Wavetek Corporation

Other

The University of British Columbia

Jds Uniphase Corporation

Acterna LLC

Wavetek Wandell Goltermann, Inc.

Pingnan Shi

Walter L Miller

Qin Zhang

Andrew E Bowyer

Gregory W Massey

Rabab K Ward

Adam A Nowotarski

Daniel Keith Chappell

Michael R Wright

Gerald K Rudolf

Reena Ramname

Kelly J Scorzato

Robert J McCammon

Julong Du

Michael J Vitale

Xiaoli Li

Qiaobing Xie

Walter Miller

The present invention provides a test device and a method enabling automatic detection of an imbalance in a power level of a channel. The test device includes a tuner, a power-level measurement system, and an evaluation unit. According to the method, a test channel is selected from a plurality of channels, by means of the tuner. A power level of the test channel and a total power level of the plurality of channels are measured, by means of the power-level measurement system. A ratio of the total power level of the plurality of channels to the power level of the test channel is then evaluated, by means of the evaluation unit, to detect an imbalance in a power level of the test channel.

Test device and method of detecting an imbalance in a power level of a channel

A method and apparatus are provided for testing susceptibility of a receiver to intermodulation distortion of a digital channel, the method including selecting a first digital channel from channels in a composite signal, determining a first power measurement from the first digital channel, determining a total power measurement from other channels in the composite signal, and determining susceptibility of the first digital channel to intermodulation distortion by comparing the first power measurement and the total power measurement with intermodulation distortion characteristics of the receiver.

CATV digital receiver intermodulation susceptibility tester

The present invention provides a test device and a method enabling automatic detection of an imbalance in a power level of a digital channel. The test device includes an attenuator, a tuner, a demodulator, and an evaluation unit. According to the method, a plurality of channels are attenuated at a plurality of attenuation levels, by means of the attenuator. A digital channel is selected from the plurality of channels, by means of the tuner. A modulation error ratio (MER) of the digital channel is measured at the plurality of attenuation levels, by means of the demodulator. A variation of the MER of the digital channel with attenuation level is then evaluated, by means of the evaluation unit, to detect an imbalance in a power level of the digital channel.

Test device and method of detecting an imbalance in a power level of a digital channel

The invention relates to a method for measuring Hum on a digital QAM carrier using a testing device for testing digital TV signals including a QAM demodulator therein, and to a testing device implementing the method. A micro-controller is used to sample a register associated with an AGC circuit in the QAM demodulator, and to process the collected register values to obtain one or more Hum characteristics.

Measuring Hum in a digital TV signal

The testing equipment of the present invention calculates a single 'AGC stress' value, which provides an indication of the stability of the level of a digital carrier based on the change in gain required to stabilize the power of an incoming cable signal over time. Ideally the AGC stress value is rated on a scale, e.g. 1 to 10 or 0 to 5, and is fed into the DQI measurement system as a new data model.

Automatic gain control stress measurement for digital carriers

A method of performing work on a communication system in accordance with a work assignment includes a step of identifying a data file associated with the work assignment, the data file including subscription information and network location information. The method also includes a step of preparing at least a first set of test parameters for performing a network test, the first set of parameters based on, at least in part, the subscription information and the network location information. The test parameters are then communicated to a test device. Thereafter, the test device performs a first test using the first set of test parameters.

Communication system work order performance method and system

A method of determining noise in a CATV channel, wherein the CATV channel comprises a predetermined frequency band, that employs digital signal processing to isolate the noise signal from an in-service television signal. The method includes an initial step of obtaining a television signal corresponding to a predetermined CATV channel, the television channel comprising a carrier signal modulated by an information signal. Thereafter, the method includes the step of sampling at least a part of the television signal to produce a digital signal segment, said digital signal segment comprising a carrier component, a noise signals component, and an information signal component, wherein said information signal component has a substantially predetermined signal pattern. The method then employs digital signal processing to separate the carrier component from the digital signal segment to produce a baseband signal substantially comprising the information signal and the noise signal. Finally, an estimate of the information signal is obtained and then subtracted from the baseband signal, thereby producing a noise signal estimate.

Noise measurement system

A method of transmitting a leakage tagging signal includes inserting a tagging signal into a CATV television signal only during portions of the television signal in which control information is present. A method according to the present invention is a method of transmitting a tagging signal in a communication system, the communication system transmitting television signals comprising control information and program information. One step of the method includes generating a tagging signal that is detectable by corresponding leakage detecting equipment. The method also includes the step of identifying a portion of a television signal in which control information is present. Finally, the method of the present invention encompasses inserting the tagging signal into the television signal only during the portion of the television signal in which control information is present.

