CN112968746B - Satellite-to-ground communication synchronous capturing method and device based on position and Doppler information - Google Patents

Satellite-to-ground communication synchronous capturing method and device based on position and Doppler information Download PDF

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CN112968746B
CN112968746B CN202110149008.4A CN202110149008A CN112968746B CN 112968746 B CN112968746 B CN 112968746B CN 202110149008 A CN202110149008 A CN 202110149008A CN 112968746 B CN112968746 B CN 112968746B
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satellite
time
ground
synchronization
communication
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CN112968746A (en
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沈洁
刘钢
贾霞
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Beijing Guodian Gaoke Technology Co ltd
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Beijing Guodian Gaoke Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/27—Acquisition or tracking or demodulation of signals transmitted by the system creating, predicting or correcting ephemeris or almanac data within the receiver
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
    • G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/42—Determining position
    • 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
    • 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
    • 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
    • H04B7/18517—Transmission equipment in earth stations
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation
    • H04J3/0644—External master-clock
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Power Engineering (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)

Abstract

The invention provides a satellite-to-ground communication synchronous capturing method and device based on position and Doppler information. In the first step, the ground terminal captures pilot signals blindly, and the second step is executed after the pilot signals are successfully captured; in the second step, the ground terminal demodulates the broadcast data, acquires satellite ephemeris, updates local parameters, and then executes the third step; in the third step, the ground terminal calculates and generates the optimal transmitting time and the used spread spectrum code according to three parameters of the local position, the satellite position and the self address; in the fourth step, the ground terminal calculates the satellite position according to the transmitting time, and further calculates the satellite-ground distance according to the signal delay, so as to calculate Doppler information; in the fifth step, the amount of advance time is calculated from the delay time before the transmission time is reached, the designated time is advanced via the reverse channel, and the ground terminal bursts data at a time after the designated time is advanced.

Description

Satellite-to-ground communication synchronous capturing method and device based on position and Doppler information
Technical Field
The invention belongs to the field of satellite communication, and particularly relates to a satellite-to-ground communication synchronous capturing method and device based on position and Doppler information, which can be used for synchronizing satellite load and ground terminals in various application scenes.
Background
The satellite communication is a microwave relay communication method realized by using a communication satellite as a relay station. For military and low rate, small capacity satellite communication systems, code Division Multiple Access (CDMA) spread spectrum communication systems are commonly employed, or with the assistance of FDMA and TDMA. CDMA has the advantages of strong anti-interference capability, smaller signal power spectrum density and good concealment. However, satellite communication systems are subject to transmission loss and mobile remote station antenna gain, and the signals are relatively weak. Under weak signal conditions, the synchronization of the pseudo-random code by the CDMA system receiver is difficult. To increase the receiver sensitivity, methods of extending the coherent integration time and increasing the number of incoherent integrations are generally adopted.
At present, a method for correcting a local clock by satellite navigation time service to obtain a high-precision clock and realizing time synchronization by a time transmission technology is adopted. The method is only aimed at the calibration of the local clock, so that the high-precision local clock is obtained or the local clock is synchronized with the time of the satellite navigation time service system. For a communication system, because of transmission delay, especially satellite communication, in the signal propagation process, the transmission delay is larger through an uplink link and a downlink link, the links generating errors are more (satellite drift, equipment delay, processing delay and the like), only synchronization of local time and satellite navigation time service system time is established, the specific moment when a transmitted signal reaches a receiving end through a satellite-to-ground link is still an uncertain amount, propagation time errors of a plurality of links are corrected, and otherwise, the scheme for directly synchronizing a local clock by utilizing satellite navigation time service cannot be directly used for synchronizing a spread spectrum signal pseudo code.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art, provides a satellite-to-ground communication synchronous capturing device based on position and Doppler information, and solves the technical problem that propagation time errors of a plurality of links need to be corrected because the traditional synchronous signal is an uncertain quantity.
