Abstract: Known sequences are detected and identified in a fast fading environment using a segmented correlator and FHT (Fast Hadamard Transform) architecture. The incoming sequence of samples or data is segmented into blocks. Each block is individually detected using a correlator/FHT segment. Each sequence identifying output of each correlator/FHT segment is summed with the corresponding output of other correlator/FHT segments. Each sum is compared with a threshold to determine whether a particular sequence has been detected and identified.

Abstract: A power line adaptive noise cancellation system receives noise signals from house power lines and adaptively cancels the received noise from a power line input signal. The system includes a power line input signal receiver, at least one power line noise signal receiver and an adaptive noise cancellation device. The input signal and the noise signals are bandpassed filtered and demodulated by a local oscillator to generate baseband signals for both the input signal as well as the noise signals. The noise signals are input into adaptive filters that filter the noise signal based on a set of adaptive weights. The output of the adaptive filters are subtracted from a delayed baseband input signal to generate a received input signal. The received input signal is also fed back to the adaptive filters for updating adaptive weights of the adaptive filters.

Abstract: Two duplex channels are provided using only three lines, two power lines and one neutral line. The transmitter/receiver of each duplex channel includes adaptive filters to cancel cross-coupling introduced by the common neutral line. Each channel is coupled to a power line using a hybrid line driver/receiver device. The hybrid line driver/receiver device includes an echo canceller and a bridge circuit to allow transmitting and receiving signals to and from a single power line with minimized echoing effects. The signal-to-noise ratios of each duplex channel is significantly increased so that two duplex channels may be implemented using only three wire connections. Thus, the communication capacity of power line communication systems is greatly increased compared to that for a single 2-wire channel.

Abstract: A ground voltage reduction device is connected between a neutral reference node and a ground node defined by two bypass capacitors of a blocking circuit. The ground voltage reduction device senses the voltage difference between the neutral reference node and the ground node and drives the ground node to reduce the voltage difference between a voltage of the ground node and a voltage of the neutral reference node.

Abstract: An impedance regulator system and method which offers a large effective high-frequency block to isolate RF signals transmitted on power lines is presented. High-current inductors in series are inductively coupled over the RF band to physically smaller, low-current coupling inductors. The coupling inductors induce a degenerative or canceling at RF frequencies in the high-current inductors, resulting in the effective inductor increase and hence higher impedance over the RF band.

Abstract: A telecommunications network service overcomes the annoying effects of transmitted noise by a signal processing which filters out the noise using interactive estimations of a linear predictive coding speech model. The speech model filter uses an accurate updated estimate of the current noise power spectral density, based upon incoming signal frame samples which are determined by a voice activity detector to be noise-only frames. A novel method of calculating the incoming signal using the linear predictive coding model provides for making intraframe iterations of the present frame based upon a selected number of recent past frames and up to two future frames. The processing is effective notwithstanding that the noise signal is not ascertainable from its source.

Abstract: A telecommunications network service overcomes the annoying effects of transmitted noise by a signal processing which filters out the noise using interactive estimations of a linear predictive coating speech model. The speech model filter uses an accurate updated estimate of the current noise power spectral density, based upon incoming signal frame samples which are determined by a voice activity detector to be noise-only frames. A novel method of calculating the incoming signal using the linear predictive coating model provides for making intraframe iterations of the present frame based upon a selected number of recent past frames and up to two future frames. The processing is effective notwithstanding that the noise signal is not ascertainable from its source.

Abstract: A telecommunications network service overcomes the annoying effects of transmitted noise by signal processing which filters out the noise using a model-based iterative signal estimator. The estimator is provided with a current estimate of the noise power spectral density, using signal frame samples determined by a voice activity detector to be noise-only frames. The signal estimator makes intra-frame iterations of the current frame while using smoothing across LSP parameters of adjacent frames, recent past frames, and up to two contiguous future frames. Non-stationary noise created by the iterative filtering is further reduced in one or more post-filtering stages that use knowledge of the nature of the low level non-stationary noise events.