1. A navigation signal broadcasting method is applied to each low-orbit satellite in a low-orbit satellite navigation system, and comprises the following steps:

acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters;

determining a first data code corresponding to a first parameter, wherein the first parameter comprises the time parameter, the ephemeris parameter and the integrity parameter;

performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component;

carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal, and broadcasting the first navigation signal through a first frequency band so that a ground receiver receives the first navigation signal; wherein the pilot component is generated based on a pilot road pseudo code;

determining a second data code corresponding to a second parameter, wherein the second parameter comprises the time parameter, the ephemeris parameter, the integrity parameter, the fine positioning parameter, the ionospheric layer parameter and the almanac parameter;

performing spread spectrum modulation on the second data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a second data component;

and performing Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal, and broadcasting the second navigation signal through a second frequency band, so that the ground receiver receives the second navigation signal and performs positioning based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band.

2. The method of claim 1, wherein the data-path pseudo-code is a weil code;

the performing spread spectrum modulation on the first data code by using the data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component includes:

and performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite through Code Division Multiple Access (CDMA) to obtain a first data component.

3. The method of claim 1, wherein the ephemeris parameters comprise at least one of: ephemeris data age, ephemeris reference time, difference between a major semi-axis and an orbit design major semi-axis, eccentricity, orbit inclination of reference time, ascension at a rising point calculated according to the reference time, amplitude at a near place, average and near point angle of the reference time, variation rate of path length, variation rate of orbit inclination, variation rate of ascension at a rising point, the difference between the satellite average motion rate and the calculated value, the first order change rate of the satellite average motion rate, the second order change rate of the satellite average motion rate, the amplitude of the cosine harmonic correction term of the latitude argument, the amplitude of the sine harmonic correction term of the latitude argument, the amplitude of the cosine harmonic correction term of the orbit radius, the amplitude of the sine harmonic correction term of the orbit radius, the amplitude of the cosine harmonic correction term of the orbit inclination, the amplitude of the sine harmonic correction term of the orbit inclination, the orbit radial correction, the orbit tangential correction and the orbit normal correction.

4. The method of claim 3, wherein the fine positioning parameters comprise at least one of: grid point ionosphere vertical delay parameter, grid point ionosphere vertical delay correction number error index.

5. The method of claim 4, wherein the almanac parameters comprise at least one of: the system comprises an almanac number, an almanac cycle count, an almanac reference time, a long half shaft deviation, an eccentricity, a perigee argument, a mean anomaly angle of the reference time, a rising point longitude, a rising point right ascension change rate, a correction quantity of an orbit reference inclination of the reference time, a difference between a satellite average motion rate and a calculated value, a satellite clock error and a satellite clock speed.

6. The method of claim 5, wherein the time parameter comprises at least one of: whole-week counting, intra-week second counting, sub-frame counting, on-satellite device delay variation, clock data age, clock variation parameter, UTC time synchronization with world coordinated time, GPS time synchronization with global positioning system, Galileo time synchronization with Galileo, Glonass GLONASS time synchronization with Beidou satellite navigation system BDS time synchronization parameter.

7. The method of claim 6, wherein the integrity parameters comprise at least one of: user distance accuracy index, satellite autonomous health mark, satellite health information, integrity and difference information health mark, low orbit satellite system integrity information satellite mark, regional user distance accuracy index, clock error correction number and inter-code deviation correction number.

8. The method of any of claims 1 to 7, wherein the second navigation signal consists of 3 main frames: the system comprises a main frame 1, a main frame 2 and a main frame 3, wherein the lengths of the main frames are different; the main frame 1 is 1800 bits and is composed of 6 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 2 is 9600 bits and is composed of 32 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 3 is 648000 bits and consists of 1800 subframes, each subframe is 360 bits, each subframe consists of 12 words, each word is 30 bits, the 1 st word of each subframe is synchronous information and is not subjected to error correction coding, other words are subjected to error correction coding by adopting a BCH (15,11,1) plus interleaving mode, and the information bits are 22 bits in total;

the broadcasting the second navigation signal through a second frequency band includes:

and broadcasting the main frame 1, the main frame 2 and the main frame 3 in sequence through a second frequency band.

9. A navigation signal receiving method, applied to a terrestrial receiver, the method comprising:

receiving a first navigation signal broadcast by a low-orbit satellite through a first frequency band in a low-orbit satellite navigation system, wherein the first navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a first data component and a pilot frequency component, the pilot frequency component is generated based on a pilot frequency channel pseudo code, the first data component is obtained by performing spread spectrum modulation on a first data code by using a data channel pseudo code corresponding to the low-orbit satellite, the first data code corresponds to a first parameter, and the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter;

receiving a second navigation signal broadcast by the low-earth orbit satellite through a second frequency band, wherein the second navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a second data component and a pilot frequency component, the second data component is obtained by performing spread spectrum modulation on a second data code by using a data path pseudo code corresponding to the low-earth orbit satellite, the second data code corresponds to a second parameter, and the second parameter comprises the time parameter, the ephemeris parameter, the integrity parameter, the precision positioning parameter, the ionospheric layer parameter and the almanac parameter; wherein the second frequency band is different from the first frequency band;

performing positioning based on the first navigation signal and the second navigation signal.

