Abstract: An echo canceling system, method of attenuating echo, and a bit pump and transceiver employing the system and method. The echo canceling system is couplable between a transmit and receive path of the bit pump and receives and attenuates the echo in a receive signal propagating along the receive path. In one embodiment, the echo canceling system includes a slave echo canceling stage that employs a filter coefficient to attenuate the echo. The echo canceling system also includes a separation circuit, coupled to the slave echo canceling stage, that generates data representing a residual echo substantially exclusive of the receive signal. The echo canceling system still further includes a master echo canceling stage, coupled to the separation circuit, that receives the data and modifies the filter coefficient based thereon.

Abstract: A PSD template for an HDSL2 transmission system includes three regions, a full-duplex region for both upstream and downstream transmission, and two half-duplex regions, a first duplex region for containing substantially upstream power and a half-duplex region for containing substantially downstream power.

Abstract: An in-phase signal is sampled at an input of a first analog-to-digital converter (41), and a quadrature signal is sampled at an input of a second analog-to-digital converter (42). The output of the first analog-to-digital converter (41) is delayed by an amount equal to one, plus an integer number times four, sample periods to provide a delayed in-pahse signal. Then the delayed in-phase signal is added to the quadrature signal to provide a sum signal. Then a tone is detected in the sum signal. In one embodiment, a data processor (32) stores the output of the analog-to-digital converters (41, 42) in memory (34) and processes the data as programmed by microcode (33).

Abstract: A method of detecting a wideband tone, having a nominal frequency but occurring anywhere within a wide range of frequencies, includes a step of bandpass filtering input data. The bandpass-filtered data is used to predict a value of the input data using an algorithm such as least-mean-squares (LMS) adaptive linear prediction. An error signal is provided as a difference between the actual and predicted values of the input data. By computing the power in the error signal, the presence or absence of a tone can be detected, because a tone causes a smaller prediction error and power than other, non-tone processes such as white noise. A high-to-low transition in power represents a start of a tone, whereas a low-to-high transition in power represents an end of a tone. A tone flag signal is provided in response to a predetermined relationship between two power computations, such as a low-to-high transition.