Spreading code multiplexing method and device in low orbit navigation system

Abstract

The invention provides a spreading code multiplexing method and device in a low orbit navigation system, and relates to the technical field of satellite coding. The method comprises the specific steps that constellation design parameters are determined, and the maximum geometric coverage area of a single satellite is determined according to the constellation design parameters; calculating a first target multiplexing condition of satellites on the same orbit plane; calculating the minimum distance between the two satellites in the constellation; and selecting a satellite from the constellation as a reference satellite, and determining the spreading codes of the satellites in the constellation according to the minimum distance between the reference satellite and other satellites, the first target multiplexing condition and the second target multiplexing condition. The constellation design parameters are processed to determine the target multiplexing condition of the satellites on the same orbit plane, and the spread spectrum codes of the satellites are determined based on the target multiplexing condition and the minimum distance between the reference satellite and other satellites, so that spread spectrum code multiplexing is realized, the operation pressure of searching the spread spectrum codes when a receiver receives signals in satellite communication is reduced, and the communication efficiency is improved. And the efficiency of searching the spreading code corresponding to the satellite during cold start of the receiver is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of satellite coding technology, and in particular to a spread spectrum code multiplexing method and device in a low-orbit navigation system. Background Art

[0002] In related technologies, the Global Navigation Satellite System (GNSS) mostly uses code division multiple access (CDMA) to broadcast navigation information. The receiver distinguishes signals between different satellites by despreading. At the same time, the spread spectrum code (pseudocode) is also a "measure" of distance changes. The spread spectrum code is an important basis for the positioning user receiver to distinguish the signals broadcast by different satellites in the navigation constellation at the same frequency, and it is also a means of distance measurement for satellites and stations. Existing navigation constellations such as BeiDou-3, GPS, and GLONASS mostly operate in the middle and high orbits of the earth. Only dozens of satellites are needed to achieve multiple coverage of the ground, so each satellite is given a unique spread spectrum code.

[0003] However, due to the large number of low-orbit constellation satellites, it is necessary to design a more complex spread spectrum code generation mechanism, which is inefficient when searching for the spread spectrum code corresponding to the satellite. Summary of the invention

[0004] The present disclosure provides a method, device and system for multiplexing spread spectrum codes in a low-orbit navigation system. The technical solution of the present disclosure is as follows:

[0005] According to a first aspect of an embodiment of the present disclosure, a spread spectrum code multiplexing method in a low-orbit navigation system is provided, comprising:

[0006] Calculating a first target multiplexing condition for satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite;

[0007] Calculating the minimum distance between two satellites in the constellation according to the constellation design parameters;

[0008] A satellite is selected from the constellation as a reference star, and a spread spectrum code of the satellite in the constellation is determined according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is a multiplexing condition of satellites between orbital planes, and the spread spectrum code is used by a receiver in satellite communication to demodulate a bandwidth signal sent by the satellite to obtain an original signal.

[0009] Optionally, the constellation design parameter includes at least one of the following:

[0010] Satellite altitude;

[0011] The maximum surface altitude at which navigation services can be provided;

[0012] Lower limit of the received signal elevation angle;

[0013] The right ascension interval of the ascending nodes between orbital planes;

[0014] Optionally, the formula for determining the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters is expressed as:

[0015]

[0016] θ=90-E0-α

[0017] Among them, θ is the ground half angle corresponding to the maximum geometric coverage area of ​​a single satellite, E0 is the lower limit of the elevation angle of the received signal, R is the equatorial radius of the earth; h is the satellite altitude; h' is the maximum surface altitude that can provide navigation services, and α is the semi-cone angle of the single satellite antenna coverage range.

