HP 8924E, Assembly

Page: 462 / 640

462
Chapter 11, Block Diagrams
Section Details
N:\mkt\MANUALS\HP8924C\ALR\blkdia.fb
Audio Analyzer
Section
Input Level Control
Switchable gain amplifiers on the A35 Audio Analyzer 1 and A36 Audio
Analyzer 2 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 A37 Measurement assembly. The A16 Host 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
A16 Host 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 A35 and A36 Audio
Analyzer assemblies, A37 Measurement assembly, and the A16 Host Controller
work together to perform the oscilloscope functions.
Display
The audio or dc signal to be displayed goes from the A36 Audio Analyzer 2
assembly to a sampler on the A37 Measurement assembly (the same sampler used
by the Spectrum Analyzer). The A16 Host Controller calculates the display level
by taking into account 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.
Trigger
The scope trigger signals from the rear-panel MEAS TRIGGER connector, the
A15 Signaling Source/Analyzer assembly, and the internal trigger signal are used
by the A37 Measurement assembly and the A16 Host Controller to determine
when to start the scope sweep. The Controller takes into account the pre-trigger
time entered from the front panel.