Navigation positioning method based on lunar orbit receiver

Abstract

The application belongs to the technical field of satellite navigation and positioning, and provides a navigation and positioning method based on a lunar orbit receiver, so as to solve problems such as time synchronization error and positioning accuracy of the lunar orbit receiver in the positioning process. The application introduces a method for bidirectional time synchronization with ground communication equipment, so that the lunar orbit receiver can accurately calculate the clock difference with the GPS system, thereby overcoming the time synchronization error caused by signal delay in the prior art, and effectively improving the positioning accuracy. Meanwhile, the lunar orbit receiver also receives the GPS satellite broadcast signal, and combines the clock difference to perform real-time positioning calculation, so as to ensure accurate positioning in the lunar orbit.

Description

Technical Field

[0001] This invention belongs to the field of satellite navigation and positioning technology, and specifically relates to a navigation and positioning method based on a lunar orbit receiver. Background Technology

[0002] Currently, satellite navigation-based positioning systems are widely used in Earth orbit, ground transportation, aerospace, and other fields. Existing ground navigation systems (such as GPS) only cover the Earth's surface and its relatively low orbits, and cannot directly provide accurate lunar position services. Therefore, the demand for navigation and positioning services using lunar orbit receivers is showing a significant upward trend. However, when navigation and positioning applications are extended to lunar orbit, due to the unique environment and distance, existing technologies face many challenges in terms of positioning accuracy and system reliability.

[0003] Existing satellite navigation technologies typically rely on one-way ranging or pseudorange calculations. These methods are well-established on Earth, allowing receivers to calculate position from multiple satellite pseudorange values ​​by receiving signals from satellites and performing pseudorandom code correlation operations. However, deploying GNSS receivers in lunar orbit to provide navigation and positioning services faces the following limitations:

[0004] (1) Increased signal propagation delay and noise interference: The Moon is 380,000 kilometers away from the Earth. The traditional one-way ranging method based on Earth orbit is significantly affected by delay and noise interference, resulting in a decrease in the accuracy of position calculation.

[0005] (2) Existing technical solutions are mostly Earth-centered and ignore the special conditions in the lunar orbital environment, such as a weak gravitational field and extreme temperature differences. The lunar orbital environment brings more uncertainties, which further affects the signal quality.

[0006] (3) Due to the obstruction of the Earth-Moon dual star system, the number of visible satellites provided by a single GNSS constellation is no more than 4 most of the time, which cannot meet the theoretical positioning requirements.

[0007] (4) The existing technology has failed to fully consider the clock difference between the ground and lunar orbit receivers, which not only makes the positioning accuracy of the existing technology low, but also limits the adaptability and efficiency of the system in the lunar orbit environment.

[0008] Therefore, in order to achieve higher accuracy and real-time performance, there is an urgent need for a new navigation and positioning system that can directly synchronize the time between the ground and lunar orbit receivers and accurately calculate the position of the lunar orbit receivers using clock differences. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a navigation and positioning method based on a lunar orbit receiver, thereby resolving the issues in the prior art. The technical solution adopted by this invention is as follows:

[0010] A navigation and positioning method based on a lunar orbit receiver includes the following steps:

[0011] Step 1: Connect the ground GPS receiver to the ground communication equipment and keep it synchronized with the GPS time system at all times;

[0012] Step 2: The ground communication equipment performs two-way time synchronization with the lunar orbit receiver to calculate the clock difference between the lunar orbit receiver and the GPS system;

[0013] Step 3: The lunar orbit receiver receives GPS satellite signals and, in conjunction with clock bias, calculates the position information;

[0014] In step 2, the lunar orbit receiver packages its local time and identification information into a data frame and sends it to the ground communication equipment. The ground communication equipment receives the data frame and records the reception time, and then sends the current timestamp and confirmation information to the lunar orbit receiver. The lunar orbit receiver receives the confirmation information and records the reception time. By calculating the round-trip delay and one-way delay, the local time of the lunar orbit receiver when the signal arrives at the ground is determined, and the clock difference between the lunar orbit receiver and the GPS system is obtained.

