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 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.