Motorola SG 2000 用户手册
2 - 8 O v e r v i e w
SG 20 00 Ins tal la tion and O pera tion M anua l
To assess fiber link status, the optical-power monitor circuit is active at all times (even when the
receiver is disabled). An integrated optical bulkhead connector and module link status indicators
enhance fiber management and reduce troubleshooting time. The receiver module is fully compatible
with the status monitor transponder for remote monitoring of key module and link performance
parameters.
receiver is disabled). An integrated optical bulkhead connector and module link status indicators
enhance fiber management and reduce troubleshooting time. The receiver module is fully compatible
with the status monitor transponder for remote monitoring of key module and link performance
parameters.
Several plug-in boards are available to configure the SG 2000 lid board for single, redundant, or
narrowcast receiver arrangements. A low-noise pre-amplifier hybrid amplifies the signal to a level
suitable for connection to the RF chassis.
narrowcast receiver arrangements. A low-noise pre-amplifier hybrid amplifies the signal to a level
suitable for connection to the RF chassis.
An SG2-FRB flatness board, at the input to the RF chassis, compensates for hybrid and accessory
response signatures. A variable attenuator circuit enables fine adjustment of the output level, and is
driven either by the standard thermal control unit (TCU) or optional ADU pilot automatic gain
control (AGC) module to compensate for temperature and input level variations.
response signatures. A variable attenuator circuit enables fine adjustment of the output level, and is
driven either by the standard thermal control unit (TCU) or optional ADU pilot automatic gain
control (AGC) module to compensate for temperature and input level variations.
The MDR-*/* circuit board provides a fixed linear equalizer for either 750 MHz or 870 MHz. This
equalizer comes in numerous values to support various levels of output tilt. The MDR board also
compensates for the low frequency roll-off inherent in plug-in diplexers.
equalizer comes in numerous values to support various levels of output tilt. The MDR board also
compensates for the low frequency roll-off inherent in plug-in diplexers.
A driver-hybrid amplifies the signal to a sufficiently high level to feed up to four power-doubling
output stages. These output hybrids can be either conventional silicon or premium gallium arsenide
types for even higher station output at low distortion. Plug-in facilities are available ahead of each
output stage for individual equalizer boards. These can be installed to customize the tilt for the
various ports. At one output, a minus 16 dB directional coupler provides signal to the optional ADU
and status-monitor modules. This signal is used only when either or both of these options is installed.
It is not necessary to terminate the coupler output when neither option is present.
output stages. These output hybrids can be either conventional silicon or premium gallium arsenide
types for even higher station output at low distortion. Plug-in facilities are available ahead of each
output stage for individual equalizer boards. These can be installed to customize the tilt for the
various ports. At one output, a minus 16 dB directional coupler provides signal to the optional ADU
and status-monitor modules. This signal is used only when either or both of these options is installed.
It is not necessary to terminate the coupler output when neither option is present.
Minus 20 dB directional test points are available at various points in the signal paths of the node.
Because these test points are 75-ohm source impedance, special test probes are not required.
Because these test points are 75-ohm source impedance, special test probes are not required.
Model JXP-* attenuator pads are used for adjusting signal levels within the signal path. The unit is
shipped with JXP-ZX versions installed.
shipped with JXP-ZX versions installed.