270 results about "Modulation bandwidth" patented technology

A chaotic communication system employs transmitting and receiving chaotic oscillating circuits. One improvement to first-generation systems is the ability to modulate a nonreactive element in the transmitting circuit, thus increasing modulation bandwidth. Other features include insertion of a gain control amplifier in a chaotic receiver; signal filtering in chaotic transmitters and receivers; use of chaotic modulation techniques for cellular telephony applications; dual-transmitter and receiver systems; a dual receiver synchronization detector; interfaces to communication systems; analog chaotic signal modulation; use of multiple chaotic transmitters and receivers; digital algorithm improvement using a cube-law nonlinear component; a Gb-only receiver; a Gb-only transmitter; and positive slope transmitter and receiver systems.

A wireless communication system includes a) a first device having a transmitter part with a Tx-antenna for transmitting an electrical signal having a signal bandwidth BWsig and b) a second device having a receiver part with an Rx-antenna for receiving the transmitted electromagnetic signal. At least one of the Tx- and Rx-antennas is a narrowband antenna having an antenna bandwidth BWant, wherein the Tx- and / or Rx-antenna bandwidths fulfil the relation BWant=k·BWsig. The system is adapted to provide that k is smaller than 1.25, and the antenna bandwidth BWant is defined as the −3 dB bandwidth of the loaded antenna when it is connected to the communication system, and the signal bandwidth BWsig is defined as the bandwidth within which 99% of the desired signal power is located.

The invention is based on a process and system for producing random numbers by means of a quantum random number generator where the method comprises the steps of operating a laser in single mode and high modulation bandwidth by means of an electrical pulse driver, transforming the phase randomized optical pulses produced before in optical pulses with random amplitude and detecting the resulting random amplitude signals by means of a fast photodiode. The numbers thus produced are truly random.

An RF transceiver having dual-mode envelope restoration architecture. In narrow-band applications such as GSM / EDGE, a switch-mode amplifier is used to provide an envelope signal for amplitude modulating the phase-modulated signals. To achieve required modulation bandwidth in wide-band applications such as WDCMA, an analog amplifier is used to provide the envelope signal. Furthermore, in the wide-band mode, the envelope modulation is applied through the base of an emitter follower while the collector voltage is scaled to achieve a desired power output in the amplitude-modulated signals.

Hybrid plasmonic waveguides are described that employ a high-gain semiconductor nanostructure functioning as a gain medium that is separated from a metal substrate surface by a nanoscale thickness thick low-index gap. The waveguides are capable of efficient generation of sub-wavelength high intensity light and have the potential for large modulation bandwidth >1 THz.

Integrated optical intensity or phase modulators capable of very low modulation voltage, broad modulation bandwidth, low optical power loss for device insertion, and very small device size are of interest. Such modulators can be of electro-optic or electro-absorption type made of an appropriate electro-optic or electro-absorption material in particular or referred to as an active material in general. An efficient optical waveguide structure for achieving high overlapping between the optical beam mode and the active electro-active region leads to reduced modulation voltage. In an embodiment, ultra-low modulation voltage, high-frequency response, and very compact device size are enabled by a semiconductor modulator device structure, together with an active semiconductor material that is an electro-optic or electro-absorption material, that are appropriately doped with carriers to substantially lower the modulator voltage and still maintain the high frequency response. In another embodiment, an efficient optical coupling structure further enables low optical loss. Various embodiments combined enable the modulator to reach lower voltage, higher frequency, low optical loss, and more compact size than previously possible in the prior arts.

The invention discloses a method of modulating a variable pulse amplitude position and improving an error rate for a visible light communication system, belonging to the field of visible light wireless communication technologies. According to the method, modulation of the variable pulse amplitude position is utilized in a modulation module of a signal transmitting end, a modulation method is multi-system modulation capable of combining pulse amplitude position modulation and pulse width modulation, transmission of communication data is guaranteed while a system dimming function is provided, improvement of the communication quality mainly includes that the transmission rate can be improved under the condition of the same symbol rates, the advantages of high multi-system modulation bandwidth efficiency and high pulse position modulation power efficiency are combined, the spectral efficiency can be effectively improved, and compared with the other multi-system modulation manner, the complexity is lower. In order to further improve the error rate of the visible light communication system, the method utilizes a channel balancer based on a feed-forward back propagation multilayer perceptron on a receiving end, so that the error rate is effectively improved, and the communication quality is further improved.

