This application provides a data sending method and apparatus. The method includes: A node generates a first modulation symbol corresponding to a first modulation scheme. The node quantizes the first modulation symbol to obtain a target symbol. The target symbol corresponds to one of a plurality of constellation points of a second modulation scheme. The node preprocesses the target symbol to obtain to-be-sent data. The preprocessing includes one or more of layer mapping, antenna port mapping, precoding, or transform precoding. The node maps the to-be-sent data to a physical resource, and sends the to-be-sent data by using the physical resource.

A serial receiver combines continuous-time equalization, analog interleaving, and discrete-time gain for rapid, efficient data reception and quantization of a serial, continuous-time signal. A continuous-time equalizer equalizes a received signal. A number N of time-interleaved analog samplers sample the equalized continuous-time signal to provide N streams of analog samples transitioning at rate reduced by 1/N relative to the received signal. A set of N discrete-time variable-gain amplifiers amplify respective streams of analog samples. A quantizer then quantizes the amplified streams of analog samples to produce a digital signal.

A repeater includes a reception unit, a permission signal generating unit that detects the state of the pulses of the signal, and generates a permission signal that permits a relay of the signal when the permission signal generating unit detects the pulses, and that inhibits the relay of the signal when the permission signal generating unit detects an end of the pulses, and a transmission unit. When detecting the end of the pulses, for the permission signal, the permission signal generating unit sets a pulse re-input monitoring period for determining whether or not the pulses of the signal are re-detected. When detecting the pulses of the signal during the pulse re-input monitoring period, the permission signal generating unit determines that the signal continues, and when not detecting the pulses of the signal, the permission signal generating units determines that the signal ends.

A synchronous communication interface includes at least one data channel configured to carry a data signal comprising a plurality of data units; a control channel parallel to the at least one data channel, the control channel configured to carry a control signal for the at least one data channel; and a circuit configured to generate the control signal that includes control information that defines each of the plurality of data units in each data signal and further includes additional information. The circuit is configured to vary a duty cycle of the control signal according to a mapping of the additional information to a plurality of discrete duty cycle states.

A multi-PAM equalizer receives an input signal distorted by inter-symbol interference (ISI) and expressing a series of symbols each representing one of four pulse amplitudes to convey two binary bits of data per symbol. High-order circuitry resolves the most-significant bit (MSB) of each two-bit symbol, whereas low-order circuitry 115 resolves the immediate least-significant bit (LSB). The MSB is used without the LSB for timing recovery and to calculate tap values for both MSB and LSB evaluation.

A test system can use first and different second driver stages to provide test signals to a device under test (DUT). A compound stage can receive signals from the driver stages and provide a voltage output signal to the DUT, such as via a gain circuit. The compound stage can include a buffer circuit configured to provide a first portion of the voltage output signal based on a first output signal from the first driver stage, and the compound stage can include a transimpedance circuit configured to provide a second portion of the voltage output signal based on a second output signal from the second driver stage. In an example, the gain circuit can receive a superposition signal comprising the first and second portions of the voltage output signal and, in response, provide a test signal to the DUT.

Encoding PAM4 or PAM8 symbols to have a power spectral density (PSD) similar to the PSD of a standard 8b10b Non-Return-to-Zero stream. In one embodiment, a transmitter includes first and second 8b10b encoders that receive first and second streams split from an original byte stream. The first and second 8b10b encoders output first and second 8b10b streams, respectively. The first and second 8b10b streams are fed into a 2-bit combiner that performs a linear combination of the first and second 8b10b streams. And a 4-level Pulse Amplitude Modulation encoder (PAM4 encoder) converts the linear combination of each two bits, received from the combiner, into a PAM4 symbol. Wherein the resulting stream of PAM4 symbols has PSD similar to the PSD of the standard 8b10b non-return-to-zero stream.

Embodiments are disclosed for a lookup table-based coding mechanism for communication systems. An example method includes receiving a signal to be transmitted, converting the signal into a converted analog signal using a digital to analog converter, receiving channel state information for a channel, calibrating the lookup table based on the channel state information, utilizing the calibrated lookup table to generate a coded analog signal based on the converted signal, and transmitting the coded analog signal, wherein the coded signal compensates for channel distortion of the channel.

In a system for calibrating PAM4 signals, an equalizer determines a first signal amplitude measurement of the PAM4 signal. The equalizer determines a first signal boost measurement of the PAM4 signal. The equalizer determines whether the first signal boost measurement and the signal amplitude measurement are substantially consistent with each other. Responsive to determining that the signal boost and the signal amplitude are not substantially consistent with each other, the equalizer determines a reference amplification modification and calibrates a PAM4 signal according to the determined reference amplification modification.

A method, system, and apparatus for calculating coefficients for inputs and corresponding output sequences for a pulse-position modulation encoder using a stored structure; wherein the structure is a subset of the values of Pascal's Triangle.