80 results about "Coded excitation" patented technology

In one embodiment, a method of receiving a decoded audio signal that has a transmitted pitch lag is disclosed. The method includes estimating pitch correlations of possible short pitch lags that are smaller than a minimum pitch limitation and have an approximated multiple relationship with the transmitted pitch lag, checking if one of the pitch correlations of the possible short pitch lags is large enough compared to a pitch correlation estimated with the transmitted pitch lag, and selecting a short pitch lag as a corrected pitch lag if a corresponding pitch correlation is large enough. The postprocessing is performed using the corrected pitch lag. In another embodiment, when the existence of irregular harmonics or wrong pitch lag is detected, a coded-excited linear prediction (CELP) postfilter is made more aggressive.

Pulse-echo imaging systems and methods are provided, including a transmit code sequencer and a pulse generation circuit, The transmit code sequencer is configured to input a transmit code sequence to the pulse generation circuit. A transducer is configured to receive electrical signals provided as pulses using coded excitation according to the transmit code sequence, and to transduce the electrical signals to pulses of energy other than electrical signals. The transducer is further configured to receive echoes of the pulses of energy other than electrical signals and convert the echoes to received electrical signals generate using coded excitation. A receive circuit is configured to receive the received electrical signals generate using coded excitation, perform analog sampling of the received electrical signals generate using coded excitation, and provide a weighted, summed digital signal by processing the analog samples. At least one example of a pulse imaging system described is configured for ultrasonic pulse-echoes. At least one example of a pulse imaging system described is a medical diagnostic imaging system.

A method of significantly reducing error propagation due to voice packet loss, while still greatly profiting from long-term pitch prediction, is achieved by adaptively limiting the maximum value of the pitch gain for the first pitch cycle within one frame. A speech coding system for encoding a speech signal, wherein said a plurality of speech frames are classified into said a plurality of classes depending on if the first pitch cycle is included in one subframe or several subframes. The pitch gain is set to a value significantly smaller than 1 for the subframes covering first pitch cycle; wherein the pitch gain reduction is compensated by increasing the coded excitation codebook size or adding one more stage of excitation for the subframes covering the first pitch cycle.

An ultrasound imaging scanner has a transducer having a number N of transducer elements. Distinct transducer elements are excited with distinct signals, which can be uniquely coded signal pulses or distinct chirps. The combined echo signal received at a particular transducer is correlated with the excitation signal applied to the particular transducer element to isolate its individual echo.

An audio signal encoder includes a transform-domain path which obtains spectral coefficients and noise-shaping information on the basis of a portion of the audio content, and which windows a time-domain representation of the audio content and applies a time-domain-to-frequency-domain conversion. The audio signal decoder includes a CELP path to obtain a code-excitation information and a LPD parameter information. A converter applies a predetermined asymmetric analysis window in both if a current portion is followed by a subsequent portion to be encoded in the transform-domain mode or in the CELP mode. Aliasing cancellation information is selectively provided in the later case.

A method for speech processing in a code excitation linear prediction (CELP) based speech system having a plurality of modes including at least a first mode and a consecutive second mode. The method includes providing an input speech signal, dividing the speech signal into a plurality of frames, dividing at least one of the plurality of frames into sub-frames including a plurality of pulses, selecting a first number of pulses for the first mode, with a second number of remaining pulses in the frame plus the first number of pulses in the first mode for the second mode, providing a plurality of sub-modes between the first mode and the second mode, forming a base layer, forming an enhancement layer, generating a bit stream including a basic bit stream and an enhancement bit stream, wherein the basic bit stream is used to update memory states of the speech system.

Certain embodiments of the present invention provide a method and system for improved ultrasound imaging using single transmission coded excitation. Certain embodiments include encoding a first ultrasound beam with a first code, transmitting the first ultrasound beam on a first path, encoding a second ultrasound beam with a second code, transmitting the second ultrasound beam on a second path and receiving echo signals from the first and second ultrasound beams. The codes may be complimentary Golay codes or other complimentary codes. The first and second paths may be adjacent scan lines. The method may also include match filtering the echo signals with corresponding matched filters. Match filtered echo signals along adjacent scan lines may be filtered, such as with a lateral averaging filter or other finite impulse response filter. Alternate complementary code transmission helps preserve or improve frame rate while maintaining signal-to-noise ratio improvement and range lobe cancellation.

Disclosed is a gas ultrasonic flowmeter intermittent excitation and signal processing system based on an adjacent peak maximum difference value. An ultrasonic transmitting transducer is excited through intermittent excitation signals (continuous non-coding excitation signals are transmitted one time, and then transmitted again after a certain period of time), and an ultrasonic signals are generated; when a receiving transducer receives ultrasonic signals, the signals are converted into echo signals; then, zero phase filtering is performed on the received echo signals, a characteristic wave corresponding to the maximum difference value of adjacent peaks in the echo signals is found, a mean value of eight zero crossing points behind the characteristic waves is adopted as a characteristic point, ultrasonic signal down flow and reverse flow transmitting time is determined, and the gas flow is calculated.

