WO2019019044A1

WO2019019044A1 - Pseudorange calculation method and terminal

Info

Publication number: WO2019019044A1
Application number: PCT/CN2017/094449
Authority: WO
Inventors: 张伟
Original assignee: 深圳市大疆创新科技有限公司
Priority date: 2017-07-26
Filing date: 2017-07-26
Publication date: 2019-01-31
Also published as: CN108513623B; CN108513623A

Abstract

A pseudorange calculation method and terminal, computer program product and computer storage medium, the method comprising: obtaining the current local time of a terminal (201); obtaining a distance between the terminal and a lost-lock satellite (202), the lost-lock satellite being the satellite that provided positioning service for the terminal before the lock was lost; calculating, according to the current time and the distance, a first transmission time used by the lost-lock satellite to transmit a satellite signal to the terminal (203); calculating a second transmission time according to the first transmission time and according to an actual time resolved from a navigation message transmitted by the lost-lock satellite (204); and calculating a pseudorange between the terminal and the lost-lock satellite according to the current time and the second transmission time (205). According to the method, frame synchronization is not needed in a pseudorange calculation process, thereby avoiding the requirement of waiting for a long time for the completion of frame synchronization, shortening the time used by the terminal to calculate the pseudorange, and increasing the speed of the pseudorange calculation.

Description

Pseudorange calculation method and terminal

Technical field

The present application relates to the field of satellite navigation technology, and in particular, to a pseudorange calculation method and a terminal.

Background technique

In order to realize the positioning function, terminals such as drones, vehicles, and mobile phones are generally implemented by setting a Global Navigation Satellite System (GNSS), for example, Global Positioning System (GPS), Beidou satellite navigation. System (BeiDou Navigation Satellite System, BDS), Global Navigation Satellite System (GLONASS) and Galileo navigation system GALILEO. When the GNSS navigation satellite signal is weak, for example, when the terminal moves through the cave, bridge hole, underground passage, building occlusion, etc., or encounters sudden interference, the terminal cannot pass the preset receiver. The satellite signal is locked and locked, causing the satellite signal to lose lock. When the satellite signal reappears, the terminal needs to recapture and track the satellite signal through the receiver to recover, and the process is called re-locking.

When some satellites lose lock, if the terminal cannot be accurately located through the receiver, the terminal can estimate the current position range according to the position information, speed information, lost lock time and application scenario before the lock is lost. For example, the terminal first acquires the current time through the receiver, and queries whether the channel of the receiver completes the bit synchronization and the frame synchronization. When the bit synchronization and the frame synchronization are completed, the code phase of the channel of the receiver and the preset bit code are read. The cycle count, the preset intra-frame bit count, the time corresponding to the preset bit, and the time corresponding to the preset code period. Then, based on these parameters, the transmission time of the satellite signal is estimated, and then the pseudorange is estimated according to the local time and the transmission time, and finally, the positioning is performed according to the obtained pseudorange.

Since the uncertainty range is large when estimating the transmission time of the satellite signal, it is not only necessary to complete the bit synchronization, but also needs to complete the frame synchronization, according to the code phase, the code period count, the bit count, the time corresponding to the preset bit, and the pre- The time corresponding to the code period is used to estimate the transmission time, and then the pseudorange is further estimated according to the transmission time, and the completion of the frame synchronization needs to wait for a long time, so that the waiting time for the terminal to calculate the pseudorange is longer.

Summary of the invention

In order to solve the technical problem that the waiting time is long when the pseudorange is calculated in the prior art, the embodiment of the present application provides a pseudorange calculation method, where the terminal calculates the real launch time by using the estimated transmission time and the obtained actual time. Thereby obtaining a pseudorange. It realizes that no frame synchronization is needed in the process of calculating the pseudorange, which improves the speed of pseudorange calculation. The embodiments of the present application also provide a terminal, a computer program product, a computer storage medium, and the like.

A first aspect of the embodiments of the present application provides a pseudorange calculation method, which may include:

Get the current time of the terminal local;

Obtaining a distance between the terminal and a lost lock satellite, the satellite that provides positioning service for the terminal before the lock is lost;

Calculating, according to the current time and the distance, a first transmission time that the lost-lock satellite transmits a satellite signal to the terminal;

Calculating a second transmission time according to the first transmission time and an actual time calculated from a navigation message transmitted by the lost lock satellite;

Calculating a pseudorange between the terminal and the lost lock satellite according to the current time and the second transmission time.

Optionally, before the calculating the second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the loss-locking satellite, the method further includes:

Obtaining a transmission error of the first transmission time;

Determining whether the transmission error satisfies a preset condition;

If so, the step of calculating the second transmission time based on the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite is performed.

Optionally, the acquiring the transmission error of the first transmission time includes:

Obtaining a satellite error of the lost lock satellite and a propagation error of the satellite signal;

Obtaining a receiver error of the terminal preset receiver;

The transmission error is obtained based on the satellite error, the propagation error, and the receiver error.

Optionally, the determining whether the transmission error meets a preset condition comprises:

Obtaining a code period of the terminal preset receiver channel;

When the transmission error is less than half of the code period, determining that the transmission error satisfies the first a preset condition, the first preset condition being included in the preset condition.

Optionally, the calculating the second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the loss-locking satellite includes:

Acquiring the actual code phase time of the navigation message transmitted from the lost lock satellite when the transmission error satisfies the first preset condition;

Obtaining a bit period of the receiver channel;

Calculating an estimated code phase time according to the first transmission time, the code period, and the bit period;

The second transmission time is calculated according to the first transmission time, the actual code phase time, and the estimated code phase time.

Optionally, after acquiring the code period of the terminal preset receiver channel, the method further includes:

Obtaining a bit period of the receiver channel when the transmission error is greater than half of the code period;

When the transmission error is less than half of the bit period, it is determined that the transmission error satisfies a second preset condition, and the second preset condition is included in the preset condition.

And acquiring, when the transmission error meets the second preset condition, an actual code phase time calculated by the navigation message transmitted from the lost lock satellite and an actual code cycle time corresponding to the preset bit inner code cycle count;

Calculating a sum of an estimated code phase time and an estimated code cycle time according to the first transmission time and the bit period;

And calculating the second transmission time according to the sum of the first transmission time, the actual code period time, the actual code phase time, and the estimated code phase time and the estimated code period time.

Optionally, the obtaining the distance between the terminal and the lost lock satellite includes:

Obtaining current terminal location information of the terminal;

Obtaining satellite position information of the lost lock satellite;

And obtaining the distance according to the terminal location information and the satellite location information.

Optionally, the acquiring the current terminal location information of the terminal includes:

Acquiring the terminal location information by at least one positioning device, wherein the positioning device comprises At least one of the following: inertial navigation, visual sensors, or ultrasound.