10. A navigation signal distribution apparatus, for use with each low earth orbit satellite in a low earth orbit satellite navigation system, the navigation signal distribution apparatus comprising:

the acquisition module is used for acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters;

a first determining module, configured to determine a first data code corresponding to a first parameter, where the first parameter includes the time parameter, the ephemeris parameter, and the integrity parameter;

the first modulation module is used for performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low-earth orbit satellite to obtain a first data component; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal;

the first broadcasting module is used for broadcasting the first navigation signal through a first frequency band so that the ground receiver receives the first navigation signal; wherein the pilot component is generated based on a pilot road pseudo code;

a second determining module, configured to determine a second data code corresponding to a second parameter, where the second parameter includes the time parameter, the ephemeris parameter, the integrity parameter, the fine positioning parameter, the ionospheric layer parameter, and the almanac parameter;

the second modulation module is used for performing spread spectrum modulation on the second data code by using the data path pseudo code corresponding to the low-earth orbit satellite to obtain a second data component; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal;

and the second broadcasting module is used for broadcasting the second navigation signal through a second frequency band, so that the ground receiver receives the second navigation signal and performs positioning based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band.

Background

A Global Navigation Satellite System (GNSS) is an important space-time information infrastructure, and a Global Navigation Satellite System is a space-based radio Navigation positioning System which can provide all-weather 3-dimensional coordinates, speed and time information for users at any place on the earth surface or in a near-earth space, plays an important role in the fields of national economic construction and national defense safety, and is widely applied to numerous fields of Navigation, positioning and time service. In recent years, with the development of the fifth Generation Mobile Communication Technology (5th Generation Mobile Communication Technology, 5G), internet of things, artificial intelligence, unmanned driving and other technologies, the demand of social production and life for precise spatio-temporal information has reached an unprecedented height, and has progressed from rough, after-the-fact, static and regional in the past to precise, real-time, dynamic and global in the present. Taking an unmanned vehicle as an example, not only real-time lane-level navigation accuracy is required, but also continuous availability of all road conditions is required. There are also many techniques that need to be improved for the satellite navigation system itself. In the existing mode, the positioning is carried out through the B1I signal, and because the B1I signal is broadcast by a Beidou navigation satellite, the change of geometric diversity is slow, and the precise single-point positioning by using the telegraph text of the B1I signal needs longer convergence time, namely the time needed for precise positioning is longer.

Disclosure of Invention

The embodiment of the invention aims to provide a navigation signal broadcasting method and device and a navigation signal receiving method, so as to reduce the time required by precision positioning. The specific technical scheme is as follows:

the embodiment of the invention provides a navigation signal broadcasting method, which is applied to each low-orbit satellite in a low-orbit satellite navigation system and comprises the following steps:

acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters;

determining a first data code corresponding to a first parameter, wherein the first parameter comprises the time parameter, the ephemeris parameter and the integrity parameter;

performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component;

carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal, and broadcasting the first navigation signal through a first frequency band so that a ground receiver receives the first navigation signal; wherein the pilot component is generated based on a pilot road pseudo code;

determining a second data code corresponding to a second parameter, wherein the second parameter comprises the time parameter, the ephemeris parameter, the integrity parameter, the fine positioning parameter, the ionospheric layer parameter and the almanac parameter;

performing spread spectrum modulation on the second data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a second data component;

and performing Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal, and broadcasting the second navigation signal through a second frequency band, so that the ground receiver receives the second navigation signal and performs positioning based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band.

The embodiment of the invention also provides a navigation signal receiving method, which is applied to a ground receiver and comprises the following steps:

receiving a first navigation signal broadcast by a low-orbit satellite through a first frequency band in a low-orbit satellite navigation system, wherein the first navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a first data component and a pilot frequency component, the pilot frequency component is generated based on a pilot frequency channel pseudo code, the first data component is obtained by performing spread spectrum modulation on a first data code by using a data channel pseudo code corresponding to the low-orbit satellite, the first data code corresponds to a first parameter, and the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter;

receiving a second navigation signal broadcast by the low-earth orbit satellite through a second frequency band, wherein the second navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a second data component and a pilot frequency component, the second data component is obtained by performing spread spectrum modulation on a second data code by using a data path pseudo code corresponding to the low-earth orbit satellite, the second data code corresponds to a second parameter, and the second parameter comprises the time parameter, the ephemeris parameter, the integrity parameter, the precision positioning parameter, the ionospheric layer parameter and the almanac parameter; wherein the second frequency band is different from the first frequency band;

performing positioning based on the first navigation signal and the second navigation signal.

