A demodulation system for demodulating an input signal is provided. The input signal includes a carrier wave modulated with data symbols selected from a plurality of candidate complex symbol values. The system includes a carrier recovery module, operative to compensate for a carrier frequency of the carrier wave and output a demodulated data signal. The carrier recovery module includes: a first complex-signal conversion module, operative to convert the input signal into a complex-valued input signal; a voltage-controlled oscillator; a mixer, for mixing the complex-valued input signal and a complex-valued output signal of the voltage-controlled oscillator, and generating a mixer output signal; a low-pass filter, coupled to the mixer, operative to filter the carrier frequency from the mixer output signal, and output a signal corresponding to the demodulated data signal; and a folding module, operative to apply a folding algorithm to the output signal of the low-pass filter.

Methods and apparatus for phased-based pre-carrier signal detection in a communication system are described. In embodiments, inphase and quadrature (IQ) data is generated from a received signal. A current phase delta value is determined from the IQ data and combined with existing phase delta value, such as an averaged phase delta value, which is compared with a threshold value to determine if a pre-carrier signal in the received signal has ended.

A synchronized I/Q detection circuit is provided. A first subset of input signals and, subsequently, a second subset of input signals are provided by a first multiplexer and received by a first phase detector. Outputs of the first phase detector are receiving, by a first reset and sampling circuit. A second set of input signals are provided by a second multiplexer and received by a second phase detector, from a second multiplexer, while the first multiplexer receives the first and second subsets of input signals. The first subset of input signals has a same phase order as the second set of input signals, and the second subset of input signals has a different phase order than the second set of input signals. Outputs of the second phase detector are received by a second reset and sampling circuit. A comparator outputs a detected phase difference based on the outputs of the first and second reset and sampling circuits.

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.

Methods and apparatus for phased-based pre-carrier signal detection in a communication system are described. In embodiments, inphase and quadrature (IQ) data is generated from a received signal. A current phase delta value is determined from the IQ data and combined with existing phase delta value, such as an averaged phase delta value, which is compared with a threshold value to determine if a pre-carrier signal in the received signal has ended.

A demodulation system for demodulating an input signal is provided. The input signal includes a carrier wave modulated with data symbols selected from a plurality of candidate complex symbol values. The system includes a carrier recovery module, operative to compensate for a carrier frequency of the carrier wave and output a demodulated data signal. The carrier recovery module includes: a first complex-signal conversion module, operative to convert the input signal into a complex-valued input signal; a voltage-controlled oscillator; a mixer, for mixing the complex-valued input signal and a complex-valued output signal of the voltage-controlled oscillator, and generating a mixer output signal; a low-pass filter, coupled to the mixer, operative to filter the carrier frequency from the mixer output signal, and output a signal corresponding to the demodulated data signal; and a folding module, operative to apply a folding algorithm to the output signal of the low-pass filter.

A system and a method that enable two or more dispersed platforms to simultaneously use respective frequency-modulated continuous-wave radar systems in a typical radar application such as synthetic-aperture radar for terrain mapping, moving-target indicator radar to track targets on the ground and air-to-air tracking of other aircraft. The systems use the same RF spectrum in their operation and also communicate through their respective radar systems while simultaneously reducing their interplatform interference through the use of both filters and coded waveforms.

An apparatus and a method for synchronizing a Digital Frequency Shift (DFS) for a signal to be transmitted over a wireless channel are disclosed. For example, the method, by a synchronizer, transmits a DFS trigger to a Digital Front End (DFE) processor and a Local Oscillator (LO) trigger to an LO in a synchronous manner, the method, by the DFE processor, applies a DFS on received data in response to receiving the DFS trigger, the method, by the LO, applies a complementary shift on a carrier signal in response to receiving the LO trigger, the method, by the upconverter, digital-to-analog converts and radio frequency modulates the digital frequency-shifted received data and the complementary-shifted carrier signal. In another example, the method, by the synchronizer, transmits a phase error to a phase error corrector that performs a phase error correction.

A synchronized I/Q detection circuit is provided. A first subset of input signals and, subsequently, a second subset of input signals are provided by a first multiplexer and received by a first phase detector. Outputs of the first phase detector are receiving, by a first reset and sampling circuit. A second set of input signals are provided by a second multiplexer and received by a second phase detector, from a second multiplexer, while the first multiplexer receives the first and second subsets of input signals. The first subset of input signals has a same phase order as the second set of input signals, and the second subset of input signals has a different phase order than the second set of input signals. Outputs of the second phase detector are received by a second reset and sampling circuit. A comparator outputs a detected phase difference based on the outputs of the first and second reset and sampling circuits.

A carrier recovery system for a receiver of a phase-modulated signal N-PSK, the system including a first pre-conditioning circuit of the signal received (S(t)), with the pre-conditioned signal (SP(t)) having a component, non-modulated in phase, at the frequency N.sub.c where .sub.c is the carrier used for the modulation N-PSK, and a carrier regeneration circuit to regenerate two sinusoidal signals in quadrature at the frequency .sub.c, with these signals being phase locked with respect to said non-modulated component in phase of the pre-conditioned signal.