Optionally, acquiring the distance according to the terminal location information and the satellite location information includes:

Obtaining a geometric distance according to the terminal location information and the satellite location information;

The distance is obtained based on the geometric distance, the satellite error, the propagation error, and the receiver error.

Optionally, before the acquiring the current time local to the terminal, the method further includes:

Acquiring the crystal temperature of the receiver preset by the terminal every preset time;

Obtaining a crystal frequency offset corresponding to the crystal temperature;

Obtaining a time deviation corresponding to the crystal frequency offset;

Adjusting the local time of the receiver according to the time offset, and setting the adjusted local time as the current time.

Obtaining a transmission time of the satellite transmitting a satellite signal to the terminal, and acquiring an initial transmission time of the satellite signal;

And adjusting the local time of the receiver according to the transmission time and the initial transmission time, and setting the adjusted local time as the current time.

Optionally, after the calculating the pseudorange between the terminal and the lost-lock satellite according to the current time and the second transmission time, the method further includes:

Positioning is performed according to at least three of the pseudoranges.

A second aspect of the embodiments of the present application provides a terminal, where the terminal includes a processor, where the processor is configured to acquire a current time local to the terminal;

Optionally, the processor is further configured to acquire a transmission error of the first transmission time;

Determining whether the transmission error satisfies a preset condition;

Optionally, the processor is further configured to acquire a satellite error of the lost-lock satellite and a propagation error of the satellite signal;

Obtaining a receiver error of the terminal preset receiver;

Optionally, the processor is further configured to acquire a code period of the terminal preset receiver channel;

When the transmission error is less than half of the code period, it is determined that the transmission error satisfies a first preset condition, and the first preset condition is included in the preset condition.

Optionally, the processor is further configured to: when the transmission error meets the first preset condition, acquire an actual code phase time of a navigation message transmitted from the loss-locking satellite;

Obtaining a bit period of the receiver channel;

Optionally, the processor is further configured to acquire a bit period of the receiver channel when the transmission error is greater than half of the code period;

Optionally, the processor is further configured to: when the transmission error meets the second preset condition, acquire an actual code phase time and a preset bit from the navigation message transmitted by the lost lock satellite The actual code cycle time corresponding to the code period count;

Optionally, the processor is further configured to acquire current terminal location information of the terminal;

Obtaining satellite position information of the lost lock satellite;

Optionally, the processor is further configured to acquire the terminal location information by using at least one positioning device, wherein the positioning device comprises at least one of the following: inertial navigation, a visual sensor, or an ultrasonic wave.

Optionally, the processor is further configured to acquire a geometric distance according to the terminal location information and the satellite location information;

Optionally, the processor is further configured to acquire, according to a preset time, a crystal temperature of a receiver preset by the terminal;

Obtaining a crystal frequency offset corresponding to the crystal temperature;

Obtaining a time deviation corresponding to the crystal frequency offset;

Optionally, the processor is further configured to: acquire a transmission time of the satellite to send a satellite signal to the terminal, and acquire an initial transmission time of the satellite signal;

Optionally, the processor is further configured to perform positioning according to at least three of the pseudoranges.

A third aspect of the embodiments of the present application provides a computer program product comprising instructions, when the computer program product is run on a computer, causing the computer to execute the pseudorange calculation method according to the first aspect of the foregoing embodiment of the present application.

A fourth aspect of embodiments of the present application provides a computer readable storage medium having instructions stored therein that, when run on a computer, cause the computer to perform the pseudo-first aspect of the first embodiment of the present application. Distance calculation method.

In the embodiment of the present application, the terminal may acquire the first transmission time of the satellite to send the satellite signal to the terminal according to the current time of acquiring the local time, the distance between the self and the lost lock satellite. Then, the terminal calculates a second transmission time according to the first transmission time and the actual time, and calculates a pseudorange between the terminal and the satellite according to the current time and the second transmission time. In the whole process of pseudorange calculation, no need to enter The line frame synchronization avoids the waiting time for the completion of the frame synchronization, shortens the time taken by the terminal to calculate the pseudorange, and improves the speed of the pseudorange calculation.

DRAWINGS

1 is an architectural diagram of a UAV receiving satellite signals for positioning in an embodiment of the present application;

2 is a schematic diagram of an embodiment of a pseudorange calculation method according to an embodiment of the present application;

3 is a schematic diagram of another embodiment of a pseudorange calculation method according to an embodiment of the present application;

4 is a schematic diagram of another embodiment of a pseudorange calculation method according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an embodiment of a terminal in an embodiment of the present application.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention. The features of the embodiments and embodiments described below may be combined with each other without conflict.

In this embodiment, the pseudorange calculation method can be applied to a terminal, and the terminal can be a drone. It can be understood that, in practical applications, the terminal can be other mobile devices besides the drone. The platform, for example, a mobile phone, a vehicle, a robot, etc., is not limited herein.

The following takes the drone as an example, and combines a specific application scenario to describe the pseudorange calculation method in the present application in detail. As shown in FIG. 1 , the drone is preset with a receiver for receiving satellite signals, and is also set. There is a positioning device, which includes at least one of the following: inertial navigation, a visual sensor, or an ultrasonic wave. It can be understood that the UAV can also include other devices, which are not limited herein. First of all, the drone can be launched by receiving more than 4 satellites at the beginning of the flight. The satellite signal is accurately located. Then, when the drone moves between the building and the cave, the satellite signal transmitted by some satellites is weakened or disappeared. At this time, the drone can only receive satellite signals transmitted by some satellites, and the satellite that originally provided the positioning service for the terminal. It becomes a lost lock satellite. At this time, the drone calculates the current time of the local terminal and acquires the distance between the terminal and the lost lock satellite through the pseudorange calculation method in the embodiment of the present application, and then calculates the loss according to the current time and distance. The lock satellite transmits the first transmission time of the satellite signal to the terminal, and then calculates the second transmission time according to the first transmission time and the actual time calculated by the navigation message transmitted from the lost lock satellite, and finally can be calculated according to the current time and the second transmission time. The pseudorange between the terminal and the lost lock satellite. When the sum of the number of pseudoranges obtained by the above calculation and the number of satellites that have not lost locks exceeds 4, the terminal can perform positioning. When the local clock is corrected by the clock difference, only more than 3 can be positioned, even when When there are more than three remaining connected satellites, the positioning result can be obtained, and the positioning result can be corrected by the pseudorange calculated by the above method to obtain a more accurate positioning result. The foregoing application scenarios are only for illustrative purposes, and the technical solutions of the technical personnel in the art are applied to other application scenarios, which are not limited herein.

For ease of understanding, the specific process in the embodiment of the present application is described below. Referring to FIG. 2, an embodiment of the pseudorange calculation method in the embodiment of the present application includes:

201. Obtain a current time local to the terminal.

In this embodiment, the terminal is provided with a receiver for receiving satellite signals. In the process of calculating the pseudorange, the terminal may first acquire the local time of the local oscillator through the crystal oscillator of the receiver, and the crystal oscillator may be a temperature-compensated crystal oscillator or Digitally compensates for crystals and more.