[0018] Optionally, the calculating, according to the maximum geometric coverage area of ​​the single satellite, the first target multiplexing condition of the satellites in the same orbital plane includes:

[0019] According to the maximum coverage range of the single satellite, the target multiplexing condition that should be satisfied by two satellites that reuse the spread spectrum code in the same orbital plane is determined, wherein the first target multiplexing condition is:

[0020] Δφ≥2θ

[0021]

[0022] Among them, Δφ is the phase difference between the two stars, T is the total number of satellites in the constellation, P is the number of orbital planes, and k= is a positive integer, T / P.

[0023] Optionally, calculating the minimum distance between two satellites in the constellation includes:

[0024] Obtain a first coordinate of a first satellite and a second coordinate of a second satellite;

[0025] Rotate the second coordinate by ΔΩ around the z-axis, and calculate the distance between the second coordinate and the first coordinate after the rotation as the distance between the two satellites, where ΔΩ is the right ascension interval of the ascending node between the orbital planes;

[0026] An extreme condition of the distance between the two satellites is determined, and the minimum distance is determined according to the extreme condition.

[0027] Optionally, determining the spread spectrum code of the satellite according to the minimum distance between the reference satellite and other satellites, the first target multiplexing condition and the second target multiplexing condition includes:

[0028] Determine a maximum value of a parameter k corresponding to a single track plane according to the first target multiplexing condition;

[0029] Determine a second target multiplexing condition, and determine a conjugation point according to the second target multiplexing condition, wherein the second target multiplexing condition is a conjugation threshold;

[0030] Generate a conjugate table according to the arrangement rule of the conjugate points between different orbital planes;

[0031] Initialization settings are performed according to constellation parameters, and conjugate points whose minimum distance from the reference star is less than the conjugate threshold are traversed and calculated to generate a conjugate point set;

[0032] The period is determined according to the maximum value of the parameter k and the number of conjugate points in the largest conjugate point set of the single orbital plane;

[0033] The first conjugate point of each column in the conjugate table is taken as the starting point, and satellite codes are marked on the conjugate points therein according to the period, wherein the interval between the starting serial numbers of the first conjugate points of adjacent columns is the maximum value of the parameter k.

[0034] According to a second aspect of an embodiment of the present disclosure, a spread spectrum code multiplexing device in a low-orbit navigation system is provided, comprising:

[0035] A coverage area determination module, used to determine constellation design parameters, and determine the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters;

[0036] A reuse condition calculation module, used for calculating the first target reuse condition of satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite;

[0037] A distance calculation module, used to calculate the minimum distance between two satellites in the constellation according to the constellation design parameters;

[0038] A spread spectrum code marking module is used to select a satellite from the constellation as a reference star, and determine the spread spectrum code of the satellite in the constellation according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is the multiplexing condition of satellites between orbital planes, and the spread spectrum code is used for a receiver in satellite communication to demodulate the bandwidth signal sent by the satellite to obtain the original signal.

[0039] According to a third aspect of an embodiment of the present disclosure, there is provided an electronic device, including:

[0040] processor;

[0041] a memory for storing instructions executable by the processor;

[0042] The processor is configured to execute the instructions to implement the method as described in any one of the first aspects.

[0043] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided. When instructions in the storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute a method as described in any one of the first aspects.

[0044] The technical solution provided by the embodiments of the present disclosure brings at least the following beneficial effects:

[0045] In this embodiment, the constellation design parameters are processed to determine the target multiplexing conditions of the satellites in the same orbital plane, and the spread spectrum code of each satellite is determined based on the target multiplexing conditions and the minimum distance between the reference satellite and other satellites, thereby realizing the reuse of the spread spectrum codes and reducing the total number of spread spectrum codes. Furthermore, the computational pressure of searching for spread spectrum codes when receiving signals in satellite communications is reduced, and the efficiency of searching for spread spectrum codes corresponding to satellites when the receiver is cold started is greatly improved.

[0046] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the description are used to explain the principles of the present disclosure, and do not constitute improper limitations on the present disclosure.

[0048] Figure 1 The present invention is a flowchart of a method for multiplexing spread spectrum codes in a low-orbit navigation system according to an exemplary embodiment.

