49 results about "Amplitude compression" patented technology

The invention discloses a signal analysis device and method based on random variable digital intermediate frequency and belongs to the field of signal analysis. According to the device and the method, for low band signals, a full digital down-conversion mode is employed, and an additional frequency conversion circuit and a zero frequency suppression circuit are removed, so the cost of a circuit, particularly the total power consumption of the circuit is reduced, a size of the circuit is greatly reduced, and a direct digital down-conversion function for the low band input signals is realized. Automatic full scale gain control and an adjustable digital mixing method are united, channel gain is automatically adjusted according to whether data collection number of bits is in a full scale or not, digital mixing effective number of bits is dynamically intercepted, and high-precision signal analysis is realized. Random sequence superposition and amplitude compression methods are combined, and high-purity digital local oscillation generation is realized. Compression is carried out based on a taylor series linear expansion method. The addressing number of bits of a lookup table is increased, high-purity digital local oscillation signals are generated, and the signal analysis precision is improved.

Pitch estimation and classification into voiced, unvoiced and transitional speech were performed by a spectro-temporal auto-correlation technique. A peak picking formula was then employed. A weighing function was then applied to the power spectrum. The harmonics weighted power spectrum underwent mel-scaled band-pass filtering, and the log-energy of the filter's output was discrete cosine transformed to produce cepstral coefficients. A within-filter cubic-root amplitude compression was applied to reduce amplitude variation without compromise of the gain invariance properties.

The invention relates to a method for the scalar quantisation-based coding of samples of a digital audio signal (S), said samples being coded over a pre-determined number of bits in order to obtain a binary frame of quantisation indices (IMIC). The samples are coded using an amplitude compression law and a pre-determined number of the least-significant bits is not taken into account in the binary frame of quantisation indices. The coding method includes a step comprising the saving (27) of at least part of the least-significant bits which are not taken into account in the binary frame of quantisation indices and the determination (28) of an enhancement stream (IEXT) containing at least one saved bit. The invention also relates to an associated decoding method including steps comprising the reception (29) of an enhancement stream (I'EXT) containing one or more extension bits and the concatenation (30) of the extension bits behind the bits originating from the binary frame in order to obtain a decoded audio signal. The invention further relates to the coder and decoder used to carry out said methods.

The invention provides a low-complexity method for reducing the peak-to-average ratio in an OFDM communication system. The method compresses the amplitude of the OFDM-modulated baseband signal, expands the received signal at the receiving end, and Restore the signal. The invention can reduce the ratio of the peak power of the signal to the average power, thereby suppressing the peak-to-average ratio of the system, and the influence on the signal can be ignored. The invention is easy to implement and can be used in various communication systems that adopt OFDM for modulation.

The invention relates to an expressway audio vehicle detection device and a method thereof. By the aid of the detection device, a microphone array signal acquisition module acquires an audio signal on a lane, the audio signal is subjected to band-splitting filtering and framing through a signal processing module after being subjected to de-noising processing through a noise suppression module, cross-correlation processing is conducted among sub-band signals, an audio space spectrogram is obtained, a vehicle detection module tracks a track of the maximum value on the audio space spectrogram and judges whether a vehicle passes, and the vehicle type and the vehicle speed are obtained through a vehicle type recognition module and a vehicle speed recognition module if the vehicle passes. The detection method is based on the device, a minimum statistical noise estimation method of the adaptive window length is adopted, the signal which is subjected to noise suppression processing is subjected to band-splitting filtering and framing processing, then cross-correlation processing is conducted among same sub-band signals, cross-correlation results are summed after being subjected to amplitude compression and are unfolded along a timer shaft, and an audio signal space-time spectrum is obtained. The method and the device have the advantages of being low in cost, low in energy consumption, easy to construct, interference resisting, capable of working in all weather and the like.

An amplitude adjustment device such as an amplitude compression device and amplitude expansion device is basically configured by a PWM modulator, a demodulator and an amplitude detector. Herein, the PWM modulator effects pulse-width modulation on an input signal to produce a pulse-width modulated signal, which is demodulated by the demodulator to produce an output signal. In addition, the amplitude detector detects an amplitude of a demodulated signal or an amplitude of the input signal to produce a control signal. A modulation factor of the pulse-width modulation is adjusted based on the control signal. In the case of the amplitude compression device, an input / output gain is changed inversely proportional to the amplitude of the input signal or amplitude of the output signal. Thus, it is possible to compress a dynamic range with respect to input / output characteristics. A full-wave rectifier, applicable to the amplitude adjustment device, is mainly configured by an inversion amplifier, an amplifier and an output section. Herein, the inversion amplifier amplifies an input signal with a gain of “−1”, while the amplifier amplifies it with a gain of “1”. Outputs of the amplifiers differ from each other in phases by 180°. The output section produces a full-wave rectified signal based on the outputs of the amplifiers. Incidentally, all of the amplifiers and output section are configured using field-effect transistors without using diodes being externally connected. Hence, it is possible to manufacture the full-wave rectifier in a form of an IC in accordance with the MOS process with ease.