202. Obtain a distance between the terminal and the lost lock satellite;

The lost lock satellite is a satellite that provides positioning services for the terminal before the lock is lost. The terminal can acquire the distance between itself and the lost lock satellite. For example, the terminal first acquires the current terminal position information of the terminal through inertial navigation, and the navigation message. The satellite ephemeris of the lost lock satellite is obtained, and the satellite position information of the lost lock satellite is obtained according to the satellite ephemeris, and then the distance between the terminal and the lost lock satellite is obtained according to the terminal position information and the satellite position information. It can be understood that, in practical applications, since the terminal location information is acquired in various ways, and the calculation result of the distance may be related to satellite error, satellite signal propagation error, receiver error, etc., the terminal acquires itself and The manner of the distance between the lost satellites may also include other manners, which are not limited herein.

It can be understood that the lost lock satellite can be one or more, for example, when the terminal only needs to count When calculating a pseudorange, the terminal can only obtain the distance from the lost lock satellite; when the terminal needs to calculate multiple pseudoranges, the terminal can separately acquire the distance from the plurality of lost lock satellites.

203. Calculate, according to the current time and distance, a first transmission time of the satellite signal sent by the lost lock satellite to the terminal;

After obtaining the current time and the distance between the terminal and the lost lock satellite, the terminal may calculate the first transmission time of the satellite signal sent by the lost lock satellite to the terminal according to the current time and the distance, for example, the first launch time is equal to the current time. Subtract the distance divided by the value of the speed of light, ie the first transmission time = current time - distance / speed of light. It can be understood that, in practical applications, the first transmission time may also be related to satellite error, satellite signal propagation error, receiver error, etc., and the first transmission time may be calculated in other ways, specifically limited.

204. Calculate a second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite;

After obtaining the first transmission time, the terminal may calculate the actual time from the locally stored navigation message transmitted by the lost-lock satellite, and the actual time may be a bit cycle time, a code cycle time, or a code phase time. Then, the second transmission time is calculated according to the first transmission time and the actual time. Here, the first transmission time uncertainty may be replaced with the calculated actual time, thereby obtaining an accurate second transmission time.

205. Calculate a pseudorange between the terminal and the lost lock satellite according to the current time and the second launch time.

After obtaining the second transmission time, the terminal may calculate the pseudorange between the self and the lost lock satellite according to the current time and the second transmission time, and the calculation manner of the pseudorange is not limited herein. It should be noted that the terminal may calculate one or more pseudoranges according to actual needs. For example, when some satellite signals in the satellites providing location services for the terminal are lost, and the satellite signals are not lost, the terminal may Only the pseudorange between one of the lost satellites is calculated; when all the satellite signals in all the satellites providing the positioning service for the terminal are out of lock, the terminal needs to calculate the pseudorange between at least four of the lost lock satellites. It can be understood that, in practical applications, the number of calculations of the pseudorange can also be flexibly set, which is not limited herein.

In the embodiment of the present application, the terminal may acquire the first transmission time of the satellite to send the satellite signal to the terminal according to the current time of acquiring the local time, the distance between the self and the lost lock satellite. Then, the terminal calculates the second transmission time according to the first transmission time and the actual time, and then according to the current time and the second transmission The time is calculated from the pseudorange between the terminal and the satellite. In the whole process of pseudorange calculation, frame synchronization is not needed, thereby avoiding the waiting time for the completion of the frame synchronization, shortening the time consumed by the terminal to calculate the pseudorange, and improving the speed of the pseudorange calculation.

In some embodiments, since the crystal oscillator of the receiver may provide a certain error in the local current time, in order to obtain the accurate current time, the terminal may adjust the current time in advance before acquiring the local current time. The terminal adjusts the current time to include:

In the first method, first, the crystal temperature of the receiver preset by the terminal is acquired every preset time;

A temperature sensor can be preset in the receiver, and the temperature of the crystal oscillator is collected by the temperature sensor. The preset time can be flexibly set according to actual needs, which is not limited herein.

Secondly, obtaining a crystal frequency offset corresponding to the crystal temperature;

The mapping table or conversion relationship between the crystal temperature and the crystal frequency offset may be preset in the terminal. After obtaining the crystal temperature, the crystal frequency offset corresponding to the crystal temperature may be obtained by querying the mapping table, or calculated by the conversion relationship. The crystal oscillator temperature corresponds to the crystal frequency deviation. That is, the terminal can also calculate the corresponding crystal frequency offset according to the formula after obtaining the crystal temperature.

Again, obtaining a time offset corresponding to the crystal frequency offset;

After obtaining the crystal frequency offset, the terminal can determine the time deviation corresponding to the crystal frequency offset. It can be understood that the time deviation corresponding to the crystal temperature can also be obtained directly.

Finally, the local time of the receiver is adjusted according to the time deviation, and the adjusted local time is set as the current time.

The formula for the terminal to adjust the local time according to the time deviation is:

among them,

For the end time corresponding to the preset time,

For the start time corresponding to the preset time, t _tick is the total time corresponding to the preset time, Δt _clk is the time deviation, and the start time corresponding to the preset time can be

Set to the current time.

The second method is: acquiring the transmission time of the satellite transmitting the satellite signal to the terminal, and acquiring the initial transmission time of the satellite signal; adjusting the local time of the receiver according to the transmission time and the initial transmission time, and setting the adjusted local time as the current time.

The formula for adjusting the local time of the receiver crystal oscillator according to the transmission time of the signal and the initial transmission time is:

t _r =t _x +e

Where t _r is the current time, t _x is the initial transmission time, and e is the transmission time. Assuming that the signal transmission time of the GPS satellite is 0.07 seconds, the current time is t _r = t _{x +} 0.07.

In some embodiments, when the terminal acquires the distance between itself and the lost lock satellite, it first acquires the current terminal location information of the terminal, and acquires the satellite position information of the lost lock satellite. The current relative position information of the terminal may be acquired by at least one positioning device, and the terminal position information in the earth coordinate system may be obtained by using the position information acquired before the satellite loses lock and the relative position information acquired by the positioning device, wherein the positioning The device includes at least one of the following: inertial navigation, a visual sensor or an ultrasonic wave, etc., for example, the terminal position information may be acquired by fusion positioning according to inertial navigation preset by the terminal, the visual sensor and the ultrasonic wave, or only one of the positioning devices may be used. Get terminal location information. It should be noted that the terminal location information obtained by the positioning device may have a certain error, and the terminal may calculate the terminal location information in combination with the error.

