37 results about "Double side band" patented technology

A method and modem for communicating serial input data over a transmission link. Serial input data is partitioned into parallel data elements prior to rotation by an invertible linear mapping. Resulting frames of parallel signal elements sequentially modulate a carrier, which is then transmitted over the link. After receipt of the modulated carrier from the link, the signal is demodulated and assembled into frames of parallel signal elements which are de-rotated by an inverse linear mapping. Thresholding the result of the inverse mapping recovers the parallel data elements, which are then re-assembled into serial output data. The linear mapping employs: 1) commuting rotation matrices for convolutionally rotating data vectors into signal vectors and vice-versa; 2) filter bank polyphase rotation matrices; or 3) computationally efficient multi-rate wavelet filter banks. Transmitter pre-emphasis places most of the information in lower baseband frequencies; complimentary de-emphasis occurs in the receiver. Logarithmic amplification of the baseband signal prior to carrier modulation improves modulation gain and transmit channel noise attenuation. Coefficients of the rotation matrix of the receiver are adaptively equalized to correct for transmission path distortion. FM double-side band is employed in systems requiring minimized cost and complexity. FM single-side band is employed in systems in which bandwidth reduction is desirable. AM is also employable.

The present invention is to provide an optical modulating system for generating a signal of a frequency (f0+2fm) and a signal of a frequency (f0−2fm) and suppressing a signal of a frequency (f0) by a DSB-SC modulator.A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f0) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f0) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

The invention discloses a microwave signal photonic frequency conversion and multichannel fiber transmission device and method realized by a polarization multiplexing modulator. The device, as shown by a figure, comprises a laser diode (LD), a polarization multiplexing Mach-Zehnder modulator (PDM-MZM), an erbium doped fiber amplifier (EDFA), a 1:N light splitter (Splitter), a polarizer (Pol), a polarization controller (PC), and a standard single-mode fiber (SMF) and a photoelectric detector (PD). The PDM-MZM is used to carry out carrier suppressed double side band modulation on radio frequency (RF) and local oscillation (LO) signals and then implement frequency mixing, and the RF and LO isolation degree of frequency conversion gain and frequency conversion signals is improved. Optical signals output by the modulator can be divided into multiple paths to implement fiber transmission, each path is adjusted via an independent polarization state, and power attenuation caused by dispersion can be compensated.

Provided is an optical communication system capable of suppressing the deterioration of an intensity waveform of an optical intensity modulated signal subjected to transformation using SSB modulation and improving a bit error ratio and a receiver sensitivity of the optical intensity modulated signal. The optical communication system includes: an optical transmitter section including: a single-side band modulation circuit configured to subject a double-side band modulated signal to generate a single-side band modulated signal; a correction circuit configured to correct an intensity of the single-side band modulated signal so that the intensity of the single-side band modulated signal becomes closer to an intensity of the double-side band modulated signal; and an optical IQ modulator configured to output an optical modulated signal; and an optical receiver section configured to receive the optical modulated signal to directly detect an intensity component of the optical modulated signal.

The invention belongs to the technical field of optical fiber communication and wireless communication convergence, in particular to a system for generating an optical cable-carried terahertz signal based on two-stage single-side band modulation. The system consists of three parts: an optically inhibited carrier double-side band signal generating part, a two-stage single-side band modulation partand a terahertz wave transmitting and receiving part. The two-stage single-side band modulation part which is the core part of the system of the invention selects one side band of a carrier-inhibiteddouble-side band to perform a primary stage signal-band data modulation and uses base band signal-side band modulation technology in the data modulation process again so as to generate the two-stage cascade single-band modulation. The system has the advantages of simple structure, low cost, low element requirements, compatibility with the prior core net system, and the like.

The invention discloses a system and a method for monitoring broadcast signals in an online manner and parallelly demodulating the same. The particular method includes enabling the system to divide channels by the aid of digital channelization technologies, separating multiple channels of mixed digital broadcast signals from one another and outputting the separated mixed digital broadcast signals in the multiple channels; enabling a monitoring module to search signals and judge whether the signals are outputted form each channel or not by the aid of automatic signal searching technologies; connecting the channels with the outputted signals to demodulation modules to demodulate the broadcast signals. The system and the method have the advantages that digital channelized receivers and digital broadcast demodulation systems are combined with one another, the digital channelization technologies on the basis of FFB algorithms, the automatic signal searching technologies and digital orthogonal demodulation technologies are provided, accordingly, functions of parallelly monitoring and demodulating the multiple channels of broadcast signals can be implemented, the system and the method are applicable to diversified broadcast signals [AM (amplitude modulation), DSB (double-side-band), SSB (single-side-band), FM (frequency modulation) and FM stereophonic broadcast signals] and are high in flexibility, and the efficiency of the broadcast receivers can be improved.

