Table of Contents
Advertisement
Position the drive control select jumper to
3
Connect a signal-level meter to the
4
band-edge carrier.
Turn the thermal level potentiometer on the TDU fully clockwise and then reduce to obtain
5
the level obtained in Step 9 under Manual Gain Control.
Automatic Drive Unit/QAM Automatic Drive Unit
The ADU and QADU operate by using surface acoustic wave (SAW) filters to select a pilot
frequency and then monitoring the amplitude of this frequency. Any change in signal level is fed
back to the Bode equalizer. It is assumed that the encountered signal level changes are due to
changes in cable attenuation and hybrid output associated with a change in temperature. The
Bode equalizer then changes its insertion loss to maintain a constant output level. The ADU
(illustrated in Figure 3-6) and QADU (Figure 3-7) maintain a more precise output level than
using the TDU or leaving the BT100 in manual control.
Figure 3-6
ADU
Figure 3-7
QADU
To set-up the ADU/QADU:
Position the drive control select jumper (Figure 2-13) temporarily to the
1
perform the complete procedure described in Manual Gain Control if not already completed.
.
AUTO
test point and tune the meter to the high
FWD OUT
Amplifier Setup
position and
MAN
BT100 Installation and Operation Manual
3-11
Advertisement
Table of Contents