The embodiment of the invention has the following beneficial effects:

the navigation signal broadcasting method and device and the navigation signal receiving method provided by the embodiment of the invention can be applied to each low-orbit satellite in a low-orbit satellite navigation system, and comprise the following steps: acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters; determining a first data code corresponding to a first parameter, wherein the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter; performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal, and broadcasting the first navigation signal through a first frequency band so that a ground receiver receives the first navigation signal; wherein, the pilot frequency component is generated based on the pilot frequency pseudo code; determining a second data code corresponding to a second parameter, wherein the second parameter comprises a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter and an almanac parameter; performing spread spectrum modulation on the second data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a second data component; and performing Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal, broadcasting the second navigation signal through a second frequency band so that the ground receiver receives the second navigation signal, and positioning based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band. The first navigation signal and the second navigation signal consider the characteristics of low orbit satellites, broadcast ephemeris and precise ephemeris are adopted to be broadcast together, and the traditional precise single-point positioning method does not need to receive other signals for calculation.

Of course, not all of the above advantages need be achieved in the practice of any one product or method of the present invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other embodiments can be obtained by referring to these drawings.

Fig. 1 is a flowchart of a navigation signal broadcasting method according to an embodiment of the present invention;

fig. 2 is a flowchart of a navigation signal receiving method according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating the broadcast of navigation signals using different frequency bands according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating a signal modulation scheme according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a frame structure of a navigation message of a first navigation signal according to an embodiment of the present invention;

FIG. 6A is a schematic diagram illustrating a layout format of navigation message subframe 1 information parameters of a first navigation signal according to an embodiment of the present invention;

FIG. 6B is a schematic diagram illustrating a layout format of navigation message subframe 2 information parameters of a first navigation signal according to an embodiment of the present invention;

FIG. 6C is a schematic diagram illustrating a layout format of navigation message subframe 3 information parameters of a first navigation signal according to an embodiment of the present invention;

FIG. 6D is a schematic diagram illustrating a layout format of navigation message subframe 4 information parameters of a first navigation signal according to an embodiment of the present invention;

FIG. 6E is a schematic diagram illustrating a layout format of navigation message subframe 5 information parameters of a first navigation signal according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating a frame structure of a navigation message of a second navigation signal according to an embodiment of the present invention;

fig. 8A is a schematic diagram of the layout format of the navigation message main frame 1 subframe 1 information parameters of the second navigation signal according to the embodiment of the present invention.

Fig. 8B is a schematic diagram of the layout format of the navigation message main frame 1 and sub-frame 2 information parameters of the second navigation signal according to the embodiment of the present invention.

Fig. 8C is a schematic diagram of the layout format of the navigation message main frame 1 subframe 3 information parameters of the second navigation signal according to the embodiment of the invention.

Fig. 8D is a schematic diagram of the layout format of the navigation message main frame 1 subframe 4 information parameters of the second navigation signal according to the embodiment of the invention.

Fig. 8E is a schematic diagram of the layout format of the navigation message main frame 1 subframe 5 information parameters of the second navigation signal according to the embodiment of the invention.

Fig. 8F is a schematic diagram of the layout format of the navigation message main frame 1 subframe 6 information parameters of the second navigation signal according to the embodiment of the invention.

Fig. 9 is a schematic diagram of a navigation message main frame 2 subframe information parameter layout format of a second navigation signal according to an embodiment of the present invention.

FIG. 10 is a diagram illustrating a navigation message main frame 3 subframe information parameter formatting of a second navigation signal according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a navigation signal broadcasting device according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of a navigation signal receiving apparatus according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of an electronic device according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of another electronic device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived from the embodiments given herein by one of ordinary skill in the art, are within the scope of the invention.

The low-orbit satellite navigation system adopts a low-orbit constellation, so that the information broadcasting time delay is short and the transmission data volume is large; the signal power is strong, the anti-interference and anti-cheating performance is good, and the service performance of indoor and other shielding areas can be enhanced; the low-orbit satellite has short earth-surrounding period and obvious change of geometric distribution diversity, and signals can also obviously accelerate the convergence of the precision positioning ambiguity, thereby providing more effective data sources for joint orbit determination, space weather monitoring and the like. In terms of coverage, although a single satellite of a low earth orbit satellite has a small coverage area, a constellation consisting of a plurality of satellites can provide global information including two polar regions and signal enhancement. The low-orbit constellation has the advantages of strong ground received signal and quick change of geometric figure, can form complementation with the medium-high orbit GNSS constellation, and is expected to realize comprehensive enhancement of the precision, the integrity, the continuity and the availability of the navigation system.