The invention discloses a polarization-multiplexing-based method and device for modulating and directly detecting optical signals. The method comprises the following steps: respectively modulating single side band radio-frequency signals and double side band baseband signals in an X polarization direction to form single side band optical signals, and modulating single side band radio-frequency signals and double side band baseband signals in a Y polarization direction to form double side band optical signals at a sending end; combining and outputting the single side band optical signals and the double side band optical signals by an optical coupler; directly detecting receiving signals at a receiving end by a photoelectric detector to obtain a hybrid frequency spectrum of the double side band optical signals and the single side band optical signals, then demodulating the hybrid frequency spectrum to obtain the single side band radio-frequency signals, reconstituting autodyne frequency components of the single side band optical signal by using the single side band optical signals obtained by demodulating, and separating the double side band baseband signals out of the hybrid frequency spectrum. By virtue of the polarization-multiplexing-based method and device for modulating and directly detecting optical signals, the whole frequency spectrum resource is reasonably used; the influence of frequency selective fading caused by chromatic dispersion of the double side band baseband signals is avoided; the transmission performance of the system is improved.

The invention discloses a method of generating light millimeter wave without light modulator and full duplex fiber wireless communication system which belongs to fields of Radio-on-Fiber (ROF) communication system. The base band data signal and radio frequency sine wave are mixed to drive the direct modulating laser to generate double-side-band signal, then transmitted to the base station via optical fiber, the base station adopts filter to separate first order side-band signal and center carrier wave. The first order side-band forms light millimeter wave whose repetition frequency is two times of radio frequency signal. The full duplex fiber wireless communication system of the invention provides five realization schemes of up-bound link and two schemes of receiver. Said method of generating light millimeter wave and full duplex fiber wireless communication system decrease the amount of light elements used, and economic effect can be obtained.

The present invention is to provide an optical modulating system for generating a signal of a frequency (f0+2fm) and a signal of a frequency (f0−2fm) and suppressing a signal of a frequency (f0) by a DSB-SC modulator.A fourth harmonic generating system for solving the above problem comprises a first DSB-SC modulator (2) a second DSB-SC modulator (3) and a signal control section (5) for controlling a modulating signal from a signal source (4) for generating modulating signals applied to the first and second DSB-SC modulators (2,3) so that a lower side-band signal (f0) generated by modulating the upper side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) and an upper side-band signal (f0) generated by modulating the lower side-band signal of the DSB-SC modulator (2) by the DSB-SC modulator (3) cancel each other.

The invention provides a double side band frequency diversity array radar system and an object positioning method thereof and belongs to the technical field of radar signal processing. The double side band frequency diversity array radar system consists of N array elements that are linearly and uniformly arranged at an interval, N is a positive integer, and each array element comprises an emitting part and a receiving part. The emitting part comprises a modulation signal generator, a double side band modulator and an emitting antenna, wherein an output end of the modulation signal generator is connected with an input end of the double side band modulator, and an output end of the double side band modulator is connected with the emitting antenna. The receiving part comprises a receiving antenna, a filter group and a positioning calculation unit, wherein the filter group consists of two narrow band filters that are different in frequency, the receiving antenna is connected with input ends of the two narrow band filters, and output ends of the two narrow band filters are connected with an input end of the positioning calculation unit.

The invention relates to a polarization multiplexing DD-OFDM-PON system and a signal transmission method, and belongs to the technical field of optical access networks. According to the polarization multiplexing DD-OFDM-PON system and the signal transmission method, radio frequency up conversion and radio frequency down conversion are adopted at the transmitting end and the receiving end of a system respectively; compared with an existing OFDM-PON system, the subcarrier using rate of the system is improved by one time. An optical-single-side-band modulation technology and a polarization multiplexing technology are adopted in the polarization multiplexing DD-OFDM-PON system and the signal transmission method, frequency spectrums of two polarization orthogonal signals are overlapped, so that the spectrum efficiency is improved by one time compared with a polarization multiplexing DD-OFDM-PON system with optical double-side bands or a DD-OFDM-PON system without the polarization multiplexing technology. An MIMO channel estimation technology is adopted in the polarization multiplexing DD-OFDM-PON system and the signal transmission method, so that the good data recovery function is achieved, the bit error rate performance of the system performance is similar to the 40 Gb / s system performance, and the system robustness is good.