It should be noted that, when acquiring terminal location information, a location model may be established, which may be established by using location information before the terminal, or may be established by other data of flight, or a combination of the two, and then passed through Kalman. The filtering calibrates the result so that the position information in the model and the position information acquired by the actual positioning device occupy different weights, and the closest terminal position information is obtained.

The satellite position information of the lost lock satellite may be satellite position information calculated according to the satellite ephemeris obtained in the navigation message preset by the terminal. The satellite ephemeris may be a satellite ephemeris of the lost lock satellite in an effective period before the lock is lost. For example, it may be a satellite ephemeris within one hour before the lock is lost, which is not limited herein.

Then, based on the terminal location information and the satellite location information, the distance between the terminal and the lost lock satellite is obtained. For example, when the terminal location information is (x, y, z) and the satellite position information is (x ^j , y ^j , z ^j ), the geometric distance r ^j between the terminal and the lost lock satellite is calculated according to the following formula:

The distance between the acquisition terminal and the lost lock satellite may be the geometric distance calculated by the above method, or may be the distance after error correction of the geometric distance. Since the obtained satellite position information may have a certain error, in order to obtain a relatively accurate distance, when the distance is obtained according to the terminal position information and the satellite position information, the geometric distance can be obtained according to the terminal position information and the satellite position information, and acquired. The satellite error of the lost lock satellite, the propagation error of the satellite signal, the receiver error of the receiver, and then the distance is obtained according to the geometric distance, satellite error, propagation error and receiver error. The satellite error may include a satellite clock error, which may include the ionospheric correction of the ionosphere where the satellite is located, and the convection of the satellite. The tropospheric correction of the layer, and the effect error caused by the multipath effect, etc., the receiver error may include the crystal clock difference of the receiver.

For example, the distance ρ ^j between the terminal and the lost lock satellite can be calculated according to the following formula:

ρ ^j =r ^j +c×Δt _r -c×Δt _j +Δ _iono +Δ _trop +Δ _mp

Where ρ ^j is the distance between the terminal and the lost lock satellite, r ^j is the geometric distance between the terminal and the lost lock satellite, c is the speed of light, Δt _r is the crystal clock difference, and Δt _j is the satellite clock of the jth satellite Poor, Δ _iono is the ionospheric correction, Δ _trop is the tropospheric correction, and Δ _mp is the multipath effect error.

In some embodiments, after obtaining the current time and the distance between the terminal and the lost lock satellite, the terminal may calculate the first transmission time of the satellite signal transmitted by the lost lock satellite to the terminal according to the current time and distance. The formula for calculating the first launch time based on the current time and distance is:

among them,

For the first launch time, t _r is the current time, r ^j is the geometric distance, and c is the speed of light.

In some embodiments, since the distance is related to satellite error, propagation error, receiver error, etc., in order to calculate a precise first transmission time,

At this time, the terminal can calculate the first launch time according to the current time, distance, satellite clock difference, crystal clock error, ionospheric correction amount, tropospheric correction amount, effect error and light speed, and the formula is:

among them,

For the first launch time, t _r is the current time, Δt _r is the crystal clock difference, Δt _j is the satellite clock of the jth satellite, r ^j is the geometric distance between the terminal and the lost lock satellite, and Δ _mp is the multipath The effect error, c is the speed of light, Δ _iono is the ionospheric correction. The ionospheric correction can be calculated by the ionospheric correction parameter and the corresponding ionospheric correction model; Δ _trop is the tropospheric correction, which can be calculated by using the appropriate tropospheric model. Tropospheric corrections, for example, the Sastamoning model, the Hopfield model, etc.

In some embodiments, after obtaining the first transmission time, the terminal may first acquire the first transmission time before calculating the second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite. The transmission error of the terminal acquiring the first transmission time includes: obtaining the satellite error of the lost lock satellite and the propagation error of the satellite signal; acquiring the receiver error of the preset receiver; and based on the satellite error, propagation error and receiver error Get the emission error. Among them, satellite errors include: satellite clock error and satellite ephemeris error, propagation error including tropospheric error, ionospheric error, multipath The effect error of the path, the error caused by the relativity, etc., the receiver error includes the receiver clock difference, the fusion positioning error, and the like.

The above different errors are calculated by different weights combined with the time of loss of lock. The above errors have time error and distance error. At a certain propagation speed, the distance error can be converted into time error to obtain the transmission error.

In some embodiments, because the time interval is short before the lock loss and the re-trap, the distance between the satellite and the terminal is short, and the satellite error, the propagation error, and the receiver error in the receiver error are compared. Small, in some cases, can be omitted, that is, the error caused by the fusion positioning is combined with the time of loss of lock to calculate the transmission error.

In the embodiment of the present application, the terminal may calculate the pseudorange when the transmission error of the first transmission time meets the preset condition, and includes two cases: 1. When the transmission error satisfies the first preset condition, the terminal calculates according to the mode 1. Pseudorange; Second, when the transmission error satisfies the second preset condition, the pseudorange is calculated according to the second method, which will be described in detail below.

I. When the transmission error satisfies the first preset condition, the pseudorange between the terminal and the lost lock satellite is calculated according to the method 1. Referring to FIG. 3, another embodiment of the pseudorange calculation method in the embodiment of the present application includes:

301: Obtain a current time local to the terminal;

It should be noted that the current time of obtaining the locality of the terminal in this embodiment is similar to the current time of obtaining the locality of the terminal in the foregoing embodiment, and details are not described herein again.

302. Obtain a distance between the terminal and the lost lock satellite;

It should be noted that, in this embodiment, the distance between the acquiring terminal and the lost lock satellite is similar to the distance between the acquiring terminal and the lost lock satellite in the foregoing embodiment, and details are not described herein again.

303. Calculate, according to the current time and distance, a first transmission time of the satellite signal sent by the lost lock satellite to the terminal;

It should be noted that, in this embodiment, the first transmission time of the satellite signal transmitted by the lost-lock satellite to the terminal is calculated according to the current time and distance, and the satellite signal is sent to the terminal by the lost-lock satellite according to the current time and distance in the foregoing embodiment. The first launch time is similar, and will not be described here.

304: Obtain a transmission error of the first transmission time;

It should be noted that, in this embodiment, the transmission error of the first transmission time is obtained, which is similar to the transmission error of obtaining the first transmission time in the foregoing embodiment, and details are not described herein again.

After obtaining the transmission error of the first transmission time, the terminal determines whether the transmission error satisfies a preset condition, and the preset condition may include a first preset condition and a second preset condition. When the transmission error satisfies the preset condition, the terminal may perform the step of calculating the second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite.