According to the present invention, there is provided a method for capturing synchronization of inter-satellite communication signals in satellite communication based on position and Doppler information, for synchronizing inter-satellite communication signals in satellite communication based on Doppler information generated by inter-satellite and relative positions and relative movements between the satellites, comprising:
In the first step, the ground terminal captures pilot signals blindly, and the second step is executed after the pilot signals are successfully captured;
In the second step, the ground terminal demodulates the broadcast data, acquires satellite ephemeris, updates local parameters, and then executes the third step;
In the third step, the ground terminal calculates and generates the optimal transmitting time and the used spread spectrum code according to three parameters of the local position, the satellite position and the self address;
in the fourth step, the ground terminal calculates the satellite position according to the transmitting time, and further calculates the satellite-ground distance according to the signal delay, so as to calculate Doppler information;
In the fifth step, the amount of advance time is calculated from the delay time before the transmission time is reached, the designated time is advanced via the reverse channel, and the ground terminal bursts data at a time after the designated time is advanced.
Preferably, the second step and the third step together constitute a forward synchronization process.
Preferably, the fourth step constitutes a reverse synchronization process together with the fifth step.
Preferably, the Doppler information includes Doppler frequency offset, phase offset and frequency rate of change.
According to the present invention, there is also provided a device for synchronizing signals of inter-satellite communication in satellite-to-ground communication based on position and doppler information, for synchronizing signals of inter-satellite communication in satellite-to-ground communication based on doppler information generated by inter-satellite and relative positions and relative movements between the satellites, comprising: the digital-to-analog converter DAC circuit comprises a controller, synchronous hardware, a digital-to-analog converter DAC circuit and a clock signal generator;
The controller comprises a message control circuit and a data link control circuit; the message control circuit is used for communicating with other parts of the satellite-to-ground communication synchronous capturing device through the network interface, and adds a message head and a message tail into the message control circuit during communication to form message information; the data link control circuit is used for controlling wireless link communication between the satellite and the ground and between the satellites;
The synchronization circuit includes: a standard time source, a Doppler signal filter, and a local pseudorandom code time manager;
the standard time source forms satellite ephemeris according to the ground time service source and through communication among a plurality of satellites;
The Doppler signal filter generates Doppler information of relative motion for controlling synchronization according to the positions among different satellites, the relative positions of the satellites and the ground and the motion speed based on satellite ephemeris formed by a standard time source;
The digital-to-analog converter DAC circuit is used for converting the digital signal output by the Doppler signal filter into an analog signal;
The clock signal generator forms a synchronous clock signal together with a clock of the local crystal oscillator under the control of the analog signal converted by the high-resolution DAC circuit, and transmits the synchronous clock signal to the local pseudo-random code time manager;
The local pseudo-random code time manager generates a local pseudo-random code and a spreading code according to the relative positions of the local pseudo-random code and the system, calculates and obtains the optimal synchronization moment according to the generated local pseudo-random code and the spreading code and the received synchronization clock signal, and sends the optimal synchronization moment to the standard time source.
Preferably, the Doppler information is obtained by measurement of a pseudo-random sequence.
Preferably, the formed synchronous clock signal is output to the synchronized device at a timing as a synchronous frequency standard signal.
According to the present invention, there is also provided a device for synchronizing signals of inter-satellite communication in satellite-to-ground communication based on position and doppler information, for synchronizing signals of inter-satellite communication in satellite-to-ground communication based on doppler information generated by inter-satellite and relative positions and relative movements between the satellites, comprising:
the first device is used for receiving time information among satellites through an antenna and forming a satellite ephemeris time source;
the second device is used as a central controller for executing state control of time service and synchronization;
The third device is used for detecting the time information of the tested end and detecting a tested time source;
a fourth device, which is used as a time source controller device and is used for carrying out the message interaction of synchronous information between the first device and the second device;
A fifth means as a message generation circuit for generating a message;
a sixth device, configured to receive network time signals of the ground time service center, and add the signals to a message generated by the fifth device, so as to form an interactable message;
seventh means for performing conversion of the optical-electrical signals to support interaction between the optical and wireless signals and the time-stamped system.
Preferably, the fourth means is state controlled by the second means acting as a central controller.
Preferably, the header and the tail of the message generated by the fifth device are identified by fixed bits, and the intermediate information is generated by encoding operation.
The invention solves the technical problem that the propagation time errors of a plurality of links are required to be corrected because the traditional synchronous signal is an uncertain quantity. The invention can reduce the frequency uncertainty of the on-board demodulation information, thereby obviously reducing the on-board despreading demodulation burden; increasing the user capacity on the reverse channel.
