US 11,159,939 B2 · Featureless low-probability interception/detection waveform via continuously variable symbol rate transmission

Abstract

Techniques are disclosed for generating a featureless low-probability-of-intercept/low-probability-of-detection (LPI/LPD) waveform via a continuously variable symbol rate transmission. A continuous-phase-modulation (CPM) signal can be represented with a phase trellis. During each symbol duration, the trellis is traversed in either a positive or negative direction in a continuous fashion from the starting phase value to the end phase value. The rate at which the trellis is traversed is varied continuously as a time-varying function. The time-varying phase velocity function, or instantaneous symbol rate, is a type of spreading code or secret key shared between the transmitter and receiver. The disclosed techniques can be implemented with CPM compromising the constant-modulus property of CPM signals.

Claims17

Dependent claims

A method of generating featureless low-probability-of-intercept/low-probability-of-detection (LPI/LPD) waveforms, the method comprising:

receiving a sequence of symbols to be wirelessly transmitted from a transmitting device to a receiving device via a carrier signal;
generating a pseudorandom phase sequence number;
generating a trellis code representing the sequence of symbols;
continuously modulating the carrier signal by traversing the trellis code at a variable traversal rate that is based on the pseudorandom phase sequence number;
and
causing the transmitting device to provide the phase sequence number to the receiving device.

3 more elements

A communication system, comprising:

a data processor configured to receive a sequence of symbols to be wirelessly transmitted from a transmitting device to a receiving device via a carrier signal;
a phase sequence generator configured to generate a pseudorandom phase sequence number;
a modulator operatively coupled to the data processor and to the phase sequence generator, the modulator configured to generate a trellis code representing the sequence of symbols received by the data processor and to continuously modulate the carrier signal by traversing the trellis code at a variable traversal rate that is based on the pseudorandom phase sequence number generated by the phase sequence generator;
and
a transmitter configured to cause the transmitting device to wirelessly broadcast the modulated carrier signal via an antenna.

2 more elements

A computer program product including one or more non-transitory machine-readable mediums encoded with instructions that when executed by one or more processors cause a process of generating featureless low-probability-of-intercept/low-probability-of-detection (LPI/LPD) waveforms to be carried out, the process comprising;

receiving a sequence of symbols to be wirelessly transmitted from a transmitting device to a receiving device via a carrier signal;
generating a pseudorandom phase sequence number;
generating a trellis code representing the sequence of symbols;
and
continuously modulating the carrier signal by traversing the trellis code at a variable traversal rate that is based on the pseudorandom phase sequence number, wherein the trellis code is traversed within a period of time that is less than a constant symbol duration.

2 more elements

Dependencies are inferred from the claim text.

Featureless low-probability interception/detection waveform via continuously variable symbol rate transmission

Life of this patent

Featureless low-probability interception/detection waveform via continuously variable symbol rate transmission

Life of this patent

Abstract

Claims17