Electronic counter measure system utilizing a digital RF memory

• US 4,743,905 A
• Filed: 08/16/1985
• Issued: 05/10/1988
• Est. Priority Date: 08/16/1985
• Status: Expired due to Fees

• Current Assignee: Northrop Grumman Corporation
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Wiegand, Richard J.
• Primary Examiner(s): Tubbesing, T. H.
• Assistant Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US06/766,305
• Time in Patent Office: 998 Days
• Field of Search: 342/13, 342/14, 342/15, 365/45, 365/191, 365/192, 365/197, 381/32, 369/59, 369/60, 333/165
• US Class Current: 342/14
• CPC Class Codes: G01S 7/38 Jamming means, e.g. producing false echoes

Abstract

An active radar jamming system using a digital radio frequency memory (DRFM) as the central subsystem in the generation and detection of specific signal characteristics. Associated systems control the operation, data processing, and loading of the DRFM. Signals generated by the jamming system are either repeated replicas of the received radar signal stored in the DRFM, or newly generated signals constructed from data loaded into the DRFM by the associated subsystems. Such associated subsystems generate appropriate data for providing carrier and noise RF signals. Systems are also provided for determining the presence of phase coding and chirp modulation in the received radar signal data contained in the DRFM, and for detecting the angle-of-arrival of the radar signal.

Claims

1. An electronic countermeasure active jamming system comprising:

antenna means for receiving and transmitting high frequency electromagnetic signals;

a digital radio frequency memory;

first control means for enabling said memory to store binary data corresponding to the received signal;

second control means for activating said memory to output the stored data for constructing a signal to be applied to the transmitting antenna means;

an RF signal data generator which generates one-bit binary logic values for storage in the digital memory, with the data being at a high logic state when the RF signal to be generated is equal to or greater than a predetermined level and at a low logic state when less than said predetermined level, and wherein the generated RF signal data corresponds to an RF signal having constant frequency and phase with respect to time;

an RF noise data generator which generates one-bit binary logic values for storage in the digital memory, with the data being at a high logic state when the RF signal to be generated is equal to or greater than a predetermined level and at a low logic state when less than said predetermined level, said values corresponding to an RF noise signal having time varying frequency and phase with respect to time; and

a detector for detecting phase coding and chirp modulation of the received signals and for analyzing the frequency spectrum of the received signal memory data to determine if the received signal was frequency modulated.

2. The jamming system of claim 1 including at least one additional section having similar antenna, memory, storing and controlling means, and further including means for determining the angle-of-arrival of the received signal.

3. The jamming system of claim 2 wherein the means for determining the angle of arrival of the received signal further calculates the average phase difference of the center frequencies in each similar section.