System information

© 2006 Cisco Systems, Inc. All rights reserved. Cisco Confidential Presentation_ID Kirkpatrick 092509
77
S-QAM FS TX Operation
 Transmitter gain is controlled through the selection of Manual or Automatic
Gain Control (AGC) mode operation.
 In Manual mode, an attenuator can be used to reduce RF power. It may
be desirable to make such adjustments to compensate for power
differences if the channel load differs from the specified value.
 In AGC mode, the microprocessor monitors the actual input composite
power and adjusts the attenuator to maintain constant RF drive level into
the laser diode.
Note: If Analog or QAM loading is to remain constant – not expanding
using AGC is OK however IF channel load differs the AGC will self
adjust accordingly resulting in RF level change at Node RX.