Two signal monobit electronic warfare receiver

• US 5,793,323 A
• Filed: 11/25/1996
• Issued: 08/11/1998
• Est. Priority Date: 11/25/1996
• Status: Expired due to Fees

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Tsui, James B. Y.
• Primary Examiner(s): Tudor, Harold J.
• Assistant Examiner(s): MONTGOMERY, CHRISTOPHER KEITH
• Application Number:
  US08/758,275
• Time in Patent Office: 624 Days
• Field of Search: 342/13-16, 342/17, 342/196, 324/76.21, 364/484, 364/485, 364/724.06
• US Class Current: 342/13
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: G01S 7/2883 using FFT processing

Abstract

A broadband gigahertz frequency range radio receiver useful in electronic warfare and other applications for incoming signal detection and identification purposes. The receiver is based on Fourier transform examination of incoming signal characteristics and provides real time accomplishment of these tasks by way of using a simplified one-bit digital representation of the incoming signals and a resulting reduction of the computational load associated with the Fourier transform operation. The receiver precedes the Fourier transform operation with signal processing which may include, for example, a limiting amplifier and two bandpass filters. Two incoming signal accommodation is provided, a characteristic which is particularly improved over the characteristics of popular presently used receivers in this field.

Claims

1. The method of characterizing one or two substantially coincident pulse-modulated electronic warfare radio frequency receiver signals, said method comprising the steps of:

converting said radio frequency receiver signals in real time from an incident analog format to a digital format of single binary bit amplitude coding;

generating a discrete Fourier transform representation of said single binary bit amplitude-coded radio frequency receiver signals, said generated Fourier transform representation including a plurality of Fourier transform coefficient signal outputs each of known Fourier frequency association and of magnitude determined by waveform characteristics of said radio frequency receiver signals;

determining by amplitude comparison of said Fourier transform coefficient signal outputs which of said Fourier transform coefficient signal outputs have sufficient signal amplitude to represent a true identifying characteristic frequency of said received radio frequency signals;

wherein

said radio frequency signals have a carrier frequency above one gigahertz and a pulse modulation rate between one-tenth microsecond and a continuous wave.

2. The method of characterizing one or two substantially coincident pulse-modulated electronic warfare radio frequency receiver signals, said method comprising the steps of:

converting said radio frequency receiver signals from an incident analog format to a digital format of single binary bit amplitude coding;

generating a discrete Fourier transform representation of said single binary bit amplitude-coded radio frequency receiver signals, said generated Fourier transform representation including a plurality of Fourier transform coefficient signal outputs each of known Fourier frequency association and of magnitude determined by waveform characteristics of said radio frequency receiver signals; and

determining by amplitude comparison of said Fourier transform coefficient signal outputs which of said Fourier transform coefficient signal outputs have sufficient signal amplitude to represent a true identifying characteristic frequency of said received radio frequency signals;

wherein

said substantially coincident pulse-modulated electronic warfare radio frequency receiver signals include modulation pulse waveforms of less than one-tenth microsecond temporal segregation at one of their leading and trailing pulse edges.

3. Coincident signal-tolerant real time broadband electronic warfare radio receiver apparatus comprising the combination of:

a one-bit analog-to-digital converter circuit connected to receive analog electrical input signals communicated to said receiver, said analog-to-digital converter circuit including real time digital output signal generation capability at data rate frequencies comprising said receiver analog electrical input signals;

said one-bit analog-to-digital converter circuit generating an electrical output signal of positive one and negative one unitary magnitude in response to said receiver analog electrical input signals;

a discrete Fourier transform generating electrical circuit connected to an output signal port of said one-bit analog-to-digital converter circuit;

digital decision logic circuitry connected to an output signal port of said discrete Fourier transform-generating electrical circuit, said decision logic circuitry including a Fourier transform signal conversion threshold of selected magnitude; and

operator communicating signal display apparatus connected with an output signal of said digital decision logic circuitry;

said wideband spectrum of radio frequency signals comprising signals above one gigahertz frequency and including pulse modulations.

4. The coincident signal-tolerant real time broadband electronic warfare radio receiver apparatus of claim 3 wherein said coincident signals comprise pulse modulated radio frequency carrier signals of greater than one gigahertz carrier frequency and between one-tenth microsecond and continuous wave pulse modulation frequency.

5. Coincident signal-tolerant real time broadband electronic warfare radio receiver apparatus comprising the combination of:

a one-bit analog-to-digital converter circuit connected to receive analog electrical input signals communicated to said receiver, said analog-to-digital converter circuit including real time digital output signal generation capability at data rate frequencies comprising said receiver analog electrical input signals;

said one-bit analog-to-digital converter circuit generating an electrical output signal of positive one and negative one unitary magnitude in response to said receiver analog electrical input signals;

a first bandpass electrical wave filter circuit capable of de-emphasizing input radio frequency signals outside of an input bandwidth of said receiver and connected to an output node of said one-bit analog-to-digital converter circuit;

a signal amplitude-limiting amplifier connected to an output port of said first bandpass electrical wave filter;

a second bandpass electrical wave filter connected to an output port of said signal amplitude-limiting amplifier and capable of excluding signals of spurious frequency generated in said signal amplitude-limiting amplifier;

a discrete Fourier transform generating electrical circuit connected to an output signal port of said second bandpass electrical wave filter;

digital decision logic circuitry connected to an output signal port of said discrete Fourier transform-generating electrical circuit, said decision logic circuitry including a Fourier transform signal conversion threshold of selected magnitude; and

operator communicating signal display apparatus connected with an output signal of said digital decision logic circuitry.