Secure modulation and demodulation
View Patent ↗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.
1. A transmitter, comprising:
a nonlinear keying modulator comprising:
a plurality of nonlinear elements including a processor;
a plurality of linear filters; and
a combination network connecting the plurality of linear filters and the plurality of nonlinear elements including the processor;
wherein the nonlinear keying modulator is configured to encrypt a received signal using the plurality of linear filters and the plurality of nonlinear, elements;
wherein the plurality of linear filters include a plurality of feedforward filters; and
wherein the nonlinear keying modulator is adjustable varying the plurality of feedforward filters.
2. The transmitter of claim 1 , wherein the nonlinear keying modulator is configured to encrypt the received signal to be decrypted by a receiver.
3. The transmitter of claim 1 , wherein the nonlinear keying modulator is configured to encrypt the received signal to be decrypted by a receiver by exchanging a key.
4. The transmitter of claim 1 , further comprising a linear modulator configured to linearly modulate the received signal.
5. The transmitter of claim 1 , further comprising a linear modulator configured to linearly modulate the received signal, wherein the nonlinear keying modulator nonlinearly modulates the output of the linear modulator.
6. The transmitter of claim 1 , further comprising a linear modulator configured to linearly modulate the received signal, wherein the linear modulator linearly modulates the output of the nonlinear keying modulator.
7. The transmitter of claim 1 ,
wherein the processor is a minimum-maximum processor.
8. The transmitter of claim 1 ,
wherein the combination network is a minimum-maximum switching matrix.
9. The transmitter of claim 1 ,
wherein the plurality of linear filters include a plurality of feedback filters; and
wherein the nonlinear keying modulator is adjustable by varying the plurality of feedback filters.
10. The transmitter of claim 1 ,
wherein the nonlinear keying modulator is adjustable by varying a topology of the combination network.
11. The transmitter of claim 1 ,
wherein poles of the plurality of linear filters are inside a unit circle.
12. The transmitter of claim 1 ,
wherein zeros of the plurality of linear filters are inside a unit circle.
13. The transmitter of claim 1 ,
wherein the nonlinear keying modulator is configured by receiving a key derived from receiver configurations.
14. A transmitter, comprising:
a nonlinear keying modulator comprising:
a plurality of nonlinear elements;
a plurality of linear filters; and
a combination network connecting the plurality of linear filters and the plurality of nonlinear elements;
wherein the nonlinear keying modulator is configured to encrypt a received signal using the plurality of linear filters and the plurality of nonlinear elements;
wherein the plurality of linear filters include a number of filter coefficients; and
wherein the nonlinear keying modulator is adjustable by varying the number of filter coefficients.
15. A transmitter, comprising:
a nonlinear keying modulator comprising:
a processor; and
a plurality of linear filters coupled to the processor,
the nonlinear keying modulator configured to encrypt a received signal by:
selecting a subset of linear filters of the plurality of linear filters based on a configuration parameter;
filtering the received signal using the selected subset of linear filters; and
processing an output of the selected subset of linear filters.
16. The transmitter of claim 15 , wherein the configuration parameter includes a number and type of linear filters to use for encrypting the received signal, and
wherein the type of linear filters includes a feedforward type and a feedback type.
17. The transmitter of claim 16 , wherein the configuration parameter further includes a number of filter coefficients for the linear filters and a number of filter stages for the nonlinear keying modulator.
18. The transmitter of claim 15 , wherein the nonlinear keying modulator further comprises a plurality of nonlinear elements, including the processor, and a combination network connecting the subset of linear filters and the plurality of nonlinear elements.