[0015] Furthermore, step 2 includes:

[0016] Step 201, the lunar orbit receiver will transmit the local time. It is packaged with its own identifier information into a data frame and transmitted to ground communication equipment via wireless signal;

[0017] Step 202: The ground communication equipment receives the wireless signal from the lunar orbit receiver, extracts the timestamp information from the data frame, and records the signal reception time when the data frame is received. ;

[0018] Step 203, the ground communication equipment sets its current timestamp The confirmation information is packaged into a data frame and sent back to the lunar orbit receiver;

[0019] Step 204: The lunar orbit receiver receives the confirmation message sent by the ground communication equipment and records the time when the signal was received. ;

[0020] Step 205: Calculate the round-trip delay during the two-way time synchronization process using the following formula:

[0021] ;

[0022] in, This indicates the transmission time of a signal from the lunar orbit receiver to the ground communication equipment and back. This indicates the time required for terrestrial communication equipment to process signals;

[0023] Step 206: The one-way delay from the lunar orbit receiver to the ground communication equipment is half the round-trip delay.

[0024] ;

[0025] Step 207, the local time of the lunar orbit receiver when the signal transmitted by the lunar orbit receiver arrives at the ground communication equipment is:

[0026] ;

[0027] Step 208, the clock bias of the lunar orbit receiver is:

[0028] .

[0029] Furthermore, step 1 includes:

[0030] Step 101: The ground GPS receiver receives signals from GPS satellites and uses a satellite-to-ground time synchronization method to synchronize the GPS receiver with the GPS system.

[0031] Step 102: The ground communication equipment is connected to the GPS receiver and keeps the time synchronized at all times.

[0032] Furthermore, step 3 includes:

[0033] Step 301: The lunar orbit receiver receives a broadcast signal from a GPS satellite. The broadcast signal includes a pseudo-random code used for pseudorange calculation.

[0034] Step 302: The lunar orbit receiver obtains the positions of GPS satellites from the satellite ephemeris in the broadcast signal;

[0035] Step 303: When the lunar orbit receiver receives a broadcast signal from a GPS satellite, the pseudorange equation is obtained as follows:

[0036] ;

[0037] In this context, the superscript 1 indicates the GPS satellite number received by the lunar orbit receiver, and the subscripts g and s represent the lunar orbit receiver and the GPS satellite, respectively. This represents the pseudorange calculated by the lunar orbit receiver between the broadcast signal transmitted from GPS satellite number 1 and the lunar orbit receiver. Represents the geometric distance from the lunar orbit receiver to the center of mass of the GPS satellite. , These represent the clock biases of the lunar receiver and the GPS satellite numbered 1, respectively. The sum of multipath effects and observation noise representing the pseudorange of the lunar receiver;

[0038] Step 304, through bidirectional time synchronization between the lunar orbit receiver and the ground communication equipment in step 2, the following is obtained:

[0039] ;

[0040] in, The clock difference between the lunar orbit receiver and the GPS system;

[0041] Step 305: When the lunar orbit receiver simultaneously receives broadcast signals from three or more GPS satellites, establish a system of equations to solve for its own position:

[0042] ;

[0043] The superscripts 1 to n represent the numbers of the n GPS satellites received by the lunar receiver; , , This indicates the position of the GPS satellite corresponding to number 1, obtained from the GPS satellite broadcast signal received by the lunar orbit receiver; , , This indicates the location of the lunar orbit receiver; This indicates the clock difference between the lunar orbit receiver and the GPS system;

[0044] In step 306, the lunar orbit receiver calculates its precise position using the equations from step 305 and the lunar orbit reference.

[0045] Furthermore, step 3 can be repeated, with the lunar orbit receiver continuously updating its pseudorange with GPS satellites and updating its position in real time.

[0046] The present invention has the following beneficial effects:

[0047] (1) Improve positioning accuracy: This invention obtains a precise clock difference with the GPS system through two-way time synchronization between the lunar orbit receiver and the ground communication equipment, which significantly reduces the positioning deviation caused by signal delay and transmission error;

[0048] (2) Improve the real-time performance of positioning: This invention adopts the method of directly receiving GPS satellite signals and ephemeris, and combining clock difference to calculate the position, which greatly reduces the dependence on ground command links and improves the real-time performance of position calculation;

[0049] (3) Improve system adaptability and reliability: This invention does not rely on frequent navigation data updates from ground equipment, enabling the lunar orbit receiver to operate stably in the complex lunar orbit environment; the system still has strong adaptability and independence when facing possible signal interruption or delay, and the reliability is significantly improved; this adaptive capability effectively copes with the special characteristics of the lunar orbit environment, such as large temperature differences and weak gravity effects, ensuring that the system can still provide efficient positioning services under extreme conditions;

[0050] (4) Simplified operation process: The two-way time synchronization design and independent position calculation method of the present invention reduce the dependence on ground navigation stations and make the operation process simple.

