CN119382737B - Quick capturing and tracking method for large frequency offset signal - Google Patents
Quick capturing and tracking method for large frequency offset signal Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7156—Arrangements for sequence synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18513—Transmission in a satellite or space-based system
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18519—Operations control, administration or maintenance
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7156—Arrangements for sequence synchronisation
- H04B2001/71563—Acquisition
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/713—Spread spectrum techniques using frequency hopping
- H04B1/7156—Arrangements for sequence synchronisation
- H04B2001/71566—Tracking
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Abstract
一种大频偏信号的快速捕获和跟踪方法，属于通信技术领域，该方法基于星历和惯导信息，计算相对速度矢量和相对加速度矢量，估算多普勒频偏和频偏变化率，对接收机进行预补偿，减少接收机的捕获频率范围，有效减低接收的复杂度和加快捕获速度；基于PMF‑FFT频偏估计算法，对频率精细估计和补偿，实现周期性频率跟踪；基于下行频偏的估计，对上行信号进行频率补偿，实现卫星和高动态平台闭环频率同步。该方法能够有效降低高动态平台接收机在大频偏下的信号捕获复杂度，加快了捕获和同步速度。
A method for fast capture and tracking of large frequency deviation signals belongs to the field of communication technology. The method is based on ephemeris and inertial navigation information, calculates relative velocity vector and relative acceleration vector, estimates Doppler frequency deviation and frequency deviation change rate, pre-compensates the receiver, reduces the receiver's capture frequency range, effectively reduces the complexity of reception and speeds up the capture speed; based on the PMF-FFT frequency deviation estimation algorithm, the frequency is precisely estimated and compensated to achieve periodic frequency tracking; based on the estimation of downlink frequency deviation, the uplink signal is frequency compensated to achieve closed-loop frequency synchronization of satellite and high-dynamic platform. The method can effectively reduce the signal capture complexity of high-dynamic platform receivers under large frequency deviation and speed up the capture and synchronization speed.
Description
Technical Field
The invention relates to the technical field of electronic communication, in particular to a rapid capturing and tracking method of a large frequency offset signal.
Background
The satellite communication system is used as a supplement of a ground communication system, has the characteristic of 'seamless' coverage to the ground, and can effectively support the communication requirements of special ground areas such as a space domain, an airspace, a sea domain, a desert and the like. At present, the measurement and control information transmission of the high-dynamic platform mainly adopts a foundation measurement and control mode, and the space-based measurement and control mode is few, so that the measurement and control information transmission of the high-dynamic platform is ensured by using a global Internet satellite communication system, and the method becomes a necessary choice. Meanwhile, because the flight time of the high-dynamic high-mobility platform is shorter, a satellite is adopted to provide a measurement and control link for the high-dynamic platform, the real-time performance of the high-dynamic platform control and telemetering can be ensured, and meanwhile, the reliability of the system is ensured by adopting a frequency hopping anti-interference system.
However, the distance and the relative speed of the high dynamic platform relative to the satellite change in real time, so that a large Doppler frequency offset is generated on the signal, and the rapid acquisition and synchronization of the signal become a reality problem.
Disclosure of Invention
Aiming at the problems of rapid capturing and rapid frequency synchronization of a large Doppler frequency offset signal under a satellite communication system and a high dynamic platform, the disclosure provides a rapid capturing and tracking method of the large frequency offset signal.
The method for rapidly capturing and tracking the large frequency offset signal mainly comprises the following steps:
S1, calculating a relative velocity vector and a relative acceleration vector of a satellite and a high-dynamic platform based on satellite ephemeris and high-dynamic platform inertial navigation, and estimating Doppler frequency offset and Doppler frequency offset change rate caused by relative motion of the satellite and the high-dynamic platform;
S2, performing frequency coarse compensation of the high-dynamic platform receiver based on Doppler frequency offset and Doppler frequency offset change rate;
S3, capturing a downlink based on PMF-FFT, and carrying out frequency fine compensation on a downlink signal according to the frequency offset estimated by the PMF-FFT;
s4, compensating the frequency of the uplink synchronous detection signal based on the downlink frequency offset estimation value;
S5, the satellite estimates the frequency difference of the uplink synchronous detection signal, the estimation result is fed back to the high-dynamic platform, and the high-dynamic platform further adjusts the sending frequency according to the frequency difference estimation value fed back by the satellite until the frequency difference meets the requirement, and the satellite frequency synchronization is completed.
Further, the step S1 specifically includes:
Acquiring satellite information by a preset satellite ephemeris, wherein the satellite is set as a geostationary GEO satellite, and the velocity vector is set as The acceleration vector isThe default ephemeris is substantially unchanged;
obtaining a speed vector as according to the inertial navigation information of the high-dynamic platform The acceleration vector is;
Calculating the relative speed vector of satellite and high dynamic platform as;
Doppler frequency offset estimation;
Calculating the relative acceleration vector of satellite and high dynamic platform as,
Doppler frequency offset change rate estimation;
Wherein c is the light speed of 3e8m/s.
