Demodulation Device Noise Elimination Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing demodulation technologies face challenges in effectively eliminating noise interference, particularly when the noise level is low or when interference waves arrive with a time lag due to reflection, leading to irregularities in frequency spectrum detection and performance deterioration.
Innovation Solution
A demodulation device incorporating a first noise elimination circuit that utilizes error information to adjust the amplitude and frequency of a noise replica signal, allowing for accurate elimination of noise even at low levels and in cases of fading, by using a combination of a first subtracter, error information generation unit, first frequency detection unit, and first amplitude adjusting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PLL circuit is used to generate a noise replica signal, then phase locking to carrier frequency is achieved, but phase comparison cannot be performed when noise level is smaller than desired wave level
Solution Approach 1:
The patent introduces an intermediary signal processing path that extracts noise components from the error signal between the desired wave and demodulated signal. This intermediary approach allows noise detection regardless of relative amplitude levels, resolving the contradiction where traditional PLL phase comparison fails when noise is weaker than the desired signal.
Solution Approach 2:
The invention changes the detection parameter from direct phase comparison of equal-frequency signals to frequency detection of error signal components. By detecting the frequency of noise-induced error components and using this to generate the noise replica, the system achieves reliable noise elimination without requiring the noise to be stronger than the desired signal.
2Productivity
If traditional noise elimination methods are used, then simple subtraction is performed, but irregularities in frequency spectrum due to fading are erroneously detected as noise
Solution Approach 1:
The system employs feedback by continuously monitoring the error signal between the desired wave and demodulated signal, detecting noise frequency components from this error, and adjusting the noise replica generation accordingly. This feedback mechanism allows the system to distinguish between actual noise and spectral irregularities caused by fading, improving detection reliability while maintaining elimination efficiency.
Solution Approach 2:
The invention implements dynamic adaptation by continuously adjusting the noise replica signal based on real-time error signal analysis. The system dynamically tracks noise frequency and amplitude changes, and adapts the subtraction process accordingly, preventing misidentification of fading-induced spectral variations as noise while maintaining effective noise elimination.
3Measurement precision
If noise replica signal amplitude is not adjusted based on error information, then simple subtraction is performed, but accurate noise elimination at low noise levels cannot be achieved
Solution Approach 1:
The system achieves self-service by automatically determining the optimal noise replica amplitude through error signal analysis. The error information generated during demodulation is directly used to adjust the noise replica amplitude, eliminating the need for external calibration or manual adjustment mechanisms while achieving high precision noise elimination even at low noise levels.
Data Source
AI summary
There is provided a demodulation device including: a first noise elimination circuit eliminating a noise in an output signal of IQ coordinates from a demodulation unit demodulating an input signal, in which the first noise elimination circuit includes: a first subtracter subtracting a first noise replica signal from the signal of the IQ coordinates that is output from the demodulation unit; an error information generation unit calculating error information of an output signal of the first subtracter to an ideal signal point of the IQ coordinates; a first frequency detection unit detecting a frequency of the noise based on the error information; and a first amplitude adjusting unit adjusting an amplitude of the first noise replica signal based on the error information and the frequency of the noise detected in the first frequency detection unit to output the first noise replica signal to the first subtracter.