The convergence time can be shortened by adopting a low-orbit satellite to transmit a low-orbit signal, and the problem of long time of traditional GNSS precision positioning is solved; the low-orbit satellite is not suitable for the traditional GNSS signal, the low-orbit navigation signal designed by the invention considers the characteristics of the low-orbit satellite, and the traditional broadcast ephemeris and the precise ephemeris are broadcast together, so that the problem that the traditional precise single-point positioning needs to receive other signals for resolving is solved.

The embodiment of the invention provides a navigation signal broadcasting method, which is applied to each low-orbit satellite in a low-orbit satellite navigation system and can comprise the following steps:

acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters;

determining a first data code corresponding to a first parameter, wherein the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter;

performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component;

carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal, and broadcasting the first navigation signal through a first frequency band so that a ground receiver receives the first navigation signal; wherein, the pilot frequency component is generated based on the pilot frequency pseudo code;

determining a second data code corresponding to a second parameter, wherein the second parameter comprises a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter and an almanac parameter;

performing spread spectrum modulation on the second data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a second data component;

and performing Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal, broadcasting the second navigation signal through a second frequency band so that the ground receiver receives the second navigation signal, and positioning based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band.

In the embodiment of the invention, the first navigation signal and the second navigation signal take the characteristics of low orbit satellites into consideration, broadcast ephemeris and precise ephemeris are adopted to be broadcast together, and the traditional precise single-point positioning needs no other signals to be received for calculation.

Fig. 1 is a flowchart of a navigation signal broadcasting method according to an embodiment of the present invention. The navigation signal broadcasting method provided by the embodiment of the present invention may be applied to each low earth orbit satellite in a low earth orbit satellite navigation system, and referring to fig. 1, the navigation signal broadcasting method provided by the embodiment of the present invention may include:

s101, acquiring time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters.

In one implementation, the time parameter may include at least one of the following parameters: the System comprises a whole-cycle count, an intra-cycle second count, a sub-frame count, an on-Satellite device delay difference, a clock data age, a clock difference parameter, a Coordinated Universal Time (UTC) Time synchronization parameter, a Global Positioning System (GPS) Time synchronization parameter, a Galileo Time synchronization parameter, a GLONASS Time synchronization parameter, and a BeiDou Navigation Satellite System (BDS) Time synchronization parameter.

In one implementation, the ephemeris parameters may include at least one of: ephemeris data age, ephemeris reference time, difference between a major semi-axis and an orbit design major semi-axis, eccentricity, orbit inclination of reference time, ascension at a rising point calculated according to the reference time, amplitude at a near place, average and near point angle of the reference time, variation rate of path length, variation rate of orbit inclination, variation rate of ascension at a rising point, the difference between the satellite average motion rate and the calculated value, the first order change rate of the satellite average motion rate, the second order change rate of the satellite average motion rate, the amplitude of the cosine harmonic correction term of the latitude argument, the amplitude of the sine harmonic correction term of the latitude argument, the amplitude of the cosine harmonic correction term of the orbit radius, the amplitude of the sine harmonic correction term of the orbit radius, the amplitude of the cosine harmonic correction term of the orbit inclination, the amplitude of the sine harmonic correction term of the orbit inclination, the orbit radial correction, the orbit tangential correction and the orbit normal correction.

The integrity parameter may comprise at least one of the following parameters: user distance accuracy index, satellite autonomous health mark, satellite health information, integrity and difference information health mark, low orbit satellite system integrity information satellite mark, regional user distance accuracy index, clock error correction number and inter-code deviation correction number.

The fine positioning parameters may include at least one of the following: grid point ionosphere vertical delay parameter, grid point ionosphere vertical delay correction number error index.

The almanac parameters may include at least one of the following: the system comprises an almanac number, an almanac cycle count, an almanac reference time, a long half shaft deviation, an eccentricity, a perigee argument, a mean anomaly angle of the reference time, a rising point longitude, a rising point right ascension change rate, a correction quantity of an orbit reference inclination of the reference time, a difference between a satellite average motion rate and a calculated value, a satellite clock error and a satellite clock speed.

S102, determining a first data code corresponding to a first parameter, wherein the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter.

It is understood that encoding the first parameter results in a first data code.

S103, performing spread spectrum modulation on the first data code by using the data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component.

The data path pseudo code is a weil code.

Performing spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite to obtain a first data component, which may include:

the first data Code is spread and modulated by using a data path pseudo Code corresponding to a low earth orbit satellite through Code Division Multiple Access (CDMA), so as to obtain a first data component.

S104, performing Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot component to obtain a first navigation signal, and broadcasting the first navigation signal through a first frequency band, so that the ground receiver receives the first navigation signal.

Wherein the pilot component is generated based on the pilot road pseudo code.

In this way, the first navigation signal is programmed with time parameters, ephemeris parameters, and integrity parameters.

And S105, determining a second data code corresponding to a second parameter, wherein the second parameter comprises a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter and an almanac parameter.