[0049] Figure 2 Schematic diagram of the satellite arrangement in the constellation.

[0050] Figure 3 This is a schematic diagram of the coverage area of ​​a single satellite.

[0051] Figure 4 Intended for conjugation.

[0052] Figure 5 It is a block diagram of a spread spectrum code multiplexing device in a low-orbit navigation system according to an exemplary embodiment.

[0053] Figure 6 It is a block diagram of a device according to an exemplary embodiment.

[0054] Figure 7 It is a block diagram of a device according to an exemplary embodiment. DETAILED DESCRIPTION

[0055] In order to enable ordinary persons in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings.

[0056] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0057] The current global satellite navigation system (GNSS) mostly uses code division multiple access (CDMA) to broadcast navigation information. The receiver distinguishes signals between different satellites by despreading. At the same time, the spread spectrum code (pseudocode) is also a "measure" of distance changes. The spread spectrum code is an important basis for the positioning user receiver to distinguish the signals broadcast by different satellites in the navigation constellation at the same frequency, and it is also a means of distance measurement for satellites and stations. Existing navigation constellations such as Beidou-3, GPS, and GLONASS mostly operate in the middle and high orbits of the earth. Only dozens of satellites are needed to achieve multiple coverage of the ground, so each satellite is given a unique spread spectrum code.

[0058] With the development of communication and navigation fusion technology, it has become a development trend for low-orbit satellites to provide communication services while taking advantage of geometric diversity to provide navigation services. Unlike traditional medium and high-orbit navigation constellations, low-orbit navigation constellations have the characteristics of a large number of satellites, strong signals, and a single satellite coverage range that is much smaller than that of medium and high-orbit satellites. If the traditional navigation satellite spread spectrum code design method is adopted, each satellite has a unique spread spectrum code, then thousands or even tens of thousands of spread spectrum code addresses are required. Taking the commonly used navigation spread spectrum code gold code as an example, the generation process requires m sequence pairs, and the number of code addresses is: where is the number of shift registers. Such a code address scale increases the complexity of the spread spectrum code generation of the navigation broadcaster on the one hand, and complicates the receiver design on the other hand. At the same time, the search domain becomes larger when the receiver is cold started, the amount of calculation increases dramatically, and the signal capture time becomes longer. A calculation method for spread spectrum code reuse that takes into account constellation design and coverage is needed. At the same time, the coverage range of a single low-orbit satellite is small, which creates conditions for spread spectrum code reuse. Through the reuse of spread spectrum codes, the purpose of simplifying on-board navigation components, reducing the complexity of user receiver hardware and software design, and reducing computing power requirements can be achieved.

[0059] Figure 1 is a flow chart showing a method for multiplexing spread spectrum codes in a low-orbit navigation system according to an exemplary embodiment. Figure 1 As shown, the method includes the following steps.

[0060] Step 101, determining constellation design parameters, and determining the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters;

[0061] Step 102, calculating a first target multiplexing condition of satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite;

[0062] Step 103, calculating the minimum distance between two satellites in the constellation according to the constellation design parameters;

[0063] Step 104, select a satellite from the constellation as a reference star, and determine the spread spectrum code of the satellite in the constellation according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is the multiplexing condition of satellites between orbital planes, and the spread spectrum code is used for the receiver in satellite communication to demodulate the bandwidth signal sent by the satellite to obtain the original signal.

[0064] The satellite communication process includes a transmitter and a receiver. The transmitter is usually a satellite and the receiver is usually a ground terminal device. The interaction between the transmitter and the receiver during satellite communication includes the following steps:

[0065] 1) Spread spectrum modulation: At the transmitting end, the original signal is modulated by a high-speed code sequence called a spread spectrum code. The frequency of the spread spectrum code is much higher than the frequency of the original signal, and the original signal can be expanded into a broadband signal. The role of the spread spectrum code is to evenly distribute the original signal over a larger frequency band, making the signal more broadband, low power and weak interference.

