Passive Proximity Sensor for Satellite Situational Awareness
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Solution Overview
Problem
Current satellite situational awareness systems face challenges in detecting nearby objects due to power drain, unwanted detection, and difficulty in determining range and velocity, particularly with active radar systems and passive radar systems using broadcast signals with repetitive structures.
Innovation Solution
A passive proximity detection system (PPDS) is deployed on or with a satellite, utilizing a receiving antenna and processing electronics to correlate a communication signal with a transmitting antenna, allowing for cooperative detection of targets by receiving signal reflections, and providing range and velocity information through correlation and frequency shifting techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active radar systems are used for satellite situational awareness, then detection capability is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies self-service by having the satellite use its own transmitted communication signals as the probing signal for radar detection, eliminating the need for separate active radar transmitters and reducing power consumption while maintaining detection capability
Solution Approach 2:
The patent makes the communication signal serve dual purposes: both for communication and for radar probing, allowing the same signal to fulfill multiple functions and reduce overall system power requirements
2Reliability
If active radar systems are deployed on satellites, then situational awareness is improved, but the satellite becomes more detectable by unwanted detection
Solution Approach 1:
The satellite uses its own communication signals for probing, making it difficult for external systems to distinguish the probing signal from normal communication traffic, thereby reducing unwanted detection
Solution Approach 2:
The communication signal acts as an intermediary that masks the radar probing function, allowing the satellite to gather situational awareness information while maintaining stealth by blending the probing function with legitimate communication signals
3Use of energy by moving object
If passive radar systems using broadcast signals are used, then power consumption is reduced, but range information becomes difficult to determine due to signal disambiguation requirements
Solution Approach 1:
The patent implements feedback by having the satellite know exactly what signal it transmitted, allowing it to correlate received echoes with its own transmitted signal to accurately determine range information without ambiguity
Solution Approach 2:
The satellite creates a copy of its own transmitted signal for correlation purposes, enabling precise range measurement by comparing the transmitted signal copy with the received echo signal
4Use of energy by moving object
If passive radar systems with non-cooperative transmitters are used, then power consumption is reduced, but the system cannot be deployed on mobile platforms
Solution Approach 1:
The satellite serves as both the platform and the signal source, eliminating the need for external non-cooperative transmitters and enabling deployment on mobile satellite platforms while maintaining low power consumption
Solution Approach 2:
The system combines communication and radar functions in a single integrated system on the mobile satellite platform, enabling both communication and situational awareness capabilities without requiring separate external signal sources
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 PPDS enables reliable detection of nearby targets with reduced power consumption, minimal detectability, and accurate range and velocity determination, suitable for satellite protection without interfering with primary payload functions.
Implementation Method 1
receiving a reflection of the communication signal transmitted by the communication antenna at the passive proximity detection system receive antenna
Implementation Method 2
processing electronics that are capable of correlating a signal received by the receiving antenna with a communication signal transmitted by a downlink or other transmitting antenna
Implementation Method 3
By determining the period of delay between the time at which the communication signal was originally transmitted and the time at which a correlated signal is received, information regarding the range to a detected target can be determined
Data Source
AI summary
A passive proximity detection system and method are provided. A transmitted signal, such as a communication signal, is sampled and placed in memory. A version of the transmitted signal, reflected by a target in the vicinity of the transmitting antenna, is sampled and compared to the stored reference sample. Correlation between the reference and reflected samples indicates the presence of a target in the vicinity of the transmitting antenna. Processing of the signals can include frequency shifts to account for Doppler shifts in the reflected energy as a result of a non-zero relative radial velocity of the target. Multiple antennas for receiving reflected energy can be provided to enhance the coverage area of the system, and/or to provide information regarding the relative location of a target. In addition, signals from multiple transmitting antennas can be used as sources of energy for probing the vicinity of those antennas for targets.