Narrow band interference frequency excision method and means

• US 5,263,048 A
• Filed: 07/24/1992
• Issued: 11/16/1993
• Est. Priority Date: 07/24/1992
• Status: Expired due to Term

• Current Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Original Assignee: Magnavox Electronic Systems Company
• Inventors: Wade, Bobby R.
• Primary Examiner(s): Swann, Tod R.
• Application Number:
  US07/920,215
• Time in Patent Office: 480 Days
• Field of Search: 375/1, 375/51, 375/57, 375/58, 375/99, 375/100, 375/101, 375/102, 375/103, 455/63, 455/222, 455/223, 455/224, 455/295, 455/296, 455/307, 380/34, 364/726, 364/827
• US Class Current: 375/148
• CPC Class Codes: H04B 1/7102 with transform to frequency domain
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10

Abstract

In a preferred embodiment, a method for excising narrow band interferers in a spread spectrum signal communication which includes the steps of: receiving the spread spectrum signal; digitizing the spread spectrum signal; transforming the digitized signal from the time domain to the frequency domain; discarding the magnitude of the digitized signal and replacing it with a normalized value; and transforming the digitized signal back to the time domain.

Claims

1. A method for excising narrow band interferers in a spread spectrum signal communication, comprising the steps of:

(a) receiving said spread spectrum signal;

(b) digitizing said spread spectrum signal;

(c) transforming, in real time, said digitized signal from a time domain to a frequency domain, with said digitized signal having a magnitude;

(d) discarding, in real time, said magnitude of said digitized frequency domain signal and replacing it with a normalized value; and

(e) transforming, in real time, said normalized signal back to said time domain.

2. A method, as defined in claim 1, wherein (d) comprises the steps of:

(d₁) utilizing a rectangular-to-polar conversion to resolve said digitized frequency domain signal into its magnitude and phase components;

(d₂) discarding said magnitude component; and

(d₃) utilizing a rectangular-to-polar conversion with the magnitude set to an arbitrary value to return said digitized frequency domain signal to a normalized spectrum.

4. A method, as defined in claim 1, where step (e) is accomplished utilizing an Inverse Fast Fourier Transform.

5. An apparatus for excising narrow band interferers in a spread spectrum signal communication, comprising:

(a) receiving means to receive said spread spectrum signal;

(b) digitizing means coupled to said receiving means to digitize said spread spectrum signal;

(c) first transforming means coupled to said digitizing means to transform, in real time, said digitized signal from a time domain to a frequency domain;

(d) rejection means coupled to said first transforming means to discard, in real time, the magnitude of said digitized frequency domain signal and replace it with a normalized value; and

(e) second transforming means coupled to said rejection means to transform, in real time, said normalized signal back to said time domain.

6. An apparatus, as defined in claim 5, wherein said rejection means comprises:

(d₁) first rectangular-to-polar conversion means to resolve said digitized frequency domain signal into its magnitude and phase components and to discard said magnitude component; and

(d₂) second rectangular-to-polar conversion means with the magnitude set to an arbitrary value to return said digitized frequency domain signal to a normalized spectrum.

7. An apparatus, as defined in claim 5, wherein said first transforming means is a Fast Fourier Transform device.

8. An apparatus, as defined in claim 5, wherein said second transforming means is an Inverse Fast Fourier Transform device.

9. A method for excising narrow band interferers in a spread spectrum time domain signal communication, comprising the steps of:

(a) receiving said spread spectrum time domain signal;

(b) digitizing said spread spectrum time domain signal;

(c) transforming said digitized time domain signal from a time domain to a frequency domain;

(d) discarding the magnitude of said digitized signal and replacing it with a normalized value by;

(d₁) utilizing a rectangular-to-polar conversion to resolve said digitized frequency signal into its magnitude and phase components;

(d₂) discarding said magnitude component; and

(d₃) utilizing a rectangular-to-polar conversion with the magnitude set to an arbitrary value to return said digitized frequency signal to a normalized spectrum; and

(e) transforming said normalized signal back to said time domain.

10. A method, as defined in claim 9, wherein step (c) is accomplished utilizing a Fast Fourier Transform.

11. A method, as defined in claim 9, wherein step (e) is accomplished utilizing an Inverse Fast Fourier Transform.

12. An apparatus for excising narrow band interferers in a spread spectrum signal communication, comprising:

(a) receiving means to receive said spread spectrum signal;

(b) digitizing means coupled to said receiving means to digitize said spread spectrum signal;

(c) first transforming means coupled to said digitizing means to transform said digitized signal from a time domain to a frequency domain;

(d) rejection means coupled to said first transforming means to discard the magnitude of said digitized frequency signal and replace it with a normalized value through the use of

(d₁) first rectangular-to-polar conversion means to resolve said digitized frequency signal into its magnitude and phase components and to discard said magnitude component; and

(d₂) second rectangular-to-polar conversion means with the magnitude set to an arbitrary value to return said digitized signal to a normalized spectrum; and

(e) second transforming means coupled to said rejection means to transform said normalized signal back to said time domain.

3. A method, as defined in claim 12 wherein step (c) is accomplished utilizing a Fast Fourier Transform.

13. An apparatus, as defined in claim 12, wherein said first transforming means is a Fast Fourier Transform device.

14. An apparatus, as defined in claim 12, wherein said second transforming means is an Inverse Fast Fourier Transform device.