QPSK Signal Conjugate Identification Using Bias Voltage Control
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Solution Overview
Problem
Conventional QPSK signal conjugate relationship identification methods are costly and require large, high-speed components, making them unsuitable for compact optical modules due to complex algorithms and high implementation costs.
Innovation Solution
A method and apparatus that control a QPSK modulator to determine bias voltages based on root mean square power, using pseudo-random and high-frequency binary sequences to identify the conjugate relationship of QPSK signals, reducing the need for high-speed signal conversion and utilizing smaller, integrated components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PDA algorithm is used for phase determining, then conjugate relationship identification can be achieved, but implementation cost increases and analog-to-digital conversion speed requirement becomes high
Solution Approach 1:
The patent extracts only the necessary information (RMS power of in-phase and quadrature components) from the received signal, avoiding the need for complex phase determination algorithms. By focusing solely on power measurements rather than full phase analysis, the system achieves conjugate relationship identification with simpler, lower-cost hardware.
2Measurement precision
If ICR and LO are used for coherent detection, then phase information can be converted to optical intensity information, but component size becomes large
Solution Approach 1:
The patent uses a simplified optical intensity detection approach that copies only the essential measurement capability (RMS power measurement) without requiring the full coherent detection system. This allows the system to obtain sufficient information for conjugate relationship identification using compact photodiodes rather than large integrated coherent receivers with local oscillators.
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
This approach simplifies the algorithm for determining QPSK signal conjugate relationships, reduces the requirement for high-speed signal processing, and allows for the use of smaller, more cost-effective components, making it suitable for compact optical modules.
Implementation Method 1
a QPSK modulator is controlled to modulate, by using a first binary sequence signal, an optical signal
Implementation Method 2
determine, within a first predetermined range, a first bias voltage in the QPSK modulator, so that the first signal at the first bias voltage is a QPSK signal and a root mean square power of the first signal at the first bias voltage is the smallest
Data Source
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AI summary
The present invention discloses a QPSK signal conjugate relationship identification method and apparatus. The method includes: receiving a first binary sequence signal, using the first binary sequence signal to modulate an optical signal, and determining, within a first predetermined range, a first bias voltage in a QPSK modulator; receiving a second binary sequence signal, using the second binary sequence signal to modulate the optical signal, determining a second range within the first predetermined range according to the first bias voltage, and determining, within the second range, a second bias voltage in the QPSK modulator; and determining a conjugate relationship of the QPSK signal according to a value relationship between the first bias voltage and the second bias voltage.