A method for operating a radio frequency communications system includes, while operating a first radio frequency communications device in a calibration mode, for each setting of a plurality of settings of a programmable gain amplifier in a receiver of the first radio frequency communications device configured in a zero-intermediate frequency mode of operation, generating an estimate of a DC offset in each of a plurality of digital samples received from an analog circuit path including the programmable gain amplifier, and storing in a corresponding storage element, a compensation value based on the estimate.

A system includes a data carrier drive apparatus and a data carrier apparatus. The data carrier apparatus includes a unit to output transmission data during a first state and adjustment data during a second state, and a current changer configured to change a current value of a current flowing from the data carrier drive apparatus to the data carrier apparatus according to data values of the transmission data and the adjustment data. The data carrier drive apparatus includes a detector to detect a detection value corresponding to the current value of the current, a determiner to determine the data value of the transmission data by comparing the detection value with a threshold value during the first state, and an updater to update the threshold value based on the detection value during the second state.

A method and system for performing quadrature amplitude modulation (QAM) decoding of a received signal includes finding for each layer a region in a first constellation diagram of the received signal, the region including a portion of the first constellation diagram, the portion having the same size of a second constellation diagram, and a first constellation order of the received signal is higher than a second constellation order of the second constellation diagram; and, for each layer: finding a first portion of bits based on bits that are constant among constellation points located in the region of the layer; decoding the received signal using a QAM decoder having the second constellation order to obtain a second portion of bits; adjusting the second portion of bits based on the region of the layer; and merging the first portion of bits with the second portion of bits to obtain a decoded symbol.

A driver circuit of a PAM-N transmitting device transmits a PAM-N signal via a communication channel, wherein N is greater than 2, and the PAM-N signal has N signal levels corresponding to N symbols. A PAM-N receiving device receives the PAM-N signal. The PAM-N receiving device generates distortion information indicative of a level of distortion corresponding to inequalities, in voltage differences between the N signal levels. The PAM-N receiving device transmits to the PAM-N transmitting device the distortion information indicative of the level of the distortion. The PAM-N transmitting device receives the distortion information. The PAM-N transmitting device adjusts one or more drive strength parameters of the driver circuit of the PAM-N transmitting device based on the distortion information.

A baud-rate phase detector uses two error samplers. One error sampler is used to determine whether the sampling time is too early error detection. The other is used to determine whether sampling time is too late. The early error sampler is configured to use a first threshold voltage. The late error sampler is configured to use a second threshold voltage. By adjusting the voltage difference between the first threshold voltage and the second threshold voltage, the phase difference between the local timing reference clock and the transitions of the data signal may be adjusted. The phase difference between the local timing reference clock and the transitions of the data signal may be adjusted to improve or optimize a desired receiver characteristic such as bit error rate or signal eye opening.

Methods, systems, and apparatus for error correction are provided. In one aspect, an error correction method includes: obtaining an output signal and an amplitude value of a feed forward equalizer (FFE), the amplitude value being a channel response amplitude value corresponding to an equivalent channel of the FFE, performing level decision on the output signal based on the amplitude value to obtain a first decision signal including (2M−1) decision symbols, M being an integer not less than 2, performing (1/(1+D)) decoding on the first decision signal to obtain a first decoded signal, determining a second decision signal based on the first decoded signal, the second decision signal including (M−1) decision symbols, determining that a burst error occurs in the second decision signal if an absolute value of the second decision signal is greater than (M−1), and correcting the burst error in the second decision signal.

An error detection and correction device includes a decision-feedback equalizer (DFE), a decision circuit, an error detection circuit, and an error correction circuit. The DFE equalizes a data signal to generate a first equalized signal. The decision circuit performs hard decision upon the first equalized signal to generate a symbol decision signal. The error detection circuit performs forward error detection at symbol positions of consecutive symbols included in the symbol decision signal to detect a head position of suspicious error that affects at least one symbol in the symbol decision signal. The error correction circuit performs error correction upon the symbol decision signal in response to the head position of the suspicious error that is detected by the error detection circuit.

A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.

This disclosure provides systems, methods and apparatuses for wireless communications. In some implementations, a first wireless communication device associated with a basic service set (BSS) receives a plurality of packets transmitted during a measurement window by a second wireless communication device associated with the BSS. The first wireless communication device determines a received signal strength indicator (RSSI) value of the plurality of received packets, determines a level of overlapping basic service set (OBSS) interference on the wireless medium during the measurement window, and adjusts one or more of a packet detect (PD) threshold, an OBSS PD threshold, or an energy detect (ED) threshold based on the determined RSSI value and the level of OBSS interference.

Systems and methods for enabling pre-compensation of timing offsets in OFDM receivers without invalidating channel estimates are described. Timing offset estimations may be sent along with the received OFDM symbols for FFT computation and generating a de-rotated signal output. The timing offset estimation may provide a reference point for dynamic tracking of timing for an OFDM signal and estimated based on an integral value associated with the OFDM signal.