When the transmission error does not satisfy the preset condition, the terminal calculates the pseudorange in the following manner: First, the second transmission time t _x of calculating the satellite signal transmitted by the lost lock satellite to the terminal is:

t _x = t _frame + N _bit × T _bit + N _cyc × T _cyc + N _cdp × T _cyc

Where t _frame is the frame start time, which can be obtained from the navigation message; N _bit is 1 frame bit count, which can be obtained after frame synchronization; N _cyc is 1 bit inner code cycle count, which can be obtained after bit synchronization N _cdp is the code phase, which can be obtained after stable tracking of the satellite; T _bit is the time corresponding to 1 bit, and T _cyc is the time corresponding to 1 code period. In the solution process of the navigation message, the code phase N _cdp is first acquired, then the 1-bit inner code cycle count N _{cyc is obtained} , and finally the 1-bit inner bit count N _{bit is obtained} . Taking the GPS L1 C/A code as an example, one frame of the GPS L1 C/A code includes 300 bits, one bit contains 20 code periods, the time corresponding to one bit is 0.02 seconds, and the time corresponding to one code period is 0.001 seconds.

After the second transmission time, the pseudorange can be calculated according to the second transmission time and the current time. The pseudorange is calculated as follows:

ρ=(t _r -t _x )×c

Where ρ is a pseudorange, t _r is the current time, t _x is the second transmission time, and c is the speed of light.

305. Acquire an actual code phase time of the navigation message transmitted from the lost lock satellite when the transmission error satisfies the first preset condition;

Whether the terminal determines whether the transmission error satisfies the preset condition comprises: acquiring a code period of the terminal preset receiver channel; determining whether the transmission error is less than half of the code period; if yes, determining that the transmission error satisfies the first preset condition. Taking the GPS L1 C/A code as an example, the code period is 1 millisecond. When the transmission error is less than 1/2 code period, that is, the transmission error is less than 0.5 milliseconds, it is determined that the transmission error satisfies the first preset condition. It should be noted that, according to different types of codes, the first preset condition can be flexibly set, which is not limited herein.

In order to accurately determine whether the incident error satisfies the first preset condition, the terminal determines whether the transmit error is less than half of the code period, and when the transmit error is less than half of the code period, the bit period of the receiver channel may be acquired first, and then Determine if the transmission error is less than half of the bit period, and if so, Then, a step of determining whether the transmission error is less than half of the code period is performed. The first preset condition is included in the aforementioned preset condition. When the transmission error satisfies the first preset condition, the actual code phase time of the navigation message transmitted from the lost lock satellite is obtained.

It should be noted that, the terminal determines whether the transmission error satisfies the first preset condition or the second preset condition, and may determine whether the transmission error satisfies the first preset condition, and then determines whether the transmission error satisfies the second preset. Condition; firstly, it is first determined whether the transmission error satisfies the second preset condition, and then it is determined whether the transmission error satisfies the first preset condition; or may be a selection judgment, or may directly determine whether the first preset condition is satisfied or satisfied The two preset conditions are not limited herein.

When the transmission error satisfies the first preset condition, the terminal may calculate the actual code phase time from the pre-stored navigation message transmitted by the lost-lock satellite.

306. Obtain a bit period of a receiver channel.

307. Calculate an estimated code phase time according to the first transmission time, the code period, and the bit period.

308. Calculate a second transmission time according to the first transmission time, the actual code phase time, and the estimated code phase time.

When the transmission error satisfies the first preset condition, the terminal acquires the bit period and code period of the receiver channel, where the navigation message can be decoded in the receiver channel. Then, calculating the estimated code phase time according to the first transmission time, the code period, and the bit period, because the first transmission time is a sum of the bit period time, the code period time, and the code phase time, when the transmission error satisfies the first preset condition It is considered that the product of the bit period and the bit period count, that is, the bit period time is accurate, and that the product of the code period and the code period count, that is, the code period time is accurate, and then the second is calculated according to the actual code phase time and the estimated code phase time. The transmission time, in particular, removes the uncertain estimated code phase time from the first transmission time, and then adds the exact actual code phase time calculated from the navigation message, that is, the second transmission time is obtained, and the calculation formula is as follows:

Where floor( ) is a round-down function and t ₀ is the sum of the bit period time and the code period time.

For the first transmission time, t ₂ is the second transmission time, t _cdp is the actual code phase time, and t _{cdp is} in the range of 0 ≤ t _cdp <b, and Δt is the difference between the actual code period time and the estimated code phase time. , b is the code phase period,

For the estimated code phase, n is the time corresponding to 1 bit.

Since the first transmission time and the second transmission time are divided into three parts, namely, a bit period time, a code period time, and a code phase time, when the transmission error is within 1/2 code period, the bit period time is accurate. which is

The code phase is accurate. The actual code period calculated from the satellite navigation message, the code cycle time, there will be three cases, respectively

Since the transmission error is less than 1/2 code period, the true value is considered to be

The center of the 1/2 code period is within the radius, then

Different code cycle times are taken under certain circumstances.

309. Calculate a pseudorange between the terminal and the lost lock satellite according to the current time and the second launch time.

After obtaining the second transmission time, the terminal may calculate the pseudorange between the terminal and the lost lock satellite according to the current time and the second transmission time, and the calculation formula is as follows:

ρ=a×(t _r -t ₂ )×c

Where ρ is a pseudorange, t _r is the current time, t ₂ is the second transmission time, and a is a time-dependent constant coefficient for converting the time unit, for example, converting milliseconds into seconds, and c is the speed of light. By calculating the above formula, an accurate pseudorange can be obtained, and then the satellite position can be calculated using a plurality of pseudoranges.

It should be noted that the pseudorange calculated by the terminal may include a pseudorange between the terminal and the at least three unlocked satellites, that is, at least three pseudoranges may be calculated, and after at least three pseudoranges are obtained, according to the at least three Pseudoranges for positioning. The terminal can also calculate a pseudo-distance according to its current situation, and combine the un-locked satellite to accurately locate, or calculate a plurality of pseudo-ranges and calculate the target pseudo-range by the least square method, and perform positioning according to the target pseudo-range. So that the terminal can quickly calculate the pseudorange, and realize the lock-up and recapture fast. Quick solution.

Taking the GPS L1 C/A code as an example, the formula for calculating the pseudorange according to the first method is:

Among them, for the GPS L1C/A code, the bit period is 20 ms, and the code period is 1 ms. Floor() is a rounding function,

For the first launch time, when

When the unit is millisecond (ms), t _r is the current time, t ₀ is the sum of the bit cycle time and the code cycle time, t _cdp is the actual code phase time, and t _{cdp is} in the range of 0 ≤ t _cdp ≤ 1 ( Ms), Δt is the difference between the actual code cycle time and the estimated code phase time, and the code period is 1 millisecond (ms).

For the estimated code phase, 0.001 is used to convert milliseconds into seconds, c is the speed of light, and ρ is the pseudorange. The true pseudorange can be calculated by the above method.

