Solar Cell Array Reverse-Bias Signaling for Low-Detectability Communication
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Solution Overview
Problem
Conventional communication systems are not feasible in situations where equipment failure occurs, or when conventional communication is undesirable, such as in high altitude long endurance aircraft, as they may be detectable or unreliable.
Innovation Solution
A solar cell array system that can emit radiation to convey messages by reverse biasing solar cells, allowing them to function as a communication device, either in visible light, infrared, or other spectra, using a bidirectional boost-buck converter with MOSFETs and a microcontroller to modulate the solar string for charging and display modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional communication systems are used in high altitude long endurance aircraft, then communication capability is provided, but the system becomes detectable and vulnerable to interception
Solution Approach 1:
The solar array serves dual functions: generating electrical power for the aircraft and transmitting communication signals. By utilizing the existing solar array structure for communication, the system eliminates the need for separate communication transmitters, thereby reducing detectability while maintaining communication capability.
Solution Approach 2:
The solar array is designed to perform multiple functions simultaneously: power generation and communication signal transmission. This multi-functionality allows the system to communicate without requiring dedicated communication equipment, thus avoiding detection while ensuring reliable communication.
2Reliability
If solar cells are reverse biased to emit radiation for communication, then secure directional communication is achieved, but the solar array cannot simultaneously maximize power generation
Solution Approach 1:
The solar array alternates between power generation mode and communication mode in periodic cycles. During non-peak communication periods, the array generates power; during required communication periods, it switches to reverse bias mode to transmit signals. This periodic switching allows both functions to be performed without continuous compromise of power generation efficiency.
Solution Approach 2:
The system dynamically switches the operational state of the solar array based on communication requirements. A controller monitors and adjusts the biasing state of the solar cells, transitioning between forward bias (power generation) and reverse bias (communication) modes as needed, optimizing the balance between power generation and communication security.
3Measurement precision
If a bidirectional boost-buck converter is used to control solar string modulation, then precise communication signaling is achieved, but the device complexity increases
Solution Approach 1:
The bidirectional boost-buck converter integrates multiple functions into a single circuit: power management, signal modulation, and communication transmission. By combining these functions that would otherwise require separate systems, the converter achieves precise signal control while minimizing overall system 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
Enables secure and directional communication, particularly in high altitude long endurance aircraft and other applications, where the solar array can display messages visible only from above, such as to satellites, while being undetectable from terrestrial or lower aircraft, and can be used in wearable or portable devices for line-of-sight communication.
Implementation Method 1
emitting a communication message from the solar cell array by reverse biasing the solar cell array so as to cause at least a portion of the solar array to emit a detectable amount of radiation corresponding to the communication message
Data Source
AI summary
In one implementation, a method for a solar cell array is provided, the method includes emitting a communication message from the solar cell array by reverse biasing the solar cell array so as to cause at least a portion of the solar array to emit a detectable amount of radiation corresponding to the communication message. In one embodiment a solar cell array circuit is provided including a solar string comprising a plurality of solar cells coupled together, a charge storage device coupled to a power bus, and a bidirectional boost-buck converter having a first and second pair of MOSFETs connected in series between positive and negative rails of the power bus with an inductor coupled from between the first and second paired MOSFETs to a charging output of the solar string.