Cable modems and systems and methods for identification of a noise signal source on a cable network

• US 6,772,437 B1
• Filed: 07/28/1999
• Issued: 08/03/2004
• Est. Priority Date: 07/28/1999
• Status: Expired due to Term

• Current Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Dailey, Tim E., Cooper, Gerald M.
• Primary Examiner(s): Srivastava, Vivek
• Assistant Examiner(s): VU, NGOC K
• Application Number:
  US09/362,785
• Time in Patent Office: 1,833 Days
• Field of Search: 348/12, 348/13, 348/192, 348/193, 455/5.1, 455/67.3, 455/115.1, 455/116, 725/111, 725/121, 725/124-6, 725/130, 725/107
• US Class Current: 725/111
• CPC Class Codes: H04N 17/00 Diagnosis, testing or measuring for television systems or their details
• CPC Class Codes: H04N 21/42676 for modulating an analogue carrier signal to encode digital information or demodulating it to decode digital information, e.g. ADSL or cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6543 for forcing some client operations, e.g. recording remote booting in general G06F9/4416
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

Cable modems are provided for measuring a noise signal power level on the upstream side of the cable network. The cable modem may be configured to make the signal power measurements at a variety of frequencies and at a selected bandwidth during a specified test time period responsive to a request received from the cable network. Methods and systems are provided for identifying a noise signal source on a cable network including specifying a time window for measurements, the desired measurements and the cable modems from which measurements are desired when the need to initiate a test to identify a noise source is detected. Tests may be initiated based on noise signal measurements by individual cable modems or by the cable services provider which indicate an unacceptable noise level. In addition, the reliability of the test measurements may be improved by not allowing any transmissions on the upstream side during the concurrent test window while cable modems are making the requested measurements. The measurements may then be used to identify which end user location(s) is the source of the noise signal.

Claims

1. A self-testing cable modem for testing a cable network, the self-testing cable modem comprising:

a media access controller coupled to a cable network, the cable network having a downstream side to the cable modem and an upstream side from the cable modem;

a processor coupled to the media access controller; and

a host interface coupled to a host system;

a signal power measurement circuit responsive to an upstream side of the cable network, the signal power measurement circuit comprising;

a bandpass filter having a selectable center frequency having an input side coupled to the upstream side of the cable network;

a power detector coupled to an output side of the bandpass filter; and

wherein the selectable center frequency is selectable responsive to the processor and wherein the processor is configured to receive commands over the cable network specifying a desired center frequency for power measurements and wherein the power detector is a power integrator.

2. A cable modem according to claim 1 wherein the bandpass filter has a selectable bandwidth and wherein the selectable bandwidth is selectable responsive to the processor and wherein the processor is configured to receive commands over the cable network specifying a desired bandwidth for power measurements.

3. A cable modem according to claim 1 wherein the processor further comprises means for determining a level of a noise signal on the upstream side of the cable network based on measurements performed by the signal measurement circuit.

4. A cable modem according to claim 3 wherein the processor further comprises means for determining a frequency of occurrence of the noise signal on the upstream side of the cable network based on measurements performed by the signal measurement circuit.

5. A method for identifying a noise signal source on an upstream side of a cable network including cable modems, the method comprising:

detecting a test initiation event;

identifying cable modems selected from the cable modems on the upstream side of the cable network to participate in a test;

requesting signal power measurements on the upstream side of the cable network from the identified cable modems;

receiving the requested signal power measurements from the identified cable modems; and

identifying at least one of the identified cable modems as the noise signal source based on the received requested signal power measurements.

6. A method according to claim 5 wherein the step of detecting comprises the step of detecting a noise signal level violating a detection criteria on the upstream side of the cable network during normal operating conditions of the cable system.

7. A method according to claim 5 wherein the step of detecting comprises the step of receiving an indication of a test initiation event from at least one of the cable modems over the upstream side of the cable network.

8. A method according to claim 5 wherein the step of identifying cable modems is followed by the step of determining a test time window and wherein the step of requesting signal power measurements further comprises the step of specifying the test time window for the requested signal power measurements by all of the identified cable modems.

9. A method according to claim 8 wherein the step of requesting signal power measurements further comprises the step of notifying a plurality of the cable modems on the upstream side of the cable network which are coupled to a branch of the upstream side of the cable network which includes at least one of the identified cable modems that no transmissions on the upstream side of the cable network should be generated during the test time window.

10. A method according to claim 9 wherein the plurality of the cable modems includes the identified cable modems.

11. A method according to claim 10 wherein the plurality of the cable modems includes at least one cable modem which is not one of the identified cable modems.

12. A method according to claim 8 wherein the step of identifying at least one of the identified cable modems comprises the step of identifying any of the identified cable modems which provided signal power measurements violating a selection criteria as the noise signal source.

13. A method according to claim 12 wherein the step of identifying at least one of the identified cable modems is followed by the step of initiating a corrective action for the identified noise signal source.

14. A method for identifying a noise signal source on a cable network, the method comprising:

receiving over a downstream side of the cable network at a cable modem a request for signal power measurements on an upstream side of the cable network at the cable modem;

measuring a signal power on the upstream side of the cable network at the cable modem; and

providing the measured signal power to a remote location over the cable network.

15. A method according to claim 14 wherein the step of receiving further comprises the step of receiving a request for signal power measurement specifying a time period for measurement and at least one frequency for measurement and wherein the measuring step further comprises the step of measuring the signal power during the specified time period and at the specified at least one frequency to provide the measured signal power.

16. A method according to claim 14 wherein the step of measuring is preceded by the step of suspending transmissions on the upstream side of the cable network during the specified time period.

17. A system for identifying a noise signal source on an upstream side of a cable network including cable modems, the system comprising:

means for detecting a test initiation event;

means for identifying cable modems selected from the cable modems on the upstream side of the cable network to participate in a test;

means for requesting signal power measurements on the upstream side of the cable network from the identified cable modems;

means for receiving the requested signal power measurements from the identified cable modems; and

means for identifying at least one of the identified cable modems as the noise signal source based on the received requested signal power measurements.

18. A system according to claim 17 wherein the means for detecting comprises means for detecting a noise signal level violating a detection criteria on the upstream side of the cable network during normal operating conditions of the cable system.

19. A system according to claim 17 further comprising means for determining a test time window and wherein the means for requesting signal power measurements further comprises means for specifying the test time window for the requested signal power measurements by all of the identified cable modems.

20. A system according to claim 19 wherein the means for requesting signal power measurements further comprises means for notifying a plurality of the cable modems on the upstream side of the cable network which are coupled to a branch of the upstream side of the cable network which includes at least one of the identified cable modems that no transmissions on the upstream side of the cable network should be generated during the test time window.

21. A system according to claim 20 wherein the means for identifying at least one of the identified cable modems comprises means for identifying any of the identified cable modems which provided signal power measurements violating a selection criteria as the noise signal source.

22. A system for identifying a noise signal source on a cable network comprising:

means for receiving over a downstream side of the cable network at a cable modem a request for signal power measurements on an upstream side of the cable network at the cable modem;

means for measuring a signal power on the upstream side of the cable network at the cable modem; and

means for providing the measured signal power to a remote location over the cable network.

23. A system according to claim 22 wherein the means for receiving further comprises means for receiving a request for power measurement specifying a time period for measurement and at least one frequency for measurement and wherein the means for measuring further comprises means for measuring the signal power during the specified time period and at the specified at least one frequency to provide the measured signal power.

24. A system according to claim 23 further comprising means for suspending all transmissions on the upstream side of the cable network during the specified time period.