Detecting signal leakage in cable networks
AssigneeViavi Solutions Inc.
InventorsAl RUTH, Rodney Harbison Weaver, Koji Okamoto
Life of this patent
Estimating the term…
Abstract
A signal leakage in a cable network may be detected by using a test device to obtain a spectrum of an electromagnetic wave propagating in vicinity of the cable network, and automatically detecting QAM channels in the obtained spectrum by detecting characteristic spectral roll-offs at boundary frequencies between QAM channels of the cable network. A test device may be used to determine which QAM channels are currently active on the cable network, thereby facilitating automatic QAM signal leakage detection.
Claims21
1-21. (canceled)
A testing device for detecting a quadrature amplitude modulated (QAM) channel signal leaking at a first location of a cable network, which propagates QAM channel signals at a QAM channel frequency spacing, the testing device comprising:
- memory to store high and low boundary frequencies of a QAM channel of the QAM channel signal;
- a receiver to detect an electromagnetic signal propagating in air proximate the first location;
- a controller operably coupled to the memory and the receiver, wherein the controller is to:
- determine power present in the electromagnetic signal as a function of frequency for a frequency band comprising the high and low boundary frequencies of the QAM channel;
- and
- detect the QAM channel signal in the electromagnetic signal based on a change in the determined power present at the high and low boundary frequencies of the QAM channel compared to the determined power present in between the high and low boundary frequencies of the QAM channel in the electromagnetic signal;
- and
- an output device to provide an indication of the detected QAM channel signal.
A method of detecting a QAM channel signal leaking at a first location of a cable network, which propagates QAM channel signals frequency-separated at a QAM channel frequency spacing, the method comprising:
- obtaining high and low boundary frequencies of a QAM channel of the QAM channel signal;
- detecting an electromagnetic signal propagating in air proximate the first location, and obtaining a power present in the electromagnetic signal as a function of frequency of the electromagnetic signal in a frequency band comprising the high and low boundary frequencies of the QAM channel;
- and
- determining that:
- a change in the obtained power present in the electromagnetic signal at the high and low boundary frequencies of the QAM channel is above a first threshold;
- and
- detecting that the QAM channel signal is leaking from the cable network.
A testing device for detecting a QAM channel signal leaking at a first location of a cable network, which propagates QAM channel signals at a QAM channel frequency spacing, the testing device comprising:
- memory to store center frequencies of two adjacent QAM channels;
- a receiver to detect an electromagnetic signal propagating in air proximate the first location;
- a controller operably coupled to the memory and the receiver and to detect the two adjacent QAM channel signals in the electromagnetic signal the controller is to:
- determine power present in the electromagnetic signal as a function of frequency for a frequency band comprising the center frequencies of the two adjacent QAM channels;
- and
- detect the QAM channel signal in the electromagnetic signal, based on a change in the determined power present at a middle point between the center frequencies of the two adjacent QAM channels;
- and
- an output device to provide an indication of the detected QAM channel signal.
Dependencies are inferred from the claim text.