Signal egress from a shielding flaw in a cable telecommunication system is detected, even where signals carried by the cable telecommunication system are quadrature amplitude modulated signals that statistically resemble broadband noise by generating a marker signal comprising a double side band, suppressed carrier signal in the fringes of contiguous frequency bands and at a power level which cannot cause perceptible interference with signals in those contiguous frequency bands. The separation of the sidebands comprising the marker signal can unambiguously identify the marker signal and can distinguish between different cable telecommunication systems installed in the same geographic area. The marker signal can be additionally coded by varying the frequency and / or amplitude of the modulating signal used to create the marker signal.

The present invention discloses a method and system for measurement of an optical device on the basis of optical double-side band modulation, belonging to the fields of optical device measurement and microwave photonics technologies. The method provided by the invention employs general optical double-side band modulation signals and optical double-side band signals after Hilbert transform to measure the spectral response of an optical device to be measured, and employs the data processing technology to modulate and obtain the spectral response of an optical device to be measured (including range response and phase response). The present invention further discloses an optical device spectral response measurement system on the basis of optical double-side band modulation. Compared with an optical device spectral response measurement technology in the prior art, the method and system for measurement of an optical device on the basis of optical double-side band modulation have larger dynamic range, wider measurement range and lower cost.

The invention discloses a microwave photon filter which comprises a radio frequency amplifier, an erbium-doped fiber amplifier, a tunable optical attenuator, a microcavity coupling system, a spectrumanalyzer and a photoelectric detector. Narrow-linewidth optical carrier wave emitted by a tunable laser passes through a polarization controller and then is processed by DP- MZM into double-side-bandlight wave, and after the double-side-band light wave is amplified by the erbium-doped fiber amplifier, the light power of the double-side-band light wave entering the micro-cavity coupling system iscontrolled by the tunable optical attenuator; wherein an optical signal output by the micro-cavity coupling system is divided into two paths, one path enters the spectrum analyzer for monitoring sideband information of the optical signal in real time, and the other path enters a VNA for monitoring a radio frequency spectrum of the optical signal after passing through the photoelectric detector; meanwhile, the VNA outputs a radio frequency signal, and the output radio frequency signal is loaded to the DP-MZM through an orthogonal mixer after passing through the radio frequency amplifier, and modulation of a sideband is realized. The microcavity coupling system is obtained by attaching the microsphere structure to the conical region of the second conical optical fiber in an over-coupling manner.

A ATSC compliant digital television (DTV) receiver. including an image rejection filter, an interpolator, a numerically controlled oscillator (NCO), a matched filter unit, a frequency converter, and a DC remover. The image rejection filter removes (filters out) an unwanted image signal and an adjacent channel's interference signal from a first intermediate frequency (IF) signal sampled at a first sampling frequency. The interpolator resamples (at a second sampling frequency) a signal output from the image rejection filter and compensates for a predetermined symbol timing offset in response to a first control signal, thereby outputting a second IF signal. The NCO down converts the second IF signal and simultaneously compensates for a predetermined carrier offset in response to a second control signal, thereby outputting a first complex signal. The matched filter unit receives the first complex signal and filters the first complex signal, thereby outputting a second complex signal. The frequency converter generates a third complex signal having a double side band from the second complex signal output from the matched filter unit. The DC remover removes (filters out) a pilot signal from a DC signal included in the third complex signal output from the frequency converter.

This invention discloses a fiber radio communication system of a simple structure and capable of providing full-duplex communication in the ROF communication system, which uses an electric mixer to generate mm wave signals at the central station and carries out double-side-band modulation to the signals to generate double-side-band modulated signals to be sent to the base station, takes the central carrier wave in the signals as the light carrier in the up link and applies a photomodulator to modulate data in the up link of a user mobile terminal onto the light carrier to be sent to the base station for treatment and picks up double-frequency one step side-band in the signals to generate necessary electric-mm waves by a photo-detector and emitted by an antenna.

