A receiver for cancelling strong signals from combined weak and strong signals includes: a first circuitry for inputting a weak and strong signal as an input; a parametric cancellation circuit for inputting a representation of the strong signal and an output of the first circuitry to produce a cancellation signal; a second circuitry electrically coupled to the parametric cancellation circuit for inputting the cancellation signal to produce a modulated output; a demodulator electronically coupled to the second circuitry for demodulating the modulated output to produce a demodulated output and an error signal, where the demodulated output is the data contained in the weak signal; and an adaptation logic circuit for inputting the representation of the strong signal, the demodulated output and the error signal to adaptively produce parameters for the parametric cancellation circuit. The parametric cancellation circuit further inputs the error signal and the parameters to produce the cancellation signal.

Techniques for differentiating orthogonally modulated symbols from different transmitters using one or more antenna arrays are described. According to some techniques, symbols received at one or more antenna arrays are grouped together by matching respective sets of receive beams for each symbol. In this manner, symbols received from a first transmitter at a first location can be differentiated from symbols received from a second transmitter at a second location, and both sets of symbols can be successfully decoded. When the symbols are received using frequency hopping, the receive beams for each symbol can be sorted according to path length, which improves performance, and also enables precise location of the transmitter(s).

An apparatus for communicating across an isolation barrier includes a differential pair of input terminals. The apparatus includes a bandpass filter circuit configured to receive a received signal on the differential pair of input terminals and to provide a received differential signal on a differential pair of nodes. The apparatus includes a demodulator directly coupled to the bandpass filter circuit and configured to directly demodulate the received differential signal on the differential pair of nodes to provide a demodulated received signal.

An apparatus for communicating across an isolation barrier includes a differential pair of input terminals. The apparatus includes a bandpass filter circuit configured to receive a received signal on the differential pair of input terminals and to provide a received differential signal on a differential pair of nodes. The apparatus includes a demodulator directly coupled to the bandpass filter circuit and configured to directly demodulate the received differential signal on the differential pair of nodes to provide a demodulated received signal.

A digital radio receiver is adapted to receive radio signals modulated using continuous phase modulation. The receiver includes components for receiving analogue radio signals having various carrier frequencies and a plurality of correlators corresponding to different bit sequences. Each of the plurality of correlators share a common estimator for estimating a frequency offset between the radio signals carrier frequencies and nominal carrier frequencies. The receiver further includes components allowing the estimator to determine which of the correlators produce the most optimal output signal.

The invention relates to a synchronous modulation system using amplitude modulation, which basically consists of a modulator and a demodulator able to transmit digital signals at double the frequency of its carrier wave. For this purpose, the system uses analog and digital circuits that combine to modulate, separately, the positive half and the negative half of the carrier sine wave, such that in a single cycle of the carrier wave, two different information bits can be sent. The demodulator-modulator unit can be easily combined with other units to form wired or wireless communication systems and even optical or sonic systems with minimal generation of parasitic harmonics, resulting in a minimum bandwidth requirement for operation.

A method and system for extracting values representative of modulation signal components from a modulated signal, the modulated signal containing a modulation signal, including developing a local clock signal which correlates in time to the modulated signal and includes a number of phase sectors per cycle and converting the modulated signal into a current that is representative of the signal and routing the current to the inverting input of an amplifier and charging one of a plurality of capacitive devices during each phase sector and sequentially connecting the capacitive devices between the output of the amplifier and the inverting input of the amplifier in non-overlapping sequences, the total of sequences being equal to one full cycle of the clock.

An OFDM system generates a channel estimate in the time domain for use in either a frequency domain equalizer or in a time domain equalizer. Preferably channel estimation is accomplished in the time domain using a locally generated reference signal. The channel estimator generates an initial estimate from a cross correlation between the time domain reference signal and an input signal input to the receiver and generates at least one successive channel estimate. Preferably the successive channel estimate is determined by vector addition (or subtraction) to the initial channel estimate. The at least one successive channel estimate reduces the minimum mean square error of the estimate with respect to a received signal.

A method for switching interval modulation includes modulating an RF input data signal while generating and inserting additional pulses in transitions of the data signal. The additional pulses are structured to shift transition noise into higher order harmonics. Higher order harmonics are easily filtered. The generating is conducted in the digital domain. The additional pulses can be used to simplify the transmit chain through optical modulators and improve the signal integrity over long distances, can be applied at the output of a transmitter to filter power amplifier distortion, and can be appplied to non-linear RF over fiber for a distributed MIMO system.

A receiver for cancelling strong signals from combined weak and strong signals includes: a first circuitry for inputting a weak and strong signal as an input; a parametric cancellation circuit for inputting a representation of the strong signal and an output of the first circuitry to produce a cancellation signal; a second circuitry electrically coupled to the parametric cancellation circuit for inputting the cancellation signal to produce a modulated output; a demodulator electronically coupled to the second circuitry for demodulating the modulated output to produce a demodulated output and an error signal, where the demodulated output is the data contained in the weak signal; and an adaptation logic circuit for inputting the representation of the strong signal, the demodulated output and the error signal to adaptively produce parameters for the parametric cancellation circuit. The parametric cancellation circuit further inputs the error signal and the parameters to produce the cancellation signal.