A sensing system. In some embodiments, the system includes a first imaging radio frequency receiver, a second imaging radio frequency receiver, a first optical beam combiner, a first imaging optical receiver, a second optical beam combiner, and an optical detector array. The first optical beam combiner may be configured to combine optical signals of the imaging radio frequency receivers. The second optical beam combiner may be configured to combine the optical signals of the imaging radio frequency receivers, and the optical signal of the first imaging optical receiver.

Example embodiments disclose a tunable optical pair source (TOPS) configured to generate first and second output optical beams having respective first and second frequencies that are phase locked with each other. The TOPS may include a first laser, such as a tunable laser, configured to generate a first laser beam, a radio frequency (RF) oscillator configured to transmit an RF reference signal, a beam splitter in optical communication with the first laser, and an electro-optic modulator configured to modulate the second split beam with the RF reference signal to form a modulated beam having a first sideband comb comprising a plurality of harmonics. Additionally, the TOPS may include an optical filter configured to receive the modulated beam and output a filtered optical beam, and a second laser configured to generate a second laser beam at the second frequency, the second laser being configured to receive the filtered optical beam as a seed.

A system may include a receiver configured to receive a communications signal from a transmitter and processing circuitry configured to: determine at least one frequency characteristic of the communications signal and compare the at least one frequency characteristic to at least one verified frequency characteristic stored by a memory associated with the processing circuitry to determine whether the transmitter is a verified transmitter. In some examples, the transmitter, receiver and communications signal are an optical transmitter, and optical receiver, and an optical signal, respectively.

An analog distributed antenna system having a set of small cells as a signal source is provided. A proposed cellular communication system includes an upper small cell unit including upper protocol processors configured to process an upper first part of a protocol stack of a small cell, a lower small cell unit including lower protocol processors configured to process a remaining second part of the protocol stack of the small cell, and a first matching switch configured to respectively match the lower protocol processors to a plurality of remote units. According to one aspect, the cellular communication system includes a common controller configured to control activation of the plurality of upper protocol processors of the upper small cell unit and the plurality of lower protocol processors of the lower small cell unit according to a required service capacity and appropriately control an operation of the first matching switch.

Microwave photonic vector network analyzer and a method for measuring scattering parameters of a microwave device are provided. The analyzer comprises a microwave source, wherein a signal loading module, an optical sampling module and a signal processing module are sequentially arranged along a signal output direction of the microwave source; an output end of the signal processing module is respectively connected with a control end of the microwave source and a control end of the optical sampling module; and two test ports of the signal loading module are connected with both ends of a device to be tested. The invention realizes direct sampling and frequency conversion for microwave signals, abandons a superheterodyne structure and/or direct frequency conversion structure in the traditional network analyzer, simplifies the structure of the system while improving the measurement frequency range and avoiding image interference, and reduces system complexity, cost and power consumption.

A photonic random signal generator includes an incoherent optical source configured to generate an optical noise signal, a filter configured to generate a filtered optical noise signal using the optical noise signal, a coupler, a photodetector, a filter, and a limiter. The coupler couples the filtered optical noise signal and a delayed version of the filtered optical noise signal to generate a first coupled signal and a second coupled signal. The photodetector generates an output signal representative of a phase difference between the filtered optical noise signal and the delayed version of the filtered optical noise signal using the first coupled signal and the second coupled signal. The filter filters the output signal representative of the phase difference to generate an analog random signal. The limiter thresholds the analog random signal based on a clock signal, to generate a digital random signal.

A discrete spectrum (DS) signal transmitter includes a first circuit element comprising a DS signal generator that generates a plurality of DS signals, each DS signal having a different DS frequency, each DS frequency being (a) a harmonic of a fundamental frequency or (b) the fundamental frequency. A second circuit element receives as an input the DS signals and that generates as an output (a) a finite summation of the DS signals or (b) pulses that represent a mathematical equivalent of a summation of an infinite number of the DS signals. An antenna is electrically coupled to an output of the second circuit element. The analog DS signals transmitted by the DS signal transmitter are received by a DS signal receiver that converts the analog DS signals to DS discrete signals and performs a fast Fourier transform of the DS discrete signals.

A photonic radio-frequency receiver with mirror frequency suppression function, in which a single modulator is utilized to form a photoelectric oscillator so as to generate high-quality and low-phase-noise optically generated local oscillators, without the need for an external local oscillator source, and at the same time, another radio-frequency port is used as a radio-frequency signal input port, thereby allowing a compact structure. By properly setting a bias point for the two-electrode modulator and orthogonally synthesizing two branches of intermediate frequency signals respectively generated by the upper and lower sideband beat frequencies of the modulated optical signal, the photonic radio-frequency receiver realizes the functions of receiving radio-frequency signals and suppressing mirror frequency signals. The present disclosure can realize a photonic mirror-frequency suppression receiver.

A Rydberg atom mixer determines a phase of modulated carrier radiation and includes: a reference radiofrequency source for reference radiofrequency radiation; a modulated carrier source for modulated carrier radiation; a vapor cell to contain gas atoms and that receives reference radiofrequency radiation and modulated carrier radiation, such that the gas atoms produce modulated light modulated; and a transmission detector that receives the modulated light from the vapor cell and produces a transmission signal from the transmission detector for determination of a phase of the modulated carrier radiation, wherein the Rydberg atom mixer mixes the reference radiofrequency radiation and the modulated carrier radiation by the gas atoms in a Rydberg electronic state to produce the intermediate frequency IF that corresponds directly to the phase of the modulated carrier radiation.

A system has a plurality of non-linear circuit stages and an intervening linear circuit stage. An input signal is provided to a first non-linear circuit stage, and from the first non-linear circuit stage, to the linear circuit stage. The first non-linear circuit stage applies a second-order distortion to the input signal and provides the resulting signal to the linear circuit stage. The resulting signal that is output from the linear circuit stage is inverted with respect to the input signal and suitably linearly processed (attenuated or amplified). This signal is then provided to a second non-linear circuit that applies a second-order distortion and outputs a signal that has an overall reduction in second-order distortion.