Broadband Reflective Phase Cancelling Network Interface
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Solution Overview
Problem
Cable television networks face signal integrity issues due to reflections caused by improper termination of coaxial cables, leading to degraded signal quality and potential service disruptions, especially in emergency situations where active signal conditioners may fail.
Innovation Solution
A network interface device with a signal splitter, active branch circuit, sensor for power consumption monitoring, selectable switch, and phase cancellation circuit that automatically adjusts signal paths to minimize reflections by converting signals into reference and phase-delayed components, recombining them to reduce signal reflections and maintain high-fidelity signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an active signal conditioner is used to amplify signals, then signal strength is improved, but reliability deteriorates when the active device fails
Solution Approach 1:
The system dynamically switches between active and passive signal paths based on the operational status of the active signal conditioner. A sensor detects whether the active device is functioning, and a switch automatically routes signals through the active path when operational or through the passive path when failed, maintaining service continuity while preserving signal amplification capability when available
Solution Approach 2:
The invention changes the operational parameters of the signal path by transitioning from an active amplified state to a passive non-amplified state based on detected conditions. This parameter change allows the system to adapt to failure conditions while maintaining acceptable signal levels for critical services
2Power
If signal amplification is provided to improve signal strength, then signal quality improves, but signal reflections and return loss worsen
Solution Approach 1:
The system dynamically adjusts the signal path configuration based on operational needs and conditions. When the active signal conditioner is inoperative, the switch automatically connects the passive path that provides better impedance matching and reduced reflections, while still allowing signal transmission for critical services
Solution Approach 2:
The switch acts as an intermediary element that selects between different signal paths with different characteristics. The passive path serves as an alternative intermediary that provides better reflection characteristics when the active path cannot be used
3Reliability
If a passive signal path is used for critical services, then reliability improves, but signal strength deteriorates
Solution Approach 1:
The system dynamically switches between passive and active paths based on the operational status of the active signal conditioner and the service requirements. Critical services can utilize the passive path for reliability while non-critical services can use the active path for enhanced signal strength when available
4Reliability
If automatic failover is implemented to improve reliability, then service continuity improves, but device complexity increases
Solution Approach 1:
The system implements self-service failover through automatic sensor detection and switch actuation without requiring external control or complex management systems. The sensor autonomously detects the operational status of the active signal conditioner and triggers the switch to appropriate paths, providing automatic reliability enhancement with minimal added complexity
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
The solution effectively improves return loss and maintains high signal quality by reducing reflections, ensuring critical passive devices like lifeline telephones function reliably even when active circuitry is inoperative, and preserving the quality of service by minimizing signal degradation.
Implementation Method 1
a phase cancellation circuit connected to the signal reduction path, the phase cancellation circuit adapted to convert the CATV signals into a reference signal and a phase-delayed signal, the phase-delayed signal being out of phase with respect to the reference signal, the phase cancellation circuit further adapted to recombine the reference signal and the phase-delayed signal to a single, reduced CATV signal
Data Source
AI summary
A network interface device including a signal splitter which conducts CATV signals through an active branch circuit, the active branch circuit including an active signal conditioner which modifies characteristics of active branch signals conducted through the active branch circuit, a sensor connected to sense normal, inoperative and abnormally operative conditions, the sensor removing a control signal indicative of inoperative and abnormal operating conditions, a selectable switch connected to the active branch circuit, the selectable switch communicating the CATV signals between the CATV network and the subscriber devices when in an activated position, and the selectable switch passing the signals to a signal reduction path when in a deactivated position, the selectable switch assuming the deactivated position in response to the de-assertion of the control signal, and a phase cancellation circuit connected to the signal reduction path.