# US 2019/0174162 A1 · Interference profile of a bursty channel > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0174162 A1 - Document ID: US20190174162A1 - Status: Published application - Kind: A1 - Application number: 15/829,778 - Filed: 2017-12-01 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: Viavi Solutions Inc. - Applicants: Viavi Solutions Inc. - Inventors: Cinna SOLTANPUR; Vincent Michael Zipparo; Daniel Keith Chappell - Web page: https://patentgrep.com/patent/US20190174162A1 ## CPC - H04B 1/1027: {assessing signal quality or detecting noise/interference for the received signal} - H04B 10/2575: Radio-over-fibre, e.g. radio frequency signal modulated onto an optical carrier - H04B 10/25751: {Optical arrangements for CATV or video distribution (adaptations of television systems for optical transmission H04N7/22)} - H04N 21/2402: {Monitoring of the downstream path of the transmission network, e.g. bandwidth available (traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876)} - H04N 21/266: Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel - H04N 21/6118: {involving cable transmission, e.g. using a cable modem} - H04N 21/615: {Signal processing at physical level (signal processing in analog two-way television systems H04N7/173)} - H04N 21/6168: {involving cable transmission, e.g. using a cable modem} - H04B: TRANSMISSION - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A network test instrument is operable to generate an interference profile for a bursty channel of a cable television network. Frequency spectrum data of a received signal is cross-correlated with predetermined frequency spectrum data to identify traces representative of noise. The interference profile may be built from the traces. ## Claims ### Claim 1 A test instrument connectable to a cable television network to provide an interference profile of a bursty channel, the test instrument comprising: a port connectable to a test point in the cable television network, wherein the test point is located downstream from a headend in the cable television network; a processing circuit to: determine frequency spectrum data of a signal in the bursty channel that is received at the test instrument via the port; cross-correlate the frequency spectrum data with predetermined frequency spectrum data to generate cross-correlation values; determine the frequency spectrum data that represents noise based on a comparison of the cross-correlation values to a threshold; and generate the interference profile from the frequency spectrum data that represents the noise. ### Claim 2 (depends on 1) The test instrument of claim 1, wherein to determine frequency spectrum data of the signal received at the port, the processing circuit is to: convert the received signal to a digital signal; and calculate a Fast Fourier Transform (FFT) of the received signal for a discrete time window of finite length. ### Claim 3 (depends on 2) The test instrument of claim 2, wherein to cross-correlate the frequency spectrum data with predetermined frequency spectrum data, the processing circuit is to: cross-correlate the FFT for the window with the predetermined frequency spectrum data to determine a cross-correlation value for the window. ### Claim 4 (depends on 3) The test instrument of claim 3, wherein to determine the frequency spectrum data that represents noise, the processing circuit is to: compare the cross-correlation value for the window with the threshold; and determine whether the FFT for the window is representative of the noise or a signal transmitted in the bursty channel based on the comparison. ### Claim 5 (depends on 4) The test instrument of claim 4, wherein to generate an interference profile, the processing circuit is to: in response to determining the FFT for the window is representative of the noise, accumulate the FFT for the window with FFT for other windows that are determined to be representative of the noise; and generate the interference profile from the accumulated FFTs. ### Claim 6 (depends on 1) The test instrument of claim 1, wherein to generate an interference profile, the processing circuit is to: for the frequency spectrum data determined to be representative of the noise, aggregate frequency spectrum data for a plurality of overlapping time windows; subtract cyclostationary portions of the aggregated frequency spectrum data; filter outliers of the aggregated frequency spectrum data having the subtracted cyclostationary portions; and generate the interference profile from the filtered, aggregated frequency spectrum data. ### Claim 7 (depends on 1) The test instrument of claim 1, wherein to determine the frequency spectrum data that represents noise, the processing circuit is to normalize the cross-correlation values prior to comparing the comparing the cross-correlation values to the threshold. ### Claim 8 (depends on 1) The test instrument of claim 1, wherein the threshold is updated based on a signal level and a noise floor determined for signals received at the test point. ### Claim 9 (depends on 1) The test instrument of claim 1, comprising a display, wherein the processing circuit is to output the interference profile to the display. ### Claim 10 (depends on 1) The test instrument of claim 1, wherein the frequency spectrum data comprises FFT data. ### Claim 11 (depends on 1) The test instrument of claim 1, wherein the interference profile has a shape that is indicative of a source of signal interference in the bursty channel. ### Claim 12 A test instrument connectable to a bursty channel in a network, the test instrument comprising: a receiver circuit to receive a radio frequency signal from the bursty channel; an analog-to-digital converter to convert the received signal to a digital signal; a spectrum analyzer to determine a power spectral density of the digital signal in a frequency domain; and a processing circuit to: cross-correlate the power spectral density of the digital signal with predetermined frequency spectrum data to generate cross-correlation values; determine whether the cross-correlation values are each representative of noise in the bursty channel or a signal transmission in the bursty channel; and generate an interference profile of the bursty channel from traces associated with the cross-correlation values determined to be representative of the noise. ### Claim 13 (depends on 12) The test instrument of claim 12, wherein the traces associated with the correlation values determined to be representative of the noise comprise FFTs of the digital signal determined by the spectrum analyzer. ### Claim 14 (depends on 12) The test instrument of claim 12, wherein the processing circuit is to filter the traces with a median filter prior to generating the interference profile from the traces. ### Claim 15 (depends on 12) The test instrument of claim 12, wherein the cross-correlation values each comprise a cross-correlation of a power spectral density of the digital signal for a finite time window with a predetermined power spectral density. ### Claim 16 (depends on 12) The test instrument of claim 12, wherein to determine whether the cross-correlation values are each representative of noise in the bursty channel or a signal transmission in the bursty channel, the processing circuit is to: compare each cross-correlation value to a threshold; and determine, for each cross-correlation value, whether the cross-correlation value is associated with the noise or the signal transmission based on the comparison. ### Claim 17 (depends on 16) The test instrument of claim 16, wherein the processing circuit is to normalize the cross-correlation values prior to comparing the cross-correlation values to the threshold. ### Claim 18 (depends on 16) The test instrument of claim 16, wherein the threshold is updated based on a signal level and a noise floor determined for a signal received from the bursty channel. ### Claim 19 (depends on 12) The test instrument of claim 12, wherein for the cross-correlation values determined to be representative of the signal transmission in the bursty channel, the processing circuit is to determine at least one of a signal level and a signal-to-noise ratio from traces associated with the cross-correlation values determined to be representative of the signal transmission. ### Claim 20 A method executable by a test instrument to provide an interference profile of a channel, the method comprising: determining frequency spectrum data of a signal received from the channel; cross-correlating the frequency spectrum data with predetermined frequency spectrum data to generate cross-correlation values; comparing the cross-correlation values to a threshold to determine the frequency spectrum data that is representative of noise in the channel; generating an interference profile that is representative of the noise; and outputting the interference profile to a display of the test instrument.