Radio Receiver Auto-Tuning via Switched Feedback Oscillation
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Solution Overview
Problem
Existing radio wave receiving apparatuses face challenges in performing automatic tuning of the tuning circuit without an accurate oscillation circuit, as they require either a system to receive actual transmission radio waves or generate a pseudo transmission wave, both of which complicate the integration of oscillation circuits on integrated circuits.
Innovation Solution
A radio wave receiving apparatus with a feedback circuit that allows positive feedback to the tuning circuit, enabling oscillation at a frequency similar to the tuning frequency without an accurate oscillation circuit, using a CPU to control the feedback and adjust the capacitance of the tuning circuit for optimal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an accurate oscillation circuit is used for tuning processing, then tuning precision is improved, but device complexity increases
Solution Approach 1:
The patent uses a simple oscillation circuit that generates an oscillation signal at a frequency similar to (but not exactly) the target radio wave frequency. This simplified copy of the oscillation function replaces the need for accurate crystal oscillators or PLL circuits, achieving sufficient tuning precision without complex hardware
Solution Approach 2:
The patent changes the approach from requiring accurate frequency generation to using frequency adjustment through capacitance variation. By changing the capacitance value of the tuning circuit while receiving actual radio waves, the system achieves precise tuning without needing an accurate oscillation circuit to begin with
2Measurement precision
If a crystal oscillator or PLL circuit is prepared for accurate oscillation, then oscillation frequency accuracy is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent extracts only the essential function of oscillation (generating a signal at similar frequency) while removing the complex components (crystal oscillators, PLL circuits) that make integration difficult. This allows the oscillation function to be implemented with simple RC circuits that can be easily integrated
Solution Approach 2:
The patent replaces expensive, complex oscillation circuits with simple, inexpensive RC oscillation circuits. The simple circuit uses readily available components (resistors and capacitors) that are easy to manufacture and integrate, sacrificing some frequency accuracy for ease of manufacture
3Measurement precision
If actual transmission radio wave reception is used for tuning, then tuning accuracy is improved, but adaptability deteriorates
Solution Approach 1:
The patent enables the receiving apparatus to perform self-tuning by using its own simple oscillation circuit to generate a test signal. The system adjusts its tuning circuit based on the received signal strength while transmitting its own oscillation signal, eliminating the need for external transmission signals or test equipment
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
Enables efficient automatic tuning of the antenna without the need for an accurate oscillation circuit, reducing the number of circuits required and allowing for reliable oscillation, while minimizing external components, thus simplifying integration.
Implementation Method 1
a feedback circuit that allows positive feedback to be made to the tuning circuit
Implementation Method 2
enabling oscillation at a frequency similar to the tuning frequency
Data Source
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AI summary
Disclosed is a radio wave receiving apparatus including: an antenna to receive a radio wave; a tuning member to allow a reception frequency of the antenna to be tuned to an intended frequency, in which tuning member a frequency characteristic is variable; a receiving member to receive a reception signal from the antenna to demodulate a modulation wave; a positive feedback member to perform a positive feedback in a signal path including the tuning member; and a switching member to turn on/off a feedback operation of the positive feedback member.