Photonic ADC Remoting with Phase Modulation for RF Sampling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fiber optic data networks do not provide the desired level of performance for sampling radio frequency (RF) signals, necessitating a more effective method for remote analog-to-digital conversion.
Innovation Solution
A method involving a remote input analog-to-digital conversion system that generates an optical sampling pulse stream, increases its rate, imparts voltage information via phase modulation, de-serializes the signal, and uses optical hybrids and detectors to convert the signal into digital format for reconstruction, leveraging a mode-locked laser, phase modulators, and optical demultiplexers to achieve high bandwidth and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current fiber optic data networks are used for sampling RF signals, then the system structure is simple, but the performance level is insufficient
Solution Approach 1:
The system divides the sampling function into multiple segments: optical sampling pulse generation, phase modulation at remote location, optical hybrid demodulation, and digital signal processing. This segmentation allows each component to be optimized independently, achieving high performance while managing complexity through functional decomposition
Solution Approach 2:
The patent introduces optical pulses as an intermediary carrier to transmit sampling information between the remote antenna and the processing unit. The optical field serves as a mediator that enables high-bandwidth signal transmission without direct electrical connection, overcoming the performance limitations of current fiber optic networks
2Speed
If optical sampling rate is increased to achieve high bandwidth sampling, then the bandwidth increases, but the system complexity increases
Solution Approach 1:
The patent replaces direct high-speed electrical sampling with optical sampling. By using optical pulses instead of electrical signals for the sampling clock, the system achieves much higher sampling rates (gigahertz to terahertz range) without the bandwidth limitations and complexity of electrical interconnects
Solution Approach 2:
The system transitions from electrical domain sampling to optical domain sampling. By moving the sampling operation into the optical frequency dimension, the system accesses vastly higher bandwidths and sampling rates that are inaccessible in the electrical domain, effectively using a different physical dimension to solve the bandwidth problem
3Measurement precision
If phase modulation is used to impart voltage information onto optical pulses, then the dynamic range increases, but linearity limitations arise
Solution Approach 1:
The optical hybrid performs coherent demodulation by mixing the phase-modulated signal with a reference optical pulse. This feedback mechanism allows accurate recovery of the original voltage information from the phase-modulated signal, maintaining linearity while achieving high dynamic range through precise phase measurement
Solution Approach 2:
The system uses phase modulation instead of direct amplitude modulation to encode voltage information. By changing the parameter from amplitude to phase, the system achieves higher dynamic range while the optical hybrid's coherent detection maintains linearity through precise phase-to-voltage conversion
4Measurement precision
If remote sampling at antenna is implemented, then the signal quality improves, but the device complexity increases
Solution Approach 1:
The patent extracts the sampling function from the centralized processing unit and places it at the remote antenna location using optical sampling pulses. This extraction allows high-quality sampling at the signal source while keeping the complex processing equipment centralized, separating the sampling function from the processing function to manage complexity
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 enables high-performance sampling and digitization of RF signals at the antenna with high bandwidth and dynamic range, overcoming linearity limitations and allowing for low sampling rate implementations, thus enhancing the efficiency of fiber optic data networks.
Implementation Method 1
A method involving a remote input analog-to-digital conversion system that generates an optical sampling pulse stream
Implementation Method 2
leveraging a mode-locked laser, phase modulators, and optical demultiplexers
Implementation Method 3
imparts voltage information via phase modulation
Implementation Method 4
uses optical hybrids and detectors to convert the signal into digital format
Implementation Method 5
directors said demodulated signals to a plurality of optical detectors of the system; detecting said demodulated signals via said optical detectors to provide analog detected demodulated signals
Data Source
AI summary
The present invention is a remote input analog-to-digital conversion (ADC) system. The system may generate low jitter, short duration optical pulses to allow for high performance sampling of an antenna signal at a remote end of the system. The system may utilize phase modulation and IQ demodulation (with a reference optical pulse stream) using separate analog-to-digital converters for I and Q to overcome linearity limitations. Low sampling rate analog-to-digital converters may be utilized by the system by using parallel, low optical pulse repetition rate paths and/or optical demultiplexer switching trees. The system is an optical fiber system.