| The SG 2000 optical node performs lightwave to RF and RF to lightwave in an optical transmission link supporting a variety of advanced hybrid/coaxial network topologies. Its 870 MHz passband increases channel capacity and supports advanced interactive services and global applications. Configured with up to three optical receivers, four high- level RF outputs, and two return path optical transmitters; the node offers unlimited flexibility in split-band or redundancy applications. In addition, ingress switching capability via headend control allows the operator to identify and isolate ingress problems and mitigate the effects. Other significant benefits of the SG 2000 include dual power supplies for redundancy, user-friendly fiber management, 15 Ampere power passing, 60/90 Volt powering, and status monitoring. The modular design makes upgrading systems and component replacement easy, with minimal system interruption.
This platform addresses split-band or redundancy applications. A standard split-band configuration has analog signals in the 52 to 550 MHz band feeding one receiver, while digital transmissions or narrowcast signals are carried between 550 and 870 MHz on another fiber and processed by the second receiver. The optional third receiver serves as a back up in the event the narrowcast receiver loses optical signal input with an automatic path switch over handled through status monitoring or manual control modules.
The node's dual return path optical transmitters also offer split-band or redundant functionality. In split-band applications, two of the four RF return signals are fed to one optical transmitter, while the remaining two signals are fed to the second transmitter. When configured for redundancy, both return lasers are active full- time, transmitting the combined RF return signals. In the event of path failure, return path redundancy is accomplished at the headend or receive site by switching to the alternate fiber.
A new series of optical transmitters (SG2-IFPT/* and SG2-DFBT/*) were developed for the SG2000. This product series, packaged to include connectors plus return path amplifiers, offer several advanced features. The SG2-IFPT/* transmitter uses an isolated Fabry-Perot laser operating at 400 uW. The SG2-DFBT/* uses a state-of-the-art uncooled, isolated distributed feedback (DFB) laser operating at 1 mW for improved link performance. Both transmitters carry a full 35 MHz of digital data or up to two video channels. The transmitter includes thermal compensation circuitry to minimize the change in received optical and RF signal level as the node temperature varies. The transmitter is enabled and disabled in response to a signal from the status monitoring transponder for economical power consumption and enhanced reliability. An integrated optical bulkhead connector provides advanced fiber management and module status indicators reduce troubleshooting time. Full compatibility with the status monitoring transponder allows remote monitoring of module and link performance.
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