Legerity, Inc.

Zarlink Semiconductor Limited

Jin Li

Yan Zhou

Vijayakumaran Velayudhan Nair

Merle L Miller

A method and apparatus is provided for DC feed control for a line card. The method includes determining if the line card is operating in a current limit region of a DC feed curve and synthesizing a curve in the current limit region. The method further includes determining a loop voltage based on the synthesized curve, and applying the loop voltage to the subscriber line. The apparatus includes logic capable of determining if the line card is operating in a current limit region of a DC feed curve and capable of determining a loop voltage based on a synthesized curve in the current limit region. The apparatus further includes circuitry for applying the loop voltage to the subscriber line.

Method and apparatus for DC feed

A method and apparatus is provided. The method includes transmitting a signal having an AC component to a subscriber line and receiving at least a portion of the transmitted signal from the subscriber line. The method includes determining at least a portion of a period of the AC component of the received signal, and performing a function of a line card in response to determining at least the portion of the period of the AC component. The apparatus includes circuitry that is capable of transmitting a signal having at least one of an AC component and a DC component to a subscriber line, and receiving at least a portion of the transmitted signal from the subscriber line. The apparatus includes a filter and computation logic. The filter is capable of filtering the DC component from the received signal. The computation logic is capable of determining a value proportional to a power of the AC component of the received signal over at least a portion of a period of the AC component. The apparatus further includes logic capable of performing a function of a line card in response to determining the value proportional to the power of the AC component.

Method and apparatus for detecting line card threshold

A method and apparatus is provided for DC level control in a line card. The method includes receiving a digital input signal, determining a first DC component value of the digital input signal at a first preselected time, and determining a second DC component value of the digital input signal at a second preselected time. The method further includes determining a difference between the first DC component value and the second DC component value. The method includes providing the first DC component value to a digital-to-analog converter in response to determining that the difference is less than a first preselected value. The apparatus includes a digital-to-analog converter and logic. The logic is coupled to the digital-to-analog converter, wherein the logic is capable of receiving a digital input signal, determining a first DC component value of the digital input signal at a first preselected time, and determining a second DC component value of the digital input signal at a second preselected time. The logic is farther capable of determining a difference between the first DC component value and the second DC component value, and providing the first DC component value to the digital-to-analog converter in response to determining that the difference is less than a first preselected value.

Method and apparatus for adaptive DC level control

A method and apparatus is provided reducing false switch hook detection in a line card coupled to a subscriber loop. The method comprises operating in a first state of the line card, receiving a control signal, and disabling switch hook detection in the line card. The method further comprises determining an initial condition of a second state of the line card, operating in the second state of the line card in response to receiving the control signal, wherein the second state begins to operate from the determined initial condition. The switch hook detection in the line card is activated.

Method and apparatus for reducing false hook detection

A method and apparatus is provided. The method includes receiving a signal over a connection from a telephonic device, determining if the signal is greater than a first preselected value, and adjusting a transient response time of a host transceiver configured to receive the signal in response to determining that the signal is greater than the first preselected value. The method further includes determining a switch hook state of the telephonic device based on a DC component of the signal. The apparatus includes first logic capable of receiving a signal over a connection from a telephonic device, second logic capable of determining if the signal is greater than a first preselected value, and third logic configured to receive the signal, the third logic being capable of adjusting a transient response of the apparatus configured to receive the signal in response to determining that the signal is greater than the first preselected value. The apparatus further includes fourth logic capable of determining a switch hook state of the telephonic based on a DC component of the signal.

Method and apparatus for switch hook detection

A signal detector includes a transform unit and a post processing test unit. The transform unit is adapted to a transform unit adapted to receive at least first and second frames of input samples, determine a first plurality of energy values for the first frame based on a first set of transform coefficients, and determine a second plurality of energy values for the second frame based on a second set of transform coefficients. The post processing test unit is adapted to identify at least one target frequency based on the first plurality of energy values. The second set of transform coefficients is based on the target frequency, and the post processing unit is adapted to determine the presence of a first signal in the input samples based on the second plurality of energy values. A method for detecting a signal is provided. A first frame of input samples is received. A first set of transform coefficients is determined based on a first plurality of frequencies. A first plurality of energy values is determined based on the first set of transform coefficients. A target frequency is determined from the first plurality of frequencies based on the first plurality of energy values. A second set of transform coefficients is determined based on the target frequency. A second frame of input samples is received. A second plurality of energy values is determined based on the second set of transform coefficients. The presence of the signal in the input samples is determined based on the second plurality of energy values.

Signal detector with coefficient swapping transform unit

A signal detector for detecting at least a first signal having a first frequency and a first minimum duration is provided. The signal detector includes a matched transform unit and an energy level detection unit. The matched transform unit is adapted to receive at least a first frame of time domain input samples at a sampling frequency and generate at least a first frequency energy value for the first frame based on at least a first subset of the time domain input samples. The first subset of the first frame has a width of less than about one half of the first minimum duration. The energy level threshold unit is adapted to compare the first frequency energy value to a threshold energy value to determine the presence of the first signal. A method for detecting at least a first signal having a first frequency and a first minimum duration is provided. The method includes receiving at least a first frame of time domain input samples at a sampling frequency. At least a first frequency energy value is generated for the first frame based on at least a first subset of the time domain input samples. The first subset of the first frame has a width of less than about one half of the first minimum duration. The first frequency energy value is compared to a threshold energy value to determine the presence of the first signal.

Signal detector with duration-based frame width

A signal detector includes a transform unit, a gain control unit, and an energy level threshold unit. The transform unit is adapted to receive a plurality of input samples and calculate a first plurality of delay values based on the input samples. Each delay value is based on at least one previous delay value and a current input sample. The transform unit is adapted to calculate a first energy value based on at least a subset of the first plurality of delay values. The gain control unit is adapted to determine if a selected delay value of the first plurality of delay values exceeds a predetermined threshold and scale the selected delay value, the at least one previous delay value used to calculate the selected delay value, and subsequent input samples received after the current input sample by a first amount in response to the selected delay value exceeding the predetermined threshold. The energy level threshold unit is adapted to determine the presence of a first signal in the input samples based on the first energy level.

Signal detector with automatic gain control

A signal detector for detecting at least a first signal having a first frequency includes a matched transform unit and an energy level threshold unit. The matched transform unit is adapted to receive at least a first frame of time domain input samples at a sampling frequency and generate at least a first frequency energy value for the first frame based on at least a first subset of the time domain input samples and a first matched filter coefficient. The sampling frequency is a non-integral multiple of the first frequency, and the first matched filter coefficient depends on the first frequency. The energy level threshold unit is adapted to compare the first frequency energy value to a threshold energy value to determine the presence of the first signal. A method for detecting at least a first signal having a first frequency is provided. The method includes receiving at least a first frame of time domain input samples at a sampling frequency. At least a first frequency energy value for the first frame is generated based on at least a first subset of the time domain input samples and a first matched filter coefficient. The sampling frequency is a non-integral multiple of the first frequency, and the first matched filter coefficient depends on the first frequency. The first frequency energy value is compared to a threshold energy value to determine the presence of the first signal.

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Austin, TX, United States of America

Jin Li