Audio Precision Portable One Plus Access User Manual

THD+N (Total Harmonic Distortion plus Noise)
The THD+N function is selected by pressing the FUNCTION
THD+N/SINAD button.
The THD+N function uses a notch (bandreject) filter to eliminate the
fundamental frequency, and then measures the amplitude of signal
remaining. The remaining signal will contain the distortion products of
the original tone and the noise present in the signal.
This measurement is known as Total Harmonic Distortion plus Noise,
or THD+N. It is almost always displayed as the ratio of the distortion
and noise to the original signal before filtering, in units of % or dB.
Two voltmeters are used in this measurement - one to measure the
signal before filtering and another to measure the filtered signal.
Figure 4-18. Main Panel in THD+N Function
FREQUENCY
COUNTER
NOTCH
FILTER
WEIGHTING
FILTERS
PRIMARY
READING
DETECTOR
BANDWIDTH
LIMITING
FILTERS
GENERATOR MONITORS
B
A
INPUT
RANGING
INPUT
TERMINATION
INPUT
TERMINATION
LCD DISPLAY
AVERAGING
SECONDARY
READING
DETECTOR
INTERNAL
JUMPER
INPUT
MONITOR
SPEAKER/
HEADPHONE
READING
MONITOR
CHANNEL A
CHANNEL B
Figure 4-19. Block Diagram of THD+N Measurement
& For more
information on
THD+N
measurement,
see the special
section on
4
Operation
Controlling the Analyzer : THD+N (Total Harmonic Distortion plus Noise) Operation
Portable One Plus Access User's Manual 4-25
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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