Motorola SG 2000 Level Control, Options and Accessories, Model Description Function, Adu

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Level Control

The gain of hybrid IC amplifiers varies with temperature. In addition, changes in system channel loading and/or splices in the fiber link can change the level of the received signal.

The standard TCU board compensates for anticipated hybrid gain changes by sensing housing temperature and signaling needed changes to the RF attenuator.

The ADU board, an optional plug-in module, monitors the amplitude of a selected pilot frequency. The pilot frequency is an available analog television channel not scrambled by the sync suppression method. Any changes in amplitude are fed back to the RF attenuator that makes appropriate corrections.

The input to the ADU contains a JXP-* pad. The factory-installed value of this pad is 6 dB (JXP-6) for bridger level outputs and 0 dB (JXP-ZX) for trunk level outputs. Under normal conditions, it should not be changed.

Options and Accessories

Table 2-3 provides a list of options and accessories for the SG 2000:

Table 2-3

Options and accessories

Model	Description	Function
ADU-*	Automatic drive	This option automatically adjusts gain by monitoring changes
	unit	in the level of the selected pilot carrier. Either an ADU or TCU
		must be installed.
TCU	Thermal control	The TCU controls amplifier gain for changes in hybrid gain at
	unit	the sensed temperature.
JXP-*A	Fixed	Attenuator pads are used to adjust amplifier levels and are
	attenuator	available in 1 dB steps from 1 through 24 dB. The appropriate
		value must be installed.
JXP-ZX	0 dB attenuator	This attenuator is used in place of JXP-*A pads when no
		attenuation is needed.
FTEC	Crowbar	The FTEC is an electronic crowbar/surge protector that can be
	overvoltage	used to replace the existing 230-volt gas discharge surge
	protection	protector.
LL-SG2	LIFELINE	This module enables the system operator to monitor the SG2
	module	from a remote location. See Section 5, “Operation” for
		parameters monitored. Several frequencies are available. See
		the product catalog for additional information.
GFAL	Test probe	This probe is used to evaluate node performance.
F/JXP	Injection probe	This probe is used to inject a signal for test purposes.

SG 2000 Installation and O peration Manual