Abstract: An apparatus for detecting at least one tone having a known frequency and duration in an input signal. The input signal is input over a period of time which is divided into frame portions including at least an initial frame portion and a last frame portion. An energy signal indicative of the energy of the input signal during each frame portion is generated. A signal filter receives the energy signal and generates a noise indicator for each frame portion based on whether noise is detected in the energy signal. A dynamic threshold determiner generates an energy threshold for each frame portion. The energy threshold for the initial frame portion is generated based on a minimum expected value of the energy signal for a subsequent frame portion. The energy thresholds for frame portions subsequent to the initial frame portion are generated based on values of the energy signals during previous frame portions and the noise indicator.

Abstract: An apparatus for detecting at least one tone having a known frequency and duration in an input signal. The input signal is input over a period of time which is divided into frame portions including at least an initial frame portion and a last frame portion. An energy signal indicative of the energy of the input signal during each frame portion is generated. A signal filter receives the energy signal and generates a noise indicator for each frame portion based on whether noise is detected in the energy signal. A dynamic threshold determiner generates an energy threshold for each frame portion. The energy threshold for the initial frame portion is generated based on a minimum expected value of the energy signal for a subsequent frame portion. The energy thresholds for frame portions subsequent to the initial frame portion are generated based on values of the energy signals during previous frame portions and the noise indicator.

Abstract: A transcoder-codec circuit arrangement that supports voice-switched hands-free radio operation. A first register is arranged to store a value indicative of a peak signal in a receive signal path, a first attenuator is coupled to the receive path, a second register is arranged to store a value indicative of a peak signal in a transmit signal path, a second attenuator is coupled to the transmit signal path, and a digital signal processor is coupled to the first and second registers and configured and arranged to update the value in the first register with a present peak receive signal level if the value in the first register is less than the present peak receive signal level. The digital signal processor is further arranged to update the value in the second register to a present peak transmit signal level if the value in the second register is less than the present peak transmit signal level.

Abstract: An apparatus for detecting at least one tone having a known frequency and duration in an input signal. The input signal is input over a period of time which is divided into frame portions including at least an initial frame portion and a last frame portion. An energy signal indicative of the energy of the input signal during each frame portion is generated. A signal filter receives the energy signal and generates a noise indicator for each frame portion based on whether noise is detected in the energy signal. A dynamic threshold determiner generates an energy threshold for each frame portion. The energy threshold for the initial frame portion is generated based on a minimum expected value of the energy signal for a subsequent frame portion. The energy thresholds for frame portions subsequent to the initial frame portion are generated based on values of the energy signals during previous frame portions and the noise indicator.

Abstract: A method and system for improved detection of analog signals, where the analog signals may be composed of one or more analog frequencies. In the method and system, an analog signal is received. A stream of data samples is created from the analog signal. Based on the stream of data samples, a confidence factor regarding the presence of the one or more analog signals is created. The confidence factor is created based upon a confidence factor calculated for each of the one or more analog frequency signals. The confidence factor calculated for each of the one or more analog frequency signals is calculated utilizing incremental energies associated with each of the one or more analog frequency signals.

Abstract: 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.

Abstract: An apparatus for determining energy threshold detection values for detecting at least one tone having a known frequency and duration in an input signal. The input signal is input over a period of time that is divided into frame portions including at least an initial frame portion and a last frame portion. An energy value is determined for the at least one tone during each frame portion. A set of control flag signals are set for the at least two frame portions based on the energy values being below a threshold value in previous frame portions and the presence of noise in previous frame portions. An offset into a data table is determined based on the control word, the offset being used to retrieve a scaling coefficient and an address of an energy value for the at least two frame portions from the data table.

Abstract: A method and system for improved detection of analog signals, where such signals are composed of one or more analog frequencies of defined duration. In the method and system, an analog signal is received. A stream of data samples is created from the received analog signal. Based on the stream of data samples, a duration is calculated for one or more analog frequencies contained within the received analog signal. The duration is calculated for the one or more frequencies by utilizing a calculated signal energy for each of the one or more analog frequencies. The calculated signal energies for each of the one or more analog frequencies are used to determine a number of frequency-specific data samples. The number of frequency-specific data samples are then utilized with a sampling rate to calculate the duration of the each of the one or more analog frequencies.

Abstract: A communications device is presented including a DTMF detector for detecting a DTMF signal. When the DTMF signal is a Mode 2 Caller ID CAS, the first DTMF tone has a frequency of about 2130 Hz, and the second DTMF tone has a frequency of approximately 2750 Hz. An input signal includes signal energy within a first portion of the input signal frequency range which includes the first DTMF tone, signal energy within a second portion of the input signal frequency range which includes the second DTMF tone, and signal energy within a third portion of the input signal frequency range which excludes the first and second DTMF tones. The DTMF signal detector includes a first and second tone detection units, an extraneous signal detection unit, and detection logic. The first and second tone detection units receive the input signal and produce an output signal dependent upon the signal energy within the respective first and second portions of the input signal frequency range.

Abstract: 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.

Abstract: A signal detector includes a transform unit and a signal alignment unit. The transform unit is adapted to receive a plurality of frames of time domain input samples and generate a plurality of energy values based on the frames of time domain input samples. Each energy value is associated with one of the plurality of frames. The signal alignment unit is adapted to identify at least a first partial energy frame and a second partial energy frame from the plurality of frames. The first partial energy frame is associated with a first frequency and has a first energy value. The second partial energy frame is associated with a second frequency and has a second energy value. The signal alignment unit determines a misalignment between the first and second partial energy frames based on the first and second energy values. A method for detecting a signal is provided. The method includes generating a plurality of energy values based on the frames of time domain input samples.

