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Technology Stocks : Harmonic Lightwaves (HLIT) -- Ignore unavailable to you. Want to Upgrade?

To: MikeM54321 who wrote (2493)	9/8/1998 3:42:00 PM
From: Hiram Walker	Respond to of 4134

Mike, well here is HLIT's system,and a good description of how and where is was implemented. I am still deciphering the data,and going through my archives. cedmagazine.com Figures 5, 6 and 7 illustrate examples of DWDM implementations. Figure 5 shows the design implemented in the TCI system in Baton Rouge, La. Broadcast signal distribution from the secondary hub to the fiber nodes was already in place using 1310 nm technology. Narrowcast lasers operating at 1550 nm were added at the headend and multiplexed over a single fiber for transmission to the hub. At the hub, narrowcast wavelengths are amplified, de-multiplexed, and individually combined with the 1310 nm broadcast signal before transport to the node. Standard 1310/1550 WDM couplers are used to combine broadcast and narrowcast signals. This approach resulted in less than 0.5 dB of additional insertion loss for the 1310-nm broadcast signals, therefore minimizing the impact on their performance at the node. Figures 6 and 7 show a design implemented in the TCI-Dallas system. Broadcast and narrowcast signal distribution is implemented using 1550 nm technology. Broadcast transport from the Arlington headend to two field OTNs (optical transport nodes) uses no more than two EDFAs in cascade to reach all fiber nodes, while maintaining the performance in Table 1. Narrowcast services are transported using eight different wavelengths multiplexed over a single fiber. All narrowcast wavelengths are amplified and de-multiplexed at OTN 1. Six of them are individually combined with the broadcast 1550-nm signal and split to feed a number of fiber nodes. The other two are transported over two dedicated fibers from OTN 1 into OTN 2, where they are finally combined with the broadcast wavelength and split to feed the remaining nodes in the system. Table 2: Available DWDM wavelengths. Figure 8 is an example of a design for optical insertion of PEG channels at the hub. In this case, the 1310 nm lasers carrying PEG programming are located in the hub. Standard 1310/1550 WDM couplers are used for insertion of PEG programming. Each 1310 nm laser targets a group of fiber nodes as required. Downstream from the 1310 nm insertion point, 1550 nm narrowcast signals are inserted using standard couplers prior to final transport into the nodes. DWDM is a practical alternative now available to HFC network designers. It has been deployed successfully in a number of TCI markets. The technology allows for the narrowcasting of high-speed data and other services, flexible network segmentation and a reduction in the number of active electronics that must be deployed outside the system headend. Bandwidth expansion is easily achieved through the activation of additional narrowcast wavelengths per service area with minimal interruption to existing services. All of these installations are HLIT's,and the blueprints were made by their engineers. Tim

To: MikeM54321 who wrote (2493)	9/8/1998 4:08:00 PM
From: Hiram Walker	Read Replies (2) \| Respond to of 4134

Mike,another great article,and they said bandwidth will be exhausted,Bullshit. You can spatially expand the network optically,and you can reuse narrowcast QAM channels. HFC has a limitless potential if the architecture is implemented correctly. cedmagazine.com The bandwidth of today's advanced networks is currently installed at 750 MHz, but recent traffic analysis studies have shown that strong arguments can be made in favor of installing 870 MHz systems. Spatial multiplexing refers to using "home run" fibers to nodes serving ever-shrinking numbers of homes passed. This allows parts of the forward spectrum to be "reused," enabling larger amounts of bandwidth to be allocated to a single user. Spectrally efficient methods of transmitting digital information such as 64 QAM and 256 QAM allow higher amounts of information to occupy each hertz of bandwidth. The use of the optical wavelength as an additional dimension to expand the performance and capacity of these advanced multi-service networks is just emerging. Such methods, referred to as optical networking, open up a wide array of possibilities, such as multi-channel transport (DWDM), passive and active optical routing, and optical cross connecting. Figure 2: Pictured is 1550 nm "blast and split," with 1310 nm WDM overlay. WDM overlay technology performs the important task of separating the broadcast and narrowcast portions of the network so they may be optimized independently. Advanced optical networking tools such as Sonet high-performance video transport, mixed format DWDM and WDM overlay technology allow operators to take full advantage of these rapidly deploying advanced services, while maintaining excellent control over equipment and operating costs. These three optical networking tools are shown schematically in Figure 1. In Sonet high-performance video transport, analog video is digitized in a 10-bit uncompressed format, which is mapped directly into a Sonet OC-3c (concatenated) frame. Sixteen of these streams are electrically multiplexed into an OC-48 rate, and eight of these optical signals can be multiplexed via 1550 DWDM into a nearly 20 Gbps data stream. Sonet high-performance video transport has advantages over DS-3-based traditional multiplexed Sonet. The OC-3c mapping allows for much higher performance and lower cost than that provided by using video codecs. Sonet high-performance video transport is also preferable to available proprietary video transport systems because full Sonet capability is needed for interfacing to other Sonet systems in the network. In addition, Sonet high-performance video transport systems have the advantages of traditional Sonet voice and data networks; namely, multiple interfaces such as DS-3, ASI, Video IF, QAM and Ethernet, add/drop capability, and cross-connect capability via time slot interchange. After amplification, the narrowcast portion of the spectrum (typically eight to 16 QAM channels plus two to three analog channels) is added via a 1550/1310 nm WDM multiplexer or a 1550/1550 nm DWDM multiplexer. Both the broadcast and narrowcast traffic are transmitted to the node, where they are received by the same photodetector. The addition of the narrowcast wavelength degrades the broadcast signal carrier-to noise ratio by less than 1 dB. Networks utilizing WDM overlay technology have an added benefit in that they allow costs to be deferred. This means that a portion of the cost of the network is deferred until the service demands on the network require the additional capacity. For the WDM overlay system, the 1310 nm overlay transmitters can be added only when the service or demographic demands require it. Each of these technologies has its own complementary place in today's HFC network configured for advanced services. Sonet high-performance video transport is used in the primary rings of the network and in regional interconnects; mixed format DWDM for the secondary interconnects; and WDM overlay technology in fiber distribution. Providing products based on these technologies, with the ability to work together in a seamless fashion, is essential for successful delivery of these advanced services. Tim