Pulsed LED Runway Lighting for Enhanced Vision Detection
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Solution Overview
Problem
Aircraft-based Enhanced Vision Systems (EVS) face difficulties in detecting approach lighting systems and airport markings due to background illumination competing with desirable signals, especially in daylight conditions, as conventional incandescent lighting is overwhelmed by visible-band and solar radiation, and LED-based systems do not emit significant radiation outside the visible band, making detection challenging.
Innovation Solution
A modulated lighting infrastructure using a network of LED emitters with control logic to generate pulsed radiation at peak brightness far beyond regulatory requirements for brief periods, maintaining average power within limits, and an aircraft-based detection system with image processors to capture and display frames where the intensity of the lighting system exceeds background illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED-based illumination is used to save energy and maintenance costs, then energy efficiency is improved, but detection capability in alternative spectral bands is lost
Solution Approach 1:
The LED illumination system operates in pulsed mode with duty cycles less than 100%, emitting intense light bursts at specific intervals. This periodic operation allows the system to maintain low average power consumption while providing periodic high-intensity signals that can be detected by EVS systems through temporal differentiation from continuous background illumination.
Solution Approach 2:
The system changes the temporal parameter of light emission by using pulsed operation instead of continuous emission. By varying the duty cycle and pulse width, the system optimizes the balance between energy consumption and detection capability, creating detectable modulation patterns in the visible band that EVS can distinguish from background.
2Reliability
If visible-band ALS emissions are increased far beyond regulatory requirements to overwhelm background illumination, then detection capability is improved, but energy consumption increases and brightness becomes inappropriate for pilots
Solution Approach 1:
Instead of continuously emitting high-intensity light, the system uses periodic pulsed emission where the LED operates at high intensity only during brief pulses. The duty cycle is kept below 100% to reduce average power consumption while maintaining peak intensities sufficient for detection by EVS systems during the pulse intervals.
Solution Approach 2:
The system prepares for detection by synchronizing pulsed emission with the integration periods of aircraft-based image sensors. By timing the high-intensity pulses to coincide with sensor exposure windows, the system ensures detectability without requiring continuous high-power operation, thus reducing overall energy consumption.
3Reliability
If visible-band ALS emissions are increased far beyond regulatory requirements to overwhelm background illumination, then detection capability is improved, but brightness becomes inappropriate for pilots
Solution Approach 1:
The system uses pulsed emission with duty cycles less than 100% to create temporal modulation that EVS can detect while keeping the temporal average brightness within regulatory limits. The human eye, being less sensitive to temporal modulation at these frequencies, perceives the averaged lower brightness, while EVS detects the high-contrast pulsed signals.
Solution Approach 2:
The pulsed temporal pattern acts as an intermediary encoding mechanism. The same physical light source serves dual purposes: it appears as moderate-intensity continuous light to human pilots while simultaneously encoding high-contrast detectable signals through temporal modulation that EVS systems can decode.
4Reliability
If conventional incandescent lighting is used, then significant SWIR band radiation is emitted for detection, but energy consumption is high and maintenance costs increase
Solution Approach 1:
The system replaces thermal radiation mechanisms (incandescent heating) with electroluminescence (LED light emission). This substitution enables precise spectral and temporal control of light emission, allowing operation in the visible band with pulsed modulation while avoiding the inefficiencies of broad-spectrum thermal radiation and enabling detection through temporal rather than spectral differentiation.
Solution Approach 2:
The system changes the operational parameters from continuous thermal emission to pulsed electroluminescence. By controlling the temporal parameters (duty cycle, pulse width, frequency) of LED emission, the system achieves detection capability through modulation while maintaining lower average power consumption compared to continuous incandescent operation.
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
Enhances situational awareness by allowing detection of approach lighting systems under adverse conditions while maintaining compliance with brightness regulations, enabling efficient use of energy in LED-based systems and reducing costs.
Implementation Method 1
each emitter of the network having a power input and generating, via light emitting diodes (LED), luminous output
Data Source
AI summary
A modulated lighting infrastructure for a runway approach lighting system includes a network of LED emitters, emitting primarily in the visible spectral band, driven by control logic to emit brief high-frequency pulses of energy at peak brightness for a fraction of their duty cycle while emitting no energy for the remainder of the duty cycle. While the pulsed emissions of the approach lighting system are so brief as to appear normal to pilots (as the average intensity is unchanged), an onboard detection system can integrate a camera for short bursts at a high frame rate to detect images of the emitted high-frequency pulses against competing atmospheric and background illumination and display the detected images to the pilot. The emitter network may include additional emitters configured to emit energy in infrared and other spectral ranges for detection by onboard enhanced vision systems.