It is understood that encoding the first parameter results in a first data code.

And S106, performing spread spectrum modulation on the second data code by using the data path pseudo code corresponding to the low earth orbit satellite to obtain a second data component.

And performing spread spectrum modulation on the second data code by using the data path pseudo code corresponding to the low earth orbit satellite through Code Division Multiple Access (CDMA) to obtain a second data component.

Namely, in the process of the first navigation signal to be broadcast by the first frequency band, CDMA is adopted for signal multiplexing, and the weil code is selected as the ranging code.

S107, the second data component and the pilot frequency component are subjected to quadrature phase shift keying QPSK modulation to obtain a second navigation signal, the second navigation signal is broadcasted through a second frequency band, so that the ground receiver receives the second navigation signal, and positioning is carried out based on the first navigation signal and the second navigation signal, wherein the second frequency band is different from the first frequency band.

The second navigation signal is programmed with time parameters, ephemeris parameters, integrity parameters, fine positioning parameters, ionosphere parameters and almanac parameters.

The ground receiver obtains the signal transmission time from the ground receiver to the satellite through the time parameter and the data path pseudo code in the received navigation signal, the distance from the ground receiver to the satellite is obtained by multiplying the transmission time by the light speed, the position of the satellite is calculated by using the ephemeris parameter, and the position of the ground receiver can be calculated by integrating the positions of more than 4 satellites and the distances from the ground receiver to the satellites. The distance accuracy from the ground receiver to the satellite is a key factor influencing the resolving accuracy, and the satellite signal passes through an ionosphere above the earth during transmission to cause signal delay, thereby seriously influencing the distance accuracy. If the ground receiver only receives a signal of a single frequency band, the ionosphere parameter or the precise positioning parameter in the navigation signal can be used for compensating part of ionosphere delay, and the distance precision is improved. The dual-band navigation signal can directly eliminate the influence caused by ionospheric delay by utilizing the relationship between different frequencies and ionospheric delay, thereby greatly improving the distance accuracy.

In the embodiment of the invention, the first navigation signal is broadcast through the first frequency band and the second navigation signal is broadcast through the second frequency band, namely, the navigation message is broadcast through two frequency bands. The broadcast signal adopts QPSK modulation, the I path (in-phase component of the signal) places data component containing navigation message information, and the Q path (quadrature component) places pilot frequency component. Therefore, the ground receiver, namely the ground navigation signal receiver can realize minute-level quick cold start by utilizing the first navigation signal through the received navigation signal which is broadcast by using the low-orbit satellite and is based on the invention; and then the second navigation signal is utilized to continuously track the position of the satellite, and the characteristic that the geometric diversity change is obvious due to the large angular velocity of the low-orbit satellite during operation is utilized, so that the cycle ambiguity of the carrier signal is quickly converged during the position calculation of the receiver, and the quick and precise positioning can be realized.

Fig. 2 is a flowchart of a navigation signal receiving method according to an embodiment of the present invention. The navigation signal receiving method provided by the embodiment of the present invention may be applied to a ground receiver, and referring to fig. 2, the navigation signal receiving method provided by the embodiment of the present invention may include:

s201, receiving a first navigation signal broadcast by a low-orbit satellite in a low-orbit satellite navigation system through a first frequency band, wherein the first navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a first data component and a pilot frequency component, the pilot frequency component is generated based on a pilot frequency channel pseudo code, the first data component is obtained by performing spread spectrum modulation on a first data code by using the data channel pseudo code corresponding to the low-orbit satellite, the first data code corresponds to a first parameter, and the first parameter comprises a time parameter, an ephemeris parameter and an integrity parameter;

s202, receiving a second navigation signal broadcast by the low-earth orbit satellite through a second frequency band, wherein the second navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a second data component and a pilot frequency component, the second data component is obtained by performing spread spectrum modulation on a second data code by using a data path pseudo code corresponding to the low-earth orbit satellite, the second data code corresponds to a second parameter, and the second parameter comprises a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionospheric parameter and an almanac parameter; wherein the second frequency band is different from the first frequency band;

s203, positioning is carried out based on the first navigation signal and the second navigation signal.

The ground receiver can realize minute-level quick cold start by utilizing the first navigation signal through the received navigation signal which is broadcasted by using the low-orbit satellite; and then the second navigation signal is utilized to continuously track the position of the satellite, and the characteristic that the geometric diversity change is obvious due to the large angular velocity of the low-orbit satellite during operation is utilized, so that the cycle ambiguity of the carrier signal is quickly converged during the position calculation of the receiver, and the quick and precise positioning can be realized.

In an alternative embodiment, as shown in fig. 3, the navigation signal is broadcast through a first frequency band channel (also referred to as a first frequency band) and a second frequency band channel (also referred to as a second frequency band) of the low-orbit satellite, wherein the first frequency band occupies a 20MHz bandwidth of 5010-5030 MHz; the second frequency band occupies 10MHz bandwidth of D2: 7065-7075 MHz.

