40results about How to "Spectrum flat" patented technology

An encoder comprises an input for inputting frames of an audio signal in a frequency band, an analysis filter dividing the frequency band into lower and higher frequency bands, a first encoding block for encoding the audio signals of the lower frequency band, a second encoding block for encoding the audio signals of the higher frequency band, and a mode selector for selecting an operating mode for the encoder among at least a first mode where signals only on the lower frequency band are encoded, and a second mode where signals on both the lower and higher frequency band are encoded. The encoder has a scaler to gradually change the encoding properties of the second encoding block in connection with a change in the operating mode of the encoder. The invention also relates to a device, a decoder, a method, a module, a computer program product, and a signal.

To provide inks and ink sets for inkjet recording, which have good fastness and good jet-out stability and which give good images with no bleeding trouble, yellow ink, black ink and magenta ink for inkjet printing contain at least two dyes each having an oxidation potential over 1.0 V (vs SCE).

The invention relates to the chaotic laser field, and specifically relates to a semiconductor chaotic laser integrated with double feedback. The semiconductor chaotic laser integrated with double feedback solves the technical problems that a current chaotic laser generation apparatus is large in volume, is easy to be influenced by the environment, and is unstable in outputting. The semiconductor chaotic laser utilizes double feedback to improve the chaotic bandwidth of an integrated device to make the frequency spectrum to be more flat. For the semiconductor chaotic laser, a double-cavity structure eliminates the fixed time delay of a common single-cavity integrated laser chip; the double feedback cavity are similar in length but are different so that the time delay characteristic of the single-cavity integrated laser is thoroughly eliminated; the security for chaotic communication, the accuracy for chaotic laser ranging, and the randomness of the randomized number are improved; and the semiconductor chaotic laser can be applied to the communication field, the remote sensing field, the sensing field and the like. The semiconductor chaotic laser integrated with double feedback only uses a DFB laser chip, a high performance photoelectric detector and a plane lens fiber to realize chaotic output and detection, and can realize simultaneous output of a chaotic laser signal and a chaotic electric signal. The semiconductor chaotic laser integrated with double feedback also has the advantages of being small in the volume of the integrated structure and being low in cost.

The embodiment of the invention provides an integrated chaotic laser chip and a laser. The laser chip comprises a first laser assembly and a second laser assembly. The first laser assembly and the second laser assembly are integrated chips of a distributed feedback laser DFB and a semiconductor amplifier SOA. Wherein the first laser assembly includes a left side DFB region and a right side SOA region, and the second laser assembly includes a left side SOA region and a right side DFB region; The right end surface of the right SOA region of the first laser assembly is plated with a low reflective film, and the left end surface of the left SOA region of the second laser assembly is plated with a high reflective film; The first laser assembly and the second laser assembly are integrally connected through the low reflective film and the high reflective film. The laser chip has the advantages of simple structure, easy operation, direct optical coupling by using refractive index matching glue, and greatly improving coupling efficiency.

The invention discloses a Windows-login-authentication-system method based on heart-sound authentication. The method includes the steps that heart-sound signals are extracted through an earphone, pre-emphasis processing is carried out, then noise passing through the heart-sound signals is removed with the wavelet de-noising method, and as heart sounds are single-cycle repeating signals, the heart-sound signals are subjected to data fusion, and the signal quality is improved. In the recognition stage, an independent wavelet extracting method based on data fusion is adopted, then a MFCC coefficient of reconstructed signals is extracted to serve as a characteristic value, an authentication method combined with the VQ algorithm and the DTW algorithm is designed, and the recognition accuracy rate is increased as far as possible. Login authentication of a PC is completed through a Winform login system.

Receivers for diversity reception of data transmitted by concatenated convolutional code (CCC) from at least one 8-VSB transmitter are described. Each receiver includes a first turbo decoder for the CCC as finally transmitted, a second turbo decoder for the CCC as initially transmitted, and an information-exchange unit connected for exchanging decoding information between the turbo decoders, which perform decoding concurrently. The turbo decoders are designed for decoding CCC formed from an outer convolutional code encoding de-interleaved Gray-coded data and a subsequent binary-coded inner convolutional code forming a 12-phase trellis code in accordance with a Gray-labeling procedure, the outer convolutional code encoding being symbol-interleaved before encoding within said inner convolutional code so said inner convolutional code has implied symbol interleaving in which the original order of data bits is preserved.

The invention relates to a photon-integrated two-zone chaotic semiconductor laser chip, which comprises a chip substrate, a main distributed feedback laser, a slave distributed feedback laser and a light waveguide, wherein the main distributed feedback laser, the slave distributed feedback laser and the light waveguide are integrated on the chip substrate; the main distributed feedback laser and the slave distributed feedback laser are connected by adopting a side-by-side mode; one end of the light waveguide is connected with the slave distributed feedback laser and the other end is used as output. The chip integrates the two distributed feedback lasers on the same chip substrate, the inner gratings both adopt equivalent displacement gratings, and the coupling efficiency of the main and the slave laser is higher. Through applying bias current to the main distributed feedback laser and the slave distributed feedback laser, the two distributed feedback lasers emit light to be injected tothe lasers to disturb the light fields, and chaotic laser with a high bandwidth and no delay characteristics is thus generated.

The present invention relates to a mobile communication field, disclosing a signal sending and receiving method and equipment based on OFDM, aiming to increase the detection performance of the signal code when the frequency-domain signal of the signal sequence is incapable of being completely sent. In the invention, after being interleaved or scrambled, the sequence of the waiting signal code has a discrete Fourier transform DFT transform, making the partly result of the DFT transform is mapped to the subcarrier of the OFDM symbol, and then sent after being modulated by the OFDM; the receiver releases the interleaving and the scrambling to the received signal, and then discriminates the sequence of the signal mode sent from the sender through correlation detection.

