FM-PM Discriminator for High-Linearity Optical Communications
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Solution Overview
Problem
High-frequency wireless communication systems face challenges such as signal attenuation, increased size, weight, and power consumption, as well as complexity in downstream receiver processing, particularly in Extremely High Frequency (EHF) systems, and limitations in linearity and bandwidth in optical intensity modulators.
Innovation Solution
A communications device utilizing first and second optical sources generating carrier signals, a modulator for signal modulation, and a frequency modulation-phase modulation (FM-PM) discriminator with a specific transfer function, coupled with an optical waveguide and an optical-to-electrical converter, which reduces complexity and power consumption while maintaining high linearity and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If optical intensity modulators are used for EHF signal transmission, then bandwidth is improved, but linearity deteriorates
Solution Approach 1:
The patent introduces an external modulator as an intermediary device between the optical source and the fiber optic cable. This external modulator serves as a mediator that imposes the EHF signal onto the optical carrier wave, enabling high bandwidth transmission while maintaining signal linearity through precise external control rather than relying on the non-linear characteristics of optical intensity modulators integrated into the laser source.
2Reliability
If RF devices are used for EHF communication, then signal transmission is achieved, but size, weight, and power consumption increase
Solution Approach 1:
The patent replaces traditional RF electronic components with optical components for signal transmission. By using optical fibers and optical modulators instead of RF coaxial cables and RF amplifiers, the system achieves EHF signal transmission with reduced power consumption, smaller size, and lower weight, while maintaining or improving transmission reliability through the inherent advantages of optical communication.
3Measurement precision
If thermal control is implemented for FM discriminators, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent employs a thermally compensated FM-PM discriminator that achieves frequency discrimination accuracy without requiring external thermal control mechanisms. The discriminator is designed to be inherently insensitive to temperature variations or includes built-in thermal compensation that automatically maintains measurement precision across temperature changes, thereby eliminating the need for complex thermal control systems and reducing overall power consumption.
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
The solution provides high linearity and bandwidth with reduced complexity and power consumption, achieving a 10 dB linearity improvement at 6 GHz with 4 GHz bandwidth and a 45% reduction in electrical power consumption compared to previous approaches.
Implementation Method 1
first and second optical sources configured to generate respective first and second optical carrier signals... a modulator coupled to the first and second optical sources and configured to modulate the first and second optical carrier signals
Implementation Method 2
frequency modulation-phase modulation (FM-PM) discriminator
Implementation Method 3
an optical waveguide coupling the transmitter and receiver together
Implementation Method 4
an optical-to-electrical converter coupled to the first and second waveguide paths and configured to generate an output signal
Data Source
AI summary
A communications device includes a transmitter device having first and second optical sources and generating respective first and second modulated optical carrier signals at first and second optical carrier frequencies based upon an input signal. The communications device also includes an optical waveguide coupled to the transmitter device, and a receiver device coupled to the optical waveguide and including an FM-PM discriminator having a transfer function with a positive slope portion and a negative slope portion so that the first optical carrier frequency is positioned on the positive slope portion and the second optical carrier frequency is positioned on the negative slope portion.