Through the above method, the terminal may calculate the first sending time according to the obtained current time, the distance between the terminal and the lost lock satellite, and when the transmitting error of the first transmitting time satisfies the first preset condition, according to the stable tracking satellite The obtained actual code phase time, the predicted code phase time calculated according to the bit period and the code period, and the first transmission time are used to calculate the second transmission time, and then the terminal and the lost lock satellite are calculated according to the current time and the second transmission time. The pseudorange between them, so that the accurate second phase can be obtained by replacing the estimated code phase time with an accurate code phase time without frame synchronization and bit synchronization, and an accurate pseudorange can be calculated. Calculate accurate location information.

2. When the transmission error meets the second preset condition, the pseudorange between the terminal and the lost lock satellite is calculated according to the second method. Referring to FIG. 4, another embodiment of the pseudorange calculation method in the embodiment of the present application includes:

401. Obtain a current time local to the terminal.

402. Obtain a distance between the terminal and the lost lock satellite;

403. Calculate, according to the current time and distance, a first transmission time of the satellite signal sent by the lost lock satellite to the terminal;

404. Acquire a transmission error of the first transmission time.

It should be noted that steps 401 to 404 in this embodiment are similar to steps 301 to 304 in the foregoing embodiment shown in FIG. 3, and details are not described herein again.

405. When the transmission error meets the second preset condition, acquire an actual code phase time calculated by the navigation message transmitted from the lost lock satellite and an actual code cycle time corresponding to the preset bit code period count;

Whether the terminal determines whether the transmission error satisfies the preset condition comprises: acquiring a code period of the terminal preset receiver channel; determining whether the transmission error is less than half of the code period; if not, acquiring a bit period of the receiver channel, when the transmission error is less than the bit period At half of the time, it is determined that the transmission error satisfies the second preset condition. It should be noted that, according to different types of codes, the second preset condition can be flexibly set, which is not limited herein.

In order to accurately determine whether the incident error satisfies the second preset condition, the terminal determines whether the transmit error is less than half of the code period, and when the transmit error is greater than half of the code period, the bit period of the receiver channel may be acquired first, and then It is judged whether the transmission error is less than half of the bit period; if so, a step of determining whether the transmission error is less than half of the code period is performed. The second preset condition is included in the aforementioned preset condition. When the transmission error satisfies the second preset condition, the terminal acquires the actual code phase time calculated by the navigation message transmitted from the lost lock satellite and the actual code cycle time corresponding to the preset bit code period count.

It should be noted that the terminal may first determine whether the transmission error is less than half of the code period, and then determine whether the transmission error is less than half of the bit period; or determine whether the transmission error is less than half of the bit period, and then determine whether the transmission error is less than the code. It is also a half of the period; it can also be a selective judgment, or it can be determined at the same time whether the transmission error is less than half of the code period or less than half of the bit period, which is not limited herein.

406. Calculate a sum of the estimated code phase time and the estimated code cycle time according to the first transmission time and the bit period;

407. Calculate a second transmission time according to a sum of the first transmission time, the actual code cycle time, the actual code phase time, the estimated code phase time, and the estimated code cycle time.

When the transmission error satisfies the second preset condition, the terminal acquires the actual code phase time and the actual code cycle time of the navigation message transmitted from the lost lock satellite, and acquires the bit period of the receiver channel, where the navigation message can be at the receiver. In-channel decoding. Then, the terminal calculates the sum of the estimated code phase time and the estimated code cycle time according to the first transmission time and the bit period, because the first transmission time is the sum of the bit cycle time, the code cycle time, and the code phase time, when the transmission error is satisfied. In the second preset condition, it is considered that the product of the bit period and the bit period count, that is, the bit period time is accurate, and then according to the first transmission time, the actual code period time, the actual code phase time, the estimated code phase time, and the estimation code. The sum of the cycle times calculates the second transmission time, specifically, the sum of the uncertain estimated code phase time and the estimated code cycle time is removed from the first transmission time, and then the exact actual code solved from the navigation message is added. Phase time And the code cycle time, that is, the second launch time is obtained, and the calculation formula is as follows:

Where floor() is the downward rounding function and t ₀ is the sum of the estimated code phase time and the estimated code cycle time.

For the first transmission time, t ₂ is the second transmission time, t _cyc is the actual code period time, t _cdp is the actual code phase time, and t _{cyc is} in the range of 0 ≤ t _cyc ≤ n, Δt is the actual code period time The difference between the sum of the phase time of the actual code and the phase time of the estimated code period time estimate code,

To estimate the sum of the code period time and the code phase time, n is the time corresponding to 1 bit.

Since the first transmission time and the second transmission time are divided into three parts, namely, a bit period time, a code period time, and a code phase time, when the transmission error is outside the 1/2 code period and within the 1/2 bit period The actual bit period calculated from the satellite navigation message, there are three cases at the bit cycle time, respectively

Since the transmission error is within 1/2 code period and 1/2 bit period, the true value is considered to be

Centered on the 1/2 bit period to the radius of the 1/2 code period, then

Different bit cycle times are taken under certain circumstances.

408. Calculate a pseudorange between the terminal and the lost lock satellite according to the current time and the second launch time.

ρ=a×(t _r -t ₂ )×c

It should be noted that the pseudorange calculated by the terminal may include a pseudorange between the terminal and the at least three unlocked satellites, that is, at least three pseudoranges may be calculated, and after at least three pseudoranges are obtained, according to the at least three Pseudoranges for positioning. The terminal can also calculate only one pseudorange according to its current situation, and the combination is not lost. The lock satellite is accurately positioned, or after calculating a plurality of pseudoranges, the target pseudorange is calculated by a least squares method, and the target pseudorange is used for positioning. Therefore, the terminal can quickly calculate the pseudorange, and realize the fast solution of the lockout and recapture.

Taking the GPS L1 C/A code as an example, the formula for calculating the pseudorange according to the second method is:

Wherein, for the GPS L1C/A code, the bit period is 20 ms, the code period is 1 ms, floor() is a downward rounding function, and t ₀ is the sum of the estimated code phase time and the estimated code period time.

For the first transmission time, t _r is the current time, t _cyc is the actual code cycle time, t _cdp is the actual code phase time, Δt is the sum of the actual code cycle time and the actual code phase time and the estimated code cycle time estimate code The difference between the sum of phase times,

To estimate the sum of the code period time estimated code phase times, 0.001 is used to convert milliseconds into seconds, c is the speed of light, and ρ is the pseudorange. The true pseudorange can be calculated by the above method.

Through the above method, the terminal may calculate the first sending time according to the obtained current time, the distance between the terminal and the lost lock satellite, and when the transmitting error of the first transmitting time satisfies the second preset condition, according to the stable tracking satellite The actual code phase time obtained after the acquisition, the actual code cycle time obtained after the bit synchronization, and the sum of the estimated code phase time calculated from the bit period and the estimated code cycle time, and the second transmission time are calculated. Time, and then calculate the pseudorange between the terminal and the lost lock satellite according to the current time and the second launch time, so that an accurate pseudorange can be calculated without frame synchronization, thereby calculating accurate position information.