An RF transceiver having dual-mode envelope restoration architecture. In narrow-band applications such as GSM / EDGE, a switch-mode amplifier is used to provide an envelope signal for amplitude modulating the phase-modulated signals. To achieve required modulation bandwidth in wide-band applications such as WDCMA, an analog amplifier is used to provide the envelope signal. Furthermore, in the wide-band mode, the envelope modulation is applied through the base of an emitter follower while the collector voltage is scaled to achieve a desired power output in the amplitude-modulated signals.

The invention discloses a silicon-based lithium niobate high-speed light modulator and a preparation method thereof. The modulator comprises a silicon substrate wafer, a lower silicon dioxide cladding, lithium niobate film, an optical waveguide, a metal electrode, a silicon V-shaped groove and a coupling optical fiber, wherein the lower silicon dioxide cladding is located on the upper surface of the silicon substrate wafer, and the lithium niobate film is located on the lower silicon dioxide cladding. The silicon-based lithium niobate high-speed light modulator has the advantages that heterogeneous integration of a lithium niobate single crystal body and a silicon single crystal body is achieved; by utilizing the thin-film lithium niobate wafer and the characteristics such as low dielectric constant and low dielectric loss of the lower silicon dioxide cladding, improvement of modulation rate (or modulation bandwidth) of the lithium niobate light modulator can be achieved; by utilizingthe thin-film lithium niobate wafer and the high insulativity of the lower silicon dioxide cladding, intensity increase of microwave electromagnetic fields distributed in the lithium niobate film canbe achieved, the modulation efficiency of electric fields to light fields is improved, and the driving voltage of the modulator is reduced.

The invention provides a low-refractivity waveguide modulator for graphene. The low-refractivity waveguide modulator comprises a substrate, lower cladding, a waveguide core layer, an ITO transparent electrode, a lower insulating medium layer, a single-layer graphene film, a metal electrode, an upper insulating medium layer and a high refractive index silicon oxide layer, wherein the lower cladding is arranged on the substrate, the waveguide core layer is arranged in the middle of the lower cladding for forming a ridge-shaped structure, the ITO transparent electrode is arranged on the waveguide core layer and the two sides and covers the exposed upper surface of the lower cladding, the lower insulating medium layer is arranged on the surface of the ITO transparent electrode, the portion, on one side of the ridge-shaped structure, of the insulating medium layer is of a disconnection shape and forms a window, the single-layer graphene film is arranged on the lower insulating medium layer, the metal electrode is arranged on one side of the ridge-shaped structure and the single-layer graphene film of the other side far away from the window, the preset distance larger than 800nm is kept between the metal electrode and the ridge-shaped structure, the upper insulating layer is arranged on the single-layer graphene film on the ridge-shaped structure, and the high refractive index silicon oxide layer is arranged on the upper insulating medium layer. The low-refractivity waveguide modulator has the advantages of being small in size, wide in modulation bandwidth, low in insertion loss and simple in preparing process.

A calibrating method for big modulation bandwidth linear FM signal frequency response relates to the technical field of testing, comprising the steps of: 1) dividing a radio frequency signal in a complete frequency range generated by a calibrating device into a plurality of frequency sections F0 to F1, F1 to F2,..., FM-2 to FM-1 and FM-1 to FM, for calibrating section by section, 2) confirming N+1 calibrating points on a single calibrating frequency section, 3) dynamically acquiring a log amplifying sensitivity R, 4) translating and searching the smallest carrier power, and 5) automatically calibrating frequency points FM one by one. The method of the invention automatically calibrates and compensates basing on the linear FM signal frequency response of an interior detection circuit and an agility damping circuit in the calibrating device and the frequency response calibration can be automatically performed without an additional testing and calibrating device for user to perform real time calibration on site. The detection circuit and the agility damping circuit are both located in a modulating channel, so not only the frequency response of linear FM signal generating module is calibrated but also the whole passage is calibrated.

