Low Probability of Detection Emergency Signaling System
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Solution Overview
Problem
Existing emergency signaling technologies face challenges in providing covert and reliable distress communication in hostile environments, where GPS and cellular coverage may be unavailable, and equipment can be intercepted or used to lure rescuers into ambushes.
Innovation Solution
A low-probability of detection (LPD) spread-spectrum communication system that adapts power and spreading factor to maintain covert operation, using emergency transceivers and rescue transceivers to transmit and receive distress messages with incremental power and range adjustments, and authorization codes to ensure secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional emergency signaling methods (GPS, cellular) are used, then reliable distress communication can be achieved, but the system becomes vulnerable to jamming, lacks covert operation capability, and requires external infrastructure
Solution Approach 1:
The system changes the fundamental parameters of signal transmission by using spread-spectrum technology with low power levels and variable spreading factors. This transforms the signal characteristics to achieve both reliability and covert operation, making the signal resistant to traditional jamming methods while maintaining detectability by authorized receivers
Solution Approach 2:
The system converts the harmful effect of potential interception into a benefit by designing the signal to be inherently difficult to detect and interpret without proper authorization codes. The low probability of detection profile ensures that even if hostile forces intercept transmissions, they cannot easily locate or exploit the distress signal
2Length of stationary object
If high power transmission is used to extend communication range, then rescuers can be reached over longer distances, but the probability of detection by hostile forces increases
Solution Approach 1:
The system dynamically adjusts transmission parameters including power level and spreading factor based on operational needs. The emergency transmitter can switch between local and extended communication ranges by modifying these parameters, allowing the system to optimize between range and covert operation in real-time
Solution Approach 2:
The system changes physical transmission parameters (power level, spreading factor) to achieve different communication ranges while maintaining low probability of detection. By using spread-spectrum techniques with variable parameters, the system can extend range without proportionally increasing detectability
3Reliability
If continuous transmission is used to ensure signal reception, then communication reliability improves, but battery power is consumed rapidly
Solution Approach 1:
The system uses periodic transmission instead of continuous transmission, sending distress signals at intervals rather than continuously. This approach maintains sufficient reliability for emergency communication while dramatically reducing power consumption to enable extended operation on battery power
Solution Approach 2:
The system incorporates automatic retry logic where the emergency transmitter autonomously retransmits signals if no acknowledgment is received, without requiring continuous operation. This self-managing approach ensures reliability while minimizing power consumption by only transmitting when necessary
Data Source
AI summary
An emergency locating system can include emergency transceivers and rescue transceivers. The emergency transceivers can be capable of repeat transmission of a distress message using a variable power level and variable spreading factor. A receive transceiver can be capable of receiving the distress messages and sending a confirmation message to the emergency transceiver. The emergency transceiver can be capable of receiving the confirmation message and terminating transmission of the distress message.