332 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.

A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.

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.

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 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.

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 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 a measuring method and system for frequency response of an electro-optical modulator. A light beam splitter divides optical carrier signals into an upper path and a lower path; in the upper path, a Mach-Zehnder modulator modulates microwave signals output by a microwave source 1 to optical carrier waves, and double-side-band signals which inhibit the carrier waves are generated, and serve as pumping signals after being amplified; and in the lower path, the electro-optical modulator to be measured modulates microwave signals output by a microwave source 2 to optical carrier waves, and double-side-band signals are generated. The frequencies of the microwave source 1 and the microwave source 2 are adjusted, so that the double-side-band signals output by the electro-optical modulator to be measured form single-side-band signals in a Brillouin medium. A photoelectric detector converts the single-side-band signals into electric signals, an amplitude-phase receiver extracts amplitude and phase information from the electric signals, and combined response of the electro-optical modulator to be measured and the photoelectric detector are obtained; and the frequency response of the electro-optical modulator to be measured is obtained by removing the frequency response of the photoelectric detector.

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 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.

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.