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AC/DC output
AC output
123
Models SE and DL
AC/DC output
Output signals are available at the AC/DC jack in the hardware interface panel at
the base of the instrument (“Hardware interfaces” on page 6). Users are
responsible for providing the cable to attach to this jack. For information about
the pinout, see “AC/DC jack” on page 134.
AC output
The AC output is the amplified SPL of Meter 1. It is weighted depending on
the "A, C, Z or F" selection for Meter 1. The maximum full-scale output
voltage occurs near the upper dB level of the selected range and is
approximately 3.16 volts "before clipping." The full usable range of this
output is 60 dB. The relationship is shown in Table 8-1.
Relative dB
Output (Vrms)
Full scale
3.16
-10 dB
1.00
-20 dB
0.316
-30 dB
0.100
-40 dB
0.0316
-50 dB
0.0100
-60 dB
0.00316
Table 8-1: AC output
NOTE: The AC output signal is not intended to be used for testing
instrument performance.
DC output
The DC output has a voltage range between 0 and 4.0 VDC that is
produced by Meter 1 and includes the time response and frequency
weighting settings for that meter. It represents and tracks the
displayed dB level in one second increments. The DC output is
linearly scaled over the range of –20 to 180 decibels. The highest
level that can be represented on any selected range is always the
ceiling of that range and depends upon the selected microphone
model.
The DC output voltage level is related to the measured decibel value
without regard to the range setting. You can calculate the SPL in
decibels from the DC output voltage, V
DC
, by this equation:
SPL = 50 (V
DC
– 0.4) dB