Ingress monitoring device in a broadband communications system

• US 6,559,756 B2
• Filed: 06/13/2001
• Issued: 05/06/2003
• Est. Priority Date: 06/13/2001
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Al-Araji, Saleh R., Quesenberry, Paul E.
• Primary Examiner(s): PHAM, TOAN NGOC
• Application Number:
  US09/880,455
• Publication Number:
  US 20020190846A1
• Time in Patent Office: 692 Days
• Field of Search: 340/286.01, 340/541, 340/545.4, 340/531, 370/248, 370/252, 370/486, 725/105, 725/107, 725/108, 359/143, 359/146, 455/63, 455/67.1, 455/423, 455/425
• US Class Current: 340/286.01
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/0817 by checking functioning

Abstract

An ingress monitoring device (400) for monitoring and detecting reverse signals that may include ingress signals. The ingress monitoring device (400) includes a processor (430) for resolving the reverse signals into predetermined sub-bands at a first resolution. A power computation circuit (435) computes a power level for each of the sub-bands. A threshold comparison circuit (445) then compares the power level that is indicative to the power level of the ingress signals for each of the sub-bands with a predetermined threshold value. When ingress signals are detected by the ingress monitoring device (400), an alarm signal is sent that indicates the specific communications equipment in which the ingress signals have been detected.

Claims

1. In a broadband communications system having forward and reverse paths, the forward and reverse paths including communications equipment for transmitting forward and reverse signals, respectively, in predetermined frequency bands, the forward and reverse signals including noise signals and carrier signals, the communications equipment including an ingress monitoring device for monitoring the reverse signals and for detecting ingress signals that may be present along with the noise and carrier signals, the ingress monitoring device comprising:

a processor for resolving the reverse signals into predetermined sub-bands at a first resolution, and for computing a power level for each of the sub-bands, and for comparing the power level that is indicative to the power level of the ingress signals for each of the sub-bands with a predetermined threshold value,

wherein when ingress signals are present along with the reverse signals, the processor provides an alarm signal that indicates the specific communications equipment in which the ingress signals have been detected.

2. The broadband communications system of claim 1, the ingress monitoring device further comprising:

a memory buffer for storing and providing a snapshot of the reverse signals to the processor.

3. The broadband communications system of claim 2, wherein a new snapshot is provided to the processor on a predetermined cycle.

4. The broadband communications system of claim 3, wherein the ingress monitoring device receives a portion of the reverse signals, and wherein an analog-to-digital converter digitizes the portion of the reverse signals and provides a digital signal to the memory buffer.

5. The broadband communications system of claim 4, wherein the portion of the reverse signals are amplified with an amplifier and provided to the analog-to-digital converter.

6. The broadband communications system of claim 1, wherein the processor comprises:

a power computation circuit for resolving the reverse signals and for computing the power level for each of the sub-bands; and

a threshold comparison circuit for comparing the power level that is indicative to the power level of the ingress signals for each of the sub-bands with the predetermined threshold value.

7. The broadband communications system of claim 1, wherein the processor comprises:

an amplitude histogram generation circuit for charting the power level of each of the sub-bands in a plurality of histogram bins, wherein the plurality of histogram bins are dependent upon a second resolution.

8. The broadband communications system of claim 7, wherein a history, defined by a predetermined value, of the power levels of each of the sub-bands is accrued in the plurality of histogram bins with each new snapshot, and wherein the power level charted in specific histogram bins are indicative to the power level associated with one of the noise signals, the ingress signals, and the carrier signals.

9. Communications equipment including an ingress monitoring device for transmitting reverse signals, the reverse signals comprising noise signals and carrier signals, the ingress monitoring device for detecting ingress signals that may also be present with the reverse signals, a method for detecting the ingress signals, the steps comprising:

resolving the reverse signals into predetermined sub-bands;

computing a power level for each of the sub-bands;

comparing the power level that is indicative of the power level of the ingress signals for each of the sub-bands with a predetermined threshold value,

wherein if ingress signals are present along with the reverse signals, an alarm signal is provided that indicates ingress signals have been detected within the communications equipment.

10. The method of claim 9, the steps, prior to resolving the reverse signals, further comprising:

splitting a portion of the reverse signals;

filtering the portion of the reverse signals;

amplifying the filtered signal;

digitizing the amplified signal;

storing the digital signal in a memory buffer; and

providing the stored digital signal that is indicative of the reverse signals.

11. The method of claim 9, wherein the steps, subsequent to computing the power level for each of the sub-bands, further comprise:

charting the power level for each of the sub-bands in histogram bins, wherein specific histogram bins are indicative of the noise signals, the ingress signals, and the carrier signals.

12. An ingress monitoring device for receiving reverse signals in a predetermined frequency band and for detecting ingress signals, the ingress monitoring device comprising:

a processor, comprising;

a power spectrum computation circuit for resolving the reverse signals into predetermined sub-bands, and for computing a power level for each of the sub-bands;

an amplitude histogram generation circuit coupled to the power spectrum computation circuit for charting the power level of each of the sub-bands in a plurality of histogram bins;

a threshold comparison circuit coupled to the amplitude histogram generation circuit for comparing the power level charted in the histogram bins that are indicative to the power level of the ingress signals for each of the sub-bands with a predetermined threshold value.

13. The ingress monitoring device of claim 12, further comprising:

a splitter for splitting a portion of the reverse signals;

a filter coupled to the splitter for filtering out unwanted signals above the predetermined frequency band of the reverse signals;

an amplifier coupled to the filter for amplifying the filtered signals;

an analog-to-digital (A/D) converter coupled to the amplifier for digitizing the amplified signals; and

a memory buffer coupled to the A/D converter for providing the digital signal as a snapshot to the power spectrum computation circuit.

14. The ingress monitoring device of claim 13, wherein the ingress monitoring device is used in communications equipment.

15. In communications equipment for transmitting forward and reverse signals in a broadband communications system, the reverse signals comprising noise signals and carrier signals, the communications equipment for monitoring and providing an alarm signal when ingress signals are present along with the reverse signals, the communications equipment comprising:

an input port for receiving the reverse signals;

a splitter for splitting the reverse signals;

an ingress monitoring device for receiving a portion of the reverse signals and for monitoring the received reverse signals for the presence of ingress signals, the ingress monitoring device comprising;

a processor for resolving the portion of the reverse signals into predetermined sub-bands at a first resolution and for computing a power level for each of the sub-bands, and for comparing the power level that is indicative to the power level of the ingress signals for each of the sub-bands with a predetermined value,

wherein when ingress signals are present along with the reverse signals, the processor provides an alarm signal that indicates the specific communications equipment in which the ingress signals have been detected.

16. The communications equipment of claim 15, wherein the alarm signal is provided to a headend in the broadband communications system.