Drawings
The invention will be more fully understood and its attendant advantages and features will be more readily understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, in which:
figure 1 schematically illustrates an overall flow diagram of a method for synchronous acquisition of satellite-to-ground communications based on position and doppler information in accordance with a preferred embodiment of the present invention.
Figure 2 schematically illustrates a functional block diagram of a position and doppler information based satellite-to-ground communication synchronization acquisition device in accordance with a preferred embodiment of the present invention.
Figure 3 schematically illustrates a hardware arrangement diagram of a satellite-to-ground communication synchronization acquisition device based on position and doppler information in accordance with a preferred embodiment of the present invention.
It should be noted that the drawings are for illustrating the invention and are not to be construed as limiting the invention. Note that the drawings representing structures may not be drawn to scale. Also, in the drawings, the same or similar elements are denoted by the same or similar reference numerals.
Detailed Description
In order that the invention may be more readily understood, a detailed description of the invention is provided below along with specific embodiments and accompanying figures.
In an embodiment of the invention, a communication frequency of 300MHz may be used, but is not limited to this frequency, under which condition doppler related information:
Satellite-ground Doppler: (actually 10KHz, taking into account the frequency source bias of 5 KHz);
Satellite-to-ground Doppler rate of change:
1. Forward synchronization procedure
The downlink channel constructs a super frame with GPS/BD-2 second pulse and time information according to 60 second intervals, and broadcasts the full network ephemeris and the configuration information of the star in a specific time slot of the super frame. And transmitting downlink data in the designated downlink time slot.
The downlink has ideal capturing, tracking and synchronizing performance because the pilot frequency and the broadcast information can be fully utilized.
2. Reverse synchronization process
The main objectives of reverse synchronization include:
(1) The frequency uncertainty of the on-board demodulation information is reduced, so that the on-board despreading demodulation burden is remarkably reduced.
(2) Increasing the user capacity on the reverse channel;
The first goal is the main burden faced on the satellite, which is still costly to process for 15KHz doppler, even with a sufficiently long pilot sequence (reverse pilot) in cases where satellite-to-ground time cannot be synchronized.
By the effective technical means of the invention, the search range of the frequency on the satellite is compressed to 4KHz, and the capturing time is improved by 3 times under the condition of the same algorithm. This is very advantageous for burst channels.
The invention is to adopt a reverse synchronization method based on GPS/BD-2+ broadcast information + pilot frequency measurement.
For example, a specific implementation method may include:
(1) The fixed terminal first accesses the network to determine its own position through (GPS/BD-2). The mobile terminal acquires the position of the mobile terminal in real time. And corrects the local time and time accuracy based on the navigation data.
(2) The terminal attempts to acquire the satellite broadcast frame after power-on (low power acquisition strategy for pilot). Acquiring a current satellite ephemeris after successful acquisition (simultaneously acquiring other satellite ephemeris of the whole network), and calculating satellite positions, relative distances and relative speeds according to the satellite ephemeris at a subsequent time (validity period of 10 minutes);
(3) Based on the relative distance and the relative speed calculation, the terminal calculates the accurate transmission frame offset, transmission time and transmission power in the appointed time slot (ensuring that the frequency of the signal received by the satellite is in the range of 3KHz, randomly selecting the frequency/time slot/spread spectrum code) according to the reverse channel spectrum configuration and the code word configuration in the broadcast information and the time slot configuration, thereby ensuring that the satellite can demodulate rapidly.
3. Synchronization flow and method
The synchronization process involves three computations:
1) Calculating satellite positions and Doppler at specified moments according to satellite ephemeris;
2) Calculating a satellite-to-ground distance for a specified time from a satellite position and a terminal position (local GPS);
3) The plurality of parameters are used as random numbers to calculate the best time slot for transmission.
In particular, fig. 1 schematically shows an overall flow chart of a method for synchronous acquisition of satellite-to-ground communication based on position and doppler information according to a preferred embodiment of the invention. The method can be used for synchronizing inter-satellite communication signals in satellite communication according to Doppler information generated by inter-satellite and relative positions and relative movements between the satellites and the ground. The synchronous processing method is respectively executed on a forward channel and a reverse channel, and the synchronous processing between the load and the ground terminal is completed. Taking three calculations to complete the synchronization as an example, the following steps are described in detail in connection with fig. 1.