The invention provides an artificial super-surface electromagnetic wave amplitude modulator based on graphene, and mainly solves the problems of small modulation scope and narrow modulation bandwidth of a conventional electromagnetic wave amplitude modulator. The artificial super-surface electromagnetic wave amplitude modulator comprises a DC power supply and a frequency selection surface, three layers of dielectric substrates and a reflecting plate laminated from top to bottom sequentially, wherein a dielectric layer with relative dielectric constant less than three is arranged between the second dielectric layer and a reflecting plate to expand wave absorption bandwidth, the frequency selection surface is formed by m*n cross period units, a rectangular-ring metal paster embedded in a graphene film is arranged in the center of each cross period unit, metallic branches are connected to the upper and lower sides of the rectangular-ring metal paster, and the horizontal metallic fine leads connect the single cross units in an entire row into one body. The structure is simple, and metal pasters embedded in the graphene films are used to widen the modulation bandwidth and increase the reflection wave modulation amplitude. The reflecting plate with high conductivity is used to reduce the transmission of electromagnetic waves by a wave absorption device. The artificial super-surface electromagnetic wave amplitude modulator is applicable to active electromagnetic hiding and electro-optical switch equipment.

The invention is an optical A / D converter based on nonsymmetrical Mach-Zehnder modulator, belonging to the optical A / D converter technical field, characterized in that: it uses nonsymmetrical M-Z modulator to modulate electric signal to synchronous multi-wavelength input pulse, and selects proper length difference of two arms DeltaL and N wavelengths, able to make offset of DC biasing point between every two adjacent wavelengths at the outgoing end bepi / N, and the modulated multi-wavelength optical pulse is divided into N synchronous optical pulses by wavelength division multiplexer, and after determined by photoelectric detector and comparer, it can obtain N digital signal outputs. And the invention can implement very large modulated bandwidth and accurately control the offset of DC biasing point of two adjacent channels, implementing higher-digit A / D conversion and easy to implement.

The invention discloses a multiband signal reconstruction method based on a clustering sparse regularization orthogonal matching tracking algorithm, relates to the technical field of information and communication, and aims at solving a problem of restoring an original multiband signal from an unknown-sparseness multi-observation-value vector in a Xampling frame after the conversion through a continuous-finite module and sampling through a modulation bandwidth converter. Because many simulation signals met a multiband signal model in a process of signal processing, the method plays an important role in enabling the compressed sensing theory to be used for simulation signals. The basic idea of the method is to convert an infinite observation value vector problem into a single-observation-value vector problem. The method comprises the following steps: carrying out the column vectorization of observation values; carrying out the extension of an observation matrix through a Kronecker product; estimating a support set of the original signal through employing the above two results and signal sparseness estimation; finally reconstructing the signal, wherein the regularization idea is used in an estimation process of the support set.

The invention provides a phase locked loop having a modulator which is based on a ΣΔ fractional N phase locked loop. In the forward path of the PLL, the output of the oscillator has an additional frequency divider which provides the output frequency of the PLL in a plurality of different phases. A multiplexer which is connected upstream of the multimodulus divider in the PLL's feedback path and which is actuated by the ΣΔ modulator, like the divider, selects the respective desired phase. This allows the minimum step size of the division factors to be reduced to values of less than 1 relative to the output frequency, which significantly reduces the quantization noise. The PLL bandwidth may therefore advantageously be the same size as the modulation bandwidth.

Determination of distance and / or position relative to one or more points by transmission of a wideband signal by a first antenna, reception of the transmitted wideband signal by a second antenna and comparison of the time delay between the transmitted and received signals. The first and second antennas are connected to a timer / processor unit. One or more of the first or second antennas is movable to an unknown position to be measured, but maintains connection to the timer / processor through a fixed or known delay communication link. The timer / processor contains a time base for generating the transmitted signal and an offset timer for measuring the time delay of the received signal. The received signal may be processed to determine a start time or leading edge that may resolve RF cycle and modulation bandwidth ambiguities and may allow positive determination of distance much shorter than a wavelength at the operation center frequency.

