Audio Precision Portable One Plus Access User Manual

Detailed Technical Diagrams
This chapter contains several diagrams to assist your understanding of
how the Portable One Plus Access accomplishes its measurement
tasks. While knowledge of the internal circuitry is not required for
operation of the instrument, it may be more intelligently applied, and
its limitations may be better understood by referring to these diagrams.
Block Diagram
Figure 6-1 is a simplified block diagram of the Portable One Plus
Access.
The generator consists of a sinewave and squarewave generator
transformer-coupled to the output connectors. When the P1-IMD
option is present, a second sinewave oscillator is added. Its output is
summed with the main oscillator to provide the necessary two-tone
signal. With the IMD waveform selected, the rear panel Analog Trigger
output carries the lower-frequency tone of the IMD tone pair for
oscilloscope triggering.
The analog analyzer consists of two identical wide-range autoranging
preamplifiers, a principal meter with filters, a secondary meter, a wow
and flutter discriminator, and phase and frequency meters.
The principal meter consists of a switchable and tunable bandpass or
bandreject filter, additional amplification, built-in high-pass and
low-pass filters, built-in CCIR and A-weighting filters, and two sockets
for optional filters. The bandreject is used in THD+N and SINAD
functions. The bandpass filter is used in the SELECTIVE modes of the
AMPLITUDE and NOISE functions and in the XTALK function.
The output of either the principal meter or the wow and flutter
discriminator feeds the primary reading detector. The primary
detector, depending on the measurement function and setup
parameters of that function, may have true RMS, average, or
quasi-peak response. The primary reading is normally displayed in the
upper-left corner of the display on the Main panel or Analyzer Only
panel and graphed with solid lines in sweeps of all functions except
PHASE.
6
Diagrams
Portable One Plus Access User's Manual 6-1
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Audio Precision Portable One Plus Access Specifications

General

Brand	Audio Precision
Model	Portable One Plus Access
Category	Test Equipment
Language	English