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CN-122026986-A - Satellite-ground transmission link time-frequency compensation method based on foundation beam

CN122026986ACN 122026986 ACN122026986 ACN 122026986ACN-122026986-A

Abstract

The invention belongs to the technical field of communication, and particularly relates to the steps of S1, signal acquisition, S2, beam angle acquisition, namely acquiring a real-time position coordinate, an operation speed vector and a carrier frequency of a satellite on a satellite load side through a satellite-borne sensor and a communication link of the satellite, and calculating an azimuth angle and a pitch angle of a satellite beam pointing to a foundation beam center point according to geographic position information of the foundation beam center point and a space geometrical relationship between the satellite and the foundation beam center point. The invention abandons the design that the prior scheme relies on a terminal GNSS module to acquire the geographical position information, and calculates the time-frequency deviation by utilizing the relative position relation between the satellite and the foundation beam central point, thereby fundamentally avoiding the influence of GNSS system signal shielding, interference or faults on a satellite communication system, ensuring the continuity and stability of a satellite-ground transmission link time-frequency compensation function, and greatly improving the anti-interference capability and the operation reliability of the satellite mobile communication system.

Inventors

  • BA TEER
  • HUANG ZHIYONG
  • CHEN KEHAN
  • ZHU LINGLI
  • Zhou Yingkang

Assignees

  • 江苏赫兹科技有限公司

Dates

Publication Date
20260512
Application Date
20251231

Claims (10)

  1. 1. The satellite-ground transmission link time-frequency compensation method based on the foundation beam is characterized by comprising the following steps of: S1, acquiring signals, namely acquiring real-time position coordinates, running speed vectors and carrier frequency of a satellite on a satellite load side through a satellite-borne sensor and a communication link of the satellite; s2, acquiring a beam angle, namely calculating an azimuth angle and a pitch angle of a satellite beam pointing to a central point by means of a space geometrical relationship between the satellite and the central point of the foundation beam according to the geographical position information of the central point of the foundation beam; s3, calculating Doppler frequency offset by combining geometrical parameters between the satellite and a ground terminal positioned at the central point of the foundation beam by using the azimuth angle and the pitch angle obtained in the step S2; s4, calculating transmission delay, namely calculating signal transmission delay in a satellite-ground transmission link by utilizing the pitch angle obtained in the step S2 and combining the spatial position relation of the satellite and the ground terminal; s5, compensating and correcting the frequency offset, namely pre-compensating a transmission signal in a signal period by using the calculated Doppler frequency offset, and correcting a received signal; And S6, time delay correction, namely performing time delay correction by using the calculated transmission time delay, and compensating residual frequency offset by using a downlink synchronous signal after frequency offset precompensation.
  2. 2. The method according to claim 1, wherein in step S1, the satellite position coordinates are obtained by combining a satellite-borne positioning module or a satellite orbit dynamics model with orbit determination data of a ground measurement and control station.
  3. 3. The method according to claim 2, wherein in the step S1, the carrier frequency is determined by a signal generator parameter of the satellite communication system, and the carrier frequency has a predetermined stable value.
  4. 4. The method according to claim 1, wherein in the step S2, the geographical location information of the center point of the ground beam includes longitude and latitude and altitude.
  5. 5. The method for time-frequency compensation of satellite-ground transmission link based on ground beam according to claim 4, wherein in the step S2, in the calculation process of azimuth angle and pitch angle, the attitude of the satellite is assumed to be ideal, the pitch angle, yaw angle and roll angle are all 0, and the azimuth angle and pitch angle are obtained by coordinate conversion software.
  6. 6. The method of claim 1, wherein in step S4, a satellite-to-earth center distance and a terminal-to-earth center distance are used for calculating the transmission delay, the satellite-to-earth center distance is a sum of an earth radius and a satellite orbit height, and the terminal-to-earth center distance is a sum of the earth radius and the terminal height.
  7. 7. The method of claim 6, wherein the calculating of the relative angular velocity between the satellite and the ground terminal takes into account the rotation of the earth and involves the angle between the orbital plane of the satellite and the equatorial plane of the earth, and the angle between the Z-axis and the equatorial plane in the overhead coordinate system, and wherein the relative angular velocity includes the relative angular velocity in the orbital plane and the relative angular velocity in the plane perpendicular to the orbital plane.
  8. 8. The method of time-frequency compensation for a satellite-to-earth transmission link based on a ground beam of claim 7, wherein the geocentric angle of the satellite orbit parameter is estimated by a geometric relationship of a spherical right triangle.
  9. 9. The method for time-frequency compensation of a satellite-to-ground transmission link based on a ground beam according to claim 8, wherein when the terminal is located at a point below the satellite and perpendicular to the satellite's flight direction, the doppler frequency offset due to the satellite motion is 0.
  10. 10. The method for time-frequency compensation of satellite-ground transmission link based on ground beam according to claim 9, wherein when the terminal is located on the track of the point below the satellite, the calculation of Doppler frequency offset is simplified, and the time-frequency offset of the satellite-ground transmission link is directly related to the relative position of the satellite and the center point of the ground wave position, which can be quickly realized by looking up a table, and the timing advance of the terminal user is related to the transmission period of the terminal signal.

