Method for signal level monitoring

• US 6,002,422 A
• Filed: 01/06/1997
• Issued: 12/14/1999
• Est. Priority Date: 01/06/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Mastenbrook, Gary E.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): Lo, Linus H.
• Application Number:
  US08/778,992
• Time in Patent Office: 1,072 Days
• Field of Search: 348/6, 348/7, 348/1, 348/13, 348/180, 348/192, 348/193, 455/3.1, 455/6.1, 455/4.2, 455/5.1
• 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 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence
• CPC Class Codes: H04N 7/165 Centralised control of user terminal subsequent to an upstream request signal H04N7/17345; Registering at central by two-way working H04N7/17309

Abstract

A cable access unit (CAU) (60) capable of monitoring power levels for a plurality of channels couples a television (80) and communication equipment (70) to an operations and maintenance center (OMC) (20). At some determined interval, the OMC (20) determines the need to measure the television signal at some particular subscriber'"'"'s location and sends a message to the CAU (60). The CAU (60) determines if the communications equipment is in use. If not, the CAU receiver is tuned to the channel, and samples and digitizes the power level. The digitized power level is assembled into a message packet and transmitted to the OMC (20).

Claims

1. In a cable television (CATV) network having a two-way hybrid fiber coaxial (HFC) cable for upstream and downstream communications where a CAU (cable access unit) located at a subscriber location, having a CAU receiver, is coupled to an OMC (operations and maintenance center) remotely located from the subscriber location, and where the CAU is in communication with the OMC by way of the CATV network and upstream communication equipment is coupled to the OMC by way of the CAU, a method of monitoring a power level of a cable television signal comprising the steps of:

at the CAU;

receiving an downstream message across the two-way HFC cable to perform a power level test;

determining that the upstream communication equipment is asleep; and

when the upstream communication equipment is asleep;

tuning the CAU receiver to a channel;

sampling and digitizing the power level of the cable television signal within the channel to create a digitized power level; and

transmitting the digitized power level to the OMC upstream across the two-way HFC cable; and

at the OMC;

comparing the digitized power level with a previously stored digitized power level; and

determining a quality of the of the cable television signal based on the step of comparing.

2. The method of claim 1 further comprising the step of assembling the digitized power level into a packet.

3. The method of claim 2 further comprising the step of decoding the packet at the OMC.

4. The method of claim 3 further comprising the step of, at the OMC, storing the digitized power level.

5. The method of claim 4 further comprising the step of, at the OMC, generating an alarm signal if the difference between the digitized power level and the previously stored digitized power level exceeds a threshold.

6. The method of claim 1 where the step of tuning the CAU receiver to a channel includes the step of retrieving a test channel from a memory.

7. The method of claim 1 where the step of tuning the CAU receiver to a channel includes the step of retrieving a test channel from the message.

8. The method of claim 1 including the step of generating, by the OMC, a power level test message.

9. In a cable television network having a two-way hybrid fiber coaxial (HFC) cable for upstream and downstream communications where a CAU (cable access unit) located at a subscriber location, having a CAU receiver, is coupled to an OMC (operations and maintenance center) remotely located from the subscriber location, and where the CAU is in communication with the OMC by way of the CATV network and upstream communication equipment is coupled to the OMC by way of the CAU, a method of monitoring a power level of a cable television signal comprising the steps of:

at the CAU;

receiving a downstream message across the two-way HFC cable to perform a power level test;

determining that the upstream communication equipment is asleep; and

when the upstream communication equipment is asleep;

tuning the CAU receiver to a channel;

sampling and digitizing the power level of the cable television signal within the channel in order to create a digitized power level;

assembling the digitized power level into a packet; and

transmitting the packet upstream across the two-way HFC cable to the OMC;

at the OMC;

decoding the packet;

storing the digitized power level;

comparing the digitized power level with a previously stored digitized power level; and

generating an alarm signal if the difference between the digitized power level and the previously stored digitized power level exceeds a threshold.