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capacity DAS networks is to drive fibre and mobile services deeper into the network. The farther one can extend fibre into the network, bringing the signal to the user, the higher the capacity the network will support. But deploying fibre for a DAS can be a complex and expensive proposition. Fortunately, some new technologies make it easier and more cost-effective. There are several technologies that come into play to make it possible to transmit more capacity over fibre – see table 1. Muxponders (or optical multiplexing solutions) are a primary category of fibre optimisation solutions. Wave division multiplexing: when it is desirable or necessary Figure 1: Block diagram showing 192 fibre pairs in a stadium. Powering your next design. Let us be your power expert. We understand that you don’t have the time to master every aspect of electronic design. As a leading manufacturer of power supplies we are here to collaborate with you to ensure your next project is a success. Dc-Dc Converters www.cui.com/PowerExpert Novum® Advanced Power Ac-Dc Power Supplies to combine transmit and receive path optical signals onto a single optical fibre, network engineers can use wave division multiplexing (WDM). Each WDM system consists of a Host and Remote modules. At the Host and Remote, a WDM chassis contains the WDM modules. Both the Host WDM module and the Remote WDM module consist of a bi-directional wavelength division multiplexer. This approach reduces the fibre needed from a single fibre pair (two fibre strands), to a single fibre strand. It reduces fibre leasing requirements by 50%, cutting operational expenses. Up to 75 MHz of RF spectrum can be transported over a single fibre strand. What’s more, existing fibre infrastructures can be used. Coarse wave division multiplexing: CWDM expands the fibre-saving properties of WDM by combining transmit and receive path optics onto a single fibre. This approach reduces the fibre needed from up to eight fibre pairs (16 strands), to a fibre pair (two fibre stands). This slashes fibre leasing requirements by a factor of eight, and up to 600MHz of RF spectrum can be transported over a fibre pair. It also allows the reuse of existing fibre infrastructures. Dense wave division multiplexing: DWDM provides even more fibre savings in situations where there are potentially hundreds of fibre pairs to be deployed. It reduces the fibre needed from up to 44 fibre pairs (88 strands), to a fibre pair, decreasing leasing requirements and operational expenses. Up to 3,000MHz of RF spectrum can be transported over a fibre pair. Existing fibre infrastructures can be reused. Serial link combiner: A serial link combiner (SLC) is a fibre multiplex/ de-multiplex network element that can support up to 225 MHz of RF spectrum over a single fibre pair. The SLC com- www.electronics-eetimes.com Electronic Engineering Times Europe October 2013 35


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