Further, the method for coarsely compensating the frequency of the high dynamic platform receiver in the step S2 includes:
Setting the working frequency of the high dynamic platform receiver as The frequency after compensation is:
Wherein, For the working frequency, the Doppler frequency offset isThe Doppler frequency offset change rate isThe high dynamic platform receiving working frequency is set asThe rapid capturing of the downlink signal is realized, t is time, and a typical value is 10ms, namely, the typical platform inertial navigation provides 100 times per second of speed and acceleration frequency.
Further, the specific method in step S3 includes:
Setting the residual error of the frequency offset after the step S2 of rough compensation as The PMF-FFT frequency acquisition window is,;
Frequency offset estimated by PMF-FFT isThe compensated frequency is:
。
Further, in the step S4, the frequency compensation method for the uplink synchronization detection signal includes:
Set the downlink signal frequency The uplink signal frequency isThe downlink frequency offset estimation value is;
Uplink-downlink frequency ratio:;
The uplink signal frequency compensation is: 。
Further, the step S5 specifically includes:
the satellite carries out frequency difference estimation on the uplink synchronous detection signals;
Feeding back the frequency difference estimation result to the high dynamic platform;
the high dynamic platform judges according to the frequency difference estimated value fed back by the satellite:
The frequency difference is less than or equal to 5KHz, the frequency synchronization of the star-end link is considered to be completed;
Otherwise, the sending frequency is adjusted, and the detection signal is sent until the frequency difference is less than or equal to 5KHz.
Compared with the prior art, the method has the advantages of (1) pre-compensating the receiver based on Doppler frequency offset estimation of ephemeris and inertial navigation information, avoiding signal capture of a high-dynamic platform receiver under large frequency offset, reducing the complexity of receiving and accelerating the capturing speed, (2) carrying out fine estimation and compensation on the received frequency offset based on a PMF-FFT frequency offset estimation algorithm, ensuring the system performance and reducing the frequency synchronization times of a star end, and (3) adjusting the sending frequency based on the frequency offset estimation of a satellite on an uplink signal, and accelerating the frequency synchronization and tracking through the closed loop feedback.
Drawings
The foregoing and other objects, features and advantages of the disclosure will be apparent from the following more particular descriptions of exemplary embodiments of the disclosure as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the disclosure.
Fig. 1 is a flow chart of a process for a method for fast acquisition and tracking of large frequency offset signals according to the present disclosure.
Detailed Description
Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are illustrated in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The present disclosure provides a method for quickly capturing and tracking a large frequency offset signal, and a processing flow of an exemplary embodiment is shown in fig. 1. As can be seen from the figure, the method comprises the following steps:
(1) Relative velocity vector calculation based on satellite ephemeris and high dynamic platform inertial navigation
Satellite velocity vector of the ephemeris position informationAnd inertial navigation position information high dynamic platform velocity vector。
Calculating the relative speed vector of satellite and high dynamic platform asThat is, the satellite and the high dynamic platform have relative speeds of=±。
(2) Doppler frequency offset estimation based on satellite and high dynamic platform relative speed
The Doppler frequency offset caused by the relative speed of the satellite and the high dynamic platform isI.e.
Wherein the method comprises the steps ofFor the operating frequency, c is the speed of light 3e8m/s.
(3) Relative acceleration vector calculation based on satellite ephemeris and high dynamic platform inertial navigation
Satellite acceleration vector of the ephemeris position informationAnd inertial navigation position information high dynamic platform acceleration vector。
Calculating the relative acceleration vector of satellite and high dynamic platform asI.e. the relative acceleration of the high orbit satellite and the high dynamic platform is=±。
(4) Doppler frequency offset change rate estimation based on satellite and high dynamic platform relative speed
The Doppler frequency offset change rate caused by the relative speed of the satellite and the high dynamic platform is as followsI.e.
Wherein the method comprises the steps ofFor the working frequency, the Doppler frequency offset isThe Doppler frequency offset change rate isC is the speed of light 3e8m/s.
(5) High dynamic platform receiver frequency coarse compensation based on Doppler frequency offset and Doppler frequency offset change rate:
the working frequency of the high dynamic platform receiver is as follows The frequency after compensation is,
(6) Capturing a downlink based on PMF-FFT, and carrying out fine frequency offset estimation and compensation:
Let the frequency offset estimated by PMF-FFT be Realizing the frequency fine compensation of the downlink signal:
(7) For upstream signals (frequency is) Frequency compensation is carried out, and the frequency after compensation is:
(8) The satellite carries out frequency difference estimation on the signal after the uplink frequency compensation, and the estimated value is that;
Feeding back the estimation result to the high-dynamic platform, judging whether the satellite-end frequency synchronization is completed or not by the high-dynamic platform according to the frequency difference estimation value fed back by the satellite, and if the satellite-end frequency synchronization is not satisfied, further adjusting the sending frequency until the satellite-end frequency synchronization is completedAnd when the frequency is not more than 5KHz, the closed loop frequency synchronization of the satellite and the high dynamic platform is considered to be completed.
