Signal Processing Apparatus Carrier Frequency Offset Correction
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Solution Overview
Problem
Current digital television broadcasting receivers face challenges in accurately determining the carrier frequency offset due to noise interference and neighboring channel signals, leading to errors in identifying the energy peaks representing the desired target signal.
Innovation Solution
A signal processing apparatus and method that includes an initial detecting module, mixer, symbol rate detecting module, judging module, and correcting module to determine an initial carrier frequency offset, adjust the signal, perform phase recovery, and selectively correct the carrier frequency offset based on the symbol rate and spectrum analysis to identify the correct energy peak representing the target signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FFT is performed on input signal to generate spectral line for determining carrier frequency offset, then the carrier frequency offset can be determined, but noise interference or neighboring channel signals may create false energy peaks leading to incorrect offset determination
Solution Approach 1:
The patent uses phase recovery feedback to verify the correctness of the initial carrier frequency offset determination. The phase recovery process takes the frequency-compensated signal as input and attempts to lock onto the correct phase. If phase locking succeeds, it confirms the initial offset determination was correct; if it fails, the system knows the initial determination was wrong due to noise or neighboring channel interference, triggering re-determination with correction logic.
Solution Approach 2:
The patent performs preliminary frequency compensation using the initially determined carrier frequency offset before performing phase recovery. This preliminary action prepares the signal in advance for the verification step, allowing the phase recovery process to efficiently validate whether the preliminary offset determination was correct or needed correction.
2Measurement precision
If the receiver must accurately determine carrier channel and symbol rate from formidable combinations, then decoding accuracy is improved, but the complexity of determining the correct values increases
Solution Approach 1:
The patent employs phase recovery as a feedback verification mechanism to validate the determined carrier channel and symbol rate. Instead of exhaustively testing all possible combinations, the system determines the most likely values using FFT-based spectral analysis, then uses phase recovery to verify correctness. This feedback loop dramatically reduces complexity while maintaining high accuracy.
Solution Approach 2:
The patent replaces exhaustive brute-force testing of all possible carrier channel and symbol rate combinations with a more efficient spectral analysis approach using FFT. Instead of mechanically testing each combination, the system uses frequency domain analysis to identify the correct parameters, substituting a complex mechanical search process with a more efficient mathematical transformation and verification approach.
Data Source
AI summary
A signal processing apparatus includes an initial detecting module, a mixer, a symbol rate detecting module, a judging module and a correcting module. The initial detecting module determines an initial carrier frequency offset of an input signal according to a spectrum of the input signal. The mixer adjusts the input signal according to the initial carrier frequency offset to generate a frequency-compensated signal. The symbol rate detecting module determines a symbol rate of the input signal. The judging module judges whether the initial carrier frequency offset is correct according to the frequency-compensated signal. When a judgment result of the judging module is negative, the correcting module determines a corrected carrier frequency offset according to the symbol rate and the spectrum.