[0066] 2) Transmission: The spread spectrum signal is transmitted to the receiving end through a transmission medium (such as air, cable, optical fiber, etc.). Due to the characteristics of spread spectrum technology, the quality and reliability of signal transmission can be effectively guaranteed even in a high-interference environment.

[0067] 3) Despreading: At the receiving end, after receiving the spread spectrum signal, the appropriate spreading code is searched from the spreading code set, and the original signal is restored by demodulating the spreading code. The receiving end uses the same spreading code as the transmitting end to despread the signal so that the signal can be restored to the original signal.

[0068] In this embodiment, through the target multiplexing condition, multiple satellites can use the same spread spectrum code, reducing the total number of spread spectrum codes. In this way, after the receiving end receives the signal during the despreading process, the computing power required in the process of searching for a suitable spread spectrum code is reduced, thereby reducing the computing pressure on the receiving end.

[0069] Assume that the design parameters of the orbit determination navigation constellation are: i:T / P / F, where: i is the orbit inclination, T / P / F are the total number of satellites in the constellation, the number of orbital planes and the phase factor respectively.

[0070] The right ascension interval of the ascending node between orbital planes is ΔΩ, and the phase difference between satellites is β, so u^'=u+β, Figure 2 This is a schematic diagram of the satellite arrangement in the constellation. Figure 2 shown.

[0071] ΔΩ=360j / P (1)

[0072]

[0073] This embodiment overcomes the problem that each satellite in the current navigation system uses a unique spread spectrum code, resulting in a large number of spread spectrum codes, and the corresponding receiver has a wide search range, is time-consuming and inefficient when despreading signals. It aims to reduce the complexity of user receiver design and the amount of signal capture calculations, improve the receiver cold start efficiency, and ultimately achieve cost reduction and efficiency improvement of the low-orbit navigation system through spread spectrum code address reuse.

[0074] Optionally, the constellation design parameter includes at least one of the following:

[0075] Satellite altitude;

[0076] The maximum surface altitude at which navigation services can be provided;

[0077] Lower limit of the received signal elevation angle;

[0078] The right ascension interval of the ascending nodes between orbital planes;

[0079] Optionally, the formula for determining the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters is expressed as:

[0080]

[0081] θ=90-E0-α

[0082] Among them, θ is the ground half angle corresponding to the maximum geometric coverage area of ​​a single satellite, E0 is the lower limit of the elevation angle of the received signal, R is the equatorial radius of the earth; h is the satellite altitude; h' is the maximum surface altitude that can provide navigation services, and α is the semi-cone angle of the single satellite antenna coverage range.

[0083] like Figure 1 As shown in the figure, R is the radius of the earth's equator, h is the satellite height, and h' is the maximum surface height that can provide navigation services, which is shown by the black dotted line in the figure. Considering that when the elevation angle of the received signal is less than the lower limit E0, the capture of the signal can be directly abandoned.

[0084] In a possible embodiment, when the constellation orbit inclination angle i>90-θ, there is a spread spectrum code that is completely unusable between the ascending and descending orbit planes with an ascending node difference near π.

[0085] Optionally, the calculating, according to the maximum geometric coverage area of ​​the single satellite, the target multiplexing condition of satellites in the same orbital plane includes:

[0086] Figure 3 is a schematic diagram of the coverage of a single satellite, such as Figure 3 As shown in the figure, based on the maximum coverage of a single satellite, two satellites in the same orbital plane that reuse spread spectrum codes should meet the following first target reuse condition:

[0087] Δφ≥2θ

[0088]

[0089] Among them, Δφ is the phase difference between the two stars, T is the total number of satellites in the constellation, P is the number of orbital planes, and k = 1, 2…, T / P.

[0090] Considering the relationship between k and the integer multiples of the number of satellites in the orbital plane and k, the number of spreading codes required for a single orbital plane when only intra-orbital multiplexing is used can be obtained.