The foregoing technical solutions are merely exemplary embodiments of the present invention, and various modifications and variations can be easily made by those skilled in the art based on the application methods and principles disclosed in the present invention, not limited to the methods described in the foregoing specific embodiments of the present invention, so that the foregoing description is only preferred and not in a limiting sense.
Claims (4)
1. A rapid capturing and tracking method of a large frequency offset signal comprises the following steps:
S1, calculating a relative velocity vector and a relative acceleration vector of a satellite and a high-dynamic platform based on satellite ephemeris and high-dynamic platform inertial navigation, and estimating Doppler frequency offset and Doppler frequency offset change rate caused by relative motion of the satellite and the high-dynamic platform;
S2, performing frequency coarse compensation of the high-dynamic platform receiver based on Doppler frequency offset and Doppler frequency offset change rate;
S3, capturing a downlink based on PMF-FFT, and carrying out frequency fine compensation on a downlink signal according to the frequency offset estimated by the PMF-FFT;
s4, compensating the frequency of the uplink synchronous detection signal based on the downlink frequency offset estimation value;
s5, the satellite estimates the frequency difference of the uplink synchronous detection signal, and feeds back the estimation result to the high-dynamic platform, and the high-dynamic platform further adjusts the sending frequency according to the frequency difference estimation value fed back by the satellite until the frequency difference meets the requirement, so that the satellite frequency synchronization is completed;
the step S1 specifically includes:
acquiring satellite information by presetting a satellite ephemeris, wherein the satellite velocity vector is set as The acceleration vector isDefault ephemeris is unchanged;
obtaining a speed vector as according to the inertial navigation information of the high-dynamic platform The acceleration vector is;
Calculating the relative speed vector of satellite and high dynamic platform as;
Doppler frequency offset estimation;
Calculating the relative acceleration vector of satellite and high dynamic platform as,
Doppler frequency offset change rate estimation;
Wherein c is the light speed of 3e8m/s,Is the frequency of the downlink signal;
the high dynamic platform receiver frequency coarse compensation method in the step S2 comprises the following steps:
Setting the working frequency of the high dynamic platform receiver before compensation as I.e. the downlink signal frequency, the compensated frequency is:
Wherein the Doppler frequency offset change rate is,
I.e. the working frequency of the compensated high dynamic platform receiver is set asThe rapid capturing of the downlink signal is realized, t is time, and the value is 10ms, namely the platform inertial navigation provides 100 times/second of speed and acceleration frequency.
2. The method according to claim 1, wherein the specific method of step S3 comprises:
Setting the residual error of the frequency offset after the step S2 of rough compensation as The PMF-FFT frequency acquisition window is,;
Frequency offset estimated by PMF-FFT isThe compensated frequency is:
。
3. The method according to claim 2, wherein in the step S4, the method for compensating the frequency of the uplink synchronization probe signal includes:
Set the downlink signal frequency The uplink signal frequency isThe downlink frequency offset estimation value is;
Uplink-downlink frequency ratio:;
The uplink signal frequency compensation is: 。
4. a method according to any one of claims 1-3, wherein step S5 comprises:
the satellite carries out frequency difference estimation on the uplink synchronous detection signals;
Feeding back the frequency difference estimation result to the high dynamic platform;
the high dynamic platform judges according to the frequency difference estimated value fed back by the satellite:
The frequency difference is less than or equal to 5KHz, the frequency synchronization of the star-end link is considered to be completed;
Otherwise, the sending frequency is adjusted, and the detection signal is sent until the frequency difference is less than or equal to 5KHz.
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| CN112540388A (en) * | 2020-11-24 | 2021-03-23 | 湖北三江航天险峰电子信息有限公司 | Satellite communication module and uplink signal Doppler compensation method thereof |
| CN113422639A (en) * | 2021-07-02 | 2021-09-21 | 东方红卫星移动通信有限公司 | Method and system for synchronization of low-orbit satellite communication system based on position and ephemeris |
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| KR100617786B1 (en) * | 2004-07-13 | 2006-08-28 | 삼성전자주식회사 | Highly sensitive global positioning system receiver and method to compensate for Doppler changes |
| CN104852875B (en) * | 2015-03-26 | 2018-07-13 | 中国人民解放军理工大学通信工程学院卫星通信军队重点实验室 | The frequency deviation estimating method of the big frequency deviation burst of high dynamic |
| CN110798422B (en) * | 2019-11-25 | 2022-01-07 | 成都天奥集团有限公司 | Low earth orbit satellite multi-carrier communication system downlink sampling frequency offset estimation and compensation method |
| CN115913339B (en) * | 2023-01-05 | 2023-05-30 | 北京太极疆泰科技发展有限公司 | Low-orbit satellite high-dynamic frequency acquisition tracking method, server and storage medium |
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| CN112540388A (en) * | 2020-11-24 | 2021-03-23 | 湖北三江航天险峰电子信息有限公司 | Satellite communication module and uplink signal Doppler compensation method thereof |
| CN113422639A (en) * | 2021-07-02 | 2021-09-21 | 东方红卫星移动通信有限公司 | Method and system for synchronization of low-orbit satellite communication system based on position and ephemeris |
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