Figure 4-1: Typical Frequency Response, 30Hz To 15 Khz - Orban OPTIMOD-FM 8500S Operating Manual

OPTIMOD-FM DIGITAL
C) Connect the audio voltmeter to the Left Analog Output.
D) Adjust output trim VR301 to make the meter read +10.0 dBu. (0 dBu = 0.775V
rms.) Verify a frequency reading of 400 Hz.
E) Verify THD+N reading of <0.03% (<0.01% typical) using a 22 kHz low pass fil-
ter in the distortion analyzer.
F) Set the M
ODE
B
YPASS
retains pre-emphasis.
G) Verify a reading (noise) of <–80 dBu at the output of the unit.
H) Using VR302, repeat steps (C) through (G) for the Right Analog Output.
4. Check frequency response of Analog I/O.
A) Verify 8500S software controls are set to their default settings. [Refer to step
(2.A) on page 4-7.]
B) Be sure you are still in B
step (3.F)].
C) Connect the oscillator to the Left Analog Input XLR connector.
D) Inject the Analog Input XLR connector with a level of +10 dBu with the oscilla-
tor set to 100 Hz.
This is 17 dB below the clip level, which allows headroom for pre-
emphasis. (75μs pre-emphasis will cause 17 dB of boost at 15 kHz.)
E) Connect the audio analyzer to the 8500S's Left Analog Output XLR connector.
F) Verify a level of 0 dBu ±1 dB. Use this level as the reference level.
G) Verify that frequency response at 50 Hz, 100 Hz, 400 Hz, 5 kHz, and 15 kHz is
within ±0.1 dB of the reference level. Figure 4-1 shows a typical result.
This procedure tests the analog input circuitry, the A/D converter, the
DSP, the D/A converter, and the analog output circuitry.
dBrA
600m
400m
200m
0
-200m
-400m
50

Figure 4-1: Typical Frequency Response, 30Hz to 15 kHz

to B .
YPASS
defeats all compression, limiting, and program equalization but
mode and that the B
YPASS
100 200 500
G
YPASS AIN
1k 2k 5k
MAINTENANCE
= 0.0 dB [see
Hz
10k
4-9