[0091] In a possible embodiment, the position where Δφ=180° in the same orbital plane is called the antipodal point, and the spread spectrum code can be reused near the antipodal point.

[0092] Optionally, calculating the minimum distance between two satellites in the constellation includes:

[0093] Obtain a first coordinate of a first satellite and a second coordinate of a second satellite;

[0094] Rotate the second coordinate by ΔΩ around the z-axis, and calculate the distance between the second coordinate and the first coordinate after the rotation as the distance between the two satellites, where ΔΩ is the right ascension interval of the ascending node between the orbital planes;

[0095] An extreme condition of the distance between the two satellites is determined, and the minimum distance is determined according to the extreme condition.

[0096] In a possible embodiment, the first coordinates of the first satellite are (x, y, z), and the second coordinates of the second satellite are (x', y', z').

[0097] x=r0cosu,y=r0sinu cosi0,z=r0sinu sini0 (6)

[0098] x′=r0cosu′, y′=r0sinu′cosi0, z′=r0sinu′sini0 (7)

[0099] The coordinates of the second satellite are rotated by ΔΩ around the z-axis and expressed as (x″, y″, z″) in a unified coordinate system.

[0100]

[0101] Among them, R z is the rotation matrix around the z-axis, and i0 is the inclination of the first orbit.

[0102] Then the distance ρ between the two satellites can be expressed as:

[0103]

[0104] The square of the distance between two satellites ρ 2 It can be expressed as:

[0105]

[0106] Analyzing the intersection extreme value, we can get:

[0107]

[0108] Since i≠0°or 180°, then Therefore:

[0109] sin(u+u′)[cosΔΩ-1]=0 (12)

[0110] When ΔΩ=0, the satellites are coplanar, the distance between the satellites remains unchanged, and the distance between the two satellites at any time can be regarded as the minimum distance between the two. When ΔΩ≠0, sin(u+u′)=0, that is, when u+u′=kπ, k∈Z, the distance between the two satellites reaches the extreme value. Among them, if u+u′=2kπ, it takes the maximum value; if u+u′=(2k+1)π, k∈N, it takes the minimum value. And it shows different monotonic forms before and after the extreme value is obtained. It can be judged that the minimum value of the actual intersection distance of the two satellites can be obtained near the extreme value analytical condition.

[0111] Optionally, determining the spread spectrum code of the satellite according to the minimum distance between the reference satellite and other satellites, the first target multiplexing condition and the second target multiplexing condition includes:

[0112] Determine a maximum value of a parameter k corresponding to a single track plane according to the first target multiplexing condition;

[0113] Determine a second target multiplexing condition, and determine a conjugation point according to the second target multiplexing condition, wherein the second target multiplexing condition is a conjugation threshold;

[0114] Generate a conjugate table according to the arrangement rule of the conjugate points between different orbital planes;

[0115] Initialization settings are performed according to constellation parameters, and conjugate points whose minimum distance from the reference star is less than the conjugate threshold are traversed and calculated to generate a conjugate point set;

[0116] The period is determined according to the maximum value of the parameter k and the number of conjugate points in the largest conjugate point set of the single orbital plane;

[0117] The first conjugate point of each column in the conjugate table is taken as the starting point, and the conjugate points therein are marked with spread spectrum codes according to the period, wherein the starting sequence number interval of the first conjugate points of adjacent columns is the maximum value of the parameter k.

[0118] Figure 4 To indicate conjugation, Figure 4 As shown, the first table is selected as the reference star. Satellites whose distance to the reference star is less than τ cannot reuse the spread spectrum code and are called the conjugate points of the reference star. Count the number of conjugate stars N s , due to symmetry, the number of conjugate points of different reference stars is similar.