As shown in fig. 4, QPSK modulation is used for the navigation signals of both bands. And generating a data component by using a data code containing positioning text information and a data path pseudo code, and orthogonally modulating the data component and a pilot frequency component generated by the pilot frequency path pseudo code on a carrier, namely obtaining a navigation signal by QPSK modulation. The signal multiplexing mode adopts Code Division Multiple Access (CDMA), and the pseudo code (ranging code) sequence is generated by adopting the truncation of the weil code. The navigation signals of the two frequency bands are determined in the manner shown in fig. 4, and the two navigation signals are respectively broadcast through the two frequency bands, so that the ground receiver receives the navigation signals and performs positioning based on the navigation signals.

In one implementation, as shown in fig. 5, the first navigation signal, i.e., the navigation signal broadcast by the first frequency band, is composed of a main frame and a sub-frame. Each main frame is 1500 bits, each main frame is composed of 5 sub-frames, each sub-frame is 300 bits, each sub-frame is composed of 10 words, and each word is 30 bits. Each character consists of a telegraph text message and a check code. The 1 st word of each subframe is synchronization information, error correction coding is not carried out, the other 9 words are error correction coded by adopting a Broadcast Channel (BCH) (15,11,1) plus interleaving mode, and the information bits are 22 bits in total.

Referring to fig. 6A, 6B, 6C, 6D, and 6E, in the embodiment of the present invention, each main frame in the first navigation signal has 5 sub-frames, each sub-frame is divided into 10 words, and the first word of each sub-frame contains synchronization information (i.e., frame synchronization header Pre) of 20 bits. And when the sub-frame is broadcast, a high-order broadcast mode is adopted. The time parameters, the ephemeris parameters and the integrity parameters are arranged in the navigation message of the first frequency band signal.

Table 1 shows the data fields of the time parameter and the meaning of each data field.

TABLE 1

Table 2 shows the data fields of the ephemeris parameters and the meaning of the respective data fields.

TABLE 2

Table 3 shows the data fields of the integrity parameter and the meaning of each data field.

In one implementation, referring to fig. 7, the second navigation signal consists of 3 main frames: the system comprises a main frame 1, a main frame 2 and a main frame 3, wherein the lengths of the main frames are different; the main frame 1 is 1800 bits and is composed of 6 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 2 is 9600 bits and is composed of 32 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 3 is 648000 bits and consists of 1800 subframes, each subframe is 360 bits, each subframe consists of 12 words, each word is 30 bits, the 1 st word of each subframe is synchronous information and is not subjected to error correction coding, other words are subjected to error correction coding by adopting a BCH (15,11,1) plus interleaving mode, and the information bits are 22 bits in total;

broadcasting a second navigation signal over a second frequency band, comprising: and broadcasting the main frame 1, the main frame 2 and the main frame 3 in sequence through a second frequency band.

Referring to fig. 8A, 8B, 8C, 8D, 8E, and 8F, in an embodiment of the present invention, the broadcast time parameter, ephemeris parameter, integrity parameter, and ionospheric parameter of the second frequency band signal message 1 st main frame are set. The first word of each sub-frame contains 20bits of synchronization information (i.e., the frame sync header Pre). The primary frame count FraID indicates the current primary frame number. The primary frame 1 subframe count FraID1 indicates the subframe number of the current primary frame 1. And when the sub-frame is broadcast, a high-order broadcast mode is adopted. Specifically, the time parameter, ephemeris parameter, and integrity parameter are shown in table 1, table 2, and table 3, and the ionosphere parameter corresponds to α in the 8-parameter Klobuchar model₀、α₁、α₂、α₃、β₀、β₁、β₂、β₃Ionospheric vertical delay corrections for global low earth orbit satellite navigation signals can be calculated, where α₀、α₁、α₂、α₃The four parameters are the amplitude component, beta, of the mean radiant flux of the sun₀、β₁、β₂、β₃The four parameters are the periodic components of the mean radiant flux of the sun.

Referring to fig. 9, in the embodiment of the present invention, the 2 nd main frame in the second navigation signal message broadcasts a fine positioning (grid point ionosphere) parameter. The precise positioning parameters are expressed by Ion and comprise grid point ionosphere vertical delay parameters and grid point ionosphere vertical delay correction error indexes. The coverage range of an ionosphere grid is 70-145 degrees of east longitude and 7.5-55 degrees of north latitude, the ionosphere grid is divided according to 5 multiplied by 2.5 degrees of longitude and latitude to form 320 grid points, the ionosphere vertical delay parameter of each grid point represents the ionosphere vertical delay of a signal in a certain grid point, and a user needs to interpolate the ionosphere correction number of the grid point to obtain the ionosphere correction number of an observation satellite puncture point so as to correct an observation pseudo range; the grid point ionospheric vertical delay correction error index is used to describe the accuracy of grid point ionospheric delay correction. Ion_i,nIndicating grid points numbered 10 x (Pnum2-1) + n, and broadcasting ionospheric delay information for 10 grid points per subframe. The primary frame 2 subframe count FraID2 indicates the subframe number of the current primary frame 2. And when the sub-frame is broadcast, a high-order broadcast mode is adopted.

