摘要:
A CPU or microprocessor which includes a general purpose CPU, such as an X86 core, and a DSP. The CPU also includes an intelligent DSP function decoder or preprocessor which examines X8 opcode sequences and determines if a DSP function is being executed. The function preprocessor includes a look-up table which stores instruction sequences which implement DSP functions. Each pattern in the look-up table is compared with an instruction sequence to determine if one of the patterns substantially matches the instruction sequence. If the DSP function preprocessor determines that a DSP function is being executed, the DSP function preprocessor converts the opcodes to a DSP macro instruction that is provided to the DSP. The DSP executes one or more DSP instructions to implement the desired DSP function in response to the macro instruction. If the X86 opcodes in the instruction cache or instruction memory do not indicate or are not intended to perform a DSP-type function, the opcodes are provided to the X86 core. Thus, the DSP offloads these mathematical functions from the X86 core, thereby increasing system performance. The DSP operates in parallel with the X86 core, providing further performance benefits. The CPU of the present invention thus implements DSP functions more efficiently than X86 logic while requiring no additional X86 opcodes. The present invention also generates code that operates transparently on an X86 only CPU or a CPU according to the present invention which includes X86 and DSPs. Thus the present invention is backwards compatible with existing software.
摘要:
A CPU or microprocessor which includes a general purpose CPU, such as an X86 core, and a DSP. The CPU also includes an intelligent DSP function decoder or preprocessor which examines X86 opcode sequences and determines if a DSP function is being executed. The function preprocessor includes a pattern recognition detector which stores instruction sequences which implement DSP functions. The pattern recognition detector compares each pattern with an instruction sequence and determines if one of the patterns substantially matches the instruction sequence. If the DSP function preprocessor determines that a DSP function is being executed, the preprocessor converts or maps the opcodes to a DSP macro instruction that is provided to the DSP. The DSP executes one or more DSP instructions to implement the desired DSP function in response to the macro instruction. If the X86 opcodes in the instruction cache or instruction memory do not indicate or are not intended to perform a DSP-type function, the opcodes are provided to the X86 core as which occurs in current prior art computer systems. Thus, the DSP offloads these mathematical functions from the X86 core, thereby increasing system performance. The CPU of the present invention thus implements DSP functions more efficiently than X86 logic while requiring no additional X86 opcodes. The present invention also generates code that operates transparently on an X86 only CPU or a CPU according to the present invention which includes X86 and DSPs. Thus the present invention is backwards compatible with existing software.
摘要:
An improved vocoder system and method for estimating pitch in a speech waveform which more accurately disregards false pitch estimates resulting from secondary excitations. The vocoder system first performs a correlation calculation on a speech frame and generates an estimated pitch value. The present invention then compares the estimated or determined pitch with a threshold value to determine if the determined or estimated pitch has a suspiciously low pitch value. If so, the present invention performs error checking to disregard pitch estimates that are the result of the First Formant frequency's contribution to the pitch estimation process. The error checking involves examining the higher multiples of the determined pitch value to ascertain whether the determined pitch value might be incorrect. The present invention determines whether one or more higher multiples are missing, whether the higher multiples are related by a common factor, and whether adjacent multiples have missing peaks. The error checking also involves searching for missing or low correlation peaks in the neighborhood of missing higher multiples of the determined pitch. If the error checking indicates that the determined pitch is probably incorrect, then a new determination is made without the correlation peak corresponding to the rejected determined pitch. This provides a more accurate pitch estimation, thus enhancing voice storage quality. The present invention thus comprises an improved correlation method for estimating the pitch parameter which more accurately disregards false correlation peaks resulting from secondary excitations, including the contribution of the First Formant.
摘要:
A signal detector includes a transform unit and a cross-frame energy level unit. The transform unit is adapted to receive at least a first and a second frame of time domain input samples. The transform unit generates at least a first frequency energy value for the first frame and a second frequency energy value for the second frame based on the time domain input samples. The cross-frame energy level unit is adapted to compare the first frequency energy value to the second frequency energy value to determine the presence of a first tone in the time domain input samples. A method for detecting a signal includes receiving at least a first and a second frame of time domain input samples. At least a first frequency energy value for the first frame and a second frequency energy value for the second frame are generated based on the time domain input samples. The first frequency energy value is compared to the second frequency energy value to determine the presence of a first tone in the time domain input samples.
