Abstract: A probing signal transmitted on a twisted pair telephone line in a DSL system is reflected and received at a DSL device. An estimate of one of a DSL data transmission signal or DSL synch symbol transmission signal is removed from the received probing signal to recover the reflected probing signal. The recovered reflected probing signal is processed to determine characteristics information of the twisted pair telephone line.

Abstract: A probing signal transmitted on a twisted pair telephone line in a DSL system is reflected and received at a DSL device. An estimate of one of a DSL data transmission signal or DSL synch symbol transmission signal is removed from the received probing signal to recover the reflected probing signal. The recovered reflected probing signal is processed to determine characteristics information of the twisted pair telephone line.

Abstract: A probing signal transmitted on a twisted pair telephone line in a DSL system is reflected and received at a DSL device. An estimate of one of a DSL data transmission signal or DSL synch symbol transmission signal is removed from the received probing signal to recover the reflected probing signal. The recovered reflected probing signal is processed to determine characteristics information of the twisted pair telephone line.

Abstract: A probing signal transmitted on a twisted pair telephone line in a DSL system is reflected and received at a DSL device. An estimate of one of a DSL data transmission signal or DSL synch symbol transmission signal is removed from the received probing signal to recover the reflected probing signal. The recovered reflected probing signal is processed to determine characteristics information of the twisted pair telephone line.

Abstract: A receiver or receiver system for high speed data communications having a radio frequency noise canceller is disclosed. The radio frequency noise canceller removes radio-frequency noise from received signals over a transmission medium by adaptively estimating the radio-frequency noise during data transmission. In one embodiment, the radio frequency noise canceller includes: an adaptive filter for producing a noise cancellation signal by filtering a reference noise signal based on filter parameters, a subtractor for subtracting the noise cancellation signal from the first signal to produce the second signal; and an update circuit for enabling, at predetermined times, modification of the parameters of the adaptive filter based on the then existing second signal. A method for removing radio frequency noise is also disclosed.

Abstract: A method and apparatus for transmitting digital sound is disclosed. The method contemplates transmitting a digital radio signal (such as an FM band signal) over a plurality of sub-channels subject to some constraints on the digital signal power. A control sub-channel, sometimes referred to as an auxiliary overhead channel is used to transmit control information which is interpreted by the receiver to identify the location and potentially the mode of the digital signals.

Abstract: A high speed modem system which utilizes multiple carriers to successively transmit frames containing data such that the frames are transmitted so that the level of the signal is minimized, and is preferably zero, at the borders between individual frames thus, reducing or eliminating interframe discontinuities and the accompanying distortion and interframe interference. The modem system includes a circuit to successively combine together the modulated carrier signals of each set to produce a frame waveform which includes an inphase signal and a quadrature signal for each carrier signal as is known in the art. The components of the inphase signal and the quadrature signal are grouped to form an I odd/Q even group and an I even/Q odd group. In order to restore the missing components in the I odd/Q even group, the I odd and the Q even components are duplicated and combined with the I odd/Q even group.

Abstract: A system and method for reducing echoes on a duplex communication channel having both transmitted and received signals carried thereon, particularly a telephone channel having digital data transmitted thereon by way of a modem. The transmitted signal is converted from a time domain signal to a frequency domain transmitted signal by a fast fourier transform process. The frequency domain transmitted signal is multiplied by a set of filter coefficients to generate estimated echo coefficients. The estimated echo coefficients are converted from the frequency domain to the time domain by an inverse fast fourier transform process and then subtracted from the received signal to generate a residual echo signal. The residual echo signal is converted to a frequency domain residual echo signal by a fast fourier transform process and then multiplied by the complex conjugate of the frequency domain transmitted signal to generate correlation frequency components.