The embodiment of the invention discloses an optical frequency comb generation system and a generation method. The optical frequency comb generation system comprises a pumping source, a coupling structure and a light force micro-cavity, wherein the pumping source is used for providing pumping light; the coupling structure is used for coupling the pumping light into the light force micro-cavity; the light force micro-cavity comprises an optical mode and a mechanical mode; the pumping light excites an optical mode in the light force micro-cavity; the optical mode is coupled with the mechanical mode to generate dynamic reaction; the dynamic reaction drives the mechanical mode, generates an optical sideband and outputs an optical frequency comb; the pumping light and the light force micro-cavity are in a big blue detuning state, the coupling structure and the light force micro-cavity are in an over-coupling state, the big blue detuning state is that the difference between the pump light frequency and the optical mode resonance frequency is larger than ten times of the mechanical mode resonance frequency, and the over-coupling state is that the optical mode loss rate and the mechanical mode resonance frequency are in the same magnitude. According to the technical scheme, the high-performance, wide-bandwidth and low-repetition-frequency optical frequency comb for chip integration can be generated.

The invention provides a Raman laser enhancement device and method based on a high-nonlinearity photonic crystal fiber, and the structure of the Raman laser enhancement device consists of an ytterbium-doped fiber laser, a Faraday isolator, a fiber combiner, a polarization controller, a single-mode fiber SM1, a single-mode fiber SM2, a high-nonlinearity photonic crystal fiber (HNL-PCF), Bragg gratings FBG1, FBG2, FBG3, and FBG4, a photonic crystal fiber, a T-shaped connector 1, a T-shaped connector 2, a spectrum analyzer and a computer processing system.

The invention relates to a photo-generated millimeter wave noise generator, which comprises a chaotic laser, an erbium-doped fiber amplifier, a second polarization controller, a high nonlinear fiber (HNLF) and a high-speed photoelectric detector which are connected in sequence, wherein the chaotic laser is composed of a semiconductor laser, a first polarization controller, a 60: 40 optical fiber coupler, a variable optical attenuator and an optical fiber reflector. The scheme of the invention provides an optical generation technology of millimeter wave noise, the bottleneck of electronic bandwidth is broken through, the implementation scheme is simple in structure, and millimeter wave noise with larger bandwidth is easy to generate; according to the technical scheme, the power of millimeter wave noise output depends on the amplification power of the erbium-doped optical fiber amplifier; compared with a conventional electronic noise source, the output power of the electronic noise source is easy to adjust, and the maximum power capable of being output is larger; according to the technical scheme, millimeter wave noise is generated through the combined action of the nonlinear effect,dispersion and the like in the high nonlinear optical fiber, the frequency spectrum of the generated millimeter wave noise is flat, and the bandwidth is larger.

The invention discloses a monolithic integrated mode-adjustable chaotic laser and a manufacturing and control method, the laser comprises a left segment and a right segment of same active equivalent Pi phase shift uniform Bragg sampling grating and a middle segment of active equivalent Pi phase shift antisymmetric Bragg sampling grating which are integrated on the same chip and share one segment of optical waveguide; the antisymmetric Bragg sampling grating is used for realizing conversion of incident light and reflected light between a TE0 mode and a TE1 mode; and the power ratio of the input light and the output light injected into the antisymmetric Bragg sampling grating in the middle section is changed by adjusting the bias current of the equivalent pi phase-shift uniform Bragg sampling grating in the left section and the right section respectively, and chaotic laser output is generated. According to the invention, the problem that a mode-tunable chaotic laser cannot be realized in the prior art is solved.

The invention discloses a dual-optical frequency comb generation system and method, pumping laser is divided into two beams of laser, the two beams of laser are respectively coupled into coupling structures, and the two coupling structures are used for respectively coupling the pump laser after light splitting into two light force microcavities; pump laser is transmitted in the light force microcavities to excite a light force microcavity optical mode, a mechanical mode is excited through light pressure, and an optical sideband, namely an optical frequency comb, is generated through the light force reaction. The comb tooth interval of the optical frequency comb is determined by the mechanical mode resonance frequency, so that the double optical frequency comb coherent with the original pump laser can be generated by selecting two optical coupling microcavities with slightly different mechanical mode resonance frequencies. The system and method can be used for producing a chip-integrated double-optical comb generation component with low cost.

The invention relates to a photo-generated millimeter wave noise generator based on a high-nonlinearity optical fiber. The photo-generated millimeter wave noise generator comprises a distributed feedback laser, an optical fiber isolator, a first polarization controller, an erbium-doped optical fiber amplifier, a second polarization controller, the high-nonlinearity optical fiber (HNLF) and a high-speed photoelectric detector which are connected in sequence. According to the scheme, millimeter wave noise is generated through an optical method, the bottleneck of electronic bandwidth is broken through, ultra-bandwidth millimeter wave noise is easy to generate, and the structure is simple; the power of output noise depends on the amplification power of the erbium-doped optical fiber amplifier,and compared with an existing electronic noise source, the output power is easy to adjust, and the maximum power capable of being output is larger. Millimeter wave noise is generated through the combined effect of the nonlinear effect, modulation instability, dispersion and the like in the high nonlinear optical fiber, the frequency spectrum of the generated noise is flatter, and the bandwidth islarger.