The present invention discloses an electro optic modulator based on two-sided metallic reflection type polarization independent crystal, wherein, the top and bottom surface of the crystal wave guide layer is adhered with an upper and a lower metallic electrodes, the crystal wave guide layer and the adhered upper and lower metallic electrodes jointly consist a wave-guide structure, an input matching circuit is connected with the upper layer metallic electrode and the lower layer metallic electrode; the incident carrier light forms a focused beam after focusing, and then the focused beam is incident onto the wave-guide structure, reflecting by the upper layer metallic electrode; a modulation electrical signal is added between the upper layer metallic electrode and the lower layer metallic electrode by the input matching circuit, the modulating signal changes the reflection index at the work corner by changing the refractivity of the wave guide layer, thereby implementing the modulation of intensity of reflected light. The invention has a polarization independent characteristic, and has a low requirement to the electro-optic coefficient of the wave guide layer crystal. At the same time, the invention has low-voltage, large modulation bandwidth, small insertion loss and transmission loss, simple production and low cost.

The invention discloses a ROF base station uplink of a wavelength-multiplexing passive optical network and its system, belonging to the optical communication field. The uplink comprises an optical coupler for coupling a part of signals in the downlink to input into the multimode laser; a mode-locking multimode laser for generating double mode-locking mode optical signals with the mode distance of millimeter wave frequency. The uplink signals are directly loaded to the double mode-locking mode optical signals for transmission by modulating the multimode laser. The system comprises a central station and a plurality of base stations including the uplink chains. The invention reduces the wavelength occupancy rate, effect from the downlink to the uplink signals, improves the modulation bandwidth, and decreases the equipment costs, realizes the amplification of the downlink double mode carrier wave, filtering and increasing of the optical carrier signal to noise ratio.

The invention discloses a microstrip resonance structure Terahertz wave modulation apparatus and the method thereof. The apparatus comprises a Terahertz wave source, a microstrip resonance structure array, a high-resistance silicon substrate, a Terahertz wave detector and a modulatable semiconductor laser; the microstrip resonance structure array is sputtered on the high-resistance silicon substrate; the Terahertz wav from the Terahertz wave source is propagated to the microstrip resonance structure array, and is propagated out through the Terahertz wave detector by the Terahertz wave modulated by the high resistance silicon substrate; the modulatable semiconductor laser is disposed on the same direction of the Terahertz wave source; the included angle between the laser shot direction of the modulatable semiconductor laser and the incidence direction of the Terahertz wave from the Terahertz wave source is 0-30 degrees; and the microstrip resonance structure array is composed by a plurality of microstrip resonance structure units. The invention achieves the advantages of high modulation speed, large modulation bandwidth, small size, compact, easily machined, and simple and convenient operation; is not sensitive to Terahertz wave, can meet the high speed communication demand of Terahertz wave.

The present invention relates to the test technology field, in particular to an adaptive large modulation bandwidth I / Q modulation error digital compensation method and an adaptive large modulation bandwidth I / Q modulation error digital compensation system. The method comprises the steps of setting a baseband signal V<o> as zero; detecting the radio frequency output via an envelope detector to obtain an envelope detection value V<e>; when the envelope detection value V<e> is a minimum value, calculating a DC bias parameter B of a vector modulation error; calculating the adjustment parameters d and f; and according to the adjustment parameters d and f and the DC bias parameter B, compensating according to the following error compensators: V<c>=C(V<o>+B), wherein the V<c> is an input vector after the error compensation. According to the scheme, a baseband signal generator, a vector modulator and a transmission channel are brought into a calibration process, the errors caused by the three parts are compensate and correct simultaneously, thereby avoiding an error caused by approximate compensation in an existing technical scheme. The scheme is realized by a baseband signal predistortion digital method, thereby avoiding the bandwidth limitation of a simulation device in the existing scheme, and realizing the high precision compensation correction of a GHz magnitude large modulation bandwidth vector modulation error.

A green LED has a substrate, a GaN heavily n-doped bottom confining layer, an active region, an upper GaN confinement layer, and a semi-transparent ohmic contact layer. The active region has less than or equal to three highly compressively strained quantum wells. The widths of the quantum wells is less than 3 nm. The active region arrangement provides a short free carrier life-time and hence an increase in the modulation bandwidth of the LED.

