Abstract: The disclosure is generally directed to an improved structure for a decimation filter. More specifically, the disclosure includes a method and apparatus for decimating an oversampled signal at the input, which is the output of an oversampling analog-to-digital converter. In accordance with one aspect of the system, an apparatus is provided for decimating an oversampled signal. The apparatus includes at least one non-recursive decimator. Specifically, the at least one non-recursive decimator is configured to receive the oversampled input signal defined by a first sampling frequency. This at least one non-recursive decimator is further configured to generate a output having a second sampling frequency. The apparatus further includes a recursive decimator. The recursive decimator is configured to receive the output of the at least one non-recursive decimator and generate an output having third sampling frequency.

Abstract: An improvement to a Reed Solomon (RS) coding scheme wherein the RS encoder and decoder is initiated based upon counting a number of timing, baud, or byte cycles from a known time stamp. The time stamp can be for example, a Tomlinson coefficient exchange frame whereby at the end of a Tomlinson coefficient exchange frame, a counter in both transmitter and receiver is actuated to begin counting a number of baud cycles. Alternatively, the counter may be initiated upon the receipt of a particular byte. Once the appropriate number of baud cycles or bytes have elapsed, the RS encoder and decoder will begin operation, thus ensuring that both RS encoding and decoding occur at the proper time, without the use of any additional framing bits.

Abstract: The present invention is generally directed to an xDSL modem that is capable of transmitting at multiple data rates. Specifically, the xDSL modem is configured to generally transmit at a high data rate (typically the highest data rate supported by the line), but will reduce its data transmission rate in response to one or more sensed conditions. In this regard, it has been found that transmitting at a data rate that is low enough to avoid significant corruption, and thus retransmission, achieves a higher overall data transmission rate than that which is achieved if re-transmissions are required. Further, various conditions may be sensed that will prompt the xDSL modem to alter its transmission rate, including detecting an unfiltered POTS device going Off-Hook. In accordance with one aspect of the present invention, at modem startup, the Off-Hook condition and other line problems are detected by direct measurement of the line impedance.

Abstract: A system and method for force-starting a voltage and current controlled element is disclosed. In a simplified embodiment, a power source is coupled to the controlled element via a start-up circuit. The start-up circuit supplies a current, or voltage, to the controlled element, responsive to the voltage or current level at a specified node being below a threshold level. Preferably, two diode-connected devices may be utilized, thereby providing current forcing capability when the voltage level at the specified node is below a threshold voltage level, as specified by the diode-connected devices.

Abstract: In general, the reference voltage stabilizer provides a system and method of stabilizing a reference voltage regardless of the sampling rate of a sample data system. An amplifier is utilized to amplify the reference voltage so as to maintain voltage level by stabilizing and isolating the initial reference voltage. A programmable current is utilized to modify the amplified reference voltage, thereby compensating for adjustment in current level of the reference voltage caused by system sampling. The programmable current may also be utilized to compensate for reference voltage errors occurring before amplification, by adding an intentional offset between required sink and source currents, and the current supplied by the programmable current.

Abstract: A system and method for a communication to communicate both POTS and XDSL are provided. In accordance with one aspect of the invention, in improved central office line card circuit is provided, wherein the line card circuit includes a two-wire signal line for electrical connection with a two-wire local loop. A line interface card interfaces with the local loop and includes a bi-directional line for bi-directional communication with the signal line. In addition, the line interface circuit further has an input line and an output line. A first channel has an output electrically connected to the input line of the line interface circuit, and the first channel has inputs for both a pulse code modulation (PCM) input and a xDSL input. Similarly, a second channel has an input that is electrically connected to the output line of the line interface circuit. In addition, the second channel has outputs for both a PCM output and a xDSL output.

Abstract: A current mirror utilizes an operational amplifier to provide linear operation over a wide output voltage range. The current mirror includes input transconductance, output transconductance, input cascode and output cascode devices. The operational amplifier has two inputs, one of which is coupled to a node between the output transistors, and the other of which is coupled to a node between the input transistors. The output of the amplifier is used to drive the control terminal of the input cascode device so that the operating voltage of the input transconductance device will be approximately equal to that of the output transconductance device.

Abstract: An apparatus is provided for concatenating Reed-Solomon and trellis encoders. Preferably, the apparatus includes an input for receiving a plurality of information bits. The plurality of information bits are divided or defined to comprise a first portion and a second portion. A Reed-Solomon encoder is disposed to receive the second portion of input bits and generate a first encoded output. A trellis encoder disposed to receive the output of the Reed-Solomon encoder and configured to generate a second encoded output. Finally, a mapper is disposed to receiver the bits output from the trellis encoder as well as the first portion of input bits.