Provided is an optical communication system capable of suppressing the deterioration of an intensity waveform of an optical intensity modulated signal subjected to transformation using SSB modulation and improving a bit error ratio and a receiver sensitivity of the optical intensity modulated signal. The optical communication system includes: an optical transmitter section including: a single-side band modulation circuit configured to subject a double-side band modulated signal to generate a single-side band modulated signal; a correction circuit configured to correct an intensity of the single-side band modulated signal so that the intensity of the single-side band modulated signal becomes closer to an intensity of the double-side band modulated signal; and an optical IQ modulator configured to output an optical modulated signal; and an optical receiver section configured to receive the optical modulated signal to directly detect an intensity component of the optical modulated signal.

In the present invention, an all digital, multi channel RF transmitter is utilized for a parallel magnetic resonance imaging (MRI) device, MRI signal generation, modulation and amplification are employed entirely digitally in the proposed RF transmitter, which enables each transmit channel to be easily and individually reconfigured in both amplitude and phase. Individual channel control ensures a homogeneous magnetic field in the multi channel RF coil in MRI Besides the homogeneous magnetic field generation, multi-frequency MRI signal generation is made easy by the present invention with very high frequency resolution. Multi-frequency enables faster image acquisition which reduces MRI operation time. Digital Weaver Single Side Band (SSB) modulation is also incorporated into the all digital transmitter to suppress unwanted bands of Double Side Band (DSB) MRI signals. The power amplifier in the MRI transmitter does not amplify the unwanted band so that SSB modulation leads to higher power efficiency.

The invention discloses a PMD (polarization mode dispersion) and CD (chromatic dispersion) simultaneous-monitoring device. The PMD and CD simultaneous-monitoring device comprises a beam splitter (1), a filter (2), a first photoelectric converter (3), a first electric band-pass filter (4), a first power meter (5), a second photoelectric converter (6), a second electric band-pass filter (7) and a second power meter (8). The invention further provides a PMD and CD simultaneous-monitoring method adopting the device. The PMD and CD simultaneous-monitoring method includes acquiring SSB (single side band) signals through a band rejection filter, calibrating SSB signal power and double-side band signal power which are used for monitoring DGD (differential group delay) and monitoring CD respectively. The PMD and CD simultaneous-monitoring device and method are applicable to a high-speed optical communication system, capable of simultaneously monitoring PMD and CD without changing a transmitter, and cost and complexity are reduced.

A single side band (SSB) response method of a radio frequency identification (RFID) tag receives a double side band (DSB) response signal whose frequency band is shifted from the RFID tag by shifting an SSB frequency band after transmitting an SSB command signal to an RFID tag. Even though the reader uses the SSB frequency band, the reader can receive a stable DSB response signal from the RFID tag.

The present invention discloses a method and system for measurement of an optical device on the basis of optical double-side band modulation, belonging to the fields of optical device measurement and microwave photonics technologies. The method provided by the invention employs general optical double-side band modulation signals and optical double-side band signals after Hilbert transform to measure the spectral response of an optical device to be measured, and employs the data processing technology to modulate and obtain the spectral response of an optical device to be measured (including range response and phase response). The present invention further discloses an optical device spectral response measurement system on the basis of optical double-side band modulation. Compared with an optical device spectral response measurement technology in the prior art, the method and system for measurement of an optical device on the basis of optical double-side band modulation have larger dynamic range, wider measurement range and lower cost.

A ATSC compliant digital television (DTV) receiver including an image rejection filter, an interpolator, a numerically controlled oscillator (NCO), a matched filter unit, a frequency converter, and a DC remover. The image rejection filter removes (filters out) an unwanted image signal and an adjacent channel's interference signal from a first intermediate frequency (IF) signal sampled at a first sampling frequency. The interpolator resamples (at a second sampling frequency) a signal output from the image rejection filter and compensates for a predetermined symbol timing offset in response to a first control signal, thereby outputting a second IF signal. The NCO down converts the second IF signal and simultaneously compensates for a predetermined carrier offset in response to a second control signal, thereby outputting a first complex signal. The matched filter unit receives the first complex signal and filters the first complex signal, thereby outputting a second complex signal. The frequency converter generates a third complex signal having a double side band from the second complex signal output from the matched filter unit. The DC remover removes (filters out) a pilot signal from a DC signal included in the third complex signal output from the frequency converter.

