Radio frequency leakage detection system for CATV system

• US 6,804,826 B1
• Filed: 07/19/2000
• Issued: 10/12/2004
• Est. Priority Date: 07/28/1999
• Status: Expired due to Fees

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Trilithic Incorporated (Lumentum Holdings Inc.)
• Inventors: Rodgers, Gregg S., Bush, Terry W.
• Primary Examiner(s): Tran, Hai
• Assistant Examiner(s): SALTARELLI, DOMINIC D
• Application Number:
  US09/619,094
• Time in Patent Office: 1,546 Days
• Field of Search: 725/143, 725/144, 725/148, 725/15, 725/17, 725/107, 725/124, 725/125, 348/192, 348/193, 348/180, 455/67.7, 455/67.13, 455/67.14, 455/67.15, 455/226.1, 455/226.2, 455/226.3
• US Class Current: 725/107
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/088 the inserted signal being digital
• CPC Class Codes: H04N 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems

Abstract

A communication circuit carries at least one signal including synchronizing intervals by which output of the signal by first apparatus coupled to the communication circuit is to be synchronized. A communication method includes selecting and modulating at least a portion of the duration of at least some of the synchronizing intervals. A modulator is provided for selecting and modulating at least a portion of the duration of at least some of the synchronizing intervals. Another communication circuit carries at least a first signal including frequencies in at least a first frequency band. A method of determining whether the first signal is escaping from the circuit includes transporting along the circuit apparatus adapted for receiving the first signal, detecting whether a received signal includes frequencies in the first frequency band, and producing an indication that the received signal includes frequencies in the first frequency band. A detector is provided for transporting along the circuit for determining whether the first signal is escaping from the circuit. The detector is adapted for receiving the first signal, detecting whether a received signal includes frequencies in the first frequency band, and producing an indication that the received signal includes frequencies in the first frequency band.

Claims

1. In a communication circuit which carries at least a first signal including frequencies in at least a first frequency band, the circuit located in an environment wherein a second signal includes frequencies in at least a second frequency band not including frequencies in the first frequency band, a method of determining whether the first signal is escaping from the circuit including transporting along the circuit apparatus adapted for receiving the first signal, detecting whether a received signal includes frequencies in the first frequency band, detecting whether a received signal includes frequencies in the second frequency band, comparing the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band, and producing an indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band.

2. The method of claim 1 further including producing an indication that the received signal includes frequencies in the first frequency band.

3. The method of claim 1 wherein comparing the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band and producing an indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band together include comparing the magnitude of received frequencies in the first frequency band to a first desired threshold and producing a third signal based upon this comparison, comparing the magnitude of received frequencies in the second frequency band to a second desired threshold and producing a fourth signal based upon this comparison, and combining the third and fourth signals to produce the indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band.

4. In a communication circuit which carries at least a first signal including frequencies in at least a first frequency band and a second signal including frequencies in at least a second frequency band not including frequencies in the first frequency band, a detector for transporting along the circuit for determining whether the first signal is escaping from the circuit, the detector adapted for receiving the first signal and the second signal, detecting whether a received signal includes frequencies in the first frequency band and the second frequency band, comparing the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band, and producing an indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band.

5. The detector of claim 4 further adapted for producing an indication that the received signal includes frequencies in the first frequency band.

6. The apparatus of claim 4 wherein the detector for comparing the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band and producing an indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band together include comparing the magnitude of received frequencies in the first frequency band to a first desired threshold and producing a third signal based upon this comparison, comparing the magnitude of received frequencies in the second frequency band to a second desired threshold and producing a fourth signal based upon this comparison, and combining the third and fourth signals to produce the indication of the relationship of the magnitude of received frequencies in the first frequency band to the magnitude of received frequencies in the second frequency band.