38 results about "Pulse distortion" patented technology

Methods and instruments for suppression of multiple scattering noise and extraction of nonlinear scattering components with measurement or imaging of a region of an object with elastic waves, where elastic wave pulse complexes are transmitted towards said region where said pulse complexes are composed of a high frequency (HF) and a low frequency (LF) pulse with the same or overlapping beam directions and where the HF pulse is so close to the LF pulse that it observes the modification of the object by the LF pulse at least for a part of the image depth. The frequency and/or amplitude and/or phase of said LF pulse relative to said HF pulse varies for transmitted pulse complexes in order to nonlinearly manipulate the object elasticity observed by the HF pulse along at least parts of its propagation, and where received HF signals are picked up by transducers from one or both of scattered and transmitted components of the transmitted HF pulses. Said received HF signals are processed to form measurement or image signals for display, and where in the process of forming said measurement or image signals said received HF signals are one or both of delay corrected with correction delay in the fast time (depth-time), and pulse distortion corrected in the fast time, and combined in slow time to form noise suppressed HF signals or nonlinear scattering HF signals that are used for further processing to form measurement or image signals. The methods are applicable to elastic waves where the material elasticity is nonlinear in relation to the material deformation.

A shift register and a method for driving the same are disclosed. The shift register includes a plurality of stages serially connected to each other. Each of the stages independently generates first and second scan pulses. The first scan pulse is simultaneously applied to a previous stage and to a corresponding gate line of a liquid crystal panel. The second scan pulse is applied to a next stage. The shift register prevents scan pulses applied to each stage from being distorted, and prevents a multi-output signal from being generated.

An amplified laser source for amplifying a laser projection that includes a diode laser source modulated by a pulse generator applying an alternate high and low voltages higher and lower than a threshold voltage for projecting a modulated optical signal. The laser source further includes a first erbium-doped fiber (EDF) for amplifying the modulated optical signal. The laser source further includes a set of Bragg gratings for receiving the modulated optical signal from the first EDF for reflecting a grating-specific pulse-distortion-reduced optical signal. The laser source further includes an electro-absorption (EA) modulator synchronized with the pulse generator for increasing an extinction ratio of the optical signals. The laser source further includes a second erbium doped fiber (EDF) for receiving and amplifying the optical signal from the EA modulator wherein the second erbium doped fiber (EDF) having a length of several meters and a diameter greater than or equal to thirty-five micrometers.

The invention describes a number of differential, balanced high-speed circuits that permit the design of a receiver with Electronic Dispersion Compensation (EDC) on a single semiconductor substrate, including the functions of an analog Fast Forward Equalizer (FFE), a Clock and Data Recovery, a Decision Feedback Equalizer (DFE), enhanced by additional circuits that permit control of the slicing level to compensate for pulse distortion, and control of the phase offset to set the optimal eye sampling time when a distorted signal is received. To provide the high speed of operation, all circuits including the phase locked loop, operate as differential circuits, which include a number of improvements in the design of the charge pump, the decision feedback equalizer, the slicing level control, and others.

The invention is applicable to the technical field of a laser, and provides a tunable dual-wavelength ultrafast optical parameter oscillator. The tunable dual-wavelength ultrafast optical parameter oscillator comprises a pulse laser pumping source, an input coupling mirror, a periodic polarization crystal with a fan-shaped structure, a dispersion compensation device, an output coupling mirror, a beam splitter and a crystal temperature control device which are sequentially arranged. Compared with the prior art, the tunable dual-wavelength ultrafast optical parameter oscillator has the advantages that by a dispersion relation between group velocity and crystal temperature of pulse laser and by controlling a working temperature of the periodic polarization crystal, group velocity mismatching between signal light and idler frequency light in the periodic polarization crystal is eliminated; and the signal light and the idler frequency light are synchronously amplified, the matching bandwidth of the optical parameter oscillator can be improved, pulse distortion caused by temporal walk-off is prevented, and the optical parameter oscillator can simultaneously output two paths of high-quality ultrashort pulse laser.

Circuitry used to de-skew data channels coupling parallel data signals over a communication link employs SOI circuitry that is subject to generating pulse distortion due to the history effect modifying threshold voltages. To substantially eliminate the pulse distortion, data signals are XOR with a repeating scramble data pattern that generates scrambled data with a minimum average ratio of logic ones to logic zeros logic zeros to logic ones. The scrambled data is sent over the communication link and de-skewed in the SOI circuitry with little or no pulse distortion. The scramble data pattern is again generated at the receiver side of the communication link after a delay time to synchronize the logic states of the scramble data pattern that generated the scrambled data with the scrambled data at the receiver side. The delayed scrambled data pattern is again XOR'ed with the scrambled data to recover the data signal.

The invention provides an optical transmitter comprising a differential encoder having first and second outputs, the first and second outputs being of opposite polarity to one another, a first RZ converter connected to the first output of the differential encoder and a second RZ converter connected to the second output of the differential encoder, and a dual electrode Mach Zehnder modulator to which an unmodulated coherent light source is coupled, wherein the output of the first RZ converter is connected to a first electrode of the Mach Zehnder modulator and the output of the second RZ converter is connected to a second electrode of the Mach Zehnder modulator. The invention provides improved signal integrity as compared with existing RZ-DPSK solution through the use of high quality RZ drivers. Furthermore, the invention gives rise to controllable RZ pulse edge chirping, providing rapid pulse compression or broadening through a dispersive fibre length. This can be used to mitigate pulse distortion in non-linear transmission links.

