Low-interference communications device using chaotic signals

• US 6,854,058 B2
• Filed: 04/23/2001
• Issued: 02/08/2005
• Est. Priority Date: 04/23/2001
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Carroll, Thomas L.
• Primary Examiner(s): Peeso, Thomas R.
• Application Number:
  US09/839,146
• Publication Number:
  US 20030007638A1
• Time in Patent Office: 1,387 Days
• Field of Search: 713/168, 713/200, 713/201
• US Class Current: 713/168
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 9/001 using chaotic signals

Abstract

The low-interference communications device uses chaotic signals which are almost periodic. A chaotic circuit driven by a sine wave signal from a function generator is produced which has narrow-band features in the power spectrum. An information signal is encoded on the chaotic signal by modulating the phase of the sine wave that drives the chaotic circuit. Periodic (narrow-band) components are then removed from the chaotic signal and the chaotic signal is transmitted to a receiver device. The chaotic signal is nonlinear, so the narrow band and broad band parts of the chaotic signal have been modulated together. The transmitted signal is relatively flat, so it will not interfere with other communications signals. At the receiver, the nonlinear chaotic signal is restored by performing a nonlinear operation on the received signal, such as squaring or cubing, to remove the narrowband components. Then the information modulated onto the narrow band component is detected. When this is accomplished it is possible to detect variations in the phase of the base frequency.

Claims

1. A device for producing a broadband communications signal comprised of:

a chaotic circuit modulated by an informational signal;

a circuit to remove a periodic part of the chaotic signal to produce a broad-band communications signal without any periodic parts;

a transmitter for transmitting the broadband signal with periodic parts removed;

a receiver for receiving the transmitted broadband signal with periodic parts removed;

a nonlinear operator circuit for reconstructing the periodic part of the chaotic signal; and

a demodulator for demodulating the informational signal contained in the chaotic signal.

2. A device, as in claim 1, wherein the demodulator is a phase demodulator.

3. A device, as in claim 1, wherein the demodulator is a frequency demodulator.

4. A device, as in claim 1, wherein the circuit to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts is a nonautonomous Duffing chaotic circuit.

5. A device, as in claim 1, wherein the circuit to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts is a piecewise linear Rossler circuit.

6. A device for producing a broadband communications signal comprised of:

a chaotic circuit modulated by an informational signal;

a circuit which produces periodic signals in order to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts;

a transmitter for transmitting the broadband signal with periodic parts removed;

a receiver for receiving the transmitted broadband signal with periodic parts removed;

a nonlinear operator circuit for reproducing the periodic part of the chaotic signal to produce a replica of the informational signal; and

a phase demodulator for demodulating the informational signal containing the chaotic signal.

7. A device for producing a broadband communications signal comprised of:

a chaotic circuit modulated by an informational signal;

a filter circuit to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts;

a transmitter for transmitting the broadband signal with periodic parts removed;

a receiver for receiving the transmitted broadband signal with periodic parts removed;

a nonlinear operator circuit for replacing the periodic part of the chaotic signal to produce a replica of the informational signal; and

a frequency demodulator for demodulating the informational signal containing the chaotic signal.

8. A device for producing a broadband communications signal comprised of:

a chaotic circuit modulated by an informational signal;

piecewise linear Rossler circuit to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts;

a transmitter for transmitting the broadband signal with periodic parts removed;

a receiver for receiving the transmitted broadband signal with periodic parts removed;

a nonlinear operator circuit for replacing the periodic part of the chaotic signal to produce a replica of the informational signal; and

a frequency demodulator for demodulating the informational signal containing the chaotic signal.

9. A device for producing a broadband communications signal comprised of:

a chaotic circuit modulated by an informational signal;

piecewise linear Rossler circuit to remove a periodic part of the chaotic signal to produce a broadband communications signal without any periodic parts;

a transmitter for transmitting the broadband signal with periodic parts removed;

a receiver for receiving the transmitted broadband signal with periodic parts removed;

a nonlinear operator circuit for replacing the periodic part of the chaotic signal to produce a replica of the informational signal; and

a phase demodulator for demodulating the informational signal containing the chaotic signal.

10. A method for producing a broadband communications signal comprised of the steps of:

producing a chaotic circuit modulated by an informational signal;

removing a periodic part of the chaotic signal piecewise linear Rossler circuit to produce a broadband communications signal without any periodic parts;

transmitting the broadband signal with periodic parts removed;

receiving the transmitted broadband signal with periodic parts removed;

replacing the periodic part of the chaotic signal to produce a replica of the informational signal using a nonlinear operator circuit for; and

demodulating the informational signal containing the chaotic signal using.