[0119]

[0120] Among them, τ is the conjugate threshold, which is also the second target reuse condition. It indicates the distance. After entering this distance, the spread spectrum codes of the two satellites cannot be reused. According to the above minimum value and monotonicity, it can be judged that the satellite numbers entering the conjugate threshold τ will be continuous. The arrangement rules of conjugate points between different orbital planes are counted to prepare for the reuse of spread spectrum codes between orbital planes. And give a conjugate table, such as Figure 4 As shown in the table, the table lists a single orbital plane, and the red part in the column is the conjugate point. Statistics on the maximum number of satellites that can be seen by ground users at any location in the world N u , then the minimum number of spreading codes required for the entire navigation constellation is in It is a collection of the number of navigation stars that are commonly seen by ground users at different locations.

[0121] Initialize the constellation parameters, select the first reference star at random, and traverse and calculate the conjugate point set with the minimum distance less than τ Where i represents the track number. Find the maximum value of a single track. by is the total number of spread spectrum codes, with the first conjugate point of each column in the conjugate table as the starting point, and the first column is marked from serial number 1. is a cycle until the column mark ends. The interval between the starting numbers of the first conjugate points in adjacent columns is k max , repeat the above process until all satellite code positions are filled.

[0122] The key point of this embodiment is to comprehensively use the spread spectrum code arrangement ideas of conjugate points and antipodal points, and prove the continuous distribution property of the minimum value of the conjugate point distance through the derivation of the analytical expression, extreme value and monotonicity of the distance between any two stars in the constellation. Through the reuse of spread spectrum codes, the design of satellite navigation components will be simplified, and the signal acquisition efficiency of the receiver during cold start will be greatly improved.

[0123] This embodiment has the advantages of greatly reducing the total number of spread spectrum code addresses, reducing the design complexity of satellite navigation components, while reducing the design complexity of user receiver hardware and software, reducing the search computing power during signal capture, and greatly improving signal capture efficiency.

[0124] Figure 5 is a block diagram of a spread spectrum code multiplexing device in a low-orbit navigation system according to an exemplary embodiment. Figure 5 , the device comprises:

[0125] A coverage area determination module 510 is used to determine constellation design parameters, and determine the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters;

[0126] A reuse condition calculation module 520, configured to calculate a first target reuse condition of satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite;

[0127] A distance calculation module 530, configured to calculate the minimum distance between two satellites in the constellation according to the constellation design parameters;

[0128] The spread spectrum code marking module 540 is used to select a satellite from the constellation as a reference star, and determine the spread spectrum code of the satellite in the constellation according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is the multiplexing condition of satellites between orbital planes, and the spread spectrum code is used for the receiver in satellite communication to demodulate the bandwidth signal sent by the satellite to obtain the original signal.

[0129] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0130] Figure 6 8 is a block diagram of an apparatus 800 according to an exemplary embodiment. For example, the apparatus 800 may be a computer, a digital broadcast terminal, a message transceiving device, a personal digital assistant, etc.

[0131] Reference Figure 6 , the device 800 may include one or more of the following components: a processing component 802 , a memory 804 , a power component 806 , a multimedia component 808 , an audio component 810 , an input / output (I / O) interface 812 , a sensor component 814 , and a communication component 816 .

[0132] The processing component 802 generally controls the overall operation of the device 800, such as operations associated with display, phone calls, data communications, camera operations, and recording operations. The processing component 802 may include one or more processors 820 to execute instructions to complete all or part of the steps of the above-mentioned method. In addition, the processing component 802 may include one or more modules to facilitate the interaction between the processing component 802 and other components. For example, the processing component 802 may include a multimedia module to facilitate the interaction between the multimedia component 808 and the processing component 802.

[0133] The memory 804 is configured to store various types of data to support operations on the device 800. Examples of such data include instructions for any application or method operating on the device 800, contact data, phone book data, messages, pictures, videos, etc. The memory 804 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0134] The power supply component 806 provides power to the various components of the device 800. The power supply component 806 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power for the device 800.

