Abstract: A method of detecting a digital leakage signal originating from a leak in a coaxial cable portion of an HFC network. The network has a transmission end from which a digital signal is transmitted to the coaxial cable portion. The digital signal is emitted into free space from the leak to produce the leakage signal. The method comprises: (a) producing a first set of samples representing the digital signal; (b) transmitting the first set of samples to a leakage detector; (c) moving the leakage detector to a detection point in the vicinity of the network; (d) receiving the leakage signal from the leak; (e) sampling the leakage signal to produce a second set of samples; and (f) performing a cross-correlation of the first set of samples with the second set of samples, to produce a cross-correlation function having a peak, whereby the leakage signal is detected from the peak.

Abstract: A leak defined by coordinates is located in a network. A signal emitted from the leak is detected at first, second and third points having first, second and third sets of coordinates, respectively. Propagation delays t1, t2 and t3 of the signal are measured, which include the propagation delays between the leak and the first, second and third points, respectively. The time difference ?t12 between delays t1 and t2 and the time difference ?t23 between delays t2 and t3 are calculated. The approximate location of the leak is determined by solving for the coordinates of the leak in at least two hyperbolic equations, where the equations are defined by the time differences ?t12 and ?t23, and by the first, second and third sets of coordinates.

Abstract: A handheld leakage detector for finding digital signal leaks in a HFC network, comprises a radio receiver, a leakage receiver, leakage sampler, a correlator, and a display. The radio receiver receives samples of the digital signal taken from the HFC network, called “reference samples.” The leakage receiver receives a leakage signal, which is a leaked version of the digital signal from the HFC network. The leakage sampler samples the leakage signal to form leakage samples. The correlator performs a cross-correlation of the reference samples and the leakage samples, to produce a correlation function. An optimizable value is determined from the correlation function. The value generally becomes more optimized as the detector approaches the leak. The leak is sought by iteratively changing the position of the detector until the value becomes substantially optimized or the leak is found.

Abstract: A handheld leakage detector for finding digital QAM signal leaks in a HFC network, comprises a radio receiver, a leakage receiver, leakage sampler, a correlator, and a display. The radio receiver receives samples of the QAM signal taken from the HFC network, called “reference samples.” The leakage receiver receives a QAM leakage signal, which is related to the QAM signal from the HFC network. The leakage sampler samples the leakage signal to form leakage samples. The correlator performs a coherent cross-correlation of the reference samples and the leakage samples, to produce a correlation peak. A value is determined from the correlation peak and displayed on the display. The value generally becomes more optimized as the detector approaches the leak. The leak is sought by iteratively changing the position of the detector until the displayed value becomes substantially optimized or the leak is found.

Abstract: A handheld leakage detector for finding digital QAM signal leaks in a HFC network, comprises a radio receiver, a leakage receiver, leakage sampler, a correlator, and a display. The radio receiver receives samples of the QAM signal taken from the HFC network, called “reference samples.” The leakage receiver receives a QAM leakage signal, which is related to the QAM signal from the HFC network. The leakage sampler samples the leakage signal to form leakage samples. The correlator performs a coherent cross-correlation of the reference samples and the leakage samples, to produce a correlation peak. A value is determined from the correlation peak and displayed on the display. The value generally becomes more optimized as the detector approaches the leak. The leak is sought by iteratively changing the position of the detector until the displayed value becomes substantially optimized or the leak is found.

Abstract: A leak defined by coordinates is located in a network. A signal emitted from the leak is detected at first, second and third points having first, second and third sets of coordinates, respectively. Propagation delays t1, t2 and t3 of the signal are measured, which include the propagation delays between the leak and the first, second and third points, respectively. The time difference ?t12 between delays t1 and t2 and the time difference ?t23 between delays t2 and t3 are calculated. The approximate location of the leak is determined by solving for the coordinates of the leak in at least two hyperbolic equations, where the equations are defined by the time differences ?t12 and ?t23, and by the first, second and third sets of coordinates.

Abstract: A system for locating an impairment in a coaxial cable network comprises an encoder, an impairment detector, and a decoder. The encoder couples to the network at a predetermined encoding point, upstream of the impairment. The encoder automatically encodes an identification code on a signal originating downstream of the encoding point and associated with the impairment. The impairment detector couples to the network at an access point, upstream from the encoding point, and receives signals from the network. The detector is adapted to detect from the received signals the signal associated with the impairment and generate a detected version of the signal. The decoder is adapted to decode the identification code from the detected version of the impairment signal. Once the identification code is determined, the encoder and encoding point are identified, and the location of the impairment is determine to be downstream of the encoding point.

