56results about How to "Estimated range is large" patented technology

The invention discloses an SOQPSK carrier synchronization method based on pilot frequency and coding joint aiding. The SOQPSK carrier synchronization method based on pilot frequency and coding joint aiding mainly solves the problems that with an existing technology, the estimation complexity is high and the estimation range is small. The SOQPSK carrier synchronization method based on pilot frequency and coding joint aiding includes the implementation steps that first, rough estimation parameters and fine estimation parameters are determined; second, rough estimation is performed through the rough estimation parameters to obtain the rough estimation value f<co> of frequency offset and the rough estimation value fai<co> of phase offset; third, fine estimation is performed through the fine estimation parameters to obtain the fine estimation value f<in> of frequency offset and the fine estimation value fai<in> of phase offset; fourth, the final estimation value f=f<co>+f<in> of frequency offset is obtained through the rough estimation value f<co> of frequency offset and the fine estimation value f<in> of frequency offset; fifth, the final estimation value fai=fai<co>+fai<in> of phase offset is obtained through the rough estimation value fai<co> of phase offset and the fine estimation value fai<in> of phase offset. Through the method, the estimation normalized frequency offset range can be widened to the range from -0.5 to 0.5, the estimation complexity is low, and the SOQPSK carrier synchronization method based on pilot frequency and coding joint aiding can be used for carrier synchronization and wireless channel estimation of a wireless communication system.

A vision system of a vehicle includes at least one camera configured to be disposed at a vehicle so as to have a field of view exterior of the vehicle. Responsive to image processing of captured image data and with the at least one camera disposed at the vehicle, the image processor determines a three dimensional object present in the field of view of the camera and determines a point of interest on the determined object. The vision system uses triangulation to determine an estimated location in three dimensional space of the determined point of interest. The vision system processes additional frames of captured image data to enhance the estimation of the location in three dimensional space of the determined point of interest. The image processor is operable to estimate a distance to the determined object by comparing multiple frames of captured image data.

A joint estimation method of timing frequency offset of satellite borne automatic identification system (AIS) signals comprises that an antenna receives radio frequency signals sent by a ground ship AIS and inputs the radio frequency signals to a receiver; the receiver demodulates the received radio frequency signals into baseband signals and inputs the baseband signals to a field-programmable gate array (FPGA) data collection module; the FPGA data collection module carries out analog-digital conversion of the received baseband signals and obtains digital baseband signals and transmits the digital baseband signals to a signal processing module; the signal processing module processes the received digital baseband signals and obtains accurate AIS ship information and transmits the accurate ship information to a data storage module; and the data storage module stores the received AIS ship information. The joint estimation method of the timing frequency offset of the satellite borne AIS signals has the advantages of eliminating the problem of poor estimation precision in an easy timing estimation working mode by introducing an autocorrelation operation and a weighting multiplication operation, confirming sampling sites by utilizing a timing estimated value, and achieving the frequency offset estimation of being largest in estimation range and smallest in estimation variance on the satellite borne AIS signals by using the autocorrelation operation, a maximum likelihood operation and signal drop sampling.

The invention discloses an iterative correlation symbol timing estimation method based on a block-type pilot frequency, which is mainly used for solving the problems that the traditional symbol timing estimation method is high in complexity and the estimation accuracy is low, and can be applied to a multi-user scene. The method disclosed by the invention comprises the following steps: firstly, removing a cyclic prefix, and carrying out fast Fourier transform, cyclic shift and integrated type sub carrier de-mapping, so as to receive the pilot frequency; secondly, selecting a determined and appropriate receiving pilot frequency and a local pilot frequency thereof through the obtained pilot frequency, and partitioning the receiving pilot frequency and the local pilot frequency thereof; thirdly, by virtue of the partitioned pilot frequency, calculating a first timing error estimation value, and obtaining a corrected pilot frequency by using the first timing error estimation value; fourthly, partitioning the corrected pilot frequency and the local pilot frequency, and calculating a second timing error estimation value; and fifthly, calculating a final timing error estimation value according to the two estimation values. The iterative correlation symbol timing estimation method disclosed by the invention has the advantages that the estimation precision is improved compared with a first path searching algorithm, the division of complex numbers is avoided, the estimation complexity is reduced, and the estimation method disclosed by the invention can be popularized to the multi-user scene of an uplink in LTE.