The following describes the method for calculating the pseudorange in the embodiment of the present application. The following describes the terminal in the embodiment of the present application from the perspective of hardware processing. As shown in FIG. 5, an embodiment of the terminal in the embodiment of the present application includes:

The processor 501 and the memory 502 (wherein the number of the processors 501 in the terminal may be one or more, and one processor 501 is taken as an example in FIG. 5). In some embodiments of the present invention, the processor 501 and the memory 502 may be connected by a bus or other means, wherein the bus connection is taken as an example in FIG.

Wherein, the program code is stored in the memory 502, and the program generation stored in the memory 502 is called. The code is used by the processor 501 to perform the following steps:

Get the current time of the terminal local;

Obtaining the distance between the terminal and the lost lock satellite, which is a satellite that provides positioning services for the terminal before it loses lock;

Calculating a first transmission time of the satellite signal transmitted by the lost lock satellite to the terminal according to the current time and distance;

Calculating a second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite;

The pseudorange between the terminal and the lost lock satellite is calculated according to the current time and the second launch time.

In some embodiments, the processor 501 is further configured to acquire a transmission error of the first transmission time;

Determining whether the transmission error satisfies a preset condition;

In some embodiments, the processor 501 is further configured to acquire a satellite error of the lost-lock satellite and a propagation error of the satellite signal;

Obtaining the receiver error of the terminal preset receiver;

The transmission error is obtained based on satellite error, propagation error, and receiver error.

In some embodiments, the processor 501 is further configured to acquire a code period of the terminal preset receiver channel;

When the transmission error is less than half of the code period, it is determined that the transmission error satisfies the first preset condition, and the first preset condition is included in the preset condition.

In some embodiments, the processor 501 is further configured to: when the transmission error meets the first preset condition, acquire an actual code phase time of the navigation message transmitted from the lost lock satellite;

Obtaining the bit period of the receiver channel;

Calculating the estimated code phase time according to the first transmission time, the code period, and the bit period;

The second transmission time is calculated based on the first transmission time, the actual code phase time, and the estimated code phase time.

In some embodiments, the processor 501 is further configured to: acquire a bit period of the receiver channel when the transmission error is greater than half of the code period;

When the transmission error is less than half of the bit period, it is determined that the transmission error satisfies the second preset condition, and the second preset condition is included in the preset condition.

In some embodiments, the processor 501 is further configured to: when the transmission error meets the second preset condition, acquire the actual code phase time of the navigation message sent from the lost lock satellite, and corresponding to the preset bit inner code period count. Actual code cycle time;

Calculating a sum of the estimated code phase time and the estimated code cycle time according to the first transmission time and the bit period;

The second transmission time is calculated according to the sum of the first transmission time, the actual code period time, the actual code phase time, and the estimated code phase time and the estimated code period time.

In some embodiments, the processor 501 is further configured to acquire current terminal location information of the terminal.

Obtaining satellite position information of the lost lock satellite;

The distance is obtained based on the terminal location information and the satellite location information.

In some embodiments, the processor 501 is further configured to acquire terminal location information by using at least one positioning device, wherein the positioning device comprises at least one of: inertial navigation, a visual sensor, or an ultrasonic wave.

In some embodiments, the processor 501 is further configured to acquire a geometric distance according to the terminal location information and the satellite location information;

The distance is obtained based on geometric distance, satellite error, propagation error, and receiver error.

In some embodiments, the processor 501 is further configured to acquire, at a preset time, a crystal temperature of a receiver preset by the terminal;

Obtaining the crystal frequency offset corresponding to the crystal temperature;

Obtaining the time deviation corresponding to the crystal frequency offset;

Adjust the local time of the receiver according to the time deviation, and set the adjusted local time to the current time.

In some embodiments, the processor 501 is further configured to: acquire a transmission time of the satellite to transmit the satellite signal to the terminal, and acquire an initial transmission time of the satellite signal;

According to the transmission time and the initial transmission time, the local time of the receiver is adjusted, and the adjusted local time is set as the current time.

In some embodiments, the processor 501 is further configured to perform positioning according to at least three pseudoranges.

It should be noted that the steps performed by the processor 501 of the terminal are similar to the steps in the foregoing embodiment shown in FIG. 2 to FIG. 4 , and details are not described herein again.

A portion of the technical solution of the present application that contributes in essence or to the prior art or the technology All or part of the solution may be embodied in the form of a software product stored in a storage medium, including instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the present invention. All or part of the steps of the methods described in the various embodiments are applied. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like. .

The above embodiments are only used to explain the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still The technical solutions described in the embodiments are modified, or the equivalents of the technical features are replaced by the equivalents. The modifications and substitutions of the embodiments do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

A pseudorange calculation method, comprising:

Get the current time of the terminal local;

Obtaining a distance between the terminal and a lost lock satellite, the satellite that provides positioning service for the terminal before the lock is lost;

Calculating, according to the current time and the distance, a first transmission time that the lost-lock satellite transmits a satellite signal to the terminal;

Calculating a second transmission time according to the first transmission time and an actual time calculated from a navigation message transmitted by the lost lock satellite;

Calculating a pseudorange between the terminal and the lost lock satellite according to the current time and the second transmission time.
The method of claim 1 wherein said method further comprises calculating said second transmission time based on said first transmission time and an actual time of solution from said navigational message transmitted by said loss of lock satellite, said method further comprising :

Obtaining a transmission error of the first transmission time;

Determining whether the transmission error satisfies a preset condition;

If so, the step of calculating the second transmission time based on the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite is performed.
The method according to claim 2, wherein the acquiring the transmission error of the first transmission time comprises:

Obtaining a satellite error of the lost lock satellite and a propagation error of the satellite signal;

Obtaining a receiver error of the terminal preset receiver;

The transmission error is obtained based on the satellite error, the propagation error, and the receiver error.
The method according to claim 2, wherein the determining whether the transmission error satisfies a preset condition comprises:

Obtaining a code period of the terminal preset receiver channel;

When the transmission error is less than half of the code period, it is determined that the transmission error satisfies a first preset condition, and the first preset condition is included in the preset condition.
The method according to claim 4, wherein said according to said first transmission time Calculating the second transmission time between the actual time calculated by the navigation message transmitted from the lost lock satellite and the second time includes:

Acquiring the actual code phase time of the navigation message transmitted from the lost lock satellite when the transmission error satisfies the first preset condition;

Obtaining a bit period of the receiver channel;

Calculating an estimated code phase time according to the first transmission time, the code period, and the bit period;

