Disclosed is receiver for a noise limited system. A front-end circuit amplifies and band-limits an incoming signal. The amplification increases the signal swing but introduces both thermal and flicker noise. A low-pass band limitation reduces the thermal noise component present at frequencies above what is necessary for correctly receiving the transmitted symbols. This band limited signal is provided to the integrator circuit. The output of the integrator is equalized to reduce the effects of inter-symbol interference and then sampled. The samples are used to apply low frequency equalization (i.e., in response to long and/or unbalanced strings of symbols) to mitigate the effects of DC wander caused by mismatches between the number of symbols of each kind being received.

Methods and apparatus to determine automated gain control parameters for an automated gain control protocol are disclosed. An example apparatus includes a first tuner to amplify an audio signal. Disclosed example apparatus also include a second tuner to amplify the audio signal. Disclosed example apparatus also include a first controller to tune the first tuner to apply a first gain representative of a first range of gains to the audio signal to determine a first amplified audio signal and tune the second tuner to apply a second gain representative a second range of gains to the audio signal to determine a second amplified audio signal, the second range of gains lower than the first range of gains. Disclosed example apparatus also include a second controller to select the first range of gains to be utilized in an automated gain control protocol when the first gain results in clipping of the first amplified audio signal and the second gain does not result in clipping of the second amplified audio signal.

The disclosure relates to an apparatus including a receiver configured to process a radio frequency (RF) signal to generate a baseband signal; a radio frequency (RF) jammer detector configured to generate a signal indicative of whether an RF jammer is present at an input of the receiver; and a receiver bias circuit configured to generate a supply voltage for the receiver based on the RF jammer indication signal. In another aspect, the apparatus includes constant gain bias circuit to maintain the gain of the receiver constant in response to changes in the supply voltage. In other aspects, the receiver bias circuit may suspend the generating of the supply voltage based on the RF jammer indication signal if the power level of the target received signal is above a threshold. In other aspects, the receiver bias circuit changes the supply voltage during cyclic prefix (CP) intervals between downlink intervals.

A system that incorporates aspects of the subject disclosure may perform operations including, for example, receiving, via an antenna, a signal generated by a communication device, detecting passive intermodulation interference in the signal, the interference generated by one or more transmitters unassociated with the communication device, and the interference determined from signal characteristics associated with a signaling protocol used by the one or more transmitters. Other embodiments are disclosed.

Systems and methods for handling cancellation of a Passive Intermodulation (PIM) signal are provided. The network device has access to and controls one or more transmitters and one or more receivers. The network device applies a determined PIM model to a transmitted signal from each transmitter of the network device, to obtain a modelled signal. The PIM model comprises a forward path model for each transmitter to the PIM source, a common non-linear model of the PIM signal from the PIM source being applied to a combined signal comprising the signals from each transmitter modelled by the forward path model, and a linear reflective path model from the PIM source to each of the receivers of the network device for a received PIM signal. The network device further subtracts the modelled signal from a received signal on each of the receivers of the network device.

Systems and methods for GNSS anti-jamming using interference cancellation are described herein. In certain embodiments, a system includes an antenna that receives signals, wherein the signals comprise a weak portion associated with one or more GNSS satellites and a strong interference portion from an interfering signal source. The system also includes a GNSS anti-jammer. The GNSS anti-jammer includes an interference isolator that receives the received signals and provides an estimated strong interference portion as an output. The GNSS anti-jammer also includes a summer that subtracts the estimated strong interference portion from the received signals to create a summed signal. Further, the GNSS anti -jammer includes a local noise remover that removes noise generated by the interference isolator from the summed signal, wherein the local noise remover is a processor that digitally removes the noise. Further, the system includes a GNSS receiver coupled to receive the summed signal from the processor.

A data transmission method is applied to a primary base station and includes: configuring, for a secondary base station, a carrier parameter used by the secondary base station; configuring, for a terminal, an autonomous rejection rule for an inter-modulation distortion occurred between a carrier used by the secondary base station and a carrier used by the primary base station; sending the carrier parameter and information associated with the autonomous rejection rule to the terminal.

A method and network node for detection of passive intermodulation (PIM) are disclosed. According to one aspect, a method includes determining values of a covariance matrix based at least in part on uplink signals received by the network node radio. The method also includes determining a plurality of uplink (UL) channel 5 eigenvalues based at least in part on an eigen-component acquisition technique. The method further includes determining a presence or absence of PIM based at least in part on a plurality of the UL channel eigenvalues.

A communication device has a controller that selects one of at least two second antennas for concurrent transmission with a first antenna. The controller monitors concurrent communication activity of a first and a second transmitter. Based on the concurrent communication activity, the controller identifies respective transmit power limits associated with intermodulation distortion (IMD) for the first antenna transmitting at the first transmit frequency and one of the at least two second antennas transmitting at the second transmit frequency. The controller identifies available total radiated power (TRP), respectively, for each of the at least two second antennas and connects the second transmitter to one of the at least two second antennas having the highest available TRP to optimize communication performance.

A radio communication system according to the present invention is a radio communication system including a transmission device and a reception device, the transmission device includes a first null insertion unit that inserts a first signal that is a signal having an electric power lower than an amplitude of the data symbols, in a time direction of data symbols, and the reception device includes a null extraction unit that extracts a first symbol that is a signal in a period corresponding to the first signal, from a received signal, a signal interpolation unit that interpolates the first symbol to reproduce interference components in periods corresponding to the data symbols, and a subtraction unit that subtracts the interference components from the received signal.