The invention relates to a biogas project big data platform system and method and belongs to the field of biogas projects; the system comprises a data acquisition module, a data transmission module and a data processing module; the data acquisition module is connected to the data processing module through the data transmission module; the data acquisition module comprises a temperature sensor, a pressure sensor, a pH value sensor, a methane sensor, a carbon dioxide sensor, a hydrogen sulfide sensor and a weight sensor. The data transmission module includes a double-sideband amplitude modulation circuit. The data processing module includes at least one user base station unit and a server unit. The user base station unit is a PC machine, and the server unit is a server; the biogas project big data platform system and method are implemented based on summary of parameter laws of biogas fermentation; intelligent monitoring, state warning and self-processing capability of the biogas projectscan be improved; guidance on optimization of the fermentation process, reduction of energy consumption for the fermentation, early warning of fermentation states and evaluation of operational effectsis provided.

The invention discloses a laser measurement method based on double-sideband modulation, which is used for measuring distance information and speed information of an object to be measured simultaneously. The laser measurement method comprises the steps of modulating a linear frequency modulation microwave signal on an optical carrier, and generating a carrier-suppressed double-sideband modulation optical signal; then using the generated double-sideband modulation optical signal as probe light, and transmitting the probe light to the object to be measured; performing frequency beating on an echo signal and a local oscillation optical signal to obtain an electric signal which simultaneously contains time delay information and Doppler frequency shift information of the echo signal, wherein the local oscillation optical signal is obtained by splitting the optical carrier or the double-sideband modulation optical signal; and finally extracting the time delay information and the Doppler frequency shift information of the echo signal from the electric signal, obtaining distance information of the object to be measured according to the time delay information, and obtaining speed information of the object to be measured according to the Doppler frequency shift information. The invention further discloses a laser measurement device based on double-sideband modulation. The laser measurement method and device based on double-sideband modulation can simultaneously realize real-time and accurate measurement for the distance information and the speed information of the object to be measured.

The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signal The invention belongs to a method for generating a single high-frequency side band millimeter wave signal by using a smaller-bandwidth intensity modulator and a lower-frequency radio-frequency signalin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal perfoin the technical field of Radio-over-Fiber (abbreviated as ROF). The system makes full use of the reliability and low cost characteristics of double-side-band modulation and the excellent signal performance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsrmance and fiber dispersion of single-side-band modulation. At a central station, multiple double-frequency technology is adopted to generate high-frequency millimeter microwaves, so the requirementsof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesof the central station on element bandwidth are reduced and the configuration of the central station is simple and easy to realize, and the cost of the central station is reduced. A base station usesa filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier wavea filter to acquire a single-side-band signal having a bandwidth which is two times of that of the conventional single-side-band. Therefore, a higher direct current component at a central carrier waveposition generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the central position generated when the single-side-band modulation is used directly is avoided and the influence of the fiber dispersion on the signal is reduced. In addition, the method can filter the centralcarrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.carrier waves of the ROF millimeter waves from a down link and be used for reusing the wavelength of an up link, and simplifies the base station.

In the present invention, an all digital, multi channel RF transmitter is utilized for a parallel magnetic resonance imaging (MRI) device, MRI signal generation, modulation and amplification are employed entirely digitally in the proposed RF transmitter, which enables each transmit channel to be easily and individually reconfigured in both amplitude and phase. Individual channel control ensures a homogeneous magnetic field in the multi channel RF coil in MRI. Besides the homogeneous magnetic field generation, multi-frequency MRI signal generation is made easy by the present invention with very high frequency resolution. Multi-frequency enables faster image acquisition which reduces MRI operation time. Digital Weaver Single Side Band (SSB) modulation is also incorporated into the all digital transmitter to suppress unwanted bands of Double Side Band (DSB) MRI signals. The power amplifier in the MRI transmitter does not amplify the unwanted band so that SSB modulation leads to higher power efficiency.

An apparatus and method for WGIO phase modulation are described. In one embodiment, the method includes the receipt of a high-speed data stream, encoded according to an 8b / 10b code. Once received, a symbol rate of the data stream is reduced by a predetermined amount. Finally, once the symbol rate is reduced, a square wave carrier is phase modulated, using the reduced data rate data stream to generate a WGIO signal having double side band spectrum distributed either side of the square wave carrier. Accordingly, in one embodiment, a 3GIO signal may be phase modulated in order to fall within a spectrum that is not currently occupied by a wireless protocol, including, for example, Wireless Local Area Network (WLAN), Wireless Wide Area Networks (WWAN), global positioning systems (GPS), or the like in order to prevent interference therebetween.