Description

Satellite-ground transmission link time-frequency compensation method based on foundation beam Technical Field The invention belongs to the technical field of communication, and particularly relates to a satellite-ground transmission link time-frequency compensation method based on a foundation beam. Background The low-orbit satellite mobile communication system has become one of core infrastructures supporting seamless coverage of the global communication network by virtue of the technical advantages of global coverage, low time delay and wide connection, and the development process of the low-orbit satellite mobile communication system can be divided into a plurality of key stages. The advent of low-orbit constellations such as iridium, orbcomm, and global, etc. in the last 90 th century has raised the first time of construction, in which the iridium system has originally achieved the "5W" global personal communication goal of "anybody (Whoever) communicating with anybody (Whomever) in any way (Whatever) anywhere (Wherever), anytime (Whenever), becoming an important milestone in the modern communications field, pushing low-orbit satellite communications from concept to practical. In 2015, with the continuous breakthrough of satellite manufacturing, rocket launching and communication technologies, low-orbit satellite communication is coming into the second construction hot tide. The United states OneWeb announces that a constellation composed of 720 satellites is constructed, starlink provides a macro plan containing 4 ten thousand satellites, and enterprises such as a star network and a wall letter publish huge constellation deployment schemes of tens of thousands of satellites in succession in China immediately following industry trends, so that the system aims at providing high-speed satellite Internet services for the world. Up to now, the field has made remarkable progress that Starlink have launched 8200 satellites, 6180 of which are put into practical operation to provide Internet access service for global users, oneWeb has completed initial deployment of 618 networking satellites and 30 standby satellites, china's star network constellation has launched 46 satellites (including 17 test satellites and 29 networking satellites) and developed an heaven-earth transmission test, and the Wen-earth transmission test has completed deployment of 72 satellites by 4 launches in 2024 years, so that the low-orbit satellite communication system is gradually entering a scale application stage. From the technical development, the first generation of low-orbit satellite communication system takes voice, short message and low-speed data service as cores, the core value is realized by realizing globalization of personal communication, the second generation of system focuses on global satellite broadband internet service, the data transmission rate is greatly improved, and along with the maturity of 5G technology and the starting of 6G research, the new generation of low-orbit satellite communication system is developing towards the direction of 'deep integration of ground and satellite', and more comprehensive and reliable communication services are required to be provided so as to meet the diversified scene demands of Internet of things, high-definition video transmission, emergency communication and the like. However, the low-orbit satellite communication system and the ground mobile communication system have essential differences in deployment environment, channel propagation characteristics and the like, and the satellite-ground transmission link faces unique technical challenges, wherein doppler frequency offset and long-varying time delay are core problems for limiting communication performance. The low orbit satellite moves along the orbit at a high speed, the moving speed relative to the earth surface can reach several kilometers per second, and the orbit height of the satellite is usually in the range of hundreds to thousands kilometers, so that the satellite-ground transmission distance shows dynamic change from far to near and from near to far in the process of once overhead passing of the satellite. For example, when the orbit height of the low orbit satellite is 600km and the maximum transmission distance corresponding to the lowest elevation angle is 1200km, the maximum Doppler frequency shift under the downlink carrier frequency 20GHz scene can reach 480kHz, the maximum Doppler frequency shift under the uplink carrier frequency 30GHz scene can reach 720kHz, and the transmission delay dynamically fluctuates between 2ms (nearest distance) and 4ms (farthest distance). The greatly and rapidly changing Doppler frequency offset and long-varying time delay can seriously damage the timing synchronization and the frequency synchronization of satellite-to-ground transmission, so that signal distortion and increase of transmission error rate become key bottlenecks affecting communication quality. In order to solv