摘要:
An improved dual tone multifrequency (DTMF) or multitone signal detector which more efficiently and reliably detects DTMF signals. The present invention performs twist computations only when the signal has become stable, thus achieving more accuracy and reliability. The DTMF detector receives a plurality of digital samples of a received signal and calculates energy values for each of the plurality of different uncorrelated frequencies. The DSP then determines maximum values of the energy values for each of the two or more frequency groups, referred to as M(1) and M(2), to detect the plurality of tones in the received signal. The DTMF detector then performs improved twist computation and thresholding. The DTMF detector first determines if the M(1) and M(2) values of the respective frame being examined have the same indices. If so, the DTMF detector compares each of the M(1) and M(2) values of the respective frame being examined with the M(1) and M(2) values of the immediately prior frame, referred to as M'(1) and M'(2), and determines if the M(1) and M(2) values of the current frame are greater than the M'(1) and M'(2) values of the prior frame. If the M(1) and M(2) values of the current frame are greater than the M'(1) and M'(2) values of the prior frame, then the DTMF detector calculates a twist value using the maximum energy values M(1) and M(2) for the current frame being examined.
摘要:
The communications processor of the present invention comprises, in a single integrated circuit chip, the combination of a central processing unit (CPU) having an execution unit with an arithmetic logic unit and accumulators, a program counter, memory, a clock generator, a timer, a bus interface, chip select outputs, and an interrupt processor; a digital signal processor (DSP) having an instruction set to carry out a digital signal processing algorithm, an execution unit for carrying out multiply and accumulate operations and an external interface; an address bus connected between the CPU and the DSP; a data bus connected between the CPU and the DSP; and a static scheduler for statically scheduling execution of the signal processing algorithm between the digital signal processor and the CPU.
摘要:
An improved dual tone multifrequency (DTMF) signal detector which uses the Goertzel DFT algorithm and which utilizes variable or differing frame widths that are frequency dependent for improved detection and reduced error. The DTMF detector includes a codec receiver which receives signals from the transmission media, and a digital signal processor (DSP) coupled to the codec. The DSP receives the digital samples and preferably applies the Goertzel DFT algorithm using differing frame lengths according to the present invention. The DTMF detector utilizes a different frame width for different tones of the possible tone frequencies according to the present invention. Thus the calculation uses a different frame length N for different ones of the uncorrelated frequencies, wherein the different frame lengths comprise at least a subset N of the number of digital samples. The different frame lengths N are designed to optimally align the calculated frequency spectrum at each of the different uncorrelated frequencies. The calculation produces an energy value for each of the different uncorrelated frequencies. The DTMF detector preferably multiplies a gain value with each of the energy values to adjust the gain of each of the energy values. After the frequency domain calculation, i.e., after energy values have been calculated for each of the different uncorrelated frequencies, and after any desired gain adjustment, the DSP determines maximum values of the energy values for each of the two or more frequency groups to detect the plurality of tones in the received signal. The DTMF detector also performs various other calculations to ensure valid tone detection.
摘要:
An apparatus and method are provided for discriminating noise in a received signal. The apparatus comprises a first signal processing means, a second signal processing means, a threshold generating means for generating a threshold value. The first signal processing means generates iteration signal samples and predicted iteration signal samples, compares the iteration signal samples and predicted signal samples to generate a predicted error parameter. The second signal processing means generates a threshold adjustment value based on generated successive iteration signal samples. A logic means logically treats the prediction error parameter, the threshold adjustment value and the threshold value to generate a noise indication value.
摘要:
An apparatus and method for discriminating and suppressing noise within an incoming signal which provide a first signal processing unit for processing the incoming signal to generate a first iteration signal representing average difference signal level of the incoming signal; a second signal processing unit for processing the first iteration signal to generate a second iteration signal representing specified aspects of the first iteration signal; a prediction unit for generating a predicted value for the second iteration signal from earlier samples of the second iteration signal; a logic unit for determining a threshold difference between the second iteration signal and the predicted value, the logic unit generating a logic output having a first value when the threshold difference exceeds a predetermined threshold value and having a second value when the threshold difference does not exceed the predetermined threshold value; and a muting unit for muting signals which is operatively connected to receive the incoming signal and the logic output, the muting unit responds to the logic output to mute the incoming signal when the logic output is at one value and to not mute the incoming signal when the logic output is at the other value.
摘要:
A method and apparatus provide a noise detector generating a logic output indicating presence of noise in an incoming signal and an attenuation controller for providing a stepped-response to noise operatively connected to respond to the logic output to record a count of noise detections. The attenuation controller includes an attenuation interval tracking unit for tracking the elapse of clocking intervals defining a predetermined attenuation interval; the attenuation interval tracking unit receives the noise detection signals and generates a decremental count signal for each clocking interval after the attenuation interval has elapsed, the decremental count signal is conveyed to a noise detection counter which alters the count of noise detections indicated by the logic output in response to the decremental count signal, the attenuation interval tracking unit restores the attenuation interval in response to receiving a noise detection; an attenuation signal generator is responsive to the noise detection count signal to set an attenuation factor according to a predetermined relationship between the count of noise detections and the attenuation factor, the attenuation signal being representative of the attenuation factor; and a logic unit for applying the attenuation signal to the incoming signal to attenuate the incoming signal in stepped fashion according to the attenuation factor.