Audio Precision Portable One Plus Access User Manual

The calculation of dBm is slightly more complicated, according to the
following formula:
where V is the measured voltage, R is the programmable impedance,
and Pr is 1 milliwatt. The log calculation is to the base 10.
The impedance used for Watt calculations is remembered separately
from the impedance used for dBm calculations. To set the impedance
references, go to the Analyzer Only Panel and select dBm or W for the
main measurement units using the upper left soft key. Then the
reference impedance for the selected unit will be shown across the
center of the display and the AMPLITUDE controls may be used to
change it.
Frequency units
.
Hz – hertz, basic unit of frequency (1/sec)
.
% - Percentage variation in frequency
.
∆% - Percentage deviation from ideal frequency
Hertz (abbreviated Hz) is the basic unit of frequency. It is a count of
the number of cycles a waveform goes through in a second. It is the
reciprocal of the number of seconds required for one cycle of a
waveform.
The % (percent) unit is used in the Wow and Flutter measurement
function to measure the variation in frequency. The Wow and Flutter
detector measures the frequency variation and reduces it to a number
in Hertz, according to the selected detector and statistical choices. This
variation is then calculated as a percentage of the 3 kHz or 3.15 kHz
intended frequency using the following formula:
where D is the frequency deviation and F is the intended frequency.
dBm
VR
=•10
2
log(
Pr
)
% =
F
H
I
K
•abs
D
F
100
& For
information
about dBm and
dBu units, see
page 4-73.
& For
information on
moving among
the panels, see
page 4-1.
4
Operation
Units : Frequency units Operation
Portable One Plus Access User's Manual 4-75
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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