The second transmission time is calculated according to the first transmission time, the actual code phase time, and the estimated code phase time.
The method according to claim 4, wherein after obtaining the code period of the terminal preset receiver channel, the method further comprises:

Obtaining a bit period of the receiver channel when the transmission error is greater than half of the code period;

When the transmission error is less than half of the bit period, it is determined that the transmission error satisfies a second preset condition, and the second preset condition is included in the preset condition.
The method according to claim 6, wherein the calculating the second transmission time according to the first transmission time and the actual time of the navigation message transmitted from the loss-locking satellite comprises:

And acquiring, when the transmission error meets the second preset condition, an actual code phase time calculated by the navigation message transmitted from the lost lock satellite and an actual code cycle time corresponding to the preset bit inner code cycle count;

Calculating a sum of an estimated code phase time and an estimated code cycle time according to the first transmission time and the bit period;

And calculating the second transmission time according to the sum of the first transmission time, the actual code period time, the actual code phase time, and the estimated code phase time and the estimated code period time.
The method of claim 1 wherein said obtaining a distance between said terminal and a lost lock satellite comprises:

Obtaining current terminal location information of the terminal;

Obtaining satellite position information of the lost lock satellite;

And obtaining the distance according to the terminal location information and the satellite location information.
The method according to claim 8, wherein the obtaining the current terminal location information of the terminal comprises:

The terminal location information is obtained by at least one positioning device, wherein the positioning device comprises at least one of: inertial navigation, a visual sensor or an ultrasound.
The method according to claim 8, wherein the obtaining the distance according to the terminal location information and the satellite location information comprises:

Obtaining a geometric distance according to the terminal location information and the satellite location information;

The distance is obtained based on the geometric distance, the satellite error, the propagation error, and the receiver error.
The method according to claim 1, wherein the method further comprises: before acquiring the current time local to the terminal, the method further comprising:

Acquiring the crystal temperature of the receiver preset by the terminal every preset time;

Obtaining a crystal frequency offset corresponding to the crystal temperature;

Obtaining a time deviation corresponding to the crystal frequency offset;

Adjusting the local time of the receiver according to the time offset, and setting the adjusted local time as the current time.
The method according to claim 1, wherein the method further comprises: before acquiring the current time local to the terminal, the method further comprising:

Obtaining a transmission time of the satellite transmitting a satellite signal to the terminal, and acquiring an initial transmission time of the satellite signal;

And adjusting the local time of the receiver according to the transmission time and the initial transmission time, and setting the adjusted local time as the current time.
The method according to any one of claims 1 to 12, wherein after calculating the pseudorange between the terminal and the lost lock satellite according to the current time and the second transmission time, The method further includes:

Positioning is performed according to at least three of the pseudoranges.
A terminal, wherein the terminal includes a processor, and the processor is configured to:

Get the current time of the terminal local;

Obtaining a distance between the terminal and a lost lock satellite, the satellite that provides positioning service for the terminal before the lock is lost;

Calculating, according to the current time and the distance, the lost lock satellite to send a satellite letter to the terminal The first launch time of the number;

Calculating a second transmission time according to the first transmission time and an actual time calculated from a navigation message transmitted by the lost lock satellite;

Calculating a pseudorange between the terminal and the lost lock satellite according to the current time and the second transmission time.
The terminal according to claim 14, wherein the processor is further configured to acquire a transmission error of the first transmission time;

Determining whether the transmission error satisfies a preset condition;

If so, the step of calculating the second transmission time based on the first transmission time and the actual time of the navigation message transmitted from the lost lock satellite is performed.
The terminal according to claim 15, wherein the processor is further configured to acquire a satellite error of the lost-lock satellite and a propagation error of the satellite signal;

Obtaining a receiver error of the terminal preset receiver;

The transmission error is obtained based on the satellite error, the propagation error, and the receiver error.
The terminal according to claim 15, wherein the processor is further configured to acquire a code period of the terminal preset receiver channel;

When the transmission error is less than half of the code period, it is determined that the transmission error satisfies a first preset condition, and the first preset condition is included in the preset condition.
The terminal according to claim 17, wherein the processor is further configured to: when the transmission error satisfies the first preset condition, acquire a navigation message transmitted from the loss-locking satellite Actual code phase time;

Obtaining a bit period of the receiver channel;

Calculating an estimated code phase time according to the first transmission time, the code period, and the bit period;

The second transmission time is calculated according to the first transmission time, the actual code phase time, and the estimated code phase time.
The terminal according to claim 17, wherein the processor is further configured to: acquire a bit period of the receiver channel when the transmission error is greater than half of the code period;

When the transmission error is less than half of the bit period, it is determined that the transmission error satisfies a second preset condition, and the second preset condition is included in the preset condition.
The terminal according to claim 19, wherein the processor is further configured to: when the transmission error meets the second preset condition, acquire a navigation message transmitted from the lost lock satellite The actual code phase time and the actual code cycle time corresponding to the preset bit inner code cycle count;

Calculating a sum of an estimated code phase time and an estimated code cycle time according to the first transmission time and the bit period;

And calculating the second transmission time according to the sum of the first transmission time, the actual code period time, the actual code phase time, and the estimated code phase time and the estimated code period time.
The terminal according to claim 14, wherein the processor is further configured to acquire current terminal location information of the terminal;

Obtaining satellite position information of the lost lock satellite;

And obtaining the distance according to the terminal location information and the satellite location information.
The terminal according to claim 21, wherein the processor is further configured to acquire the terminal location information by using at least one positioning device, wherein the positioning device comprises at least one of: inertial navigation, vision Sensor or ultrasound.
The terminal according to claim 21, wherein the processor is further configured to acquire a geometric distance according to the terminal location information and the satellite location information;

The distance is obtained based on the geometric distance, the satellite error, the propagation error, and the receiver error.
The terminal according to claim 14, wherein the processor is further configured to acquire a crystal temperature of a receiver preset by the terminal every preset time;

Obtaining a crystal frequency offset corresponding to the crystal temperature;

Obtaining a time deviation corresponding to the crystal frequency offset;

Adjusting the local time of the receiver according to the time offset, and setting the adjusted local time as the current time.
The terminal according to claim 14, wherein the processor is further configured to acquire a transmission time of the satellite to transmit a satellite signal to the terminal, and acquire an initial transmission time of the satellite signal;

And adjusting the local time of the receiver according to the transmission time and the initial transmission time, and setting the adjusted local time as the current time.
The terminal according to any one of claims 14 to 25, wherein the processor is further configured to perform positioning according to at least three of the pseudoranges.
A computer program product comprising instructions, wherein the computer program product, when run on a computer, causes the computer to perform the pseudorange calculation method according to any one of claims 1 to 13.
A computer readable storage medium, wherein the computer readable storage medium stores instructions that, when run on a computer, cause the computer to perform the pseudorange calculation of any one of claims 1 to 13 method.