337 results about "Single side band" patented technology

A method and system for generating and transmitting optical signals with only one sideband. Single-sideband optical signal transmission reduces the signal impairment effects associated with dispersion. Such transmission also increases the spectral efficiency of optical transmission systems. Single-sideband modulation also makes possible electrical compensation for optical link dispersion during transmission. Single-sideband modulation is generated using the modulating data signal and its Hilbert transform, which is approximated by a tapped-delay time filter. Line coding is used to remove the low-frequency content in the modulating data signal, avoiding the inefficiencies of tapped-delay-line filter approximated Hilbert transformers at low frequencies. Line coding can also help optical single side band signal generation and transmission using a simple optical filter instead of Hilbert transformers.

The invention discloses a microwave photon phase shifter based on a dual-polarization modulator and relates to the technical fields of microwaves and optical communication. The microwave photon phase shifter is mainly applied to microwave photon signal processing. The microwave photon phase shifter is shown in attached drawings and comprises a tunable laser source, a radio frequency signal source, a dual-polarization modulator, an optical band pass filter, a polarization controller, a polarizer and a photoelectric detector. The dual-polarization modulator is composed of Y branching units, upper and lower parallel Mach-Zehnder modulators MZM1 and MZM2 and a polarization beam combiner. According to the scheme, single side band modulation is achieved by utilizing the dual-polarization modulator and the optical band pass filter, the phase difference between optical carrier waves and side bands is changed by combining with the polarization controller and the polarizer, and accordingly dephased microwave signals are obtained after frequency beating of the photoelectric detector. 360-degree continuous phase shift of the microwave signals can be achieved, and the amplitude can be kept unchanged. In addition, the microwave photon phase shifter has the advantages of being simple in structure, easy to operate, wide in band width and the like.

With the normal modulation method, it is difficult to construct a Hilbert transform device because it is complicated. To solve the problem, a single sideband modulated optical pulse train is generated by driving a Mach-Zehnder optical modulator for optical pulse generation with a laser source's sine wave clock signals that have been rendered 90 degrees out of phase from each other. The generated pulse train is applied to an optical modulator, modulated with an NRZ (nonreturn-to-zero) data signal, and filtered by a narrow-band optical filter to obtain one of two sidebands.

The invention discloses an integral wired-wireless optical fiber asymmetric full-duplex access method and system. A light with the frequency being f0 is divided into two beams; one beam is modulated by a high-speed QAM (Quadrature Amplitude Modulation) millimeter-wave signal single side band with the frequency being fRF to generate a light carrier OLO1 (Optical Line Output 1) and a signal side band BBD with same polarization; and the other beam is inhibited and modulated by a local oscillator carrier with the frequency being fRF to generate an OLO2 with the same frequency as the BBD, after the OLO2 is orthogonal and combined with the OLO1, excess optical frequency components are filtered, and a downward infusion optical signal is generated. The infusion optical signal is transmitted to a base station through optical fiber, and can provide wired or wireless access. When the base station is accessed in a wired manner, a wavelength interpolation device separates the OLO2, the BBD from the OLO1, the OLO2 is subjected to coherent demodulation so as to obtain a downlink baseband signal, and the OLO1 carries an uplink low-speed signal and is back to a central station through the optical fiber; and when the base station is wirelessly accessed, a polarization beam splitter separates the OLO1, the BBD and the OLO2, the OLO1 is an optical millimeter-wave signal and is converted to electrical millimeter-wave through a photoelectric detector, and the OLO2 carries an uplink low-speed millimeter-wave signal and is back to the central station through the optical fiber, so that wired or wireless asymmetric full-duplex access is realized.

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.

