WO2016145947A1 - Navigation satellite signal receiver and cold start method therefor - Google Patents

Abstract

A navigation satellite signal receiver and a cold start method therefor. The method comprises: receiving navigation message data of a plurality of satellites, performing bit synchronisation on the navigation message data, and storing the bit-synchronised navigation message data; performing frame synchronisation on the navigation message data, and after finishing frame synchronisation, acquiring a TOW and sub-frame number of a current sub-frame; determining a sub-frame number of a previous sub-frame according to the current sub-frame number, if the sub-frame number of the previous sub-frame is 1, 2 or 3, reversely searching navigation message data of the previous sub-frame to obtain partial ephemeris data, and storing same into an ephemeris storage area; continuously receiving the navigation message data, storing ephemeris data in the navigation message data into the ephemeris storage area, after obtaining complete ephemeris data of a first sub-frame, a second sub-frame and a third sub-frame, decoding the ephemeris data, and acquiring all ephemeris parameters; and after acquiring ephemeris parameters of a pre-set number of satellites, starting to perform positioning. The method achieves quick cold start of a navigation satellite signal receiver.

Description

 Navigation satellite signal receiver and cold start method thereof

Technical field

The present invention relates to the field of satellite navigation and positioning, and more particularly to a navigation satellite signal receiver and a cold start method thereof.

Background technique

 Global Navigation Satellite System System, GNSS) is a satellite-based radio navigation system. The satellite continuously transmits its ephemeris parameters and time information. After receiving the information, the user calculates the three-dimensional position, three-dimensional direction and motion speed and time information of the receiver through calculation.

Global Positioning System System, GPS) For example, the space part uses 24 satellites with a height of about 20,200 kilometers to form a satellite constellation. 21+3 satellites are near circular orbits with an operating period of approximately 11 hours and 58 minutes. Distributed on six orbital planes (four per orbital surface) with an orbital inclination of 55 degrees. The distribution of satellites allows for the observation of more than four satellites at any time anywhere in the world, and maintains a good positioning resolution geometry (DOP).

Global Positioning System or Beidou Satellite Navigation System (BeiDou Navigation Satellite) System, BDS), usually updated every 2 hours. On the other hand, existing satellite signal receivers such as GPS receivers or BD receivers only download satellite data when in operation, and update the ephemeris in the satellite signal receiver based on the downloaded satellite data. If the receiver is to restart after a long period of inactivity (eg, sleep for more than 24 hours), since the ephemeris/almanac in the receiver is no longer valid, the receiver can only be started in cold or warm start mode. . Cold start requires re-capture, tracking, and demodulation of the satellite, and collects the complete ephemeris, which takes longer to locate, even for 30 to 80 seconds, and consumes more power.

Taking GPS navigation satellites as an example, the navigation message sent by each navigation satellite is composed of different frames, and in each frame of the transmitted message, it is composed of several subframes. The navigation message of each frame is 1500 bits long and is divided into 5 subframes, each subframe is 300 bits long, and each bit is 20 ms long. Each subframe consists of 10 words, each word is 30 bits long, and the last 6 bits of each word are parity codes.

The starting mode of the navigation satellite signal receiver is generally divided into three types: cold start, warm start and hot start. Cold start refers to the startup of the receiver without storing the clock information, satellite ephemeris, almanac, and historical receiver position. It usually takes about 40s from the start to the first position. The warm start and the hot start are utilized respectively. The effective almanac and ephemeris stored inside the receiver can shorten the time from booting to the first positioning to about 30 seconds and about 2 seconds.

At present, in the cold start mode of the receiver, the receiving channel starts collecting ephemeris subframe data after the frame synchronization is completed, and after collecting the data of one subframe (300 bits), storing the entire subframe to the ephemeris storage area. And then continue to wait to collect the complete next subframe. Since each time the data stored in the ephemeris storage area is in units of sub-frames, the incomplete ephemeris data before the successful frame synchronization is wasted, which takes more time.

Summary of the invention

The present invention aims to solve the above technical problems at least to some extent.

The primary object of the present invention is to overcome the shortcomings of the long navigation time of the existing navigation satellite signal receiver, and to provide a fast cold start method for the navigation satellite signal receiver.

It is a further object of the present invention to provide a navigation satellite signal receiver capable of rapid cold start.

In order to solve the above technical problem, the technical solution of the present invention is as follows:

A cold start method for a navigation satellite signal receiver, the method comprising the steps of:

S1: receiving navigation data of a plurality of satellites and performing bit synchronization on the satellites, and storing the navigation message data after the bit synchronization;

S2: performing frame synchronization on the navigation message data, and after completing the frame synchronization, acquiring the TOW and the subframe number of the current subframe;

S3: determining a subframe number of the previous subframe according to the current subframe number. If the subframe number of the previous subframe is 1, 2, or 3, performing reverse search on the navigation message data of the previous subframe to obtain a partial star. Calendar data, and stored in the ephemeris storage area;

S4: Continue to receive the navigation message data, and store the ephemeris data in the navigation message data into the ephemeris storage area, and after obtaining the complete ephemeris data of the first, second, and third sub-frames, perform the ephemeris data. Decode and obtain all ephemeris parameters;

S5: After acquiring the ephemeris parameters of the preset number of satellites, the positioning is started.

In a preferred solution, the ephemeris storage area includes a TOW storage area, a subframe data area, and a subframe marking area;

The TOW storage area stores a TOW;

The subframe data area stores ephemeris data of the first, second, and third subframes, respectively;

The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe.

