Abstract: A physical layer transceiver, configured for retrieving signal samples from a prescribed network medium having an undetermined length, includes a digital feedforward equalizer, configured for generating equalized signal samples from the retrieved signal samples and based on supplied equalizer settings, and an equalizer controller. The equalizer controller is configured for supplying selected equalizer settings that overcome intersymbol interference encountered by transmission of the signal samples across the prescribed network medium. The equalizer controller is configured for supplying prescribed initial equalizer settings to the digital feedforward equalizer, receiving equalized signal samples from the digital feedforward equalizer, and selectively changing the prescribed initial equalizer settings based on comparing the equalized signal samples to a prescribed equalization threshold.

Abstract: A network receiver is configured for receiving a modulated carrier signal from another network transceiver via a network medium, the modulated carrier signal may be either a pulse position modulated (PPM) carrier or a quadrature amplitude modulated (QAM) carrier. The network receiver is configured to select an optimal gain setting for the input amplifier corresponding to whether the modulated carrier is PPM or QAM.

Abstract: A pulse transmitter includes a phase correction module configured for detecting a phase error between a transmit clock and a prescribed clock specification at a transmit clock instance. The transmit clock instance represents an instance in time in which the pulse transmitter is to transmit data according to the prescribed clock specification. The pulse transmitter also includes pulse shape tables, each configured for outputting a corresponding waveform sample set of a prescribed waveform relative to a corresponding phase offset. Hence, the pulse transmitter is able to compensate for phase differences between the transmit clock utilized by the pulse transmitter and the prescribed clock specification, by outputting a selected waveform sample set that has a corresponding phase offset that compensates for the detected phase error, optimizing the performance of pulse position modulation communications systems that are adversely affected by transmit jitter.

Abstract: A network receiver is configured for receiving a modulated carrier signal representing a data frame from a network transmitter via a network medium, the receiver includes an adaptive equalizer with a finite impulse response filter for filtering the received signal. The filter utilizes a plurality filter coefficients. A cache stores a plurality of sets of coefficients for use by the filter and the equalizer selects a set of coefficients for receiving the data frame.

Abstract: A circuit for demodulating a modulated carrier includes a sampler receiving the modulated carrier signal and generating a digital carrier signal represented by a sequence of sample values in accordance with a clock signal at a first sampling frequency. A complex mixer frequency shifts the digital carrier signal by a frequency equal to one fourth the sampling frequency to generate a frequency shifted data signal with a sampling rate at the first sampling frequency. A decimation circuit generates four decimated signals from the frequency shifted signal, each at a decimated sampling rate. A resampling circuit generates a data signal at the decimated sampling rate and at a phase independent of the clock signal.

Abstract: A network receiver is configured for receiving a modulated carrier signal representing a data frame from another network transceiver via a network medium, the modulated carrier signal may be either a pulse position modulated (PPM) carrier, a quadrature amplitude modulated (QAM) carrier, or a compatibility mode frame including both PPM and QAM portions. The network receiver is configured to select an A/D sampling clock frequency corresponding to the detected frame type.

Abstract: A device for modulating a carrier signal comprises a mapper generating a baud rate data signal at a first data value frequency. A complex mixer and an upsampling device are used to increase the data value frequency and spectrum shift the data signal. A finite impulse response filter operating on the data signal to generate filtered first signal with characteristics that provide for reduced side band noise when the filtered signal is mixed to generate a quadrature amplitude modulated carrier.

Abstract: A network receiver is configured for receiving a base band carrier signal from another network transceiver via a network medium. A variable gain amplifier generates an amplified base band signal. An A/D converter generates a sequence of sample values representing the base band signal in response to the amplified base band signal. A gain control circuit monitors the sequence of sample values for a plurality of monitoring intervals in a sample time period, determines a range for each monitoring interval, and determines a gain setting for the variable gain amplifier.

Abstract: A method for demodulating a modulated carrier includes sampling the modulated carrier with an A/D converter clocking at a first sampling frequency to generate a modulated carrier series of samples occurring at the first sampling frequency. The first sampling frequency it selected to optimize a digital signal processor (DSP) design from demodulating a carrier modulated in accordance with a first transmission specification to recover base band data. The method includes generating a second series of samples occurring at a second sampling frequency representing the base band data. The second series of samples is calculated from the first series of samples and the second sampling frequency is selected to optimal a DSP design for recovering data from the base band data signal encoded in accordance with a second transmission specification.

Abstract: A system for detecting a pulse position is provided in a telephone wire network. An absolute value detector determines the absolute value of a received pulse signal supplied from a telephone wire, and produces a waveform envelope. A low-pass filter filters out high frequency components of the envelope. An integrator performs the time integration of the filtered envelope to produce an integrated waveform representing the energy of the received pulse signal. A slicing circuit determines when the integrated waveform crosses threshold level to detect the time position corresponding to the arrival time of the received pulse signal. The arrival time position is translated into a digital value representing data received form the telephone wire.