A packet detection method is disclosed. The packet detection method includes the following operations: receiving a wireless communication signal; calculating a delay correlation function of the wireless communication signal; calculating a delay related output value and a threshold value according to the delay correlation function; and determining whether the wireless communication signal satisfies a feature of a wireless network packet or not according to the delay related output value and the threshold value.

The present disclosure provides a method for estimating a frequency offset, including: extracting sampling points from an input signal according to preset intervals to obtain a plurality of groups of sampling points, with the preset intervals of the groups of sampling points being different; performing processes on a current sampling point and the groups of sampling points to obtain data of arguments of complex numbers corresponding to the preset intervals; and determining an estimation value of a frequency offset of a current input signal according to the data of arguments of complex numbers corresponding to the preset intervals. The present disclosure further provides an apparatus for estimating a frequency offset, an electronic device and a computer-readable medium.

Various examples of methods and systems are provided for vibrational frequency detection (e.g., noncontact vital sign detection) using digitally assisted low intermediate frequency (IF) architectures. In one example, a transceiver system is configured to transmit a modulated signal generated by modulating a local oscillator (LO) signal with an IF carrier; generate an IF signal by down converting a received signal comprising backscatter with the LO signal; and simultaneously sample the IF carrier and the IF signal. A vibration frequency can be determined by demodulating the sampled IF signal with the sampled IF carrier. In another example, a method includes generating and transmitting a modulated signal; receiving backscatter of the modulated signal; generating an IF signal by down converting the received signal with the LO signal; simultaneously sampling the IF carrier and the IF signal; and determining a vibration frequency by demodulating the sampled IF signal with the sampled IF carrier.

A sampling phase difference compensation apparatus includes a signal generator, a signal analyzer and a compensator. The signal generator generates a first signal and a second signal, and outputs the first and second signals to a first path in a first time interval and a second path in a second time interval, respectively. The signal analyzer receives a transmitted first signal from the first path and a transmitted second signal from the second path, and performs a predetermined calculation on the transmitted first and second signals to determine a phase difference relationship, which is associated with a frequency-dependent phase difference and a sampling phase difference, between the transmitted first and second signals. The transmitted first signal is associated with the first signal, and the transmitted second signal is associated with the second signal. The compensator performs a phase difference compensation according to the phase difference relationship.

A novel quadrature phase-shift keying (QPSK) demodulator, called the bowknot quadrature phase-shift keying (BQPSK) demodulator, is disclosed. The BQPSK demodulator uses a delay circuit to delay a BQPSK signal and mixes the delayed BQPSK signal with the undelayed BQPSK signal to output an I-channel data signal and a Q-channel data signal. The BQPSK demodulator further uses a phase rotation circuit to demodulate the orthogonal data signals and obtain a recovery clock signal. The BQPSK demodulator neither uses an A/D converter nor uses a quadrature oscillator, featuring high data rate, low power consumption, simple architecture and superior reliability. The BQPSK demodulator can be realized by digital circuits and analog circuits.

A receiver receives binary information from a transmission using a binary amplitude shift keying where information symbols are represented by a signal including a first power state and a second power state. A duration of a bit includes a first part where the second power state is applied irrespective of which binary value is represented, and a second part where a binary value is represented by any of the first power and a third power state or a combination pattern of the first power state and the third power state. A sampling circuit is arranged to retrieve samples of the received signal during the second part and discard samples during the first part. A duration of the retrieving of samples is selected to be a time corresponding to the duration of the second part plus a time based on an expected synchronization error.

A system and method for data communication using amplitude-encoded sinusoids. The method includes encoding the input digital data using a plurality of symbol waveforms where each of the plurality of symbol waveforms occupies a period of a composite encoded waveform and represents at least one bit of the input digital data. A first symbol waveform of the plurality of symbol waveforms is defined by a sinusoid of a first amplitude and a second symbol waveform is defined by a sinusoid of a second amplitude different from the first amplitude. The method includes generating an encoded analog waveform from a representation of the composite encoded waveform.

A system of measuring and correcting for distortions in homodyne systems and a method for operating a data processing system to provide an estimate of distortions in homodyne systems are disclosed. The method for operating a data processing system to provide an estimate of a distortion introduced by a homodyne system when the homodyne system processes a time a multi-tone time domain input signal, x(t), to obtain a time domain output signal, y(t) includes receiving a frequency spectrum, X(f), of the multi-tone time domain input signal, x(t) and measuring an output frequency spectrum, Y(f), when the homodyne system operates on x(t). A plurality of parameters of a model that represents a linear frequency response of the homodyne system when operating on X(f) to arrive at Y(f) by fitting the model to Y(f) and X(f) is determined, and the model is applied to X(f) and Y(f) to estimate the distortions.

A packet detection method is disclosed. The packet detection method includes the following operations: receiving a wireless communication signal; calculating a delay correlation function of the wireless communication signal; calculating a delay related output value and a threshold value according to the delay correlation function; and determining whether the wireless communication signal satisfies a feature of a wireless network packet or not according to the delay related output value and the threshold value.

A method of transporting digital data in an active distributed antenna system DAS. The method includes receiving data from at least one data source, processing the received data, and providing the processed data as digital real-valued passband data for further transport within the DAS. An apparatus and computer program configured to perform the method are also provided.