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.
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.
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.
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.
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.
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.
Model JXP-* attenuator pads are used for adjusting signal levels within the signal path. The unit is shipped with JXP-ZX versions installed.
SG 2000 Installation and O peration Manual
