An apparatus includes a first circuit to receive a first input data, a second input data and coefficients, generate a first distortion term and a second distortion term based, respectively on the first input data and the coefficients and the second input data and the coefficients, and change a polarity of the first distortion term and the second distortion term. A first subtraction circuit subtracts the first distortion term from the first input data and generates first difference data, and a second subtraction circuit subtracts the second distortion term from the second input data and generates second difference data. A transmit data-path generates a RF output. The first difference data and the second difference data compensate, based on the polarity changes of the first distortion term and the second distortion term, respectively, one or more impairments of the RF output.

A stereo-phonic frequency modulation receiver includes: a frequency modulation demodulation circuit, receiving a reception signal, and generating a demodulated signal according to the reception signal; a frequency-division demultiplexer, generating a sum signal, a difference signal and a pilot amplitude signal according to the demodulated signal; a dual sound channel separation circuit, generating a left-channel output signal and a right-channel output signal according to the sum signal and a weakened difference signal; and a weakening circuit, weakening the difference signal according to the pilot amplitude signal or a signal-to-noise ratio (SNR) to generate the weakened difference signal.

A method for processing an FM stereo signal. The FM stereo signal is digitized and divided into overlapping blocks, which are transformed into the frequency domain. Individual spectral lines of the difference signal are lowered if these have a higher magnitude than the respective spectral lines of the sum signal. The sum and difference signals are then transformed back.

A stereo-phonic frequency modulation receiver includes: a frequency modulation demodulation circuit, receiving a reception signal, and generating a demodulated signal according to the reception signal; a frequency-division demultiplexer, generating a sum signal, a difference signal and a pilot amplitude signal according to the demodulated signal; a dual sound channel separation circuit, generating a left-channel output signal and a right-channel output signal according to the sum signal and a weakened difference signal; and a weakening circuit, weakening the difference signal according to the pilot amplitude signal or a signal-to-noise ratio (SNR) to generate the weakened difference signal.

The present disclosure provides a method and a system to estimate LO leakage and quadrature error parameters for a transmitter RF front end, such as a direct up-conversion transmitter RF front end, in a joint fashion. The proposed method utilizes a PN sequence inserted at the transmitter baseband. At the observation receiver side, an RX accumulator is implemented to sum receiver signals to take advantage of a despreading gain using the same PN sequence from transmitter side. Through the despreading process, the receiver-transmitter channel may be estimated and used to extract the quadrature error parameters. The estimated channel may also be used to eliminate user data interference presented within the RX accumulator output, which may further be used to compute the LO leakage.

A system and method for self-interference cancellation using a full duplex adaptive array includes at least four ports within the network array, with at least two transmission elements at a first port and a second port, and at least one receiving element at a third port and a fourth port. A signal is transmitted along a first network path from the two transmission elements of the first port to the receiving element of the fourth port. The signal is transmitted along a second network path from the two transmission elements of the first port to the receiving element of the third port. A weight is applied to at least one of the two transmission elements of the first port, which modifies the signal transmitted along the second network path to cancel signal interference caused by the signal at the third port during full duplex operation of the network array.