The invention discloses an intensity code based synthetic aperture laser radar system which is applied to synthetic aperture laser radar imaging. The intensity code based synthetic aperture laser radar system is formed by a code element signal generation unit, a 90 to 10 fiber coupler, a sending and receiving lens, a 50 to 50 fiber coupler, two balanced detectors, a data acquisition module and a signal processing program module. An echo signal is obtained by a heterodyne coherent detection and balance detection technology based on a multistage intensity laser code modulation pulse signal and a two-dimensional image of a target is obtained after distance direction and azimuth direction compression processing. According to the intensity code based synthetic aperture laser radar system, the signal modulation speed is high, the modulation bandwidth can reach more than 5 GHz under the condition that the requirements of the airborne platform flight speed are met, and the system is of a polarization-maintaining fiber structure and accordingly the amplitude stability is high, a light path is easy to adjust, the detection sensitivity is high, and the range resolution reaches the centimeter magnitude.

The invention relates to a terahertz modulator based on mode coupling and belongs to the technical field of electromagnetic functional devices. The terahertz modulator is formed by a substrate, a mode coupling artificial microstructure and a controllable dynamic semiconductor material. The mode coupling artificial microstructure comprises a bright mode resonance unit and a dark mode resonance unit. The dark mode resonance unit is located at the center of the bright mode resonance unit, and the two resonance units are subject to mode coupling to form an electromagnetic induction transmission window. The dynamic semiconductor material is located at the position of an opening of the dark mode resonance unit; under additional excitation, the dark mode working mode can be changed so that mode coupling between a bright mode and a dark mode is affected, and finally the tunable electromagnetic induction transmission window is obtained. The bright mode resonance unit and the dark mode resonance unit have the same resonance frequency point, so that very good coupling can be achieved between the bright mode and the dark mode, and the modulation bandwidth has a high Q value and large modulation depth. The terahertz modulator is processed in a micro machining mode, and a preparation process is mature and reliable. An obtained device is flexible and convenient to use and has very high potential application value in the field of terahertz wireless communication.

The invention discloses a light modulator with a four-layer graphene structure and belongs to the field of photoelectronic techniques. The light modulator comprises an SOI light guide, a first ridge part and a second ridge part overlapping the first ridge part are arranged above a semiconductor light guide layer of the SOI light guide, two graphene layers are arranged between the semiconductor light guide layer and the first ridge part, another two graphene layers are arranged between the first ridge part and the second first ridge part, and all the functional layers are isolated from one another through isolation media; one graphene layer between the semiconductor light guide layer and the first ridge part is connected with one graphene layer between the first ridge part and the second first ridge part through one metal electrode, and the other graphene layer between the semiconductor light guide layer and the first ridge part is connected with the other graphene layer between the first ridge part and the second first ridge part through another metal electrode. The light modulator has the advantages of being smaller in size, high in modulation rate and convenient to integrate, wherein the extinction ratio of a 5 micrometer active area is as high as 30 dB, and the modulation rate of a 3 dB modulation bandwidth is as high as 114.8 GHz.

The invention discloses a data transmission method suitable for two-way transmission of a cable TV network. The method is implemented based on EOC technology, and includes: configuring four bandwidth modes using orthogonal frequency division multiplexing modulation technology; generating The time domain waveform of the preamble symbol, the frame control OFDM symbol and the data OFDM symbol; the time domain waveform of the preamble symbol, the frame control OFDM symbol and the data OFDM symbol will be generated The multiplexing symbols are combined to form a complete LoREOC physical frame; and the LoREOC physical frame is used for data transmission to realize data transmission suitable for two-way transmission of cable television networks. The present invention solves the problem of low resource utilization rate and poor compatibility of current relevant standards for my country's specific frequency spectrum division.

A high-speed, high-performance optical modulator operating with a reduced drive voltage without sacrificing modulation bandwidth. The modulator has an optical waveguide fabricated on a crystal substrate. A signal electrode is on a ridge on the substrate. Ground electrodes are formed on both sides of the signal electrode. A gap between the signal and ground electrodes is at least 44 μm, and an interaction length of the signal electrode is at least 41 mm. The modulator can operate at 40 Gbps or higher.