RF Tuner Input Filter Adjustment for Antenna Impedance Mismatch
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Solution Overview
Problem
Radio frequency (RF) signal receivers, such as televisions, face performance issues due to unknown impedance from indoor antennas, leading to mistuning, lower gain, higher noise, and poor frequency response, as the impedance varies and is not compatible with the typical 75 ohm source used in tuner design.
Innovation Solution
An electronically adjustable RF input filter system that dynamically adjusts its center frequency and bandwidth based on measured impedance, using control signals to compensate for the varying impedance presented by the antenna system, ensuring optimal frequency response and tuning performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed 75 ohm source is used in tuner design, then the tuner can be designed with simple fixed parameters, but it cannot adapt to antennas with unknown or varying impedance
Solution Approach 1:
The patent applies dynamics by making the filter parameters adjustable and variable rather than fixed. The electronically adjustable input filter allows the center frequency and bandwidth to be dynamically modified based on the actual antenna impedance characteristics, enabling adaptation to different antenna types while maintaining manageable complexity through electronic control.
Solution Approach 2:
The patent changes the parameters of the input filter electronically to match the antenna's impedance characteristics. By adjusting the center frequency and bandwidth parameters based on measured or detected antenna impedance, the system adapts to various antenna types without requiring complete redesign, resolving the contradiction between adaptability and complexity.
2Manufacturing precision
If the tuner uses fixed filter parameters designed for 75 ohm source, then the device complexity is low, but the frequency response and tuning accuracy deteriorate with unknown impedance
Solution Approach 1:
The patent implements feedback by measuring the actual antenna impedance and using this information to adjust the filter parameters. The system detects the antenna characteristics and feeds this information back to the control mechanism that adjusts the input filter, thereby improving tuning accuracy while managing complexity through automated electronic control rather than manual adjustment.
Solution Approach 2:
The tuner performs self-adjustment by automatically detecting antenna impedance characteristics and modifying its own filter parameters accordingly. This self-service capability improves tuning accuracy without requiring external intervention or complex manual alignment procedures, as the system autonomously adapts to the connected antenna.
3Adaptability or versatility
If electronic alignment with adjustable RF filters is used, then adaptability to different tuning conditions is improved, but the antenna impedance causes mistuning and shifts center frequency
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the input filter parameters before the actual tuning operation based on the detected antenna impedance characteristics. By preparing the filter settings in advance according to the antenna type, the system prevents center frequency shifts and mistuning from occurring during operation, thereby maintaining frequency accuracy while preserving adaptability.
Solution Approach 2:
The patent uses preliminary anti-action by anticipating and counteracting the effects of antenna impedance on filter tuning. The system detects potential impedance mismatches and applies compensatory adjustments to the filter parameters in advance, preventing center frequency shifts and mistuning before they occur, thus maintaining both adaptability and frequency accuracy.
Data Source
AI summary
A system, apparatus and/or method provides frequency response adjustment of an RF input filter of an RF tuner based on impedance of an antenna system that is providing reception of RF signals to the RF tuner. The frequency response adjustment is preferably accomplished dynamically and/or with respect to each frequency tuned. Particularly, the system, method and/or apparatus provides compensation at the RF tuner level for mistuning effects produced on the RF tuner by antenna system impedance presented at the antenna input that is other than a designed for impedance. Frequency response of an RF input filter for the RF tuner is electronically adjustable with an independent or semi-independent control voltage signal based on one or more measured parameters of a tuning frequency. Frequency response adjustment may include adjustment of a center frequency of the RF input filter bandpass frequency range and/or altering the bandpass frequency range of the RF input filter. The subject invention expands the capability of an RF signal receiver, particularly one using at least one electronically adjustable RF filter at the input of an electronic alignment type tuner.