Referring to fig. 10, in an embodiment of the present invention, the almanac parameters are broadcast in the 3 rd main frame in the second navigation signal message. Each subframe of the 3 rd main frame broadcasts an almanac for one satellite. The primary frame 3 subframe count FraID3 indicates the subframe number of the current primary frame 3, and the subframe is broadcast with a high-order broadcast first.

Table 4 shows the data fields of the almanac parameters and the meaning of each data field.

TABLE 4

A dual-band broadcasting mode is adopted, and the first navigation signal carries time parameters, ephemeris parameters and integrity parameters and is used for rapidly capturing a satellite; the second navigation signal carries time parameters, ephemeris parameters, integrity parameters, precision positioning parameters, ionosphere parameters and almanac parameters, and is used for continuously tracking the satellite and carrying out precision positioning.

Corresponding to the navigation signal broadcasting method provided in the above embodiment, an embodiment of the present invention further provides a navigation signal broadcasting apparatus, which is applied to each low-earth satellite in a low-earth satellite navigation system, as shown in fig. 11, the apparatus may include:

an obtaining module 1101, configured to obtain a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter, and an almanac parameter;

a first determining module 1102, configured to determine a first data code corresponding to a first parameter, where the first parameter includes a time parameter, an ephemeris parameter, and an integrity parameter;

a first modulation module 1103, configured to perform spread spectrum modulation on a first data code by using a data path pseudo code corresponding to a low earth orbit satellite, to obtain a first data component; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the first data component and the pilot frequency component to obtain a first navigation signal;

a first broadcasting module 1104, configured to broadcast a first navigation signal through a first frequency band, so that the ground receiver receives the first navigation signal; wherein, the pilot frequency component is generated based on the pilot frequency pseudo code;

a second determining module 1105, configured to determine a second data code corresponding to a second parameter, where the second parameter includes a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter, and an almanac parameter;

a second modulation module 1106, configured to perform spread spectrum modulation on a second data code by using a data channel pseudo code corresponding to the low earth orbit satellite, so as to obtain a second data component; carrying out Quadrature Phase Shift Keying (QPSK) modulation on the second data component and the pilot frequency component to obtain a second navigation signal;

the second broadcasting module 1107 is configured to broadcast a second navigation signal through a second frequency band, so that the ground receiver receives the second navigation signal and performs positioning based on the first navigation signal and the second navigation signal, where the second frequency band is different from the first frequency band.

Optionally, the data path pseudo code is a weil code;

the first modulation module 1103 is specifically configured to perform spread spectrum modulation on the first data code by using a data path pseudo code corresponding to the low earth orbit satellite through code division multiple access CDMA, so as to obtain a first data component.

Optionally, the ephemeris parameters include at least one of the following parameters: ephemeris data age, ephemeris reference time, difference between a major semi-axis and an orbit design major semi-axis, eccentricity, orbit inclination of reference time, ascension at a rising point calculated according to the reference time, amplitude at a near place, average and near point angle of the reference time, variation rate of path length, variation rate of orbit inclination, variation rate of ascension at a rising point, the difference between the satellite average motion rate and the calculated value, the first order change rate of the satellite average motion rate, the second order change rate of the satellite average motion rate, the amplitude of the cosine harmonic correction term of the latitude argument, the amplitude of the sine harmonic correction term of the latitude argument, the amplitude of the cosine harmonic correction term of the orbit radius, the amplitude of the sine harmonic correction term of the orbit radius, the amplitude of the cosine harmonic correction term of the orbit inclination, the amplitude of the sine harmonic correction term of the orbit inclination, the orbit radial correction, the orbit tangential correction and the orbit normal correction.

Optionally, the fine positioning parameter includes at least one of the following parameters: grid point ionosphere vertical delay parameter, grid point ionosphere vertical delay correction number error index.

Optionally, the almanac parameters include at least one of the following parameters: the system comprises an almanac number, an almanac cycle count, an almanac reference time, a long half shaft deviation, an eccentricity, a perigee argument, a mean anomaly angle of the reference time, a rising point longitude, a rising point right ascension change rate, a correction quantity of an orbit reference inclination of the reference time, a difference between a satellite average motion rate and a calculated value, a satellite clock error and a satellite clock speed.

Optionally, the time parameter includes at least one of the following parameters: whole-week counting, intra-week second counting, sub-frame counting, on-satellite device delay variation, clock data age, clock variation parameter, UTC time synchronization with world coordinated time, GPS time synchronization with global positioning system, Galileo time synchronization with Galileo, Glonass GLONASS time synchronization with Beidou satellite navigation system BDS time synchronization parameter.