A single side band transmitter having reduced DC offset includes a current source modulation module, a current mirror module, a 1st mixing module, a 2nd mixing module, a summing module, and a power amplifier. The current source module is operably coupled to modulate, in accordance with a modulation protocol (e.g., FSK) data to produce an in-phase current component and a quadrature current component. The current mirror module is operably coupled to mirror the in-phase current component to produce a mirrored in-phase current component and is also operably coupled to mirror the quadrature current component to produce a mirrored quadrature current component. The 1st mixing module is operably coupled to mix the mirrored in-phase current component with an in-phase current component of a local oscillation to produce a 1st mixed current signal. The 2nd mixing module is operably coupled to mix the mirrored quadrature current component with a quadrature component of the local oscillation to produce a 2nd mixed current signal. The summing module is operably coupled to sum the 1st and 2nd mixed current signals to produce an up converted signal. The power amplifier amplifies the up converted signal prior to transmission as a radio frequency signal.

A method and apparatus is disclosed herein for transmitting data wirelessly. In one embodiment, the transmitter comprises a first group of stages comprising a first plurality of XOR gates and a first plurality of transistors, each XOR gate of the first plurality of XOR gates having a pair of inputs coupled to one bit of a first set data bits and a first clock, both corresponding to a I quadrature baseband signal component, and having a first output coupled to drive one of the first plurality of transistors; a group plurality of stages comprising a second plurality of XOR gates and a second plurality of transistors, each XOR gate of the second plurality of XOR gates having a pair of inputs coupled to one bit of a second set of data bits and a second clock, both corresponding to a Q quadrature baseband signal component, and having a second output coupled to drive one of the second plurality of transistors, wherein the outputs of the first and second plurality of transistors are summed at a node to obtain a single-side band (SSB) RF output.

The invention discloses an optical single-side band modulation based optical device measuring method. By substituting a narrow linewidth laser with fixed output wavelength in an original measuring device by two tunable narrow linewidth lasers which are connected in parallel and utilizing the method of controlling the two lasers to operate alternatively, the measuring range of the optical single-side band measuring technology is widened from 0.4nm to 40nm or above, and accordingly, testing of response of optical devices to any wavelength in a certain wave band is realized. The invention further discloses an optical single-side band modulation based optical device measuring device and a using method thereof. Compared with existing single-side band measuring technology, measuring range of the measuring device is widened greatly.

The invention discloses a distributed type optical fiber sensing device which comprises a frequency stabilized laser, a single side band modulator, an optical pulse generator, an optical amplification unit, a scrambling unit, an optical circulator or optical coupler, a sensing optical fiber, a light splitting unit, a first optical detector, a second optical detector, a third optical detector, a high-speed data collecting unit and a system control and data processing unit. The system control and data processing unit is respectively and electrically connected with the frequency stabilized laser and the optical pulse generator, and the system control and data processing unit is electrically connected with the single side band modulator through a microwave generator. The distributed type optical fiber sensing device has the advantages that a high-stability laser light source is adopted to be combined with microwave frequency modulation, and temperature, strain and vibration can be simultaneously measured through the unique control and data processing process.

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 discloses a high-precision fiber bragg grating low-frequency strain sensing demodulation system which comprises a narrow linewidth laser, an electro-optic / acoustic optical modulator, a radio-frequency signal generator, a narrow linewidth optical fiber filter, a coupler, a circulator, a first fiber bragg grating sensor, a second fiber bragg grating sensor, a photoelectric detector and a strain demodulation module. The narrow linewidth laser provides narrow linewidth laser, the electro-optic / acoustic optical modulator modulates the narrow linewidth laser, the radio-frequency signal generator generates a chirp signal, the narrow linewidth optical fiber filter filters the modulated laser, and the coupler divides the obtained single-side-band laser capable of being tuned within the predetermined bandwidth into two paths of light sources. The circulator transmits the light reflected by the first fiber bragg grating sensor and the second fiber bragg grating sensor to the detector, the first fiber bragg grating sensor and the second fiber bragg grating sensor respectively receive outside strain and temperature signals, the photoelectric detector performs photovoltaic conversion on the light reflected by the first fiber bragg grating sensor and the second fiber bragg grating sensor, and the strain demodulation module obtains wavelength difference between the first fiber bragg grating sensor and the second fiber bragg grating sensor according to digital signals and obtains strain values of the fiber bragg grating strain sensors.