A method of significantly reducing error propagation due to voice packet loss, while still greatly profiting from long-term pitch prediction, is achieved by adaptively limiting the maximum value of the pitch gain for the first pitch cycle within one frame. A speech coding system for encoding a speech signal, wherein said a plurality of speech frames are classified into said a plurality of classesdepending on if the first pitch cycle is included in one subframe or several subframes. The pitch gain is set to a value significantly smaller than 1 for the subframes covering first pitch cycle; wherein the pitch gain reduction is compensated by increasing the coded excitation codebook size or adding one more stage of excitation for the subframes covering the first pitch cycle.

An excitation signal coding apparatus capable of improving an error resilience by changing an excitation vector search method (more specifically, an error minimization criterion during a search). This coding apparatus is allowed to choose either of an ordinary search method and the search method of the present invention with using information input from a transmission channel condition monitoring section (215). That is, an ordinary search method is used when the transmission channel condition is good and no packet discarding is observed on the receiving side, and the search method of the present invention is used otherwise (when packet discarding is observed on the receiving side at a discarding rate of 5% or more, for example).

A speech coding method of significantly reducing error propagation due to voice packet loss, while still greatly profiting from a pitch prediction or Long-Term Prediction (LTP), is achieved by limiting or reducing a pitch gain only for the first subframe or the first two subframes within a speech frame. The method is used for a speech class decided by a classification algorithm; the classification algorithm is designed, depending on at least one pitch cycle length compared to one subframe size. Speech coding quality loss due to the pitch gain reduction is compensated by increasing a coded excitation codebook size or adding one more stage of excitation only for the first subframe or the first two subframes within the speech frame.

The present invention discloses an instantaneous elasticity imaging code detection method and a system. The method comprises the steps: an instantaneous low-frequency signal sent by a signal generator is subjected to power amplification to drive an electromagnetic vibrator and motivate the generation of an instantaneous shear wave inside a medium; modulating the coding of an ultrasonic pulse signal, detecting and tracking the vibration signal of the instantaneous shear wave based on the coded excitation technique to obtain a coded ultrasonic echo signal; amplifying and sampling the received coded ultrasonic echo signal to obtain coded detection echo discrete data; decoding according to the digital pulse compression technique to obtain a vibration displacement signal generated during the propagating process of the shear wave in a to-be-detected medium; according to the extracted displacement signal, calculating the speed of the instantaneous shear wave and the elastic modulus of the to-be-detected medium; and outputting the speed of the instantaneous shear wave and the elastic modulus of the to-be-detected medium. According to the technical scheme of the invention, the average emission energy of signals is improved, and the signal-to-noise ratio of echo signals is increased. Meanwhile, the system detection sensitivity and the ultrasonic penetration capability are improved. Moreover, the vibration signal extraction quality of the shear wave is improved, and the depth-detection penetrating power of the instantaneous elasticity imaging process is enhanced.

The present invention relates to a method and apparatus providing tissue harmonic imaging using an ultrasound machine. Coded pulses and the phase inverted version of the said coded pulses with time bandwidth greater than 1 are transmitted into the tissue. Backscattered echoes are received and filtered before or after coherent summation. Decoding / compressing of the received echoes of the coded pulses is implemented naturally through the propagation of the specially designed ultrawide band (>80%) waveforms inside tissue and pulse inversion. Costly decoding / compression filter are not necessary.

The present invention discloses a method of improving the coded speech quality in low bit rate analysis-by-synthesis (AbS) speech coders. This is accomplished by relaxing the waveform matching constraints for non-stationary plosive speech segments of speech signals by suitably shifting pulse locations of the coded excitation signal. The shifting results in the coded signal having phase information that does not exactly match original signal in places where it is perceptually insignificant to the listener. Furthermore, a technique for adaptive phase dispersion is introduced to the coded excitation signal to efficiently preserve important signal characteristics such as the energy spread of the original signal.

The application provides a method and a device for ultrasonic imaging as well as ultrasonic imaging equipment. The method comprises the following steps: a control excitation component applies coded excitation of different frequencies to each array element in an ultrasonic probe, so as to enable each array element to utilize the applied coded excitation for producing and emitting ultrasonic signals; ultrasonic echo signals returned by the ultrasonic probe are received; the coded excitation applied to each array element is utilized for decoding the corresponding ultrasonic echo signals; and beam forming is carried out after the decoded ultrasonic echo signals are weighted, so as to obtain beam forming signals and display ultrasonic images according to the beam forming signals. Through the way of applying the coded excitation of different frequencies to each array element, the invention can increase the energy carried by the ultrasonic signals, promote the penetration force, enable the received ultrasonic echo signals not to interfere with each other and improve the image contrast. The image resolution is also improved by adopting the weighting method for beam forming.

A method for detecting a target or targets in a medium. The method incorporates generating beams of ultrasonic wave energy each having a modulation envelope and causing each beam of wave energy to impact a target region having a multiplicity of targets and demodulating each signal generated by vibration of each target caused by the interaction of a respective ultrasound wave energy beam having a modulation envelope with each of the targets and receiving each demodulated signal from each target by a multiplicity of sensors. Thereafter, each time-of-flight of each demodulated signal from each of the targets to each of the multiplicity of sensors is computed to determine the location of a respective target.

