A data communication method in which input digital data is received and encoded into an encoded waveform having zero crossings representative of the input digital data. The encoding includes generating the encoded waveform based upon a continuous piecewise function having sinusoidal components. The continuous piecewise function may be used in generating a plurality of symbol waveforms, each of which occupies a period of the encoded waveform and represents bits of the input digital data. The plurality of symbol waveforms are defined so that a value of a phase offset used in the continuous piecewise function is different for each of the plurality of symbol waveforms, thereby resulting in each symbol waveform having a different zero crossing. An encoded analog waveform is generated from a representation of the encoded waveform and transmitted to a receiver.

A data communication method in which input digital data is received and encoded into an encoded waveform having zero crossings representative of the input digital data. The encoding includes generating the encoded waveform based upon a continuous piecewise function having sinusoidal components. The continuous piecewise function may be used in generating a plurality of symbol waveforms, each of which occupies a period of the encoded waveform and represents bits of the input digital data. The plurality of symbol waveforms are defined so that a value of a phase offset used in the continuous piecewise function is different for each of the plurality of symbol waveforms, thereby resulting in each symbol waveform having a different zero crossing. An encoded analog waveform is generated from a representation of the encoded waveform and transmitted to a receiver.

In one embodiment, an apparatus includes a bi-directional coupler for coupling an upstream signal and a downstream signal to a termination load. A test point detection mechanism is configured to detect when a test point device is inserted in a test point connector. The test point device is configured to perform a test of the upstream signal or the downstream signal. A switch is configured to switch from being coupled to the termination load to being coupled to the test point device when the test point device is detected as being inserted in the test point connector. The switch is configured to switch from being coupled to being coupled to the test point device to the termination load when the test point device is detected as being removed from being inserted in the test point connector.

In an embodiment, a method includes: receiving an audio frame; decomposing the received audio frame into M sub-band pulse-code modulation (PCM) audio frames, where M is a positive integer number; predicting a PCM sample of one sub-band PCM audio frame of the M sub-band PCM audio frames; comparing the predicted PCM sample with a corresponding received PCM sample to generate a prediction error sample; comparing an instantaneous absolute value of the prediction error sample with a threshold; and replacing the corresponding received PCM sample with a value based on the predicted PCM sample when the instantaneous absolute value of the prediction error sample is greater than the threshold.

A level shift circuit lowers a voltage of a first differential signal by a second voltage value and outputs a lowered first differential signal as a second differential signal. A first differential circuit receives the first differential signal and outputs a third differential signal. A second emitter follower circuit receives the third differential signal at a base of a pair of second transistors. A second differential circuit receives the second differential signal at a base of a pair of third transistors. An output terminal is electrically connected to one of a first output node electrically connected to an emitter of the one of the second transistors and a collector of the one of the third transistors and a second output node electrically connected to an emitter of the another of the second transistors and a collector of the another of the third transistors and outputs a driving signal.

A level shift circuit lowers a voltage of a first differential signal by a second voltage value and outputs a lowered first differential signal as a second differential signal. A first differential circuit receives the first differential signal and outputs a third differential signal. A second emitter follower circuit receives the third differential signal at a base of a pair of second transistors. A second differential circuit receives the second differential signal at a base of a pair of third transistors. An output terminal is electrically connected to one of a first output node electrically connected to an emitter of the one of the second transistors and a collector of the one of the third transistors and a second output node electrically connected to an emitter of the another of the second transistors and a collector of the another of the third transistors and outputs a driving signal.

A system and method for encoding multi-bit features into sinusoidal waveforms at selected phase angles. The method includes receiving input digital data and encoding the input digital data in a sinusoidal waveform by modulating the sinusoidal waveform at selected phase angles within a period of the sinusoidal waveform, thereby creating a modulated sinusoidal waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the modulated sinusoidal waveform. The modulating includes forming a first data notch at a first phase angle of the selected phase angles wherein the first data notch includes a first plurality of transition features and subtends a first phase angle range about the first phase angle, the first plurality of transition features being representative of a first plurality of bit values included within the input digital data.

A system and method for encoding multi-bit features into sinusoidal waveforms at selected phase angles. The method includes receiving input digital data and encoding the input digital data in a sinusoidal waveform by modulating the sinusoidal waveform at selected phase angles within a period of the sinusoidal waveform, thereby creating a modulated sinusoidal waveform. An encoded analog waveform is generated, using a digital-to-analog converter, from a digital representation of the modulated sinusoidal waveform. The modulating includes forming a first data notch at a first phase angle of the selected phase angles wherein the first data notch includes a first plurality of transition features and subtends a first phase angle range about the first phase angle, the first plurality of transition features being representative of a first plurality of bit values included within the input digital data.

An apparatus for generating an output signal, may comprise a signal path having an analog signal path portion having an analog magnitude droop, a digital signal path portion having a digital magnitude droop, a digital-to-analog converter for converting the digital input signal into the analog signal, a first digital compensation filter that compensates for the analog magnitude droop, and a second digital compensation filter that compensates for the digital magnitude droop, such that the first digital compensation filter and the second digital compensation filter together compensate for magnitude droop of the signal path to ensure a substantially flat passband response of the signal path. An apparatus may include a delta-sigma modulator for quantization noise shaping of a digital signal, a digital-to-analog converter configured to generate an analog signal from the digital signal, and an amplifier configured to amplify the analog signal and powered from a charge pump, wherein the charge pump is configured to operate at a switching frequency approximately equal to a zero of a modulator noise transfer function of the delta-sigma modulator, such that the impact of charge pump noise on a total harmonic distortion noise of the apparatus is minimized.

A multi-carrier data communications system and method having high spectral efficiency. The method includes encoding input digital data at selected phase angles of a plurality of sinusoidal waveforms to create a plurality of modulated sinusoidal waveforms. An output analog waveform is generated where the output analog waveform includes a plurality of encoded analog communication signals corresponding to a plurality of digital representations of the plurality of modulated sinusoidal waveforms. The encoding is performed so that adjacent ones of the plurality of modulated sinusoidal waveforms are separated in frequency by less than 15 Hz and any sideband included within the output analog waveform is of a power at least 50 dB below a power of the encoded analog communication signal associated with the sideband.