[0135] The multimedia component 808 includes a screen that provides an output interface between the device 800 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch screen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touch, slide, and gestures on the touch panel. The touch sensor may not only sense the boundaries of the touch or slide action, but also detect the duration and pressure associated with the touch or slide operation. In some embodiments, the multimedia component 808 includes a front camera and / or a rear camera. When the device 800 is in an operating mode, such as a shooting mode or a video mode, the front camera and / or the rear camera may receive external multimedia data. Each front camera and rear camera may be a fixed optical lens system or have a focal length and optical zoom capability.

[0136] The audio component 810 is configured to output and / or input audio signals. For example, the audio component 810 includes a microphone (MIC), and when the device 800 is in an operating mode, such as a call mode, a recording mode, and a speech recognition mode, the microphone is configured to receive an external audio signal. The received audio signal can be further stored in the memory 804 or sent via the communication component 816. In some embodiments, the audio component 810 also includes a speaker for outputting audio signals.

[0137] I / O interface 812 provides an interface between processing component 802 and peripheral interface modules, such as keyboards, click wheels, buttons, etc. These buttons may include but are not limited to: a home button, a volume button, a start button, and a lock button.

[0138] The sensor assembly 814 includes one or more sensors for providing various aspects of status assessment for the device 800. For example, the sensor assembly 814 can detect the open / closed state of the device 800, the relative positioning of components, such as the display and keypad of the device 800, and the sensor assembly 814 can also detect the position change of the device 800 or a component of the device 800, the presence or absence of user contact with the device 800, the orientation or acceleration / deceleration of the device 800, and the temperature change of the device 800. The sensor assembly 814 may include a proximity sensor configured to detect the presence of a nearby object without any physical contact. The sensor assembly 814 may also include an optical sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, the sensor assembly 814 may also include an accelerometer, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

[0139] The communication component 816 is configured to facilitate wired or wireless communication between the device 800 and other devices. The device 800 can access a wireless network based on a communication standard, such as WiFi, a carrier network (such as 2G, 3G, 4G or 5G), or a combination thereof. In an exemplary embodiment, the communication component 816 receives a broadcast signal or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 816 also includes a near field communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on radio frequency identification (RFID) technology, infrared data association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology and other technologies.

[0140] In an exemplary embodiment, the apparatus 800 may be implemented by one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors or other electronic components to perform the above method.

[0141] In an exemplary embodiment, a storage medium including instructions is also provided, such as a memory 804 including instructions, and the instructions can be executed by the processor 820 of the device 800 to complete the above method. Optionally, the storage medium can be a non-transitory computer-readable storage medium, for example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0142] Figure 7 900 is a block diagram of a device 900 according to an exemplary embodiment. For example, the device 900 may be provided as a server. Figure 7 , the apparatus 900 includes a processing component 922, which further includes one or more processors, and a memory resource represented by a memory 932 for storing instructions, such as an application, that can be executed by the processing component 922. The application stored in the memory 932 may include one or more modules, each corresponding to a set of instructions. In addition, the processing component 922 is configured to execute the instructions to perform the above method.

[0143] The device 900 may also include a power supply component 926 configured to perform power management of the device 900, a wired or wireless network interface 950 configured to connect the device 900 to a network, and an input / output (I / O) interface 958. The device 900 may operate based on an operating system stored in the memory 932, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, or the like.

[0144] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the following claims.

[0145] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for multiplexing spread spectrum codes in a low-orbit navigation system, characterized in that: include: Determining constellation design parameters, and determining a maximum geometric coverage area of ​​a single satellite according to the constellation design parameters; Calculating a first target multiplexing condition for satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite; Calculating the minimum distance between two satellites in the constellation according to the constellation design parameters; A satellite is selected from the constellation as a reference star, and a spread spectrum code of the satellite in the constellation is determined according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is a multiplexing condition of satellites between orbital planes, and the spread spectrum code is used by a receiver in satellite communication to demodulate a bandwidth signal sent by the satellite to obtain an original signal.

