Option Installation
Page 5-20
Owner’s Manual
TVM450/S/TVM550/S/TVM550II/TVM550IIS
AGC (TVM550IIS)
AGC Operation
The AGC can process a Left and Right stereo pair, plus two independent audio
channels (SAP and AUX). Each of the four channels enters at a rear panel con-
nector and is buffered before the AGC subassembly. When the AGC is OFF, the
audio signals bypass the AGC subassembly, and the normal front-panel audio
adjustments are functional. See Table 5-3 for the relationship of peak input to
modulation and peak output of a reference receiver.
Table 5-3. AGC in OFF Mode
Rear Panel
Input Level dBm
(Peak)
Potentiometer
Adjustment
Output Level dBm
(Peak)
Aural
Modulation
+10
Fully CCW
0
100%
0
Center
0
100%
–10
Fully CW
0
100%
Configuring the AGC2000
Before installation, review the setting of the Unity Gain jumper (P7) by comparing
the program material and input levels to be expected Table 5-4. The factory de-
fault setting will most likely provide satisfactory operation and should be used if in
doubt. The jumper has four positions that indicate an average audio level over
time (see Figure 5-17). Users may move the jumper to give lower average audio
levels for coordination with other channels in the system. However, users cannot
move the jumper to give higher audio level if the amplitude excursions exceed
the limiting value. As a rule of thumb, signals with minimal excursions in dynamic
level may benefit from the –6 dB setting, assuming the average level is accept-
able, while signals with extreme excursions within the program material may
benefit from the –15 setting to prevent limiting.
Table 5-4 Steady-State Output vs. Input
Rear Panel
Input Level
(rms) dBm
Potentiometer
Adjustment
Jumper –6
Output Level
(dBm)
Jumper –9
Output Level
(dBm)
Jumper –12
Output Level
(dBm)
Jumper –15
Output Level
(dBm)
> +18
Level exceeds input buffer range
+18
n/a
–2.25
–4.5
–6.75
+14
n/a
Limiting
–3.25
–5.5
–7.75
+10
n/a
–2
–4.25
–6.5
–8.75
+8
n/a
–2.5
–4.75
–7
–9.25
+4
n/a
–3.5
–5.75
–8
–10.25
0
n/a
–4.5
–6.75
–9
–11.25
–6
n/a
–6
–8.25
–10.5
–12.75
–9
n/a
–6.75
–9
–11.25
–13.5
–12
n/a
–7.5
–9.75
–12
–14.25
–15
n/a
–8.25
–10.5
–12.75
–15
–20
n/a
–9.5
–11.75
–14
–16.25
–40
n/a
–14.5
–16.75
–19
–21.25
–60
n/a
–19.5
–21.75
–24
–26.25
