Orban OPTIMOD-FM 8500S, Operating Manual

Page: 241 / 335

OPTIMOD-FM DIGITAL OPERATION
3-77
Test Modes
Setup: Test
Parameter
Labels Units Default Range (CCW to CW) Step
MODE --- Operate Operate, Bypass, Tone ---
BYPASS GAIN dB 0.0
−
18 … +25
1
TONE FREQ Hz 400 16, 20, 25, 31.5, 40, 50,
63, 80, 100, 125, 160,
200, 250, 315, 400, 500,
630, 800, 1000, 1250, 1600,
2000, 2500, 3150, 4000, 5000,
6300, 8000, 9500, 10000,
12500, 13586.76, 15000 LOG
TONE LVL % 91 0 … 121 1
TONE CHAN --- L+R
L+R, L
−
R, LEFT; RIGHT
---
PILOT --- ON ON, OFF ---
Table 3-13: Test Modes
The Test Modes screen allows you to switch between
O
PERATE
, B
YPASS
,
and
T
ONE
.
When you switch to B
YPASS
or T
ONE
, the preset you have on air is saved and will be
restored when you switch back to O
PERATE
.
Table 3-13 shows the facilities available. Facilities are self-explanatory, except for the
following:
•
The
T
ONE
L
VL
control is calibrated under the assumption that the stereo pilot
tone contributes 9% to the total modulation. Hence, a T
ONE
L
VL
setting of 91%
produces 100% modulation (91% + 9%).
Note that when the Optimod is in
T
ONE
mode and its analog or digital L/R out-
puts are set to
F
LAT
(instead of
P
RE
-E
MPH
), these outputs apply 50 μ s or 75 μ s
deemphasis to the output of the tone oscillator. Applying deemphasis this way is
only correct if equipment downstream from the Optimod, like a transmitter’s ste-
reo encoder, applies preemphasis before final transmission.
•
In B
YPASS
mode, preemphasis is still applied to the signal path. The B
YPASS
G
AIN
control calibration allows enough internal headroom to make swept frequency
response measurements without internal clipping. When the
B
YPASS
G
AIN
control
is set to
0.0
dB and the
AI R
EF
VU
control is set to 0.0 dBu, you will observe a gain
of approximately –17 dB from the analog input to the analog output at 100 Hz.
If the
AO P
RE
-
E
control is set to P
RE
-
E
and the 8500S is configured for 75
µ
s pre-
emphasis, the gain from analog input to analog output will be approximately 0
dB at 15 kHz.