Moving Object Command Link With Dynamic Beam Power Control
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Solution Overview
Problem
Establishing and maintaining a reliable command link between a stationary transmitter and a moving object is challenging due to the limited dynamic range of the receiver and large dynamic range variations caused by atmospheric conditions and changing distances, which affect the signal-to-noise ratio (SNR).
Innovation Solution
A moving object command link system that uses a source of electromagnetic radiation with a steering mechanism, variable attenuator, and divergence controller to modulate the beam's power and size, along with polarization modulation, to ensure the signal remains above the receiver's noise floor and below its saturation level, while tracking multiple objects using dichroic beam splitters and object track cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transmitter uses a fixed power beam, then the system is simple to operate, but the receiver cannot handle large dynamic range variations caused by changing distances and atmospheric conditions
Solution Approach 1:
The transmitter dynamically adjusts beam power using a variable optical attenuator (VOA) based on real-time feedback from the receiver about signal strength and atmospheric conditions. This dynamic adjustment allows the system to adapt to changing distances and atmospheric turbulence while maintaining the receiver within its optimal dynamic range.
Solution Approach 2:
The system implements a feedback loop where the receiver measures the incoming signal strength and sends control signals back to the transmitter. The transmitter uses this feedback to adjust the VOA setting, thereby maintaining the beam power at an optimal level despite variations in distance or atmospheric conditions.
2Reliability
If the transmitter increases beam power to compensate for distance, then the signal reaches the receiver, but the receiver may saturate when the object is close
Solution Approach 1:
The system dynamically adjusts beam power based on the real-time distance to the target object. When the object is far away, the VOA allows higher power transmission; when the object is close, the VOA reduces power to prevent receiver saturation. This dynamic control ensures the receiver operates within its linear range under all conditions.
Solution Approach 2:
The system changes the beam power parameter in real-time based on measured distance and receiver signal strength. By continuously adjusting this parameter through the VOA, the system prevents receiver saturation while ensuring adequate signal strength at all ranges.
3Device complexity
If the beam divergence is fixed, then the system is simpler to control, but the beam size varies significantly with distance affecting signal quality
Solution Approach 1:
The system uses a dynamic divergence control mechanism that adjusts the beam divergence angle based on the distance to the target. This active control compensates for distance variations, maintaining a consistent beam size at the target and thereby consistent signal quality, while adding complexity to the control system.
4Device complexity
If the system tracks a single object, then the tracking mechanism is simpler, but the system cannot simultaneously monitor multiple targets
Solution Approach 1:
The tracking system is designed with multi-functionality to handle both single and multiple object tracking. The same optical tracking infrastructure and control algorithms are used regardless of whether one or multiple objects are being tracked, allowing the system to adapt to different operational requirements without requiring completely separate systems.
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 system improves the accuracy and reliability of the command link by maintaining a suitable signal level and beam size over varying distances and conditions, enhancing the dynamic range and tolerance to atmospheric fluctuations.
Implementation Method 1
A source outputs a beam of electromagnetic (EM) radiation
Implementation Method 2
a variable optical attenuator (VOA) can be used to modulate the average output power of the laser beam based on the brightness of the reflected light
Implementation Method 3
The dichroic beam splitter is preferably further arranged to transmit incoming light that is within a first spectral band to the first object track camera and to reflect incoming light that is within a second spectral band to the second object track camera
Data Source
AI summary
A moving object command link system includes a transmitter which outputs a EM beam and a steering mechanism which directs the beam toward one or more objects, at least one of which is moving. The system may include a variable attenuator which modulates the average output power of the beam, and/or a divergence controller to maintain a desired beam size. The beam may be polarized, and the system may include a polarization modulator which changes the beam's polarization in accordance with a predetermined sequence and schedule. The system may include a 1×2 switch to selectively provide the beam to one of first and second outputs. A tiltable dichroic beam splitter may be used to couple beams received from first and second objects to track cameras having respective boresights that are offset with respect to each other.