The invention discloses an ultrasonic control release and monitor imaging method for medicament-carried contrast microbubbles and a microbubble breakage evaluation method. In the ultrasonic contrast monitor imaging method, a local, fixed-point and conformal control release function and a low-energy coded excitation monitor imaging function of medicament-carried ultrasonic contrast encapsulated microbubbles are realized on the conventional fully digital ultrasonic imaging system, so that working modes and the functions of the conventional fully digital diagnostic ultrasonic equipment are substantially extended. The local, fixed-point and conformal control release method of the medicament-carried ultrasonic contrast encapsulated microbubbles is firstly developed on the conventional fully digital ultrasonic imaging system; then the medicament-carried contrast microbubbles of a lesion region before and after medicament release are monitored by a low-energy coded excitation monitor imaging method; and finally, a method for evaluating medicament release capacity based on radio frequency echo data of the monitor imaging and variation in scatterer concentration of a region of interest is developed.

The present invention is related to a method for coding excitation signal of a target speech comprising the steps of: extracting from a set of training normalised residual frames, a set of relevant normalised residual frames, said training residual frames being extracted from a training speech, synchronised on Glottal Closure Instant (GCI), pitch and energy normalised; determining the target excitation signal of the target speech; dividing said target excitation signal into GCI synchronised target frames; determining the local pitch and energy of the GCI synchronised target frames; normalising the GCI synchronised target frames in both energy and pitch, to obtain target normalised residual frames; determining coefficients of linear combination of said extracted set of relevant normalised residual frames to build synthetic normalised residual frames close to each target normalised residual frames; wherein the coding parameters for each target residual frames comprise the determined coefficients.

The invention discloses a method for performing weld-joint ultrasonic detection through a frequency-phase compound coding excitation signal, relates to the technical field of welding structure quality detection, and aims at solving the problem that in existing weld-joint ultrasonic detection, a satisfactory detection result cannot be obtained when a frequency coding signal or a phase coding signal is separately adopted for excitation. The method comprises the following steps that the frequency-phase compound coding signal is edited; the frequency-phase compound coding signal is guided into a signal generator; the signal generator sends out a frequency-phase compound coding pulse signal; the excitation signal is loaded into an ultrasonic detection probe after passing through a power amplifier; the probe converts the electric signal into a sound signal to be loaded into a detected workpiece; ultrasonic waves are transmitted in the detected workpiece and reflected when the ultrasonic waves encounter an interface; the probe receives the sound signal and converts the sound signal into an electric signal; an ultrasonic acquisition card receives the electric signal; mismatched filtering is performed on an echo signal and the phase coding signal to obtain an intermediate result; matched filtering is performed on the intermediate result and the windowed frequency coding signal to obtain a final detection result. The method is applied to the field of welding quality detection.

The invention discloses a quasi one-time orthogonal complementary Golay (A,B) code ultrasonic phased array coded excitation method. The method comprises the following steps: coded excitation is carried out by Golay A code; Golay A to B code excitation transition of received echo is realized by software algorithm, and twice stimulated echoes of Golay A,B are obtained (orthogonal complementary Golay coded excitation condition is formed); pulse compression is carried out, decoding is realized by summarizing vectors, so that quasi one-time orthogonal complementary Golay coded excitation technology is realized, and replaces the traditional double-emission scheme with physical hardware. An effective noise inhibition-deconvolution algorithm is used, FPGA(Field Programmable Gate Array) is used for realizing excitation transition algorithm of sequence Golay A code excitation to Golay B code, in order to realize the purpose of quasi one-time excitation; the traditional Golay A,B code separated excitation scheme is improved, operation efficiency of the phased array system is increased by 50%, signal to noise ratio (related to coding length Lc) is greatly improved, the problem of decoding effect influenced by inconsistent received waveforms due to position changes of twice emissions in some dynamic scanning processes is avoided, and the method has an important application value in practical engineering.

A method of significantly reducing error propagation due to voice packet loss, while still greatly profiting from long-term pitch prediction, is achieved by adaptively limiting the maximum value of the pitch gain for the first pitch cycle within one frame. A speech coding system for encoding a speech signal, wherein said a plurality of speech frames are classified into said a plurality of classesdepending on if the first pitch cycle is included in one subframe or several subframes. The pitch gain is set to a value significantly smaller than 1 for the subframes covering first pitch cycle; wherein the pitch gain reduction is compensated by increasing the coded excitation codebook size or adding one more stage of excitation for the subframes covering the first pitch cycle.

A module capable of appropriately selecting a linear predictive coding (LPC)-based or a code excitation linear prediction (CELP)-based speech or audio encoder and a transform-based audio encoder according to a feature of an input signal is a module that performs as a bridge for overcoming a performance barrier between a conventional LPC-based encoder and an audio encoder. Also, an integral audio encoder that provides consistent audio quality regardless of a type of the input audio signal can be designed based on the module.