages from the Peak+, Peak
−
, and RMS detectors are
measured on the A2A33 Measurement assembly. The Controller
calculates the displayed value taking into account the detector selected
from the front panel, the gain of the amplifiers, and the source of the
input signal (demodulators, front panel).
Distortion and SINAD Measurements
Distortion and SINAD can be measured on 300 Hz to 10 kHz audio
signals. The Controller calculates distortion and SINAD by comparing
the ratio of the voltage after the variable notch filter to the ratio of the
voltage before the notch filter.
Oscilloscope Functions
The Test Set has no specialized oscilloscope assemblies. The A2A80 and
A2A40 Audio Analyzer assemblies, A2A33 Measurement assembly, and
the Controller work together to perform the oscilloscope functions.
The audio or dc signal to be displayed goes from the A2A40 Audio
Analyzer 2 assembly to a sampler on the A2A33 Measurement
assembly (the same sampler used by the Spectrum Analyzer). The
Controller calculates the display level by taking the value of the
measured signal at each point of the sweep, the gain of the signal path
in the Audio Analyzer assemblies, and the volts-per-division setting.
The oscilloscope’s trigger signals from the side-panel connector, the
A2A32 Signaling Source/Analyzer assembly, and the internal trigger
signal are used by the A2A33 Measurement assembly and the
Controller to determine when to start the scope sweep. The Controller
adds the pre-triggering time entered from the front panel.