Circuit for LPI signal detection and suppression of conventional pulsed signals

A pulse/LPI signal discriminator comprising:

• (a) a series circuit connected to a threshold detector that produces a trigger signal when an input to the detector is above a predetermined threshold;
• (b) an input to the series circuit being connected to an input of an IF amplifier that soft-limits any high-peak short-pulse IF signals in a received IF signal;
• (c) the IF amplifier being connected to circuitry that further compresses the amplitude of high-peak signals, said circuitry having an output connected to an integrator;
• and
• (d) the integrator integrating a received signal over a predetermined period of time and producing a high output signal when a LPI signal is present in the received IF signal, an output from the integrator being connected to the threshold detector whereby a high output from the integrator produces said trigger signal from the threshold detector.

A receiver for determining parameters of an incoming signal, comprising:

• (a) a plurality of receiver channels, each channel including a respective antenna for receiving said incoming signal;
• (b) a down converter associated with each of said plurality of receiver channels for converting said incoming signal to an intermediate frequency signal;
• (c) an analog-to-digital converter with a circular FIFO memory as a buffer operatively coupled to receive said IF signal and to provide a digital signal in response to a trigger signal, said digital signal being indicative of the phase and amplitude of said incoming signal in said channel;
• (d) a digital processor operatively coupled to receive said digital signal from each of said plurality of channels and for determining parameters of the digital signal;
• and
• (e) a pulse/LPI signal discriminator operatively coupled to one of said down converters for producing a trigger signal when a signal in the discriminator is above a predetermined threshold, said trigger signal being applied to the memory to thereby gate digitized data in the memory to a digital processor for processing.