IP Library › Granted Patent US 7,369,658
Granted Patent B2
US 7,369,658 · App. 10/429,271 · Granted May 6, 2008

Secure modulation and demodulation

View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 7,369,658
App. No.
10/429,271
Granted
May 6, 2008
Kind
B2
Abstract

A system and method are disclosed for securely transmitting and receiving a signal. A nonlinear keying modulator is used in the transmitter to encrypt the signal using a nonlinear keying modulation technique. A nonlinear keying demodulator is used in the receiver to decrypt the signal.

Claims (93)

1. A transmitter for securely transmitting a signal, including:

an input interface for receiving the signal; and

a nonlinear keying modulator configured to encrypt the signal using a nonlinear keying modulation technique;

wherein the nonlinear keying modulator has a nonlinear transfer function that is variable depending on the signal, and

wherein the nonlinear keying modulator has an associated nonlinear keying demodulator with a transfer function that is an inverse of the nonlinear transfer function and that can be used to decrypt a nonlinear keying modulation encrypted signal;

wherein the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying modulator is configured by receiving a key derived from the configurations of a receiver; and the key includes topology information for deriving a topology of the nonlinear elements, the combination network, and the linear filters.

2. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator is configured to encrypt the signal to be decrypted by a receiver.

3. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator is configured to encrypt the signal to be decrypted by a receiver by exchanging a key.

4. A transmitter for securely transmitting a signal as recited in claim 1 , further including a linear modulator configured to linearly modulate the signal.

5. A transmitter for securely transmitting a signal as recited in claim 1 , further including a linear modulator configured to linearly modulate the signal; wherein the nonlinear keying modulator nonlinearly modulates the output of the linear modulator.

6. A transmitter for securely transmitting a signal as recited in claim 1 , further including a linear modulator configured to linearly modulate the signal, wherein the linear modulator linearly modulates the output of the nonlinear keying modulator.

7. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements.

8. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and the plurality of nonlinear elements include a minimum-maximum processor.

9. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and the combination network is a minimum-maximum switching matrix.

10. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters having a number of filter coefficients, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; and

the nonlinear keying modulator is adjustable by varying the number of filter coefficients.

11. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; wherein the plurality of linear filters include a plurality of feedforward filters; and

the nonlinear keying modulator is adjustable by varying the number of feedforward filters.

12. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; wherein the plurality of linear filters include a plurality of feedback filters; and

the nonlinear keying modulator is adjustable by varying the number of feedback filters.

13. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; and

the nonlinear keying modulator is adjustable by varying the topology of the combination network.

14. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and

the poles of the plurality of linear filters are inside a unit circle.

15. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and

the zeros of the plurality of linear filters are inside a unit circle.

16. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying modulator is configured by receiving a key derived from the configurations of a receiver.

17. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying modulator is configured by receiving a key derived from the configurations of a receiver; and

each of the plurality of linear filters is configured to be the inverse of a corresponding linear filter in the receiver.

18. A transmitter for securely transmitting a signal as recited in claim 1 , wherein:

the nonlinear keying modulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the plurality of nonlinear elements are a plurality of minimum-maximum processors;

the nonlinear keying modulator is configured by receiving a key derived from the configurations of a receiver; and

the function of each of the plurality of minimum-maximum processors is configured to be the inverse of a corresponding minimum-maximum processor in the receiver.

19. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator is a first nonlinear keying modulator; and the transmitter further includes a second nonlinear keying modulator coupled to the first nonlinear keying modulator.

20. A transmitter for securely transmitting a signal as recited in claim 1 , wherein the nonlinear keying modulator is a first nonlinear keying modulator; and the transmitter further includes a second nonlinear keying modulator coupled to the first nonlinear keying modulator in a cascaded configuration.

21. A receiver for decrypting a securely transmitted signal, including:

an input interface for receiving the signal; and

a nonlinear keying demodulator configured to decrypt the signal using a nonlinear keying demodulation technique;

wherein the nonlinear keying demodulator has a nonlinear transfer function that is variable depending on the signal, and

wherein the nonlinear keying demodulator has an associated nonlinear keying modulator with a transfer function that is an inverse of the nonlinear transfer function and that can be used to encrypt a signal;

wherein the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying demodulator is configured by receiving a key derived from the configurations of a transmitter; and

the key includes topology information for deriving a topology of the nonlinear elements, the combination network, and the linear filters.

22. A receiver for decrypting a securely transmitted signal as recited in claim 21 , further including a linear demodulator configured to linearly demodulate the signal.

23. A receiver for decrypting a securely transmitted signal as recited in claim 21 , further including a linear demodulator configured to linearly demodulate the signal; wherein the nonlinear keying demodulator nonlinearly demodulates the output of the linear demodulator.

24. A receiver for decrypting a securely transmitted signal as recited in claim 21 , further including a linear demodulator configured to linearly demodulate the signal, wherein the linear demodulator linearly demodulates the output of the nonlinear keying demodulator.

25. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements.

26. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and the plurality of nonlinear elements include a minimum-maximum processor.

27. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and the combination network is a minimum-maximum switching matrix.

28. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters having a number of filter coefficients, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; and

the nonlinear keying demodulator is adjustable by varying the number of filter coefficients.

29. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; wherein the plurality of linear filters include a plurality of feedforward filters; and

the nonlinear keying demodulator is adjustable by varying the number of feedforward filters.

30. A receiver for decrypting a securely transmitted signal as recited in claim 21 wherein:

the nonlinear demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; wherein the plurality of linear filters include a plurality of feedback filters; and

the nonlinear keying demodulator is adjustable by varying the number of feedback filters.

31. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the linear filters and nonlinear elements; and

the nonlinear keying demodulator is adjustable by varying the topology of the combination network.

32. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and

the poles of the plurality of linear filters are inside a unit circle.

33. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements; and

the zeros of the plurality of linear filters are inside a unit circle.

34. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying demodulator is configured by receiving a key derived from the configurations of a transmitter.

35. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the nonlinear keying demodulator is configured by receiving a key derived from the configurations of a transmitter; and

each of the plurality of linear filters is configured to be the inverse of a corresponding linear filter in the transmitter.

36. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein:

the nonlinear keying demodulator includes a plurality of linear filters, a plurality of nonlinear elements and a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;

the plurality of nonlinear elements are a plurality of minimum-maximum processors;

the nonlinear keying demodulator is configured by receiving a key derived from the configurations of a transmitter; and

the function of each of the plurality of minimum-maximum processors is configured to be the inverse of a corresponding minimum-maximum processor in the transmitter.

37. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein the nonlinear keying demodulator is a first nonlinear keying demodulator; and the receiver further includes a second nonlinear keying demodulator coupled to the first nonlinear keying demodulator.

38. A receiver for decrypting a securely transmitted signal as recited in claim 21 , wherein the nonlinear keying demodulator is a first nonlinear keying demodulator; and the receiver further includes a second nonlinear keying demodulator coupled to the first nonlinear keying demodulator in a cascaded configuration.