As shown in fig. 1, the method for capturing synchronous satellite-to-ground communication based on position and doppler information according to the preferred embodiment of the present invention comprises:
in a first step 101, the ground terminal blindly acquires the pilot signal, and after success, performs a second step 102.
In a second step 102, which is a forward synchronization process, and a third step 103, the ground terminal demodulates the broadcast data, acquires satellite ephemeris, updates local parameters, and then performs the third step 103.
In a third step 103, the ground terminal calculates the best transmit time and spreading code to use based on three parameters, namely the local position, satellite position and its own address. The ground terminal executes the process to finish the forward synchronization of the star to the ground.
In a fourth step 104 (the fourth step and the fifth step 105 together form a reverse synchronization process), the ground terminal accurately calculates the satellite position according to the transmitting time, and further calculates the satellite-ground distance according to the signal delay, so as to calculate doppler information, for example, the doppler information includes information such as doppler frequency offset, phase offset, frequency change rate, and the like.
In a fifth step 105, the amount of advance time is calculated from the delay time before reaching the transmission time, the designated time is advanced via the reverse channel, and the ground terminal bursts data at a time after the designated time is advanced. And finishing the reverse synchronization processing process through the steps.
Figure 2 schematically illustrates a functional block diagram of a position and doppler information based satellite-to-ground communication synchronization acquisition device in accordance with a preferred embodiment of the present invention.
As shown in fig. 2, the satellite-to-ground communication synchronization acquisition device based on position and doppler information according to the preferred embodiment of the present invention includes: a controller 21, synchronization hardware 22, digital-to-analog converter DAC circuitry, and a clock signal generator 232. For example, the controller may employ a general purpose Digital Signal Processor (DSP) and the synchronization hardware may be programmed by the FPGA. The implementation method is based on a general chip, but is not limited to the above manner, and for example, an application specific integrated circuit implementation can be designed.
The controller 21 includes a message control circuit 201 and a data link control circuit 202.
The message control circuit 201 is configured to communicate with other parts of the satellite-to-ground communication synchronous capturing device through a network interface, and adds a message header and a message tail into the message control circuit during communication to form message information.
The data link control circuitry 202 is used to control the wireless link communications between the satellites and the ground and between the satellites.
The synchronization hardware 22 includes: a standard time source 221, a doppler signal filter 222 and a local pseudorandom code time manager 223.
Standard time source 221 forms satellite ephemeris from terrestrial time sources via communication between a plurality of satellites.
The Doppler signal filter 222 generates Doppler information, such as Doppler frequency offset, phase offset, frequency change rate, and the like, for relative movement based on the satellite ephemeris formed by the standard time source 221, based on the position between the satellites and the relative position of the satellites to the ground, and the speed of movement. Such doppler information may be obtained by measurement of a pseudo random sequence. The Doppler signal filter obtains the information of the required Doppler frequency offset and phase offset and is used for controlling synchronization.
The DAC circuit is, for example, a high-resolution DAC circuit 231, and is configured to convert the digital signal output from the doppler signal filter 222 into an analog signal.
The clock signal generator 232 forms a synchronizing clock signal together with the clock of the local crystal oscillator under the control of the analog signal converted by the high resolution DAC circuit 231 and delivers the synchronizing clock signal to the local pseudorandom code time manager 223, and the formed synchronizing clock signal (standard timing signal), that is, a synchronizing frequency standard signal, is output to the synchronized device at a timing.
The local pseudorandom code time manager 223 generates information such as local pseudorandom codes, spread spectrum codes, etc. according to the relative positions of the local and system, calculates the best synchronization time from these information and the received synchronization clock signal, and sends the best synchronization time to the standard time source 221. The standard time source is typically broadcast via an ephemeris in a GPS or beidou system for time service to a satellite system.
A closed loop system is formed by the hardware device standard time source 221, the doppler signal filter 222, the high resolution DAC circuit 231, the clock signal generator 232, the local pseudorandom code time manager 223, connected by signal lines.
Figure 3 schematically illustrates a hardware arrangement diagram of a satellite-to-ground communication synchronization acquisition device based on position and doppler information in accordance with a preferred embodiment of the present invention. The control module therein may be regarded as a refinement to the controller circuit of fig. 2. The synchronous device adopts the form of satellite load and ground terminal message interaction to carry out time service.