The invention discloses a light single sideband modulation method. According to the light single sideband modulation method, a light carrier wave is divided into two routes, with regard to one route of the two routes, light intensity modulation of a suppressed even order sideband is conducted at first, then one first-order sideband signal is filtered out from obtained light intensity modulation signals, and finally the one first-order sideband signal which is filtered out is merged with the other route light carrier wave to enable a final light sideband modulation signal to be obtained. The invention further discloses a light single side band modulator, optical device measuring equipment and an optical device measuring method, wherein the light single side band modulator, the optical device measuring equipment and the optical device measuring method adopt the modulation method. The light single sideband modulation method can effectively eliminate influence of second-order sideband of the single sideband signal so as to improve dynamic range of a system. The optical device measuring equipment and the optical device measuring method based on the modulation method can solve the problem of selection of an optical device to be tested and the problem of measuring error caused by the second-order sideband of the sideband signal under the condition of guaranteeing measurement accuracy.

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 provides a WDM-PON-RoF wired / wireless selectable access system and method based on SSB-OFDM. In the WDM-PON wired / wireless selectable access system, an OLT enables N ways of 4QAM-OFDM radio frequency signal single side bands to be modulated on N different optical carriers, and the N ways of 4QAM-OFDM radio frequency signal single side bands are reused as down link signals. RN distributes one way of optical OFDM signals and two ways of optical carriers with different radio frequencies for each ONU. According to the different user demands, each ONU conducts beat frequency on the optical OFDM signals and one way of optical carriers with small / large frequency spaces with the optical OFDM signals, therefore, wired / wireless access is achieved, and the other way of optical carriers are used as a modulating light source of up-link signals. The WDM-PON wired / wireless selectable access system and method are used, selectable access of wired signals or 60 GHz frequency band wireless signals can be achieved, the purpose of being free of light sources of the ONUs is achieved, and the cost and the complexity of the ONUs are lowered. An SSB and OFDM modulating technology is used in the WDM-PON wired / wireless selectable access system, and the spectrum efficiency is improved.

The invention discloses an optical device measuring method based on optical single side band modulating. The optical device measuring method includes the steps of making improvements on the basis of an optical device measuring technology based on optical single side band modulating in the prior art, dividing optical single side band swept-frequency signals into two paths during photovoltaic conversion, filtering carrier waves of one of the two paths, adjusting the length of optical path of the other path, in the end using a balance photoelectric detector to conduct balance photoelectric detection of two optical signal paths, and obtaining electrical signals after conversion. The invention further discloses an optical device measuring device based on the optical single side band modulating. Compared with the prior art, the optical device measuring method eliminates errors introduced into the measuring results due to beat frequencies of numerous high-order side bands and residual first-order side bands of optical single side band modulating signals through the method of balance photoelectric detection and obtains the measuring results of higher accuracy.

Provided are methods and systems for receiving and processing optical signals are provided. A dual single side band (SSB) modulation scheme is utilized to take advantage of given wavelengths' bandwidth. Modulation schemes are employed that modulate each SSB with their In-phase (I) and Quadrature (Q) components. The methods and systems discussed perform MIMO de-multiplexing algorithms to remove any imaging components of the left and right SSBs provided by the modulators. Various algorithms can be employed, including but not limited to inserting time interleaved training sequences into the channels of the right and left SSB signals or by employing a constant-modulus-algorithm (CMA) de-multiplexing.

A hearing-aid apparatus using ultrasonic waves is inserted and mounted within an external auditory meatus of an ear, generates an ultrasonic wave band signal by single side band amplitude modulation of a sound signal that is received through a microphone, and outputs the ultrasonic wave band signal and a carrier signal that is used for single side band amplitude modulation as an ultrasonic wave signal to a transfer medium in a predetermined beam direction. Therefore, the ultrasonic wave signal forms a focal area in a damaged hearing organ area, the ultrasonic wave band signal is restored to a sound signal by nonlinear characteristics of a transfer medium in the focal area, and the damaged hearing organ detects the sound signal.

