Audio Precision Portable One Plus Access User Manual

The amplitude is measured using true RMS detection except in a few
of the filtering modes described below. Several types of filters may
also be applied to the amplitude measurement.
The type of filter is selected by the lower left soft key. Three types of
filters are available:
.
UN-WTD – The ‘unweighted’ selection provides no filtering
except selectable bandwidth-limiting:
.
The lower center soft key selects the lower band limit (<10
Hz, 22 Hz or 400 Hz).
.
The lower right soft key selects the upper band limit (>300
kHz, 22 kHz, 22 kHz-QPK, 30 kHz, 80 kHz). The 22
kHz-QPK selection uses the quasi-peak detector instead of
the true RMS detector in accordance with CCIR-468. The
22 Hz lower limit is only available if the upper limit is 22
kHz; the <10 Hz lower limit is only available with other
upper limits.
.
SELECTIVE – This selection provides a tunable bandpass filter.
The filter has a bandwidth of 1/3 octave. No other filtering is
provided. The top right corner of the display shows the filter
center frequency, which can be adjusted with the FREQUENCY
controls. The SELECTIVE filter can be used to create
spectrum-analysis sweeps. In this type of measurement, a
narrow bandpass is swept across a range of frequencies, taking
an amplitude measurement at each step.
.
WTD – The ‘weighted’ selection allows selection of a variety of
weighting filters with a selectable lower band limit. The lower
center soft key selects the lower band limit (<10 Hz or 400 Hz).
The lower right soft key selects among the following weighting
filters:
.
ANSI/IEC-A – A-weighting filter per IEC 179, true RMS
detector
.
CCIR-1k – Weighting per CCIR-468, true RMS detector
.
CCIR-2k – Weighting per CCIR-468, but with 0 dB gain
point at 2 kHz rather that 1 kHz, true RMS detector
.
CCIR-QPK – Weighting per CCIR-468, quasi-peak detector
& The shapes of the
bandwidth-limiting filters
are shown in Appendix E.
& For more
information on
sweeps, see page
4-59.
4
Operation
Controlling the Analyzer : Amplitude Operation
Portable One Plus Access User's Manual 4-19
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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