Although the distribution type Brillouin time domain analysis has been given wide attention, it has not been well applied due to pulse distortion and high power of Raman amplification. According to the invention, the distribution type Brillouin amplifying technology and the frequency comb technology are combined and applied in a long-distance distribution type Brillouin time domain analysis system. Strength noise transferring and nonlinear effects caused by distribution type Raman amplification are solved; because the input light power is quite low, reliability of the system is guaranteed; and pulse shapes are restored by use of the frequency comb and incidence pulse light frequency mixing method, distortion of the pulse is avoided, thereby solving the problem of deterioration of spatial resolution caused by the deformation of the pulse and reducing transient-state gain saturation to some extent.

The invention relates to a coherent pulse laser radar which comprises a seed signal generation device, a signal transmitting and receiving module, a local oscillator signal modulation device and a frequency mixing device, wherein the seed signal generation device is used for generating a narrow linewidth seed laser signal; the signal transmitting and receiving module is used for modulating and amplifying the narrow linewidth seed laser signal and then transmitting the narrow linewidth seed laser signal as well as receiving an end surface light return signal reflected back by a to-be-tested object; the local oscillator signal modulation device is used for performing pulse modulation on the narrow linewidth seed laser signal to obtain a modulation signal; and the frequency mixing device is used for performing frequency beating processing on the end surface light return signal and the modulation signal to obtain a beating signal. According to the technical scheme, the local oscillator signal modulation device is additionally mounted on a local oscillator optical path, so that pulse modulation is performed on the narrow linewidth seed laser signal to obtain the modulation signal, and when the modulation signal and the end surface light return signal are subjected to frequency beating treatment, pulse distortion and strength distortion after frequency beating treatment are reduced,and the end surface information is reduced as far as possible finally.

A method of mitigating the effect of deterministic (only slowly changing) pulse distortions along an optical fiber communications link transmitting a train of pulses, and apparatus for performing it. Plural copies of the pulse train are made and are all coherently added together with the original train after delaying each copy by a different amount. The amplitude and phase of each copy are independently adjusted, normally by a computer, to optimize the resulting pulse shape. The technique is capable of mitigating (not totally eliminating) distortions of diverse origin, including but not limited to polarization mode dispersion, chromatic dispersion, multiple reflections, and self-phase modulation, even if they interact with each other.

The invention provides a low-frequency broadband satellite-borne SAR imaging ionosphere phase error compensation method, which is characterized in that series decomposition is carried out on ionosphere phase error to three terms based on Legendre orthogonal basis, and the obtained errors are mutually orthogonal, so that the problem of order coupling of an existing assessment method is solved; then, based on an expression of each order derived based on an orthogonal model, influence of zero-order phase error on broadening of direction images, first-order phase error on translation of distance images, on pulse broadening caused by second-order phase error and on pulse distortion caused by third-order phase error are quantitatively evaluated; and based on the influence, ionosphere total electron content TEC information can be obtained, and ionosphere influence compensation can be carried out on the images. The method can accurately reflect the influence of true ionosphere phase error on low-frequency broadband satellite-borne SAR imaging, and thus ionosphere influence compensation precision is improved.

The specification describes an optical transmission system for high speed, high capacity digital pulse transmission, i.e. at least 10 Gb/s at a duty cycle of at least 10%, which uses transmission fiber with a dispersion value greater than 20 ps/(nm-km) or more negative than -5 ps/(nm-km). The system operates in the pseudo-linear transmission mode (PLTM). In the PLTM it was discovered that pulse distortion decreases, i.e. eye closure penalty actually decreases, as the dispersion value increases. System performance actually improves by increasing the value of absolute dispersion of the transmission fiber.

A method of correcting RF pulse distortion is provided. The method can include obtaining a specified time-domain waveform. The method may also include directing a radio frequency power amplifier (RFPA) of a magnetic resonance imaging (MRI) scanner to generate output RF pulses based on the specified time domain waveform. The method may also include measuring the output time-domain waveform of the output RF pulse. The method may also include determining a modified time domain waveform corresponding to the excitation RF pulse based on the specified time domain waveform and the output time domain waveform. The method may also include instructing the MRI scanner to use the waveform generator and the RFPA, and based on the modified time-domain waveform, generate excitation RF pulses to excite one or more slices of the subject in the MRI scan.

A method and apparatus for writing data to an optical storage medium are disclosed. A write signal indicating power levels of a laser diode is generated by encoding and decoding codewords. The codewords are generated and decoded according to a Successive State Change Criterion (SSCC) or SSCC II proposed by the present invention. By doing so, toggling (i.e. state changing) times occurring in channels transferring the codewords can be significantly reduced to avoid the problems of pulse distortion and disappearance in high frequency transmission. Alternatively, toggles appearing in the respective channels can be spread to avoid interference between the channels. Further, a phase adjustment device for adjusting a phase of each codeword is disclosed.