[0051] (5) Enhance the value of scientific exploration: Since the present invention significantly improves the positioning accuracy and real-time performance of the lunar orbit receiver, it can provide precise navigation support for tasks such as lunar resource exploration, lander positioning, and deployment of scientific research equipment. Compared with the prior art, the present invention has important technical and social benefits in promoting lunar scientific exploration and deep space research, and meets the requirements of high efficiency, safety and reliability for future lunar exploration missions. Attached Figure Description

[0052] Figure 1 This is an overall flowchart of the present invention;

[0053] Figure 2 This is a schematic diagram of the principle and structure of the present invention. Detailed Implementation

[0054] The following will be based on embodiments of the present invention. Figures 1-2 The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0055] This invention aims to propose a navigation and positioning method based on a lunar orbit receiver to address issues such as time synchronization errors and positioning accuracy during the positioning process. Specifically, to overcome the complexity and signal propagation delays inherent in existing technologies within the lunar-Earth communication environment, this invention introduces a method for bidirectional time synchronization with ground communication equipment. This allows the lunar orbit receiver to accurately calculate the clock difference with the GPS system, thereby overcoming the time synchronization errors caused by signal delays in existing methods and effectively improving positioning accuracy. Simultaneously, the lunar orbit receiver also receives GPS satellite broadcast signals and performs real-time positioning calculations based on the clock difference, ensuring a precise position within lunar orbit.

[0056] A navigation and positioning method based on a lunar orbit receiver, the specific steps of which are as follows:

[0057] Step 1: The ground system mainly consists of two key components: a ground GPS receiver and communication equipment, which are connected and kept synchronized with the GPS time system at all times.

[0058] Furthermore, the specific method for step 1 is as follows:

[0059] Step 101: The ground GPS receiver is responsible for receiving signals from GPS satellites and using the satellite-to-ground time synchronization method to synchronize the GPS receiver with the GPS system.

[0060] The specific process for time synchronization between a ground-based GPS receiver and GPS satellites is as follows:

[0061] (1) First, accurately measure the position of the ground GPS receiver antenna, obtain the position of the GPS satellite based on the received GPS navigation message information, and calculate the distance between the GPS satellite and the receiver. .

[0062] (2) The receiver can obtain the signal transmission time by measuring the difference between its own atomic clock time and the time of the received GPS satellite signal, and then obtain the pseudorange value from the GPS satellite to the receiver. .

[0063] (3) If the effects of the ionosphere, troposphere, equipment delay, and measurement factors are not considered, the pseudorange between the receiver and the GPS satellite can be expressed as: In an ideal scenario, the time difference between the ground receiver's atomic clock and the GPS satellite's atomic clock is: This enables time synchronization between the ground GPS receiver and the GPS time system.

[0064] In step 102, the communication device is connected to the GPS receiver and keeps time synchronized at all times. Therefore, as can be seen from step 101, the communication device has also achieved time synchronization with the GPS system.

[0065] Step 2 involves two-way time synchronization between the ground communication equipment and the lunar orbit receiver, allowing the calculation of the clock difference between the lunar orbit receiver and the GPS system. Specifically, in Step 2, the lunar orbit receiver packages its local time and identification information into a data frame and sends it to the ground communication equipment. The ground communication equipment receives the data frame, records the reception time, and then sends the current timestamp and acknowledgment information to the lunar orbit receiver. The lunar orbit receiver receives the acknowledgment information and records the reception time. By calculating the round-trip delay and one-way delay, the local time of the lunar orbit receiver when the signal arrives on the ground is determined, thus obtaining the clock difference between the lunar orbit receiver and the GPS system.

[0066] Furthermore, the specific method for step 2 is as follows:

[0067] Step 201: First, the lunar orbit receiver will transmit the local time. The device and its identifier information are packaged into a data frame and transmitted to ground communication equipment via wireless signal. The data frame format includes a start bit, timestamp, device identifier, check bit, and end bit.

