Digital Return Path Encoding for Cable TV Signal Bundling
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Solution Overview
Problem
Current cable television (CATV) return path systems face high costs and bandwidth limitations due to the need for high-speed optical equipment to transmit analog return signals, which restricts the number of signals that can be bundled and transmitted effectively.
Innovation Solution
A method that converts analog return signals to digital format, encodes them using a reduced bit representation, and transmits these encoded signals across an optical link, allowing for a lower transmission rate while maintaining signal accuracy, enabling more signals to be bundled and transmitted efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-speed optical equipment is used to transmit analog return signals, then signal transmission capability is improved, but equipment cost increases and bandwidth limitations occur
Solution Approach 1:
The patent replaces the mechanical/electronic system of direct analog signal transmission with high-speed optical equipment with a digital signal processing system. By converting analog return signals to digital format and applying compression algorithms, the system achieves reliable signal transmission while using lower-cost, lower-speed optical equipment. The digital domain processing substitutes for the need for high-bandwidth analog optical transmission.
Solution Approach 2:
The patent changes the fundamental parameter of signal representation from analog continuous waveform to digital discrete samples. This parameter change enables the application of digital signal processing techniques including compression and bundling, which reduce the transmission rate requirements and allow multiple signals to be combined, thereby reducing equipment costs while maintaining transmission capability.
2Measurement precision
If high-speed optical equipment is used to transmit analog return signals, then transmission quality is maintained, but the number of signals that can be bundled is limited
Solution Approach 1:
The patent merges multiple individual return signals into bundled groups for simultaneous transmission over the optical link. By converting each analog signal to digital format and compressing them individually before bundling, the system can combine many more signals than would be possible with direct analog transmission. The compression reduces the bit rate of each signal, freeing up bandwidth to accommodate additional bundled signals.
Solution Approach 2:
The patent segments the transmission process into distinct stages: individual signal conversion from analog to digital, independent compression of each signal, grouping into bundles, and collective transmission. This segmentation allows each signal to be optimized independently through compression before being combined, enabling higher overall productivity in terms of number of bundled signals while maintaining accuracy through digital processing.
3Measurement precision
If full bit rate is transmitted across the optical link, then signal fidelity is preserved, but transmission rate remains high increasing costs
Solution Approach 1:
The patent applies compression algorithms that change the parameter of bits per sample from the full N-bit rate to a reduced rate while preserving signal fidelity. The compression process identifies and eliminates redundant information in the digital samples, allowing faithful reconstruction of the analog signal at a lower bit rate. This reduces the transmission rate and associated costs while maintaining the necessary signal fidelity for high-quality audio and video return paths.
Data Source
AI summary
An efficient means for transmitting digitized return path signals over a cable television return path is disclosed. In one embodiment of the invention, the cable television return path includes a node that receives an analog return signal from a subtree of the cable television system and generates a digital transport signal representative of the analog return path signal. The digital transport signal, however, is not a digitized form of the analog return signal. Rather, the digital transport signal is encoded such that fewer bits are used to represent the analog return signal without substantially impacting the accuracy and dynamic range of the signal. At the hub, the digital transport signal is decoded and converted to produce an analog signal that is a close approximation of the analog return signal.