Operating instructions
OPTIMOD-AM DIGITAL INSTALLATION
2-19
would be if your format is predominantly talk, because talk does not re-
quire frequencies below approximately 80Hz.
All highpass filters have greater than 30dB/octave rolloff and have a
notch at 25Hz to remove any signaling tones and to protect transmitters
that might be adversely affected by modulating frequencies in this area.
Technically, what you have just done is to set the highpass filter cutoff
frequency in the TX1/DAY
transmission preset. This transmission preset is
the default.
7. Set external AGC mode.
Most of the processing structures in the 9400 control level with a preliminary
AGC (Automatic Gain Control). If you are using a suitable automatic gain control
at the studio (such as an Orban 8200ST OPTIMOD-Studio or 464A Co-Operator),
the AGC in the 9400 should be defeated. This is so that the two AGCs do not
“fight” each other and so they do not simultaneously increase gain, resulting in
increased noise.
A) Press the N
EXT button.
B) Set external AGC mode by turning the knob.
Set the field to Y
ES if you have a external AGC (such as an Orban 1100,
1101, 6300, 8200ST OPTIMOD-Studio, Orban 464A Co-Operator, or similar
AGC) installed at your studio feeding the studio-to-transmitter link. This
setting appropriately defeats the 9400’s AGC for all presets.
Set the field to N
O If you do not have an external AGC installed; this setting
enables the 9400 AGC status to be determined by the selected preset.
If you are using an Orban 4000 Transmission Limiter, set field to NO (so
that the AGC function in the 9400 continues to work). The Orban 4000 is
a transmission system overload protection device and is normally oper-
ated below threshold. It is not designed to perform an AGC or gain-
riding function, and it cannot substitute for the AGC function in the
9400.
8. Select your primary input (analog or digital).
A) Press the N
EXT button.
B) If your main input source is digital, turn the knob to select D
IGITAL or
D
IGITAL+J17. Otherwise, select ANALOG.
The only digital encoding that typically uses J.17 pre-emphasis (of which
we are aware) is NICAM. D
IGITAL, not DIGITAL+J17, is appropriate for al-
most anyone using the digital input.
9. Select the stereo/mono mode.
A) Press the N
EXT button.
B) Choose the operating mode of the analog AM processing chain.
If you intend to operate in CQUAM® AM stereo, choose S
TEREO.