A PAM reception circuit includes a first comparison circuit that outputs a first bit value in two-bit values based on a result of a comparison between a reception signal of pulse amplitude modulation 4 in which the two-bit values are associated with four potential levels divided by three threshold values by gray codes and a first threshold value which is a center of the three threshold values, an absolute value circuit that outputs an absolute value of a difference between the reception signal and the first threshold value or a negative value obtained by inverting a sign of the absolute value from a positive sign to a negative sign, and a second comparison circuit that outputs a second bit value in the two-bit values based on a result of a comparison between a second threshold value which is larger than the first threshold value in the three threshold values.

A backscatter radio system having a transceiver module and a transponder. The transceiver module is configured to generate and transmit a radio frequency pulse signal with Pulse Position Modulation (PPM). The generated radio frequency pulse signal includes a power and information transferring pulse and a time reference pulse within a dual symbol duration comprising a first and a second symbol periods. The power and information transferring pulse enables a power injection to a rectifier circuit in the transponder and the time reference pulse enables an excitation of a resonance signal in a resonance circuit in the transponder. A response radio frequency pulse signal with PPM is generated using the resonance signal generated in the resonance circuit with a time offset such that the first and second symbol periods are separated in the time domain.

Aspects of the subject disclosure may include, for example, a node device includes an interface configured to receive first signals. A plurality of coupling devices are configured to launch the first signals on a transmission medium as a plurality of first guided electromagnetic waves at corresponding plurality of non-optical carrier frequencies, wherein the plurality of first guided electromagnetic waves are bound to a physical structure of the transmission medium. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, a node device includes an interface configured to receive first signals. A plurality of coupling devices are configured to launch the first signals on a transmission medium as a plurality of first guided electromagnetic waves at corresponding plurality of non-optical carrier frequencies, wherein the plurality of first guided electromagnetic waves are bound to a physical structure of the transmission medium. Other embodiments are disclosed.

In one aspect, an apparatus includes: a pulse frequency modulation (PFM) voltage converter to receive a first voltage and provide a second voltage to a load; and a pulse generator. The PFM voltage converter may include an inductor to store energy based on the first voltage and a switch controllable to switchably couple the first voltage to the inductor. The pulse generator may be configured to generate at least one pulse pair to control the switch, where this pulse pair is formed of a first pulse and a second pulse substantially identical to the first pulse, where the second pulse is separated from the first pulse by a pulse separation interval, when the second voltage is less than a first threshold voltage.

In one aspect, an apparatus includes: a pulse frequency modulation (PFM) voltage converter to receive a first voltage and provide a second voltage to a load; and a pulse generator. The PFM voltage converter may include an inductor to store energy based on the first voltage and a switch controllable to switchably couple the first voltage to the inductor. The pulse generator may be configured to generate at least one pulse pair to control the switch, where this pulse pair is formed of a first pulse and a second pulse substantially identical to the first pulse, where the second pulse is separated from the first pulse by a pulse separation interval, when the second voltage is less than a first threshold voltage.

The present application is directed to a method of short pulse generation. The method includes the step of creating, via electrical circuitry in a master oscillator, a square wave pulse with a predetermined pulse repetition rate. The method includes the step of retiming the square pulse with a clock. The method includes the step of recovering an electrical signal from the retimed square pulse. Further, the method includes the step of sending the recovered electrical signal to a modulator for modulating an optical signal.

The continuous demand for capacity and the limited available spectrum in wireless and wired communication has led to reliance on advanced modulation techniques to dramatically increase the number of bits per hertz per second. This demand in capacity and using the higher order constellations shorten the link range, and as a result, system gain becomes an important characteristic. The modulation techniques described here improve the system gain by, e.g., as much as 2.5 dB in high order modulations such as 4096-QAM. The modulation techniques include reducing the peak to average ratio and adding shaping gain. These techniques dramatically improve the system capacity, system gain, power consumption and system cost.

The continuous demand for capacity and the limited available spectrum in wireless and wired communication has led to reliance on advanced modulation techniques to dramatically increase the number of bits per hertz per second. This demand in capacity and using the higher order constellations shorten the link range, and as a result, system gain becomes an important characteristic. The modulation techniques described here improve the system gain by, e.g., as much as 2.5 dB in high order modulations such as 4096-QAM. The modulation techniques include reducing the peak to average ratio and adding shaping gain. These techniques dramatically improve the system capacity, system gain, power consumption and system cost.

Techniques for reducing the complexity and power requirements of precompensation units, as well as equalizers, devices, and systems employing such techniques. In an illustrative method for providing high speed equalization, the method comprises: obtaining a channel response that presents trailing intersymbol interference in a signal having a sequence of symbols from a symbol set; determining a distribution of threshold values for a precompensation unit corresponding to said channel response with said symbol set; deriving a reduced set of threshold values from said distribution; and implementing a decision feedback equalizer with a reduced-complexity precompensation unit employing the reduced set of threshold values. In a related illustrative method for providing high speed equalization, the method comprises: obtaining a channel response that presents trailing intersymbol interference in a signal having a sequence of symbols from a symbol set, the channel response and symbol set corresponding to an initial distribution of threshold values for a precompensation unit; deriving a filter that converts the channel response into a modified channel response, the modified channel response and symbol set corresponding to an improved distribution of threshold values in that the improved distribution includes fewer distinct threshold values or reduced spacing between at least some adjacent threshold values; and implementing a decision feedback equalizer with a reduced-complexity precompensation unit employing the threshold values in the improved distribution.