269 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 BW_sig 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 BW_ant, wherein the Tx- and/or Rx-antenna bandwidths fulfil the relation BW_ant=k·BW_sig. The system is adapted to provide that k is smaller than 1.25, and the antenna bandwidth BW_ant is defined as the −3 dB bandwidth of the loaded antenna when it is connected to the communication system, and the signal bandwidth BW_sig 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.

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 an ultra wide band hopping frequency synthesizer based on digital up-conversion. The ultra wide band hopping frequency synthesizer based on digital up-conversion comprises a PC, a field-programmable gate array ( FPGA ), a clock generator, a DA converter and a low-pass filter, wherein a hopping frequency sequence storer, a hopping frequency carrier signal generating unit, a modulation base band interpolation filtering unit and an up-conversion unit are arranged in the FPGA, the hopping frequency sequence storer is connected with the hopping frequency carrier signal generating unit through a signal line, and the hopping frequency carrier signal generating unit and the modulation base band interpolation filtering unit are connected with the up-conversion unit through two signal lines respectively. According to the ultra wide band hopping frequency synthesizer based on digital up-conversion, a digital base band is directly modulated onto a carrier wave by means of digital up-conversion, and then hopping frequency signals modulated by any digits are generated, hopping frequency bandwidth reaches 800MHz, modulation bandwidth is larger than 100MHz, and carrier wave leakage and IQ imbalance are avoided.

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.

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 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.

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 present invention directly modulates the VCO in accordance with transmission data, reduces the circuit scale and current consumed during transmission and obtains a highly accurate modulated output. A transmission data signal converted into an IQ modulation signal with a predetermined modulation bandwidth that is phase-modulated by the select control signal inputted to the ROM via the modulation circuit. The IQ modulation signal is converted into an analog signal by means of the DAC, and the analog signal is inputted to the gm adjustment device via the noise filter before being converted to an appropriate signal level that corresponds with the control sensitivity of the VCO. The converted analog signal is inputted to a second input terminal for controlling the direct frequency of the VCO and the oscillation frequency of the VCO is modulated. Switching of the BAND of the VCO is controlled by inputting a control signal that is outputted by the BAND CTRL to the third input terminal of the VCO and the control terminal of the gm adjustment device at the same time as controlling the transmission conductance of the gm adjustment device in order to establish the modulation depth of the input signal from the second input terminal of the VCO that corresponds with the VCO control sensitivity, which varies for each BAND, at a target modulation depth, whereby a highly accurate modulated output is obtained.