Motorola BT100 operation manual Automatic Drive Unit/QAM Automatic Drive Unit

Amplifier Setup 3-11

3Position the drive control select jumper to AUTO.

4Connect a signal-level meter to the FWD OUT test point and tune the meter to the high band-edge carrier.

5Turn the thermal level potentiometer on the TDU fully clockwise and then reduce to obtain 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:

1Position the drive control select jumper (Figure 2-13) temporarily to the MAN position and perform the complete procedure described in Manual Gain Control if not already completed.

BT100 Installation and Operation Manual