FM Transmitter Power Feedback for Accessory-Induced Interference
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Solution Overview
Problem
FM transmitters in mobile devices often exceed regulatory power limits when accessories are connected, leading to potential interference with other telecommunication systems and broadcast stations, as the existing methods fail to dynamically adjust output power in real-time to account for increased radiated power due to accessory-induced coupling.
Innovation Solution
Incorporating a measurement circuit within the FM transmitter to monitor and adjust the output power level based on detected radio signal power, allowing for real-time adjustments to maintain compliance with regulatory limits, either independently or in cooperation with the host device, by reducing power when exceeding allowed thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the FM transmitter operates at high power to ensure reliable signal transmission, then the signal coverage and reception quality are improved, but the risk of interfering with other telecommunication systems and exceeding regulatory limits increases
Solution Approach 1:
The patent implements a feedback mechanism where a measurement circuit continuously monitors the actual radiated power of the FM transmitter and feeds this information back to a control unit. The control unit compares the measured power against regulatory limits and dynamically adjusts the output power level to maintain compliance while ensuring reliable transmission. This closed-loop control system resolves the contradiction by automatically adapting the transmitter power to the actual operating conditions.
Solution Approach 2:
The patent employs dynamic power adjustment rather than fixed power operation. The transmitter power level is continuously adapted based on real-time measurements of the actual radiated power, which varies depending on accessory connections and coupling conditions. This dynamic approach allows the system to operate at high power when safe and reduce power when necessary to prevent interference, thus resolving the contradiction between reliability and harmful effects.
2Adaptability or versatility
If accessories are connected to the mobile device, then the functionality and user experience are enhanced, but the radiated power of the FM transmitter increases due to accessory-induced coupling, potentially exceeding regulatory limits
Solution Approach 1:
When accessories are connected to the mobile device, the measurement circuit detects the resulting increase in radiated power caused by accessory-induced coupling. The control unit receives this feedback and automatically reduces the transmitter power level to compensate for the increased coupling, ensuring that the total radiated power remains within regulatory limits. This allows the system to maintain accessory compatibility while preventing excessive power radiation.
Solution Approach 2:
The system takes preliminary anti-action by proactively reducing the transmitter power level when accessory connections are detected or when power measurements indicate increased coupling. Rather than waiting for regulatory violations to occur, the control unit preemptively adjusts the power level to prevent exceeding limits, thus maintaining both accessory versatility and compliance.
3Reliability
If the output power is dynamically adjusted in real-time to maintain regulatory compliance, then interference is prevented and legal requirements are met, but the device complexity increases due to additional measurement and control circuits
Solution Approach 1:
The measurement circuit serves multiple functions: it measures the actual radiated power for regulatory compliance, detects changes in operating conditions caused by accessory connections, and provides data for both power adjustment and potential other control functions. By making the measurement circuit multi-functional, the patent reduces the need for separate dedicated circuits for each function, thus mitigating the increase in device complexity while maintaining reliable regulatory compliance.
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
Effectively maintains output power within regulatory limits, preventing interference while ensuring reliable FM signal transmission, even when accessories are connected, thereby meeting international regulatory requirements and enhancing user experience.
Implementation Method 1
measuring, with the measuring device, a radio signal power of a radio signal transmitted by the radio transmitter at an output stage of the radio transmitter
Data Source
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AI summary
According to one exemplary embodiment of the present invention, an apparatus is provided comprising a radio transmitter having an output stage with an adjustable output power level, a measurement circuit configured to measure a radio signal power of the radio transmitter and a control block connected to the measurement circuit wherein the measurement circuit is connected to the output stage of the radio transmitter where the radio signal power is measured; and wherein the control block is configured to adjust the output power level of the radio transmitter based on the measured radio signal power at the radio transmitter output stage.