The first device 301 receives time information between satellites through an antenna to form a satellite ephemeris time source;
the second device 302 is used as a central controller for performing state control of timing and synchronization;
the third device 303 is configured to detect time information of the detected end, and perform detected time source detection. For example, satellite loading detects the time source information of the ground terminals via time delay messages.
The fourth device 304 is used as a time source controller device for performing a message interaction of synchronization information with the first device 301 and the second device 302, wherein the second device 302 is used as a central controller for performing state control on the fourth device;
The fifth device 305 is used as a message generating circuit for generating a message, wherein the header and the tail of the message are generally identified by fixed bits, and the intermediate information is generated by encoding operation. The message generating circuit generates a message according to the control of the time source controller. The message head and the message tail of the message issued by the time source are fixed, and the intermediate information is generated by encoding. This is achieved by hardware encoding registers.
The sixth device 306 is configured to receive network time signals of the ground time service center, and add the signals to the message generated by the fifth device 305 to form an interactable message.
The seventh means 307 is for performing conversion of the optical-electrical signal to support interaction between the optical signal and the wireless signal and the time-given system.
The present invention has at least the following advantages over the prior art:
1. The application range is wide, and the frequency uncertainty of the on-board demodulation information can be reduced due to the adoption of satellite ephemeris and Doppler information, so that the on-board despreading demodulation burden is obviously reduced.
2. The method has low implementation cost and high reliability, and can be realized by programming by adopting a general FPGA or DSP. Because of adopting a mature device, the reliability is higher;
3. the synchronization capability is strong, and the capturing time is improved by 3 times. This is very advantageous for burst channels, improving overall synchronization performance;
4. The expansibility is high, and the expansibility is good due to the adoption of the star-ground cooperative algorithm. Increasing the user capacity on the reverse channel.
It should be noted that, unless specifically stated otherwise, the terms "first," "second," "third," and the like in the specification are used merely as a distinction between various components, elements, steps, etc. in the specification, and are not used to denote a logical or sequential relationship between various components, elements, steps, etc.
It will be appreciated that although the invention has been described above in terms of preferred embodiments, the above embodiments are not intended to limit the invention. Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims (3)

1. A synchronous acquisition device for satellite-to-ground communication based on position and doppler information, for synchronizing signals of the satellite-to-ground communication in satellite communication according to doppler information generated by inter-satellite and relative positions and relative movements between the satellites, comprising:
The digital-to-analog converter DAC circuit comprises a controller, synchronous hardware, a digital-to-analog converter DAC circuit and a clock signal generator;
The controller comprises a message control circuit and a data link control circuit; the message control circuit is used for communicating with other parts of the satellite-to-ground communication synchronous capturing device through the network interface, and adds a message head and a message tail into the message control circuit during communication to form message information; the data link control circuit is used for controlling wireless link communication between the satellite and the ground and between the satellites;
The synchronization circuit includes: a standard time source, a Doppler signal filter, and a local pseudorandom code time manager;
the standard time source forms satellite ephemeris according to the ground time service source and through communication among a plurality of satellites;
The Doppler signal filter generates Doppler information of relative motion for controlling synchronization according to the positions among different satellites, the relative positions of the satellites and the ground and the motion speed based on satellite ephemeris formed by a standard time source;
The digital-to-analog converter DAC circuit is used for converting the digital signal output by the Doppler signal filter into an analog signal;
The clock signal generator forms a synchronous clock signal together with a clock of the local crystal oscillator under the control of the analog signal converted by the high-resolution DAC circuit, and transmits the synchronous clock signal to the local pseudo-random code time manager;
The local pseudo-random code time manager generates a local pseudo-random code and a spreading code according to the relative positions of the local pseudo-random code and the system, calculates and obtains the optimal synchronization moment according to the generated local pseudo-random code and the spreading code and the received synchronization clock signal, and sends the optimal synchronization moment to the standard time source.
2. The position and doppler information based satellite-to-ground communication synchronization acquisition device of claim 1, wherein the doppler information is obtained by measurement of a pseudo-random sequence.
3. The position and doppler information based satellite-to-ground communication synchronization acquisition device according to claim 1 or 2, wherein the formed synchronization clock signal is output to the synchronized device at regular time as a synchronization frequency standard signal.
CN202110149008.4A 2021-02-03 2021-02-03 Satellite-to-ground communication synchronous capturing method and device based on position and Doppler information Active CN112968746B (en)

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