Optionally, the integrity parameter includes at least one of the following parameters: user distance accuracy index, satellite autonomous health mark, satellite health information, integrity and difference information health mark, low orbit satellite system integrity information satellite mark, regional user distance accuracy index, clock error correction number and inter-code deviation correction number.

Optionally, the second navigation signal consists of 3 main frames: the system comprises a main frame 1, a main frame 2 and a main frame 3, wherein the lengths of the main frames are different; the main frame 1 is 1800 bits and is composed of 6 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 2 is 9600 bits and is composed of 32 subframes, each subframe is 300 bits, each subframe is composed of 10 words, and each word is 30 bits; the main frame 3 is 648000 bits and consists of 1800 subframes, each subframe is 360 bits, each subframe consists of 12 words, each word is 30 bits, the 1 st word of each subframe is synchronous information and is not subjected to error correction coding, other words are subjected to error correction coding by adopting a BCH (15,11,1) plus interleaving mode, and the information bits are 22 bits in total;

the second broadcasting module 1107 is specifically configured to broadcast the primary frame 1, the primary frame 2, and the primary frame 3 in sequence through the second frequency band.

Corresponding to the navigation signal receiving method provided in the above embodiment, an embodiment of the present invention provides a navigation signal receiving apparatus, which is applied to a terrestrial receiver, and as shown in fig. 12, the apparatus includes:

a first receiving module 1201, configured to receive a first navigation signal broadcast by a low-earth-orbit satellite in a low-earth-orbit satellite navigation system through a first frequency band, where the first navigation signal is obtained by performing Quadrature Phase Shift Keying (QPSK) modulation on a first data component and a pilot frequency component, the pilot frequency component is generated based on a pilot channel pseudo code, the first data component is obtained by performing spread spectrum modulation on a first data code by using the data channel pseudo code corresponding to the low-earth-orbit satellite, the first data code corresponds to a first parameter, and the first parameter includes a time parameter, an ephemeris parameter, and an integrity parameter;

a second receiving module 1202, configured to receive a second navigation signal broadcast by a low-earth-orbit satellite through a second frequency band, where the second navigation signal is obtained by performing quadrature phase shift keying QPSK modulation on a second data component and a pilot frequency component, the second data component is obtained by performing spread spectrum modulation on a second data code by using a data path pseudo code corresponding to the low-earth-orbit satellite, the second data code corresponds to a second parameter, and the second parameter includes a time parameter, an ephemeris parameter, an integrity parameter, a precision positioning parameter, an ionosphere parameter, and an almanac parameter; wherein the second frequency band is different from the first frequency band;

and a positioning module 1203, configured to perform positioning based on the first navigation signal and the second navigation signal.

An embodiment of the present invention further provides an electronic device, as shown in fig. 13, including a processor 1301, a communication interface 1302, a memory 1303, and a communication bus 1304, where the processor 1301, the communication interface 1302, and the memory 1303 complete mutual communication through the communication bus 1304.

A memory 1303 for storing a computer program;

the processor 1301 is configured to implement the method steps of the navigation signal broadcasting method when executing the program stored in the memory 1303.

The embodiment of the present invention further provides an electronic device, as shown in fig. 14, which includes a processor 1401, a communication interface 1402, a memory 1403, and a communication bus 1404, where the processor 1401, the communication interface 1402, and the memory 1403 complete communication with each other through the communication bus 1404.

A memory 1403 for storing a computer program;

the processor 1401 is configured to implement the method steps of the navigation signal receiving method when executing the program stored in the memory 1403.

The communication bus mentioned in the electronic device may be a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The communication bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, only one thick line is shown, but this does not mean that there is only one bus or one type of bus.

The communication interface is used for communication between the electronic equipment and other equipment.

The Memory may include a Random Access Memory (RAM) or a Non-Volatile Memory (NVM), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.

The Processor may be a general-purpose Processor, including a Central Processing Unit (CPU), a Network Processor (NP), and the like; but also Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components.

In yet another embodiment provided by the present invention, a computer-readable storage medium is further provided, in which a computer program is stored, and the computer program, when executed by a processor, implements the method steps of the navigation signal dissemination method described above.

In yet another embodiment provided by the present invention, a computer readable storage medium is further provided, in which a computer program is stored, and the computer program, when executed by a processor, implements the method steps of the above navigation signal receiving method.

In a further embodiment of the present invention, there is also provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method steps of the navigation signal dissemination method as described above.

In a further embodiment of the present invention, there is also provided a computer program product comprising instructions which, when run on a computer, cause the computer to perform the method steps of the navigation signal receiving method described above.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the apparatus, the electronic device, the computer-readable storage medium, and the computer program product embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiments.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.