A modem includes a modulator and a demodulator. The demodulator includes a direct current removing (DCR) circuit to transition between an acquisition mode, where the DCR circuit operates with a first loop gain; and a tracking mode, where the DCR circuit operates with a second loop gain. The second loop gain is smaller than the first loop gain, and the timing of the transition between the acquisition mode and tracking mode is programmable.

Systems and methods are provided for peak to average power ratio (PAPR) reduction in multichannel digital front-ends (DFEs). A transmitter may be configured to reduce PAPR during multichannel transmission, with the reducing comprising: generating a plurality of frequency-domain symbols, each of which corresponding to a particular one of a plurality of subcarriers; assigning the subcarriers to a plurality of channels, wherein a number of channels is less than a number of subcarriers; and generating a plurality of time-domain signals corresponding to the channels. An adjustment to reduce PAPR may be applied to at least one of the time-domain signals, with the adjustment being based on symbols boundaries. The adjustment may comprise sign inversion. Adjusted and unadjusted waveforms may be generated for two or more of the time-domain signals; and selection may be made between generated adjusted waveforms based on particular criteria. The criteria may comprise lowest peak.

A modem includes a modulator and a demodulator. The demodulator includes a direct current removing (DCR) circuit to transition between an acquisition mode, where the DCR circuit operates with a first loop gain; and a tracking mode, where the DCR circuit operates with a second loop gain. The second loop gain is smaller than the first loop gain, and the timing of the transition between the acquisition mode and tracking mode is programmable.

An in-medium monitoring system for monitoring material carried within a pipe. The system includes an acoustic device installed within the pipe that generates voltage signals indicative of changes in the material, such as flow rate or leaks, a hardware unit that includes a detector module and a communication module, a switch for switching the voltage signals to and communication signals from the hardware unit. The hardware unit and a power source are attached to the pipe. The acoustic device may be detector or a sensor. The communication module may communicate date through the sensor in the medium or outside of the pipe to a fixed network. The hardware unit may include a log detection amplifier for generating an amplified pulsed output signal without voltage gain and without significantly adding noise.

A very low intermediate frequency (VLIF) receiver and a method of controlling a VLIF receiver. The method comprises estimating energy levels in first and second signals and detecting interference from a first adjacent channel interferer based upon a difference in energy in the first and second signals. The first signal comprising a first on-channel portion and an adjacent channel portion and the second signal comprises an intermediate frequency translation of the first on-channel portion. The energy levels are estimated for corresponding time instances and the adjacent channel interferer is of the adjacent channel portion. The VLIF receiver is then controlled based upon the detected interference.