[0068] Step 202: The communication device receives the signal from the lunar orbit receiver via the antenna, extracts the timestamp information from the data frame, and records the time of signal reception when the data frame is received. .

[0069] Step 203, the ground communication equipment sets its current timestamp The local time (i.e., the time when the communication device sends the signal) and acknowledgment information are packaged into a data frame and sent back to the lunar orbit receiver. This data frame also includes a start bit, timestamp, device identifier, check bit, and end bit.

[0070] Step 204: The lunar orbit receiver receives the confirmation message sent by the ground communication equipment and records the time when the signal was received. .

[0071] Step 205: Calculate the round-trip delay during the two-way time synchronization process using the following formula:

[0072] ;

[0073] in, This indicates the transmission time of a signal from the lunar orbit receiver to the ground communication equipment and back. This indicates the time required for terrestrial communication equipment to process signals.

[0074] Step 206: The one-way delay from the lunar orbit receiver ground to the communication equipment is half the round-trip delay.

[0075] ;

[0076] Step 207, the local time of the lunar orbit receiver when the signal transmitted by the lunar orbit receiver arrives at the ground communication equipment is:

[0077] ;

[0078] Step 207, because the time of the ground communication equipment and the GPS system has been synchronized, that is... Therefore, the clock bias of the lunar orbit receiver is:

[0079] ;

[0080] Step 3: The lunar orbiter receives GPS satellite signals and, combined with clock bias data, calculates the final position information. The specific steps are as follows:

[0081] Step 301: The lunar orbit receiver can receive broadcast signals from GPS satellites, which contain pseudo-random codes for subsequent pseudorange calculations.

[0082] Step 302: Simultaneously, the lunar orbit receiver can also obtain the position of GPS satellites from the satellite ephemeris contained in the GPS satellite signals.

[0083] Step 303, taking the reception of a broadcast signal from one GPS satellite as an example, the pseudorange equation obtained by the lunar orbit receiver is:

[0084] ;

[0085] In this context, the superscript 1 indicates the GPS satellite number received by the lunar orbit receiver, and the subscripts g and s represent the lunar orbit receiver and the GPS satellite, respectively. This represents the pseudorange calculated by the lunar orbit receiver between the broadcast signal transmitted from GPS satellite number 1 and the lunar orbit receiver. Represents the geometric distance from the lunar orbit receiver to the center of mass of the GPS satellite. , These represent the clock biases of the lunar receiver and the GPS satellite numbered 1, respectively. This represents the sum of the multipath effect and observation noise of the lunar receiver pseudorange.

[0086] Step 304, through the two-way time synchronization between the lunar orbit receiver and the ground communication equipment in step 2, we can obtain:

[0087] ;

[0088] in, This refers to the clock difference between the lunar orbit receiver and the GPS system.

[0089] Step 305: When the lunar orbit receiver simultaneously receives broadcast signals from three or more GPS satellites, it can establish a system of equations to solve for its own position, i.e.:

[0090] ;

[0091] Here, the superscripts 1 to n represent the numbers of the n GPS satellites received by the lunar receiver. , , This indicates the position of the GPS satellite corresponding to number 1, which can be obtained from the GPS satellite broadcast signal received by the lunar orbit receiver. , , This represents the position of the lunar orbit receiver, which is also an unknown quantity that needs to be solved. This represents the clock difference between the lunar orbit receiver and the GPS system, which has already been calculated in step 2.

[0092] In step 306, the lunar orbit receiver, using the equations from step 305 and a lunar orbit reference, can impose certain constraints on its position, eliminating calculation results that do not conform to the actual lunar orbit position, and finally calculating its precise position. For step 3, this process can be repeated cyclically; the lunar orbit receiver continuously updates its pseudorange with GPS satellites and updates its position in real time to ensure accurate and reliable positioning.

