Digital Return Path Encoding for Cable TV Signal Transmission
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Solution Overview
Problem
Current cable television (CATV) return path systems require high-speed, costly optical equipment to transmit analog return signals, limiting bandwidth and increasing costs due to the need for high-speed data transmission rates.
Innovation Solution
A method and device that converts analog return signals to a digital format, encodes them to reduce the number of bits transmitted, and decodes them back to an analog signal at the hub, allowing for lower transmission rates without significant loss of accuracy, enabling more signals to be bundled and transmitted efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed optical equipment is used to transmit analog return signals, then transmission accuracy is maintained, but equipment cost increases and bandwidth is limited
Solution Approach 1:
The patent creates a digital copy of the analog return signal, transmits this digital representation over the optical link, and then reconstructs the analog signal at the receiving end. This digital copy approach allows for more efficient transmission compared to direct analog-to-optical conversion, reducing the need for expensive high-speed optical equipment while maintaining signal fidelity.
2Speed
If high-speed data transmission is used to maintain signal accuracy, then transmission rate increases, but the number of signals that can be bundled decreases
Solution Approach 1:
The patent segments the transmission process into distinct stages: analog-to-digital conversion at the transmitting end, digital transmission over the optical link, and digital-to-analog conversion at the receiving end. This segmentation allows for optimization at each stage, enabling multiple signals to be bundled and transmitted efficiently by managing the data rate requirements through proper encoding and compression techniques.
3Measurement precision
If full-rate digital transmission is used to ensure signal fidelity, then data rate increases, but transmission efficiency decreases
Solution Approach 1:
The patent changes the parameters of signal representation by converting from analog continuous signals to digital discrete signals, and further optimizing the digital format used for transmission. By adjusting parameters such as bit depth, sampling rate, and encoding format, the system achieves an optimal balance between signal fidelity and transmission efficiency, allowing accurate signal transmission at reduced data rates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the number of bits transmitted across the optical link, allowing for a lower transmission rate while maintaining signal accuracy, thereby increasing the number of return signals that can be communicated, and is cost-effective and suitable for high-speed operations.
Implementation Method 1
The digital signal is used to modulate an optical data transmitter and the resulting optical signal is sent over an optical fiber
Implementation Method 2
At the hub, the optical signal is detected by an optical receiver, and the detected digital signal is used to drive a D/A converter
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.