Chaos Modulator Auto-Indexing for Signal Detection Reduction
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Solution Overview
Problem
Existing digital communications systems using spread-spectrum or chaos communications struggle to effectively hide signal features from adversaries, reducing the effectiveness of chaotic spreading and modulation techniques.
Innovation Solution
A transmitter for a chaos communications system that incorporates chaos generators performing auto-indexing, temporal automatic gain control, increased path diversity, and sequence lock up prevention, enhancing the system's ability to spread and modulate signals chaotically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional modulation and coding techniques are used with chaotic spreading, then synchronization between transmitter and receiver is straightforward, but the effectiveness of chaotic spreading is reduced
Solution Approach 1:
The patent segments the modulation process into two independent parts: chaotic sequence generation and data modulation. The chaotic sequence is generated by a dedicated chaos generator that operates independently from the data modulation process, allowing each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent introduces an intermediary chaotic sequence that serves as a mediator between the data signal and the transmission waveform. This chaotic sequence is generated by a chaos generator that processes the data signal through a series of mathematical operations, creating a transformed signal that maintains synchronization while enhancing the chaotic spreading effectiveness.
2Object-affected harmful factors
If signals are spread over a wide frequency band to achieve LPI/LPD, then signal detectability is reduced, but signal energy is distributed and may become difficult to recover
Solution Approach 1:
The patent dynamically changes the frequency parameters of the chaotic sequence over time. The chaos generator produces sequences with varying frequency characteristics that adapt to the transmission conditions, allowing the signal to maintain low detectability across a wide frequency band while concentrating energy in specific time-frequency regions for effective recovery.
Solution Approach 2:
The patent employs dynamic chaotic sequence generation where the chaotic parameters are continuously adjusted during transmission. This dynamic behavior ensures that the signal maintains its low-probability-of-detection characteristics while preserving sufficient energy concentration for reliable signal recovery through the correlation process.
3Adaptability or versatility
If multiple chaotic signals share a common RF channel to achieve spectral reuse, then capacity is increased, but interference between signals increases
Solution Approach 1:
The patent generates asymmetric chaotic sequences for different users by varying the initial conditions and parameters of the chaos generator. Each user receives a unique chaotic sequence that is asymmetric in its statistical properties, allowing multiple signals to share the frequency spectrum without producing symmetric interference patterns that would cause mutual interference.
Solution Approach 2:
The patent assigns different local quality characteristics to each chaotic sequence, including unique initial conditions, parameter sets, and temporal patterns. This local differentiation ensures that each signal occupies a distinct subspace in the signal space, enabling spectral reuse while maintaining low interference between concurrent transmissions.
Data Source
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AI summary
A transmitter for a chaos communications system employing chaotic symbol modulation that perform auto-indexing, temporal gain control, increased path diversity and sequence lock up prevention. The transmitter includes a symbol mapper that converts a series of information bits to a series of bit symbols, and a chaos modulator providing chaotic spreading modulation of the bit symbols. The chaos modulator includes a plurality of chaos generators, one for each bit symbol, providing a chaos sequence for the bit symbols. Each chaos modulator includes a RAM/ROM that provides auto-indexing where a chaos sequence output from the RAM/ROM is fed back to an input of the RAM/ROM from which a chaos sequence at a next address in the RAM/ROM is selected as the output of the modulator.