The present invention relates to a quadrature divider which may be used in a phase locked loop or frequency synthesiser or with a single side band mixer. According to a preferred embodiment the divider takes a quadrature input and has a quadrature output. The divider has four analog mixers 1, 2, 3 and 4. The first two mixers 1, 2 take the in-phase quadrature input, while the second mixers 3, 4 take the quadrature-phase quadrature input. The outputs and feedback loops of the mixers are properly arranged such that the in-phase and quadrature-phase outputs of the divider have a determinisitic phase sequence relationship based on the phase sequence relationship of the corresponding quadrature inputs. Third order harmonics may be minimised or reduced by addition or subtraction of the mixer outputs. As the divider is able to take a quadrature input, there is no need for a dummy divider in the phase locked loop, thus saving space and power.

The invention discloses a device and a method for generating frequency doubling single side band optical carrier millimeter waves in the field of optical communication. The device comprises an adjustable optical source, a radio frequency signal source, an electric amplifier, an electric shunt, a phase shifter and a nested Mach-Zehnder modulator, wherein the output end of the adjustable optical source is connected with the optical input end of the nested Mach-Zehnder modulator; the output end of the radio frequency signal source is connected with the input end of the electric amplifier; the output end of the electric amplifier is connected with the input end of the electric shunt; two output ports of the electric shunt are connected with a radio-frequency driving port of an upper arm sub-modulator of the nested Mach-Zehnder modulator and an input port of the phase shifter respectively; and the output end of the phase shifter is connected with a radio-frequency driving port of a lower arm sub-modulator of the nested Mach-Zehnder modulator. The method comprises the steps of: regulating the phase shift amount of the phase shifter, and arranging the main bias voltage of the nested Mach-Zehnder modulator and the bias voltage of the upper arm and lower arm sub-modulators reasonably. By the device and the method, a structure of a system is simplified, and the tenability and expansibility of the system are improved.

The invention discloses an optical fiber sensing method, an optical fiber sensing device and a using method of the optical fiber sensing device. In the optical fiber sensing method disclosed by the invention, a transmission function curve of an optical fiber grating is obtained by adopting a method for ensuring an optical single side band sweep frequency signal modulated by a microwave sweep frequency signal to pass through the optical fiber grating. The optical fiber sensing device disclosed by the invention comprises a microwave sweep frequency source, a narrow linewidth laser, a broadband single side band modulator, a narrow-band optical fiber grating sensor, an optical detector, a microwave amplitude-phase information extraction module, a data processing control module and a display module. The invention also discloses the using method of the optical fiber sensing device. Compared with the prior art, the optical fiber sensing method and the optical fiber sensing device have high sensing accuracy and large measurement range and the distributed sensing can be implemented by adopting a mode that a plurality of narrow-band optical fiber gratings with different stop-band center wavelengths are cascaded.

The invention provides an up converter and a signal processing method thereof. The up converter mainly comprises a local frequency synthesizer, a quadrature modulator, a power automatic gain control module and a power attenuation module. The signal processing method mainly comprises: based on received frequency scale input signal and set frequency allocation data, the local frequency of various frequency points is generated, a radio frequency local signal having the local frequency and baseband signals of I and Q ways are mixed in the quadrature modulation mode to obtain a single side band radio frequency modulation signal; and the power of the single side band radio frequency modulation signal is subjected to automatic gain control, and then to accurate power control. The up converter can output the signals (such as navigation signal) compatible with a plurality of frequency points, and the frequency by which the signals are outputted can be conveniently changed in real time by a user during operation.

