Method and apparatus for determining the direction of arrival of a signal

• US 3,906,505 A
• Filed: 10/09/1973
• Issued: 09/16/1975
• Est. Priority Date: 10/09/1973
• Status: Expired due to Term

• Current Assignee: Stephen E. Lipsky
• Original Assignee: Stephen E. Lipsky
• Inventors: Lipsky, Stephen E.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Blum, T. M.
• Application Number:
  US05/404,312
• Time in Patent Office: 707 Days
• Field of Search: 343/16R,119,123
• US Class Current: 342/432
• CPC Class Codes: G01S 1/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 3/06 Means for increasing effective directivity, e.g. by combining signals having differently oriented directivity characteristics or by sharpening the envelope waveform of the signal derived from a rotating or oscillating beam antenna comparing amplitude of signals having differently oriented directivity characteristics to determine direction G01S3/16, G01S3/28

Abstract

The method and apparatus for determining the direction of arrival of a signal utilizes a pair of omnidirectional antenna elements, the outputs of which are phase combined such that the elements are effective to form a pair of simultaneous cardioid reception patterns. Separate logarithmic data signals are generated which are a function of the magnitude of the signal as received by each of the reception pairs. The logarithmic data signals are then normalized to eliminate any signal time variation therein and to form a resultant signal indicative only of the direction of arrival of the received signal.

Claims

1. Apparatus for determining the direction of arrival of a signal comprising a pair of omnidirectional antenna elements, means for phase combining the output signals from said elements such that said elements are effective to form a pair of simultaneous cardioid reception patterns, means for generating separate data Signals representative of the magnitude of the signal received by each of the cardioid patterns respectively and means for detection and signal normalization, said detection and signal normalization means being frequency independent throughout the instantaneous radio frequency band over which the cardioid pattern is capable of being formed, thus providing a resultant signal indicative only of the direction of arrival of said received signal.

2. The apparatus of claim 1 wherein said means for the detection and signal normalization comprises means for amplifying said detected signals to form separate data signals.

3. the apparatus of claim 2 wherein said amplifying means comprises a video logarithmic amplifier.

4. The apparatus of claim 2 wherein said detection means comprises a radio frequency detector.

5. The apparatus of claim 1 wherein said phase combining means comprises a quadrature hybrid.

6. The apparatus of claim 1 wherein each of said reception patterns is 180* out of phase with the other.

7. The apparatus of claim 1 wherein said phase combining means sums an in-phase component of the output of one of said elements with a 90* phase-shifted component of the output of the other of said elements.

8. The apparatus of claim 1 further comprising means for sensing the polarity of said normalized detection signal to determine whether the data signal associated with one of said patterns is greater than the data signal associated with the other of said patterns.

9. The apparatus of claim 8 further comprising means for forming a second pair of simultaneous cardioid reception patterns, said second pattern pair being oriented at a 90* angle from the first pattern pair and means for processing the signals received by said second pattern pair to form a second resultant signal indicative only of the direction of arrival of a received signal.

10. A method for determining the direction of arrival of a signal comprising the steps of forming a pair of simultaneous cardioid reception patterns, detecting over a broad range within the frequency band over which the cardioid patterns are capable of being formed the output of each of said patterns caused by a signal received thereby, separately logarithmically amplifying the signals representative of the amplitude of the detected output of each of said patterns, respectively, subtracting one of said logarithmic signals from the other of said logarithmic signals such that any signal time variation therein is eliminated, and forming a resultant signal indicative only of the direction of arrival of said received signal.

11. The method of claim 10 wherein said patterns are formed by combining the in-phase component of the output of one element of an omnidirectional antenna element pair with the 90* out-of-phase component of the output of the other element in said pair.

12. The method of claim 10 further comprising the step of sensing whether or not one of said logarithmic signals is greater than the other.