A digital circuit in a baseband receiver to compensate for the IQ mismatch by aligning the amplitude of Ĩ with {tilde over (Q)} and by aligning the phase of {tilde over (Q)} to be 90 degrees away from Ĩ.

A digital receiver being adapted for receiving an MSK modulated signal, comprises a digital front-end unit (10) adapted for providing samples having a phase value (θ.sub.measure) of a down-mixed signal, a phase compensation unit (11) adapted for compensating the phase value (θ.sub.measure) by delivering a phase offset compensated sample having a phase value (θ.sub.sync), and a coherent demodulator (12) adapted for recovering information content from the phase offset compensated sample. The phase compensation unit (11) is adapted for analyzing a phase value (θ.sub.sync) of the phase offset compensated sample, calculating a phase offset value (θ.sub.offset) based on the phase value (θ.sub.sync) of the phase offset compensated sample, and applying the phase offset value (θ.sub.offset) when delivering a subsequent phase offset compensated sample.

A method of transmitting a Physical Layer Convergence Procedure (PLCP) frame in a Very High Throughput (VHT) Wireless Local Area Network (WLAN) system includes generating a MAC Protocol Data Unit (MPDU) to be transmitted to a destination station (STA), generating a PLCP Protocol Data Unit (PPDU) by adding a PLCP header, including an L-SIG field containing control information for a legacy STA and a VHT-SIG field containing control information for a VHT STA, to the MPDU, and transmitting the PPDU to the destination STA. A constellation applied to some of Orthogonal Frequency Division Multiplex (OFDM) symbols of the VHT-SIG field is obtained by rotating a constellation applied to an OFDM symbol of the L-SIG field.

A method for automatically detecting a packet mode in a wireless communication system supporting a multiple transmission mode includes: acquiring at least one of data rate information, packet length information and channel bandwidth information from a transmitted frame; and determining the packet mode on the basis of the phase rotation check result of a symbol transmitted after a signal field signal and at least one of the data rate information, the packet length information and the channel bandwidth information acquired from the transmitted frame.

A Radio Frequency (RF) receiver may include a lower-order phase shift keying (PSK) demodulation circuit configured to generate at least one locking parameter when performing a lower-order PSK demodulation of an RF receive signal having an interfering PSK signal component. A higher-order PSK demodulation circuit has a higher order than the lower-order PSK demodulation circuit, and locks to the RF receive signal using the at least one locking parameter from the lower-order PSK demodulation circuit. The higher-order PSK demodulation circuit performs the higher-order PSK demodulation of the RF receive signal based upon locking to the RF receive signal to determine the interfering PSK signal component.

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 Radio Frequency (RF) receiver may include a lower-order phase shift keying (PSK) demodulation circuit configured to generate at least one locking parameter when performing a lower-order PSK demodulation of an RF receive signal having an interfering PSK signal component. A higher-order PSK demodulation circuit has a higher order than the lower-order PSK demodulation circuit, and locks to the RF receive signal using the at least one locking parameter from the lower-order PSK demodulation circuit. The higher-order PSK demodulation circuit performs the higher-order PSK demodulation of the RF receive signal based upon locking to the RF receive signal to determine the interfering PSK signal component.

A system and method involve receiving, at a processor, a phase modulated signal such as an optical or electromagnetic signal, using one or more samples of an in-phase component I(t) and a quadrature component Q(t) of the received phase modulated signal to generate, at the processor, a processed signal using the equation [A−B×I(t)]×Q(t), where A and B are numerical parameters, and inputting the processed signal into a receiver operatively connected to the processor. The processed signal may be filtered prior to being input into the receiver. Parameters A and B may be selected to vary complexity and performance of the receiver while controlling distortion for different modulation indices.

Embodiments of the present invention provide a carrier synchronization method, circuit, and system. The method includes performing n times frequency multiplication on a received signal; performing narrowband filtering at least twice and rectangular wave shaping at least twice on the signal obtained after the n times frequency multiplication; and performing n times frequency division on the signal obtained after the filtering and shaping, to restore a carrier signal. The variable n is a positive integer greater than or equal to 4.

A method of transmitting a Physical Layer Convergence Procedure (PLCP) frame in a Very High Throughput (VHT) Wireless Local Area Network (WLAN) system includes generating a MAC Protocol Data Unit (MPDU) to be transmitted to a destination station (STA), generating a PLCP Protocol Data Unit (PPDU) by adding a PLCP header, including an L-SIG field containing control information for a legacy STA and a VHT-SIG field containing control information for a VHT STA, to the MPDU, and transmitting the PPDU to the destination STA. A constellation applied to some of Orthogonal Frequency Division Multiplex (OFDM) symbols of the VHT-SIG field is obtained by rotating a constellation applied to an OFDM symbol of the L-SIG field.