A method and an apparatus for transmitting a wakeup packet in a wireless LAN system are proposed. Particularly, a transmission device configures a wakeup packet and transmits the wakeup packet to a receiving device. The wakeup packet includes a sequence configured with first information and second information by applying an OOK method. The first information and the second information are configured with an on-signal or an off-signal. The on-signal is transmitted through a first symbol, which is generated by applying a first sequence to K consecutive subcarriers in the 20 MHz band and performing 64-point IFFT. The off-signal is transmitted through a second symbol, which is generated by applying a second sequence to K consecutive subcarriers in the 20 MHz band and performing 64-point IFNT. The first information and the second information are transmitted through a third symbol in which the first symbol or the second symbol is repeated.

A wireless communications system configured to perform wireless communication by using a first band dedicated to the system and a second band shared by the system and another wireless communications system, the system including: a base station configured to transmit in the first band to the terminal, a control signal permitting data transmission in the second band from a terminal to the base station; and the terminal configured to detect an available carrier wave of the second band after a predetermined time from the transmission of the control signal by the base station, the terminal performing the data transmission after waiting until detection of the available carrier wave.

This disclosure relates to data converters for electronic systems. An example system includes a primary analog to digital converter (ADC) circuit, a slope calculation circuit, a digital phase lock loop (DPLL) circuit, a sampling error circuit, and a summing circuit. The primary ADC circuit samples an input signal and produces a digital output signal representative of the input signal. The slope calculation circuit generates a digital slope signal representative of slope of the input signal, and the DPLL circuit provides a sampling clock signal to the primary ADC circuit. The sampling error circuit generates a sampling error signal representative of sampling error by the primary ADC circuit using the digital slope signal and the sampling clock signal. The summing circuit receives the sampling error signal and the digital output signal of the primary ADC circuit and generates an adjusted digital output signal representative of the input signal.

A digital television (DTV) receiving system includes an information detector, a resampler, a timing recovery unit, and a carrier recovery unit. The information detector detects a known data sequence which is periodically inserted in a digital television (DTV) signal received from a DTV transmitting system. The resampler resamples the DTV signal at a predetermined resampling rate. The timing recovery unit performs timing recovery on the DTV signal by detecting a timing error from the resampled DTV signal using the detected known data sequence. The carrier recovery unit performs carrier recovery on the resampled DTV signal by estimating a frequency offset value of the resampled DTV signal using the detected known data sequence.

The present disclosure discloses a method of transmitting a signal, a wearable communication device and a terminal device. The method includes: receiving, by a wearable communication device, a modulated wave signal transmitted by a terminal device; demodulating the modulated wave signal to obtain a to-be-decoded signal; performing a waveform shaping process on the to-be-decoded signal to obtain a square wave signal, where a high level in the square wave signal is configured to represent a first preset value, and a time interval is existed between two high levels corresponding to any two adjacent first preset values; acquiring time interval eigenvalues in the square wave signal; acquiring a one-to-one mapping relation of the interval eigenvalues and a plurality of coding sequences; and performing, according to the time interval eigenvalues and the mapping relation, a first decoding process and a second decoding process on the square wave signal to obtain original data.

A backscatter tag communicate device includes, in part, a receiver configured to receive a WiFi packet conforming to a communication protocol defining a multitude of codewords, a mapper configured to map at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol, and a frequency shifter configured to shift a frequency of the second multitude of codewords such that the frequency shifted codewords are characterized by a single sideband spectrum. The communication protocol may be the 802.11b communication protocol. The mapper may optionally map the first subset of the multitude of codewords by changing phases of the first subset of the multitude of codewords.

A circuit for demodulating an input signal is described. The circuit may be configured to demodulate signals modulated with amplitude-based modulation schemes, such as amplitude shift keying (ASK). The demodulator may comprise a clock extractor configured to generate a clock signal in response to receiving an amplitude-modulated input signal, a phase shifter configured to generate a sampling signal by phase-shifting the clock signal by approximately /2, and a sampler configured to sample the input signal in correspondence to one or more edges (such as one or more falling edges) of the sampling signal. In this way, the amplitude-modulated input signal may be sampled at its peak, or at least near its peak, thus ensuring high signal fidelity.

A digital television (DTV) receiving system includes an information detector, a resampler, a timing recovery unit, and a carrier recovery unit. The information detector detects a known data sequence which is periodically inserted in a digital television (DTV) signal received from a DTV transmitting system. The resampler resamples the DTV signal at a predetermined resampling rate. The timing recovery unit performs timing recovery on the DTV signal by detecting a timing error from the resampled DTV signal using the detected known data sequence. The carrier recovery unit performs carrier recovery on the resampled DTV signal by estimating a frequency offset value of the resampled DTV signal using the detected known data sequence.

A communication device of the disclosure includes a phase synchronizer, a first modulator, and a detector. The phase synchronizer generates a second signal on a basis of a first signal received from a communication partner. The first modulator is able to modulate the first signal on a basis of the second signal. The detector detects that synchronization between the first signal and the second signal is lost.

A digital television (DTV) receiving system includes an information detector, a resampler, a timing recovery unit, and a carrier recovery unit. The information detector detects a known data sequence which is periodically inserted in a digital television (DTV) signal received from a DTV transmitting system. The resampler resamples the DTV signal at a predetermined resampling rate. The timing recovery unit performs timing recovery on the DTV signal by detecting a timing error from the resampled DTV signal using the detected known data sequence. The carrier recovery unit performs carrier recovery on the resampled DTV signal by estimating a frequency offset value of the resampled DTV signal using the detected known data sequence.