SECAM Frequency Demodulator Using Arctangent Approximation
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Solution Overview
Problem
Conventional SECAM chrominance signal recovery methods require complex circuit configurations due to the need for arctangent calculations, which complicate the process of demodulating frequency-modulated signals.
Innovation Solution
A frequency demodulator that utilizes both real and imaginary number portions to generate a frequency-demodulated chrominance signal through arctangent approximation, simplifying the circuit configuration by using a phase differentiator and phase estimator to calculate phase differences between neighboring samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If arctangent calculation is used to calculate phase difference in frequency demodulator, then chrominance signal can be recovered, but circuit configuration becomes complex
Solution Approach 1:
The patent changes the mathematical approach by using arctangent approximation instead of exact arctangent calculation. This parameter change in the calculation method reduces the complexity of the circuit configuration while maintaining sufficient accuracy for chrominance signal recovery. The approximation allows for simpler circuit implementation while still achieving the required measurement precision for phase difference calculation.
2Ease of operation
If CORDIC or lookup table is used to approximate arctangent function, then phase difference can be calculated, but calculation process becomes complex
Solution Approach 1:
The patent employs arctangent approximation to simplify the calculation process. By changing the mathematical approach from exact arctangent to approximation methods, the system achieves ease of operation in calculating phase difference while reducing the complexity of the calculation process. This allows for more efficient signal processing without requiring complex CORDIC algorithms or large lookup tables.
Data Source
AI summary
An apparatus for recovering a chrominance signal from a sequential color with memory (SECAM) composite video baseband signal (CVBS), and more particularly, to a frequency demodulator and method of recovering a SECAM chrominance signal which can utilize both a real number portion and an imaginary number portion, and generate a frequency-demodulated chrominance signal using an arctangent approximation, and thereby can simplify a circuit configuration of a frequency demodulator to perform a fixed-point calculation is provided. A frequency demodulator for recovering a chrominance signal, the frequency demodulator comprises a phase differentiator generating a phase difference component between neighboring samples from an input signal and a phase estimator calculating a phase difference between the neighboring samples by using an arctangent approximation, based on the generated phase difference component, wherein the frequency demodulator generates a frequency-demodulated chrominance signal and the phase difference corresponds to the chrominance signal.