48results about How to "Good autocorrelation properties" patented technology

The invention provides a method and an apparatus for restraining cross-correlation interference in GNSS. The invention comprises the following steps: step A, detecting and demodulating a strong signal in a receiving signal; step B, generating a spreading code synchronized to a certain strong signal; step C, carrying out segmentation on the receiving signal according to a certain length; step D, carrying out segmentation on the spreading code that is generated in the step B; step E, generating a set of orthogonal codes such as a Walsh code and a set of orthogonal codes with a certain length, for example, a set of Walsh codes; step F, generating a set of outputs after corresponding multiplication of an output of the step D with an output of the step E; step G, generating a set of outputs after corresponding summation of convolution by an output of the step C with the outputs of the step F; step H, generating a set of outputs after corresponding multiplication of the outputs of the step F with the outputs of the step G; step I, generating an output after accumulation of a set of data referring to the outputs of the step H; step J, carrying out merging of segments on the outputs of the step I and then generating an output. According to the invention, the method has low complexity of algorithm and the apparatus has a good comprehensive property.

The invention relates to an MC-CDMA-based underwater acoustic communication system and a PAPR suppression method, and the method comprises the steps: enabling a transmitting end to code input data after mapping, carrying out the serial-parallel conversion of the input data into q sub-data streams bi, and copying the bit of each sub-data stream bi into Np parts; generating a chaotic sequence according to the number U of subcarriers, and circularly multiplying the chaotic sequence by the basic spread spectrum sequence to generate a chaotic composite spread spectrum sequence C; multiplying each sub-data stream bi by the chaotic composite spread spectrum sequence C, and converting the multiplied sub-data streams bi into time domain signals through IFFT; and calculating the peak-to-average power ratio PAPR of the system according to the frequency band signal after up-conversion sampling. According to the PAPR suppression method disclosed by the invention, by changing the generation mode ofthe spreading code, the chaotic sequence is cyclically multiplied by basic spreading sequences such as an M sequence, a Walsh sequence or a completely complementary CCS sequence to generate a chaoticcomposite spreading sequence, so that the peak-to-average power ratio suppression characteristic of the system is improved. Compared with an amplitude limiting method, the method does not cause in-band distortion and out-of-band leakage. Compared with a probability method, the method is simple in operation mode and low in operation complexity.

The invention provides a synchronous sequence sending method, and a synchronous detection method and apparatus. The sending method comprises the following steps: setting a target synchronous sequencewith good autocorrelation property, wherein at least a segment of sequence intercepted on the time domain or the frequency domain of the target synchronous sequence is a sub-synchronous sequence, thesub-synchronous sequence has good autocorrelation property, and the sub-synchronous sequences have good cross-correlation property; and sending the target synchronous sequence to a terminal. In the synchronous sequence sending method provided by the embodiment of the invention, for terminals with different bandwidths or terminals with different carrier intervals, after a base station side sends the same target synchronous sequence, the terminals can intercept the corresponding sub-synchronous sequences according to own requirements to perform synchronous detection, thereby not only ensuring the synchronous detection accuracy, but also improving the application range of the target synchronous sequence.

The invention discloses a synchronous data acquisition system and acquisition method based on LabVIEW and a sound card. The acquisition system comprises a LabVIEW upper-layer controller, the sound card, a loudspeaker, and a sound sensor, the sound card is connected with the LabVIEW upper-layer controller, the loudspeaker, and the sound sensor, the LabVIEW upper-layer controller generates a coding signal, an analog-to-digital converter for controlling the sound card transmits the data in a sound wave manner, the loudspeaker increases the amplitude of the sound wave signal, the sound sensor receives the echo sound signal and attenuates the amplitude to a certain value, and the LabVIEW upper-layer controller controls the analog-to-digital converter of the sound card to read the echo data and display the data after real-time processing. The most critical synchronization control technology is adopted in the data acquisition process to replace an expensive data acquisition device, the cost is low, the operation is simple, the versatility is high, and the acquisition system and acquisition method have wide application prospects in the fields of industrial automation, and test and measurement.

The invention provides a waveform design method of an expanding zero-correlation zone; the method includes steps of forming a zero-correlation sequence by applying an initial regular base sequence generating method, introducing a spread spectrum radar polyphase code sequence to perform Kronecher multiplication with the zero-correlation sequence, so that the final sequence has quasi-perfect self-correlation property and perfect cross-correlation property within a certain zone, and has a larger zero correlation zone; thereby effectively reducing the mutual influence of the echo of adjacent distance units and improving the target detecting precision.

The invention discloses a primary synchronization signal generation method and device, and a computer readable storage medium. The method comprises the steps: acquiring ZC sequences corresponding to three root indexes, wherein the three ZC sequences have the same length; carrying out the discrete Fourier transform on the three ZC sequences to obtain frequency domain sequences in one-to-one correspondence with the three ZC sequences; respectively expanding the three frequency domain sequences to obtain expanded sequences in one-to-one correspondence with the frequency domain sequences; carryingout the inverse discrete Fourier transform on the three extended sequences to obtain time domain sequences in one-to-one correspondence with the extended sequences; and combining the three time domain sequences to obtain a main synchronization signal. The main synchronization signal generated by the scheme can balance the autocorrelation performance and the frequency offset resisting performance,and the time-frequency synchronization between the user terminal and the base station can be realized quickly.