OPTIMOD-FM OPERATION
3-59
The multiplex power controller is operational with both the Two-Band and
Five-Band processing structures. It is not operational in Test mode and will
not prevent the 8400’s test oscillator from producing illegal modulation. It is
the responsibility of the operator to make sure that the test oscillator does not
violate the ITU requirements. (To ensure this, never modulate the carrier
with a single L+R tone that produces total carrier modulation, including pilot
tone, of more than 24%.)
If you apply sinewaves below 100 Hz to the Five-Band structure and use a
slow attack time and fast release time on the Band 1 compressor, the multi-
plex power controller may not be able to produce enough extra gain reduc-
tion in Band 1 to control power correctly. This is because this combination
of settings causes Band 1 to lower its compression ratio, and if the output
level of the Band 1 compressor is too large, then the peak level is controlled
by the bass clipper instead of the Band 1 compressor. However, even if you
can find some combination of test tones and custom processing settings that
are insufficiently controlled, program material will always be controlled cor-
rectly.
Test Modes
The Test Modes screen allows you to switch between Operate, Bypass, and Tone. When
you switch to
Bypass or Tone, the preset you have on air is saved and will be restored
when you switch back to
Operate.
Table 3-10: Test Modes (below) shows the facilities
available, which should be self-
explanatory.
Setup: Test
Parameter Labels Units Default Range (CCW to CW) Step
Mode --- Operate Operate, Bypass, Tone ---
Bypass Gain dB 0.0
−18 … +15
1
Bypass 30 Hz HPF --- ON Off, On ---
Tone Frequency 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 Mod. Level % 91 0 … 100 1
Tone Mod. Type --- L+R
L+R, L−R, LEFT; RIGHT;
MONO
---
Pilot --- ON ON, OFF ---
Table 3-10: Test Modes
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