Abstract: The present invention comprises an improved vocoder system and method for estimating the pitch of a speech signal. The speech signal comprises a stream of digitized speech samples. The speech samples are partitioned into frames. For each frame of the speech signal, an optimal order-two inverse filter is determined. The optimal order-two inverse filter is determined by computing an order-two inverse filter at various locations within the speech frame. For each order-two inverse filter an energy value is calculated which represents the proportion of energy which would remain if the speech signal were filtered with the order-two inverse filter. The order-two inverse filter which minimizes the energy proportion is chosen to be the optimal order-two inverse filter. The optimal order-two inverse filter is then used to filter the samples of the speech frame. An autocorrelation is performed on the filtered signal for a range of tine-delay values.

Abstract: A vocoder system and method for estimating the pitch of a speech signal. The speech signal comprises a stream of digitized speech samples. The speech samples are partitioned into frames. For each frame of the speech signal, the following processing steps are performed. First, an optimal order-two inverse filter is determined based on the samples of the speech frame. Second, a dominant formant frequency is calculated from the coefficients of the optimal order-two inverse filter. Third, an autocorrelation function is calculated on the samples of the speech frame. The autocorrelation is performed for a range of time-delay values over which the pitch period and its multiples might be expected to occur. Fourth, the peaks of the autocorrelation function are analyzed incorporating the knowledge of the dominant formant period (which is the inverse of the dominant formant frequency). Normally, the dominant formant is the first formant.

Abstract: An improved vocoder system and method for estimating pitch in a speech waveform which pre-filters speech data with improved efficiency and reduced computational requirements. The vocoder system is preferably a low bit rate speech coder which analyzes a plurality of frames of speech data in parallel. Once the LPC filter coefficients and the pitch for a first frame have been calculated, the vocoder then looks ahead to the next frame to estimate the pitch, i.e., to estimate the pitch of the next frame. In the preferred embodiment of the invention, the vocoder filters speech data in a second frame using a plurality of the coefficients from a first frame as a multi pole analysis filter. These coefficients are used as a "crude" two pole analysis filter.

Abstract: A microprocessor configured to detect a plurality of consecutive instructions comprising a predefined instruction sequence is provided. The predefined sequence indicates that subsequent instructions belong to an alternate instruction set. In one embodiment, the number of subsequent instructions which belong to the alternate instruction set is encoded in the predefined instruction sequence. The subsequent instructions are routed to an execution unit or a separate processor for execution. Each instruction sequence within a program may be coded using the instruction set which most efficiently executes the function corresponding to the instruction sequence. In one embodiment, the microprocessor executes the x86 instruction set and the alternate instruction set is the ADSP 2171 instruction set. The predefined instruction sequence may comprise MOV instructions having the same destination, or identical XOR instructions.

Abstract: A microprocessor configured to detect a memory operation having a predefined data address is provided. The predefined data address indicates that subsequent instructions belong to an alternate instruction set. In one embodiment, a second memory operation having the predefined data address indicates that instructions subsequent to the second memory operation belong to the original instruction set. The memory operations effectively provide a boundary between the instructions from dissimilar instruction sets. Instructions are routed to an execution unit configured to execute the instruction set indicated by the most recently detected memory operation having the predefined address. Each instruction sequence within the program may be coded using the instruction set which most efficiently executes the function corresponding to the instruction sequence. The program may be executed more quickly than an equivalent program coded entirely in either instruction set.

Abstract: A system and method for performing echo cancellation in a communications network including a bi-directional two-wire communication line, and a four-wire communication line having a transmit path and a receive path. The system includes a filter coupled to the receive path for reducing the echo component. The filter uses a number of filter coefficients and selectively employs either a full LMS coefficient calculation technique to compute the filter coefficients during a first period of time to achieve quick convergence, or a sign-sign LMS coefficient calculation technique to compute the filter coefficients during a second period of time to achieve improved stability and convergence. The filter uses a power estimation of the transmit path signal to direct the filter as to which coefficient calculation technique to use.

Abstract: An improved vocoder system and method for estimating pitch in a speech waveform. The vocoder receives digital samples of a speech waveform and generates a plurality of parameters based on the speech waveform, including a pitch parameter. The present invention comprises an improved method for estimating and correcting the pitch parameter using correlation techniques. The method comprises first performing a correlation calculation on a frame of the speech waveform, which produces one or more correlation peaks at respective numbers of delay samples. The vocoder then compares the one or more correlation peaks with a clipping threshold value. If a single peak at location P.sub.d is greater than the clipping threshold, then the vocoder performs additional calculations to ensure that this single correlation peak is not a second or higher multiple of the true pitch. In the preferred embodiment, the vocoder assumes the peak at location P.sub.

Abstract: An improved dual tone multifrequency (DTMF) or multitone signal detector which more efficiently detects DTMF signals. For each received frame, the present invention initially performs only a portion of the Goertzel DFT algorithm for each of the possible tone frequencies and then analyzes the interim accumulated energies. The DTMF detector then selects one or more frequencies from each of the tone groups which have the largest energy values, and the detector only completes calculation of the Goertzel DFT algorithm on those selected one or more frequencies. In other words, the DTMF detector discontinues calculation of the Goertzel DFT algorithm on one or more frequencies which have low accumulated interim energies. This reduces the computational requirements and provides improved performance.

Abstract: 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.