[0093] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, substitutions, or variations made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A method of navigation positioning based on a lunar orbit receiver, characterized in that, The method comprises the following steps: Step 1, the ground GPS receiver is connected with the ground communication device and keeps time synchronization with the GPS time system at all times; Step 2, the ground communication device carries out two-way time synchronization with the lunar orbit receiver, so as to calculate the clock difference between the lunar orbit receiver and the GPS system; Step 3, the lunar orbit receiver receives the GPS satellite signal and calculates the position information in combination with the clock difference; In step 2, the lunar orbit receiver packs the local time and identification information into a data frame and sends the data frame to the ground communication device; the ground communication device receives the data frame and records the receiving time, and then sends the current time stamp and confirmation information to the lunar orbit receiver; the lunar orbit receiver receives the confirmation information and records the receiving time; the clock difference between the lunar orbit receiver and the GPS system is determined by calculating the round-trip delay and the one-way delay, and the local time of the lunar orbit receiver when the signal reaches the ground is obtained.

2. The method of claim 1, wherein, Step 2 comprises: Step 201, the lunar-orbit receiver packs local time and its own identifier information into a data frame, and sends it to the ground communication device through a wireless signal; Step 202, the ground communication device receives the wireless signal sent by the lunar orbit receiver, extracts the timestamp information in the data frame, and records the receiving signal time when the data frame is received ; Step 203, the ground communication equipment packs its current time stamp and the confirmation information into a data frame, and sends it back to the lunar-orbit receiver; Step 204, the lunar-orbit receiver receives the confirmation information sent by the ground communication device and records the time when the signal is received ; Step 205, the round-trip delay in the two-way time synchronization process is calculated by the following formula: ； wherein, represents the transmission time of the signal from the lunar orbiting receiver to the ground communication device and back from the ground communication device to the lunar orbiting receiver, represents the time required for the ground communication device to process the signal; Step 206, the one-way delay from the lunar orbit receiver to the ground communication device is half of the round-trip delay: ； Step 207, the local time of the lunar orbit receiver when the signal sent by the lunar orbit receiver reaches the ground communication device is: ； Step 208, the clock difference of the lunar orbit receiver is: 。 3. The method of claim 1, wherein, Step 1 comprises: Step 101, the ground GPS receiver receives the signal from the GPS satellite, and uses the satellite-ground time synchronization method to realize time synchronization between the GPS receiver and the GPS system; Step 102, the ground communication device is connected with the GPS receiver and keeps time synchronization at all times.

4. The method of claim 3, wherein, Step 3 comprises: Step 301, the lunar orbit receiver receives the broadcast signal of the GPS satellite, and the broadcast signal comprises a pseudo-random code for pseudo-range calculation; Step 302, the lunar orbit receiver obtains the position of the GPS satellite from the satellite ephemeris in the broadcast signal; Step 303, when the lunar orbit receiver receives the broadcast signal of one GPS satellite, the pseudo-range equation obtained is: ； where the superscript 1 denotes the number of the GPS satellite received by the lunar orbit receiver, and the subscripts g and s represent the lunar orbit receiver and the GPS satellite, respectively, represents the pseudo-range between the broadcast signal transmitted from the GPS satellite numbered 1 to the lunar orbit receiver calculated by the lunar orbit receiver, represents the geometric distance from the lunar orbit receiver to the center of the GPS satellite, , represents the clock error of the lunar receiver and the GPS satellite numbered 1, respectively, represents the sum of the multipath effect and the observation noise of the lunar receiver pseudo-range; Step 304, through the two-way time synchronization between the lunar orbit receiver and the ground communication device in step 2, the following is obtained: ； wherein, is the clock difference between the lunar orbit receiver and the GPS system; Step 305, when the lunar orbit receiver simultaneously receives the broadcast signals of three or more GPS satellites, an equation set is established to solve the position of the lunar orbit receiver: ； Wherein, the superscript 1~n represents the n GPS satellite number received by the lunar receiver; , , Indicates the position of the GPS satellite corresponding to the number 1, which is obtained from the GPS satellite broadcast signal received by the lunar orbit receiver; , , Indicates the position of the lunar orbit receiver; Indicates the clock difference between the lunar orbit receiver and the GPS system; Step 306, the lunar orbit receiver solves the accurate position of the lunar orbit receiver through the equation set in step 305 in combination with the lunar orbit reference.

5. A lunar orbit receiver based navigation positioning method according to claim 1 or 4, characterized in that, Step 3 can be recycled, and the lunar orbit receiver continuously updates the pseudo-range between the lunar orbit receiver and the GPS satellite and updates the position in real time.

Images