Receiver AGC Control for 50/60 Hz EMI Noise Attenuation

Solution Overview

Problem

Wireless receivers face undesirable signal-to-noise ratios due to electromagnetic interference (EMI) from sources like high voltage electrical power lines, which distort signals and result in poor output quality.

Innovation Solution

A receiver system comprising an antenna, filter, automatic gain control device, and processor that detects noise within a predetermined frequency range and adjusts gain to attenuate noise, using a method that includes signal conversion to digital, filtering, peak detection, and commanding the automatic gain control device to attenuate noise at specific frequencies like 50 Hz and 60 Hz.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional receivers are used near power lines, then the receiver can receive wireless signals, but the electromagnetic interference from power lines distorts the signal and creates noise, resulting in undesirable signal-to-noise ratios

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidelectromagnetic interference from power lines

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful electromagnetic interference from power lines into a detectable signal characteristic. By identifying the specific frequency signature of power line interference (50/60 Hz and harmonics), the system detects the presence and magnitude of EMI, then applies targeted attenuation only to those frequency components. This transforms the previously harmful broad-spectrum interference into a controlled, selectively reduced noise source, improving signal-to-noise ratio without affecting other frequency bands.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies different processing qualities to different frequency components of the received signal. Instead of uniformly attenuating all frequencies or applying blanket filtering, the system identifies specific frequency ranges affected by power line interference and applies selective attenuation only to those localized frequency bands. This preserves the quality of desirable signal components in other frequency ranges while removing harmful interference components.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If broad-spectrum filtering is applied to remove all noise, then noise attenuation improves, but desirable signal components may also be attenuated, reducing signal quality

Engineering Contradiction:

Improvenoise attenuationVSAvoidsignal quality

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies different processing qualities to different frequency components of the received signal. Instead of uniformly attenuating all frequencies or applying blanket filtering, the system identifies specific frequency ranges affected by power line interference and applies selective attenuation only to those localized frequency bands. This preserves the quality of desirable signal components in other frequency ranges while removing harmful interference components.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs a feedback mechanism where the processor continuously monitors the received signal for characteristics of power line interference, determines the appropriate attenuation level, and adjusts the filtering parameters accordingly. This closed-loop approach ensures that attenuation is applied dynamically based on actual interference conditions, preventing over-attenuation of desirable signals while maintaining effective noise reduction when interference is present.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8116711B2Receiver system and method that detects and attenuates noise in a predetermined frequency range

Publication Date: 2012.02.14 APTIV TECHNOLOGIES AG

AI summary

A receiver system and method for detecting and attenuating noise in a predetermined frequency range. The system includes at least one antenna, at least one filter, at least one automatic gain control device, and at least one processor. The at least one antenna receives at least one signal that includes at least one AM signal. The signal passes through the at least one filter. The at least one automatic gain control device adjusts the gain of the at least one signal to attenuate noise in the at least one signal. The at least one processor performs the steps including detecting when said noise is within a predetermined frequency range, and commanding the at least one automatic gain control device when the detected noise is within the predetermined frequency range, such that the automatic gain control device attenuates the noise that is within the predetermined frequency range.