Interference source identification

• US 5,048,015 A
• Filed: 06/14/1990
• Issued: 09/10/1991
• Est. Priority Date: 06/14/1990
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: AT&T, Inc.
• Inventors: Zilberfarb, Yossi
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): TON, DANG T
• Application Number:
  US07/538,367
• Time in Patent Office: 453 Days
• Field of Search: 370/104.1, 370/107, 370/110.4, 370/111
• US Class Current: 370/312
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal

Abstract

A method and apparatus for immediately identifying the presence and the source of interference in a communications system. A separate identification code is superimposed on each signal transmitted from a separate transmitter. At any receiver, if an undesired signal causes interference, it can be idenified via its associated identification code. In one embodiment, spread spectrum chip sequences are used as the identification codes.

Claims

1. A receiver for receiving a desired transmitted signal, from among a plurality of transmitted signals, each of the transmitted signals comprising a data signal and a superimposed identification signal, each identification signal having a predetermined amplitude, the receiver comprising:

means for comparing the amplitude of the identification signal of the desired transmitted signal to an amplitude of an identification signal of at least one other transmitted signal from the plurality transmitted signals; and

means for causing an alarm condition when said means for comparing indicates that said amplitude of said identification signal from said at least one other transmitted signal is greater than a predetermined fraction of said amplitude of said identification signal of said desired transmitted signal.

2. The receiver of claim 1 wherein the identification signal is a pseudorandom sequence of tones.

3. The receiver of claim 1 wherein the identification signal is a pseudorandom sequence of digital bits.

4. The receiver of claims 1, 2 or 3 further including means for repetitively correlating the received signal to a plurality of predetermined identification codes for a predetermined amount of time.

5. The receiver of claims 1, 2, or 3 further comprising table lookup means connected to said means for comparing for identifying one or more transmitters that are associated with a particular identification code.

6. The receiver claims 1, 2, or 3 wherein the receiver is a satellite receiver.

7. The receiver claim 4 wherein the receiver is a satellite receiver.

8. The receiver claim 5 wherein the receiver is a satellite receiver.

9. In a receiver for receiving a desired transmitted signal, from among a plurality of transmitted signals, the transmitted signals comprising a data signal and a superimposed identification signal, each identification signal having a predetermined amplitude, a method of identifying interference in a transmitted signal comprising the steps of:

comparing the amplitude of the identification signal of the desired transmitted signal to the amplitude of the identification signal of at least one other transmitted signal from the plurality of transmitted signals;

outputting an alarm signal when said step of comparing indicates that said amplitude of said identification signal from said at least one other transmitted signal is greater than a predetermined fraction of said amplitude of said identification signal of said desired transmitted signal.

10. The method of claim 9 wherein the identification signal is a pseudorandom sequence of tones.

11. The method of claim 9 wherein the identification signal is a pseudorandom sequence of digital bits.

12. The method of claims 9, 10, or 11 further including the step of repetitively correlating the received signal to a plurality of predetermined identification codes for a predetermined amount of time.

13. The method of claims 9, 10, or 11 further comprising the step of identifying, one or more transmitters that are associated with a particular identification code causing an alarm condition.

14. The method of claims 9, 10, or 11 wherein the receiver is a satellite receiver.

15. The method of claim 12 wherein the receiver is a satellite receiver.

16. The method of claim 13 wherein the receiver is a satellite receiver.