Chaotic Amplitude Modulation With Constant Envelope Spreading
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spread spectrum communications signals face security compromises due to detectable statistical, higher-order, and cyclostationary features, and unwanted detection issues arise from amplitude modulation, limiting data throughput and security.
Innovation Solution
Generating a chaotic amplitude modulated signal with a constant power envelope using orthogonal chaotic spreading sequences and discrete time baseband modulation, such as quadrature amplitude modulation, to eliminate cyclostationary features and maintain data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pseudorandom sequences are used for spread spectrum modulation, then signal generation is straightforward, but statistical and cyclostationary features become detectable compromising security
Solution Approach 1:
The patent transforms the spreading sequence from conventional pseudorandom to chaotic sequences, fundamentally changing the statistical parameters and eliminating cyclostationary features. This parameter change makes the signal indistinguishable from noise while maintaining spread spectrum properties, thereby enhancing security and reducing detectability
Solution Approach 2:
The patent uses chaotic sequences that replicate the desirable properties of pseudorandom sequences (spread spectrum capability, processing gain) while eliminating their harmful characteristics (detectable statistical features). The chaotic signal copies the functional aspects needed for communication while discarding the exploitable features
2Reliability
If PSK modulation is used to create a stationary power envelope, then cyclostationary features are eliminated, but data throughput is limited
Solution Approach 1:
The patent segments the modulation process into two independent components: chaotic spreading sequences for security and amplitude modulation for high data throughput. This segmentation allows each component to optimize its function without compromising the other, achieving both security and productivity
Solution Approach 2:
The patent creates a composite modulation scheme combining chaotic sequences with amplitude modulation. This composite approach integrates the security benefits of chaotic signals with the high throughput capabilities of amplitude modulation, achieving both objectives simultaneously
3Productivity
If amplitude modulation is used to increase data throughput, then productivity improves, but cyclostationary features are introduced compromising security
Solution Approach 1:
The patent introduces chaotic sequences as an intermediary between the data signal and the amplitude modulated waveform. This intermediary eliminates cyclostationary features while preserving the amplitude modulation structure needed for high throughput, acting as a security-enhancing layer
Data Source
AI summary
Systems (400, 500, 600) and methods (300) for generating a chaotic amplitude modulated signal absent of cyclostationary features by preserving a constant variance. The methods involve: generating a PAM signal including pulse amplitude modulation having a periodically changing amplitude; generating a first part of a constant power envelope signal (FPCPES) by dividing the PAM signal by a square root of a magnitude of the PAM signal; generating a second part of the constant power envelope signal (SPCPES) having a magnitude equal to a square root of one minus the magnitude of the PAM signal; and generating first and second spreading sequences (FSS and SSS). The methods also involve combining the FPCPES with the FSS to generate a first product signal (FPS) and combining the SPCPES with the SSS to generate a second product signal (SPS). A constant power envelope signal is generated using the FPS and SPS.