| 摘要 |
The bandwidth of a two-way broadband signal transmission system is expanded by frequency stacking shared band signals. The up conversion (stacking) and down conversion (destacking) systems utilize matched filters, preferably in a multiplexer configuration, which are directly connected, without a combiner, to output the stacked frequency signal in the case of the up conversion system, and without a splitter to separate the frequency stacked signals in the down conversion system. A single base local oscillator signal is used to generate all of the local oscillator signals needed in the system for up and down conversion. In a coax/HFC cable system in which shared band signals from multiple groups of subscribers are frequency stacked in service area nodes for transmission to a headend containing the down conversion system, the single base local oscillator signal is generated by a redundant high quality local oscillator in the headend and transmitted to all of the service area nodes in the broadband downstream signal. A comb generator in each service area node and in the headend generates the local oscillator signals needed for up/down conversion as harmonics of the base local oscillator signal for system wide frequency stability. The frequency stacked signals can be further frequency stacked for hub-to-hub and hub-to-headend interactive broadband signal transport.
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