Abstract: A telephone line interface or data access arrangement (DAA) is provided which draws power for the customer premises equipment from the telephone line. The DAA includes a shunt regulator as the power source drawing power from the telephone line, and a line modulator in series with the shunt regulator. A sense resistor is placed in series between the line modulator and shunt regulator to sense the line current. Accordingly, DC termination and AC modulation characteristics as presented by the DM to the telephone line can be adjusted by variation of an AC signal with DC offset input to the amplifier driving the line modulator without requiring a different DAA for use in regions or countries having various DC termination and AC modulation requirements. The differential feedback from a sense resistor reduces the noise induced in the circuit from the shunt regulator.

Abstract: A method and apparatus for controlling the DC line current on a telephone line and reducing the amount of error introduced to the system. The error is reduced by compensating for a DC error term introduced by an analog to digital converter having a DC offset. The DC offset is controlled digitally, allowing software to be used to limit the DC error in accordance with predefined parameters. Predefined parameters can be set to accommodate varying country specifications instead of using switches to control resistors and capacitors. In addition, changes in a country's requirements can be accomplished through software, instead of changing components or redesigning a circuit board. The use of software results in increased flexibility by allowing an infinite number of settings via software or software updates, allowing changes to be made quickly and easily throughout the world, and allowing error terms to be accommodated digitally.

Abstract: A telephone line interface or data access arrangement (DAA) is provided which draws power for the customer premises equipment from the telephone line. The DAA includes a shunt regulator as the power source drawing power from the telephone line, and a line modulator in series with the shunt regulator. A sense resistor is placed in series between the line modulator and shunt regulator to sense the line current. Accordingly, DC termination and AC modulation characteristics as presented by the DM to the telephone line can be adjusted by variation of an AC signal with DC offset input to the amplifier driving the line modulator without requiring a different DAA for use in regions or countries having various DC termination and AC modulation requirements. The differential feedback from a sense resistor reduces the noise induced in the circuit from the shunt regulator.

Abstract: A telephone line interface or data access arrangement (DAA) includes a shunt regulator in series with a line modulator. A sense resistor is placed in series between the shunt regulator and line modulator to provide a measurement of an amount of noise in the DAA shunt regulator, which is fed back to the line modulator. The line modulator is capable of adjusting the AC modulation and DC termination presented to the telephone line. The method includes drawing power from the telephone line using a shunt regulator, modulating the telephone line in series with the shunt regulator, sensing a level of noise in the shunt regulator, and feeding back the sensed level of noise to the line modulator.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: The number of separate signals necessary in a serial interface are reduced by combining a transmit data signal with a clock signal having a rate equal to a multiple of a bit rate of the transmit data signal, before encoding for transmission. The number of separate signals in a serial interface may be reduced further by sigma-delta (&Sgr;/&Dgr;) encoding the transmit data into 1-bit samples, thus eliminating the need for a frame sync signal. By combining the transmit data with a higher rate clock signal, jitter in the recovered clock signal at the receiving end is greatly reduced or even eliminated. At the receiving end, the higher speed clock is recovered at the multiplied rate, used to latch the transmit data from the combined data and higher clock signal, and divided back to the data rate to provide an original bit clock along with an original transmit data signal.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: A network interface circuit employing differentially driven capacitive couplings across a high voltage isolation boundary and in which a &Sgr;/&Dgr; CODEC is positioned on the line side of the high voltage interface. In this manner, only four wires cross the high voltage boundary, namely differential pairs for transmit data and receive data. The transfer functions for setting AC and DC parameters, such as impedance matching, are provided by digital filters. Further, with the CODEC on the line side of the high voltage isolation interface, the data which crosses the interface is modulated at the &Sgr;/&Dgr; data rate and, thus, capacitive coupling can be used across the high voltage isolation boundary without the loss of DC data.

Abstract: A method and apparatus to receive and demodulate call related information, e.g., Caller ID information, in an audio codec placed on the line side and powered by current drawn from the telephone line. The audio codec includes a 1st order &Sgr;/&Dgr; A/D converter to digitize the signal from the telephone line with &Sgr;/&Dgr; modulation. The 1st order &Sgr;/&Dgr; A/D converter may be a scaleable component capable of alternative operation in a 2nd order. The &Sgr;/&Dgr; encoded digitized signal is digitally processed by a DSP including an amplifier module, a digital filter, a limit/slice module, and an FSK decoder to receive and output the call related information. Placement of the audio codec on the line side and the scaleable &Sgr;/&Dgr; A/D converter provides significantly reduced power requirements for the audio codec, thus allowing operation from power derived from the telephone line.

Abstract: The present invention provides a method for interlocking a connector for a communication card including a first connection portion for connection to signals in the communication card relating to a first device such as a cellular telephone. A second connection portion in the interlocking connector provides for connection to signals in the communication card relating to a second device such as the PSTN. A blocking portion of the interlocking connector prevents electrical connection with the second connection portion and allows electrical connection with the first connection portion when the interlocking connector is connected to the communication card. A communication card is also provided which comprises modem circuitry, and an interface for connection between the modem circuitry and a computing device. A PSTN interface is provided for connection between the modem circuitry and a telephone line, and a cellular telephone interface is provided for connection between the modem circuitry and a cellular telephone.

Abstract: The present invention provides an interlocking connector for a communication card including a first connection portion for connection to signals in the communication card relating to a first device such as a cellular telephone. A second connection portion in the interlocking connector provides for connection to signals in the communication card relating to a second device such as the PSTN. A blocking portion of the interlocking connector prevents electrical connection with the second connection portion and allows electrical connection with the first connection portion when the interlocking connector is connected to the communication card. A communication card is also provided which comprises modem circuitry, and an interface for connection between the modem circuitry and a computing device. A PSTN interface is provided for connection between the modem circuitry and a telephone line, and a cellular telephone interface is provided for connection between the modem circuitry and a cellular telephone.