2. The method according to claim 1, characterized in that The constellation design parameters include at least one of the following: Satellite altitude; The maximum surface altitude at which navigation services can be provided; Lower limit of the elevation angle of the received signal; The right ascension interval of the ascending nodes between orbital planes.

3. The method according to claim 2, characterized in that The formula for determining the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters is expressed as: θ=90-E0-α Among them, θ is the ground half angle corresponding to the maximum geometric coverage area of ​​a single satellite, E0 is the lower limit of the elevation angle of the received signal, R is the equatorial radius of the earth; h is the satellite altitude; h' is the maximum surface altitude that can provide navigation services, and α is the semi-cone angle of the single satellite antenna coverage range.

4. The method according to claim 3, characterized in that The calculating, according to the maximum geometric coverage area of ​​the single satellite, the first target multiplexing condition of the satellites in the same orbital plane comprises: According to the maximum coverage range of the single satellite, the target multiplexing condition that should be satisfied by two satellites that reuse the spread spectrum code in the same orbital plane is determined, wherein the first target multiplexing condition is: Δφ≥2θ Among them, Δφ is the phase difference between the two stars, T is the total number of satellites in the constellation, P is the number of orbital planes, and k is a positive integer, T / P.

5. The method according to claim 2, characterized in that: The calculating the minimum distance between two satellites in the constellation includes: Obtain a first coordinate of a first satellite and a second coordinate of a second satellite; Rotate the second coordinate by ΔΩ around the z-axis, and calculate the distance between the second coordinate and the first coordinate after the rotation as the distance between the two satellites, where ΔΩ is the right ascension interval of the ascending node between the orbital planes; An extreme condition of the distance between the two satellites is determined, and the minimum distance is determined according to the extreme condition.

6. The method according to claim 1, characterized in that The step of determining the satellite's spread spectrum code according to the minimum distance between the reference satellite and other satellites, the first target multiplexing condition, and the second target multiplexing condition comprises: Determine a maximum value of a parameter k corresponding to a single track plane according to the first target multiplexing condition; Determine a second target multiplexing condition, and determine a conjugation point according to the second target multiplexing condition, wherein the second target multiplexing condition is a conjugation threshold; Generate a conjugate table according to the arrangement rule of the conjugate points between different orbital planes; Initialization settings are performed according to constellation parameters, and conjugate points whose minimum distance from the reference star is less than the conjugate threshold are traversed and calculated to generate a conjugate point set; The period is determined according to the maximum value of the parameter k and the number of conjugate points in the largest conjugate point set of the single orbital plane; The first conjugate point of each column in the conjugate table is taken as the starting point, and the conjugate points therein are marked with spread spectrum codes according to the period, wherein the starting sequence number interval of the first conjugate points of adjacent columns is the maximum value of the parameter k.

7. A spread spectrum code multiplexing device in a low-orbit navigation system, characterized in that: include: A coverage area determination module, used to determine constellation design parameters, and determine the maximum geometric coverage area of ​​a single satellite according to the constellation design parameters; A reuse condition calculation module, used for calculating the first target reuse condition of satellites in the same orbital plane according to the maximum geometric coverage area of ​​the single satellite; A distance calculation module, used to calculate the minimum distance between two satellites in the constellation according to the constellation design parameters; A spread spectrum code marking module is used to select a satellite from the constellation as a reference star, and determine the spread spectrum code of the satellite in the constellation according to the minimum distance between the reference star and other satellites, the first target multiplexing condition and the second target multiplexing condition, wherein the second target multiplexing condition is the multiplexing condition of satellites between orbital planes, and the spread spectrum code is used for a receiver in satellite communication to demodulate the bandwidth signal sent by the satellite to obtain the original signal.

8. An electronic device, characterized in that: include: processor; a memory for storing instructions executable by the processor; The processor is configured to execute the instructions to implement the method according to any one of claims 1 to 6. 9 . A computer-readable storage medium, when instructions in the storage medium are executed by a processor of an electronic device, the electronic device is enabled to execute the method according to any one of claims 1 to 6.

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