Satellite search and rescue signal frequency estimation method

Abstract

Provided is a satellite search and rescue signal frequency estimation method. By the adoption of a loop iteration processing structure, a narrow-band filter is used for meeting the requirement of a Kay fast frequency estimator for simple-frequency signals. The satellite search and rescue signal frequency estimation method comprises the following implementation steps that satellite search and rescue signals are received through a medium earth orbit local user terminal, coarse frequency estimation is conducted on the satellite search and rescue signals, and the band width of a BPF1 is designed; the signals pass through the BPF1, and signals s1 are obtained and divided into two channels; down-conversion is conducted on one channel of the s1, the sampling frequency is reduced further through an extractor, and output signals s2 of the extractor are used for iterative estimation; the s2 pass through a BPF2, medium frequency estimation is conducted so as to obtain omega2, the omega2 is used as the center frequency of the BPF2 to conduct filtering on the s2, loop iteration is conducted in this way, and omega3 is obtained and used as the center frequency of a BPF3; the other channel of the s1 passes through the BPF3, and signals s3 are obtained; fast frequency estimation is conducted on the s3.

Description

technical field [0001] The invention relates to a high-precision satellite search and rescue signal frequency estimation method, which belongs to the technical field of satellite navigation. Background technique [0002] The global satellite search and rescue system COSPAS-SARSAT was jointly established by the United States, the former Soviet Union, France and Canada in 1979, aiming to provide effective search and rescue SAR (Search And Rescue) services to various ships, aircraft and individual users around the world . The system currently has more than 35 member countries, and China became a member of the organization in 1994. During the more than 20 years of operation of the system, as of 2006, 6,167 search and rescue operations have been successfully carried out, and more than 22,035 people in distress have been successfully rescued, with an average of 3 people rescued every day. It has played an extremely critical role in humanitarian rescue and other fields. When the ...

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Problems solved by technology

However, the DFT-based algorithm requires a large amount of computation to search for the position of the spectral peak

[0004] PLL can be used to accurately measure FOA, but since the signal is in a short format, the loop bandwidth must be increased in order to shorten the capture time, but the increase in loop bandwidth will reduce the noise suppression ability, resulting in reduced tracking accuracy. The improved method adopts the frequency assist method to convert the initial The frequency difference is narrowed within the fast capture band, which can ensure precise synchronization in the pilot band, but requires an additional precise frequency measurement link outside the PLL loop, which increases the complexity of the system

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