The present invention relates to a single side band modulator for splitting a signal into a first split signal and a second split signal 90 degrees out of phase with the first split signal. A first double balanced mixer modulates the first split signal and includes a transformer, a modulating signal input, and a first diode ring. The transformer connects the first diode ring to a quadrature hybrid. A second double balanced mixer modulates the second split signal and includes a transformer, a modulating signal input, and a second diode ring. The transformer of the second double balanced mixer connects the second diode ring to the quadrature hybrid. The first and second diode rings are connected in parallel and are connected to a third transformer which performs the function of a power combiner.

This invention provides an approach to lock the optical phase of a single sideband, carrier-suppressed coherent-AM analog optical link, so that for example an RF signal can be transmitted with high fidelity over fibers. In some embodiments, a method comprises providing a RF locking signal; impressing an RF input signal and the RF locking signal onto the optical field of a suppressed carrier; introducing the optical spectrum to a photonic integrated circuit comprising a microresonator filter and a finite impulse response filter; selectively passing the double sideband, associated with the locking frequency, through the finite impulse response filter; and recovering a RF output signal, wherein a feedback loop provides dithering to stabilize the optical phase of the link and thus preserve amplitude / phase integrity for the RF-photonic signal. The disclosed method is especially suited to the filtering of RF-photonic signals via use of the resonance passbands derived from microdisks or micro-rings.

The invention relates to a phase-sensitive optical time-domain reflectometer based on a linear frequency-modulation pulse and a measurement method of the phase-sensitive optical time-domain reflectometer. The phase-sensitive optical time-domain reflectometer comprises a laser device, a single side band modulator SSBM, an acoustic optical modulator AOM, an erbium-doped optical fiber amplifier EDFAI, an EDFAII, an arbitrary waveform generator AWG, an optical fiber circulator, a fiber Bragg grating filter FBG, a photoelectric detector, a data collection module and a to-be-measured optical fiber, wherein laser enters the single side band modulator SSBM and is modulated into pulsed light by virtue of the acoustic optical modulator AOM, and the pulsed light is amplified by virtue of the erbium-doped optical fiber amplifier EDFAI and enters the to-be-measured optical fiber through the optical fiber circulator; and a backward Rayleigh scattering signal is output through the optical fiber circulator, a backward Rayleigh scattering optical signal is amplified by virtue of the erbium-doped optical fiber amplifier EDFAII and is detected and converted into an electric signal through the fiber Bragg grating filter FBG, and the data collection module executes data collection and data analysis. By the utilizing linear frequency-modulation pulse, the measurement time is shortened, and the dynamic performance of a system is improved; and the scheme provided by the invention is convenient and feasible, and the structure of the system is relatively simple.

A frequency synthesizer for mixing reference frequencies using at least one control signal has a local oscillator, frequency dividers for dividing a frequency generated from the local oscillator and generating at least one control signal, and a single side band (SSB) mixer for mixing the reference frequencies, using the frequency generated from the local oscillator and the control signal. The frequency synthesizer has a simplified structure, and can easily mix reference frequency signals without a need for additional power.

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 Doppler frequency shift detection method and device based on the photonic technology. A continuous laser light source is divided into two branches through a coupler, wherein one branch enters a carrier inhibition type single side band modulation module and is modulated by emitted microwave / millimeter wave signals, and a generated single optical side band enters an electro-optical modulator and is modulated by the microwave / millimeter wave signals which are reflected and contain Doppler frequency shift information; the second branch enters an acoustic optical modulator to conduct certain optical frequency shift; the two branches enter a low-speed photoelectric detector after outputs of the two branches are merged, and the two branches generate low-frequency radio frequency signals at beat frequency; the generated radio frequency signals are subjected to spectral analysis, and then the Doppler frequency shift amount and direction can be obtained. The Doppler frequency shift detection method and device are based on the photonic technology, the structure is simple, the whole detection process has nothing to do with the carrier frequency of the microwave / millimeter wave signals to be detected, and Doppler frequency shift detection can be carried out within a wide frequency band range.

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.