Abstract: A system for detecting and locating a digital TV leakage signal in an HFC network. The system comprises a headend unit and a leakage detector. The headend unit receives the TV signal at the headend for use as a reference signal. The reference signal is sampled at a rate corresponding to a time reference signal, to produce reference signal samples. The reference signal samples and timestamp are transmitted to the leakage detector. The detector receives the digital TV signal from a leakage source, for detection as a leakage signal. The detector includes a cross-correlation processor. The leakage signal is sampled at a rate corresponding to the time reference signal, to produce leakage signal samples. The cross-correlation processor performs a cross-correlation of the reference signal samples with the leakage signal samples to produce a cross-correlation function having a peak, and the TV leakage signal is detected from this peak.

Abstract: A step attenuator circuit is mounted on a printed circuit board and has a highpass filter network passing high frequency signals and a lowpass filter network passing low frequency signals. The lowpass network presents a high shunt reactance to the high frequency signals. The lowpass network includes an attenuator network. The attenuator network attenuates the low frequency signals by a specified amount. Parasitic capacitance exists between the highpass network and the attenuator network, causing an amount of electrical energy from the high frequency signals to be absorbed by the attenuator network. A first capacitive circuit is used to compensate for parasitic capacitance. The first compensation circuit is connected across the attenuator network and is coupled to the parasitic capacitance. Consequently, the amount of electrical energy from the high frequency signals absorbed by the attenuator network is reduced, and, as a result, the insertion loss of the step attenuator is reduced.

Abstract: A system for detecting and locating a digital TV leakage signal in an HFC network. The system comprises a headend unit and a leakage detector. The headend unit receives the TV signal at the headend for use as a reference signal. The reference signal is sampled at a rate corresponding to a time reference signal, to produce reference signal samples. The reference signal samples and timestamp are transmitted to the leakage detector. The detector receives the digital TV signal from a leakage source, for detection as a leakage signal. The detector includes a cross-correlation processor. The leakage signal is sampled at a rate corresponding to the time reference signal, to produce leakage signal samples. The cross-correlation processor performs a cross-correlation of the reference signal samples with the leakage signal samples to produce a cross-correlation function having a peak, and the TV leakage signal is detected from this peak.

Abstract: A system and method to range a distance to a source of CPD on a two-way cable system, comprises a fixed CW signal injected into a downstream signal path, a swept signal transmitted from a network analyzer, a mixer for generating an up-converted swept signal, and a source of CPD in the two-way cable system that mixes the fixed CW signal and the swept signal to create an upstream swept signal. The network analyzer receives the upstream swept signal and determines a complex frequency response created by the source of CPD. An impulse response is determined from the complex frequency response, and the distance to the source of CPD is determined from the impulse response.

Abstract: A system for pinpointing CDP sources in a two-way HFC CATV network comprises a headend CPD radar unit, a return path switch, and a computer. The radar unit is coupled to a headend combiner. The return path switch is coupled between the nodes of the CATV network and the radar unit. The computer is connected to the radar unit and the return path switch. The computer controls the radar unit and switch and causes them to perform constant sequential CPD monitoring of the nodes of the network. The system further comprises a portable radar-calibrator unit that is carried into the field and connected to various points along the coaxial cable portion of the network. The portable radar unit is used to detect CPD sources in the field and to calibrate the network as to time delay. The portable unit communicates with the headend radar unit through the CATV network.

Abstract: A system and method to range a distance to a source of CPD on a two-way cable system, comprises a fixed CW signal injected into a downstream signal path, a swept signal transmitted from a network analyzer, a mixer for generating an up-converted swept signal, and a source of CPD in the two-way cable system that mixes the fixed CW signal and the swept signal to create an upstream swept signal. The network analyzer receives the upstream swept signal and determines a complex frequency response created by the source of CPD. An impulse response is determined from the complex frequency response, and the distance to the source of CPD is determined from the impulse response.

Abstract: A system and method to range a distance to a source of CPD (Common Path Distortion) on a two-way cable system, comprising a local CPD source and a cross-correlator. The local CPD source generates a local distortion signal from a downstream signal, wherein the downstream signal includes multiple carriers of TV channels. The source of CPD in the cable system mixes the carriers of the TV channels to create an upstream actual distortion signal. The cross-correlator performs a cross-correlation between the local distortion signal and the upstream actual distortion signal to create a cross-correlation plot, and the distance to the source of CPD is determined from the round-trip time.