CATV Amplifier Input Impedance With Passive Modem Bypass
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Solution Overview
Problem
Existing cable television amplifiers disrupt Internet and VoIP services when they lose power, causing connectivity issues for users.
Innovation Solution
Incorporating a directional coupler into the amplifier to bypass power failures by connecting VoIP and unamplified video/data signals directly to a passive modem port and coupling them back to the amplifier input, while maintaining a 75 ohm input resistance using switching mechanisms, ensuring continuous Internet access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bypass switching or relays are installed to switch the feed cable directly to the modem when the amplifier loses power, then Internet connectivity is maintained during power outages, but device complexity increases
Solution Approach 1:
The patent extracts the bypass switching function from external components and integrates it directly into the amplifier's internal circuitry. The directional coupler and impedance maintenance circuit are built-in components that automatically provide the bypass path without requiring separate external switches or relays, thereby maintaining reliability while reducing overall system complexity.
Solution Approach 2:
The patent introduces a directional coupler as an intermediary component that automatically directs signals along different paths based on amplifier power status. This intermediary element simplifies the control logic by providing automatic signal routing without requiring complex control circuits or external switching mechanisms.
2Stability of the object's composition
If a 75 ohm resistor is connected to ground upon power loss to maintain input impedance, then impedance stability is maintained for frequencies up to 300 MHz, but device complexity increases due to switching mechanisms
Solution Approach 1:
The patent combines the impedance maintenance function with the existing bypass switching circuitry. The same switching mechanism that routes the signal bypasses the amplifier also connects the 75 ohm resistor to ground, eliminating the need for separate impedance control components and reducing overall device complexity while maintaining impedance stability.
Solution Approach 2:
The switching mechanism serves multiple functions simultaneously: it provides the bypass path for signal routing and maintains input impedance by connecting the 75 ohm resistor to ground. This multi-functionality reduces the number of separate components needed and simplifies the overall circuit design.
3Reliability
If switching means are added to open the connection between input terminal and amplifier input for frequencies exceeding 300 MHz, then impedance maintenance is improved for higher frequencies, but device complexity increases
Solution Approach 1:
The patent implements preliminary action by pre-configuring the switching mechanism to automatically open the connection between the input terminal and amplifier input when power is lost. This pre-programmed response ensures proper impedance maintenance for high frequencies without requiring real-time control logic or complex decision-making circuits.
Data Source
AI summary
A passive directional coupler is receptive of VoIP, Internet, and video/data signals, and is used in a CATV amplifier device to couple the video/data signals from a cable drop input port to the input terminal of an amplifier, and to passively bypass the VoIP and Internet signals to a modem port, for insuring continuous connection of the VoIP and Internet signals to the a modem of a user connected to the modem port, regardless of the loss of power to the amplifier or the failure of the amplifier, in one embodiment of the invention. In another embodiment, a switching circuit is responsive to the loss of power to the amplifier, for electrically connecting a 75 ohm resistor between a source of reference potential, and the common connection between the directional coupler and the amplifier, for maintaining a 75 ohm impedance at the directional coupler output to the common connection. In a preferred embodiment, the switching circuit also opens the common connection between the directional coupler and amplifier, upon the loss of power to the amplifier.