Pseudo-chaotic communication method exploiting symbolic dynamics
First Claim
1. A data coding method comprising:
- accepting digital data for coding;
pseudo-chaotically coding the digital data by allocating the digital data to a state sequence assigned according to a chaotic map;
converting the pseudo-chaotically coded data to analog form and modulating the pseudo-chaotically coded data into synchronization frames.
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Abstract
A pseudo-chaotic coding/modulation method. The coding method exploits symbolic dynamics of a chaotic map at the transmitter to encode data. The encoding synthesizes the chaotic map based upon the data to be transmitted. In a preferred embodiment, pseudo-chaotic iterates are generated from a digital implementation of a Bernoulli shift map. The output of the shift map is translated by a mapping, preferably implemented by a digital signal processor, to allow transitions between states in a transmitted signal to differ, and the translated map is used to drive a modulator (for example PPM, FSK, PSK, QAM, etc.). In the specific case of pulse-position modulation (PPM) the translated map is used to modulate pulse train positions within a periodic synchronization frame. The preferred embodiment uses a shift register to implement an approximation of the Bernoulli shift map acting as a form of convolutional code with a number of states equal to the symbolic states defined on the chaotic map. A receiver may use fewer states and still decode the data signal, allowing receiver scalability.
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Citations
16 Claims
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1. A data coding method comprising:
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accepting digital data for coding;
pseudo-chaotically coding the digital data by allocating the digital data to a state sequence assigned according to a chaotic map;
converting the pseudo-chaotically coded data to analog form and modulating the pseudo-chaotically coded data into synchronization frames. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A data coding and decoding method, the method comprising steps of:
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accepting digital data for coding;
pseudo-chaotically coding the digital data by applying a chaotic map having N states;
converting the pseudo-chaotically coded data to analog form;
modulating the pseudo-chaotically coded data to produce a modulated signal;
transmitting the modulated signal over a channel;
receiving, at a receiver, a signal from the channel;
decoding the pseudo-chaotically coded data from the signal, the decoding comprising Viterbi detection matched to the chaotic map with N or fewer than N states. - View Dependent Claims (11, 13, 14, 15, 16)
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12. A data coding system comprising:
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a pseudo-chaotic data encoder for pseudo-chaotically encoding digital data, the pseudo-chaotic data encoder comprising a shift register for shifting the digital data and a digital signal processor for translating shifted digital data according to a selected chaotic map;
a digital to analog converter for converting the pseudo-chaotically shifted and translated digital data;
a modulator for modulating output of the digital to analog converter for transmission on a communication channel; and
a receiver for demodulating and decoding the pseudo-chaotically coded data from the signal, the decoding comprising Viterbi detection matched to the chaotic map with N or fewer than N states.
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Specification