Pulsed leakage tagging signal

Disclosed are method and apparatus which measure signal level of an RF signal. The measured RF signal includes a baseband signal modulated onto a first carrier signal having a first frequency and the baseband signal includes program information and control information. The method and apparatus digitize the RF signal which includes the baseband control information and determine a signal level measurement from the baseband control information in the digitized RF signal. Furthermore, method and apparatus are disclosed which determine from the digitized RF signal whether a tagging signal is present in the RF signal.

Method and apparatus for measuring a radio frequency signal having program information and control information

A method of reducing noise in video signal, by processing the pixels of a process frame of video signal in conjunction with a selected number of previously processed frames to determine values for target pixels in the process frame by applying a temporal motion detector to determine whether a target pixel has a still or motion status and further processing the pixels with motion status by impulse recognition step to further determine whether the pixel should be classified as having a still or a motion status. The pixels are then checked via a spatial motion detecting step to obtain a motion index value to the pixels and the motion index value is used in a motion adaptive temporal filter to define the pixel value of the still pixel. The motion index value of the pixels is used to set a dynamic threshold in a detailed motion active spatial filter to define the pixel value for the motion pixels. The system may be integrated with a converter box for converting digital signals to analog for use in conjunction with analog television sets services by digital signals.

Noise reduction for video signals

An RF circuit for use as a front end for a combined leakage signal detector and signal level monitor includes a shared frequency conversion stage utilized for both leakage signals and signal level monitoring ('SLM') signals. One embodiment of the present invention includes an RF circuit comprising a first RF input, a second RF input, a frequency conversion circuit and a coupling device. The first RF input is operable to receive first signals to be monitored, the first signals being in a first frequency range. The second RF input is operable to receive leakage signals to be detected, the leakage signals also being in a first frequency range. The frequency conversion circuit is operable to convert signals in the first frequency range to signals in a second frequency range, the frequency conversion circuit operable to receive unconverted first signals and unconverted leakage signals and produce output signals therefrom. The output signals produced by the frequency conversion stage have a frequency in the second frequency range. The coupling device alternately connects the first RF input to the frequency conversion circuit and the second RF input to the frequency conversion circuit. The output signal may then be provided to a suitable measurement circuit that performs leakage signal detection or signal level monitoring using known methods.

RF circuit for use in a combined leakage detector and signal level

The system for reducing composite beat, composite second order beat and thermal (snow) noise impairments in a television system digitizes individual frames to apply digitized a grey scale values (v.sub.(i,j)) to the pixels in the frames and then applying a spatial filter to a block of pixels including the then current pixel being processed to determine the pixel (P.sub.(min)) with the minimum grey scale value (v.sub.(min)) and the pixel (P.sub.(max)) in the block with the maximum grey scale value (v.sub.(min)). V.sub.(max) -v.sub.min is compared with a threshold value (v.sub.(T)) and if v.sub.(max) -v.sub.min) &gt;v.sub.(T), the value (v.sub.(i,j)) of the pixel being processed remains unchanged, but if v.sub.(max)-v.sub.(min).notgreaterthan.v.sub.(T), a value (v.sub.(av.)) equal to the weighted average value of pixels in the block is used as the grey scale value v.sub.(R-i,j) for the pixel being processed. The block preferably, will be composed of a number of adjacent pixels in a row or a number of adjacent pixels in a column or both processed simultaneously or preferably in sequence i.e. the pixels processed along the rows and then along the columns with the values assigned to the pixels when processing along the rows used as the initial values for the pixels when processing along the columns. In more preferred cases, a plurality of frames are each subject to static filtering and then the adjacent frames in the sequence are subject to time filtering (provided motion is not detected) to provide a better average value vZ.sub.(mean) for the processed pixel in the specific frame being processed.

System for reducing beat type impairments in a TV signal

A method for reducing the effect of a composite triple beat (CTB) of a visual image is obtained by digitizing the signal for the image frame, dividing the digital signal into a plurality of stripes extending perpendicular to the horizontal lines of the image to form subpictures and determining the average intensity of the signal in each of the horizontal lines of each of the subpictures. An average value for each of the lines in each of the subpictures is then obtained and the component of the signal forming the composite triple beat signal for each line of each subpicture is estimated. Then the estimated triple beat signal is subtracted from its corresponding portion of the digitized signal to provide corrected subpictures. The corrected subpictures are then recombined to form a clean signal providing the cleaned visual image. In a preferred arrangement plurality of consecutive frames are treated as above described to provide average corrections for each line based on the average for the corresponding lines in the subpictures in the plurality of frames and then the subpictures for the frame to be shown next are corrected using the average corrections values to provide an even clearer signal.

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Indianapolis, IN, United States of America

Pingnan Shi