In a preferred solution, the method further includes: in step S4, obtaining the complete ephemeris data of the first, second, and third subframes according to the ephemeris already stored in the ephemeris storage area. The data is calibrated to the missing bit number, and the navigation message data is continuously received. If the ephemeris data in the navigation message data is not the ephemeris data of the stored incomplete subframe, the complete ephemeris data of the subframe is stored to the ephemeris. If the ephemeris data in the navigation message data is the ephemeris data of the incomplete sub-frame that has been stored, the complete sub-frame is synthesized by combining the stored ephemeris data, thereby obtaining the complete first , ephemeris data for the 2nd and 3rd subframes.

In a preferred solution, the method further includes: after acquiring the ephemeris parameters of the three or four satellites in step S5, calculating the satellite position and velocity, and combining the time and information of the pseudorange, Doppler measurement. The receiver position information is solved to complete the cold start of the navigation satellite signal receiver to the first positioning process.

In a preferred solution, the method further includes: checking the validity of the local clock of the receiver before receiving the navigation message data, and if the local clock is valid, reading the effective time limit of the ephemeris stored in the receiver and The local clock is compared. If the ephemeris stored in the receiver is within the valid time limit, the hot start mode is entered; if the ephemeris stored in the receiver exceeds the valid time limit, the valid time limit of the almanac stored in the receiver is read and the local clock is read. For comparison, if the local almanac is within the valid time limit, enter the warm start mode; if the receiver local clock time is invalid, or the ephemeris and almanac stored in the receiver exceed their respective valid time limits, the receiver enters the cold start mode. .

In a preferred solution, the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite signal receiver.

A navigation satellite signal receiver, the navigation satellite signal receiver comprising:

Receiving channel: The number of receiving channels is multiple. Each receiving channel is used to receive navigation message data of different navigation satellites, and perform bit synchronization and frame synchronization on the navigation message data. After completing frame synchronization, obtain the TOW of the current subframe. And the subframe number;

a data processing unit: configured to determine a subframe number of the previous subframe according to the current subframe number, and if the subframe number of the previous subframe is 1, 2, or 3, perform reverse search on the data of the previous subframe. Part of the ephemeris data is stored in the ephemeris storage area, and the ephemeris data in the subsequently received navigation message data is stored in the ephemeris storage area until the complete first, second and third sub-frame stars are obtained Calendar data

The solving unit is configured to decode the ephemeris data according to the obtained ephemeris data of the complete first, second and third sub-frames, and obtain all ephemeris parameters, And according to the ephemeris parameters to calculate the satellite position and speed, combined with the pseudorange, Doppler measurement time and information, solve the position information of the navigation satellite signal receiver.

In a preferred solution, the number of the ephemeris storage areas is multiple, and is correspondingly disposed in each receiving channel.

In a preferred solution, the ephemeris storage area includes a TOW storage area, a subframe data area, and a subframe marking area;

The TOW storage area stores a TOW;

The subframe data area stores ephemeris data of the first, second, and third subframes, respectively;

The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe.

In a preferred solution, the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite signal receiver.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

In the general cold start mode, after the frame synchronization is completed, the navigation satellite signal receiver starts to collect the navigation message data, and then stores it in units of sub-frames. In the process of collecting the navigation message data, the navigation message before the frame synchronization succeeds. The data is discarded, which wastes a certain amount of time. The cold start method of the navigation satellite signal receiver of the invention preserves all the collected navigation message data bits before the frame synchronization is completed after the frame synchronization is successful, and effectively utilizes the time, thereby saving time and improving the cold start of the receiver. speed. The navigation satellite signal receiver of the present invention is the basis for the implementation of the cold start method described above, and the navigation satellite signal receiver and the cold start method of the present invention combine to realize rapid cold start of the navigation satellite signal receiver.

DRAWINGS

1 is a structural diagram of a navigation satellite signal receiver of the present invention.

Figure 2 is a flow diagram of a typical navigation satellite signal receiver from start to first location.

3 is a flow chart of a method for cold start of a navigation satellite signal receiver according to the present invention.

4 is a flow chart of a method for collecting missing data bits in a ephemeris storage area according to the present invention.

Fig. 5 is a view showing the storage structure of the ephemeris storage area of the present invention.

detailed description

The drawings are for illustrative purposes only and are not to be construed as limiting the scope of the invention;

The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

A cold start method for a navigation satellite signal receiver, the method comprising the steps of:

S1: receiving navigation data of a plurality of satellites and performing bit synchronization on the satellites, and storing the navigation message data after the bit synchronization;

S2: performing frame synchronization on the navigation message data, and after completing the frame synchronization, acquiring the TOW and the subframe number of the current subframe;

S3: determining a subframe number of the previous subframe according to the current subframe number. If the subframe number of the previous subframe is 1, 2, or 3, performing reverse search on the navigation message data of the previous subframe to obtain a partial star. Calendar data, and stored in the ephemeris storage area;

S4: Continue to receive the navigation message data, and store the ephemeris data in the navigation message data into the ephemeris storage area, and after obtaining the complete ephemeris data of the first, second, and third sub-frames, perform the ephemeris data. Decode and obtain all ephemeris parameters;

S5: After acquiring the ephemeris parameters of the preset number of satellites, the positioning is started.

In a specific implementation process, the ephemeris storage area includes a TOW storage area, a subframe data area, and a subframe marking area;

The TOW storage area stores a TOW;

The subframe data area stores ephemeris data of the first, second, and third subframes, respectively;

The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe.

In a specific implementation process, the method further includes: in step S4, obtaining the complete ephemeris data of the first, second, and third subframes by: calibrating according to ephemeris data already stored in the ephemeris storage area The missing bit number continues to receive the navigation message data. If the ephemeris data in the navigation message data is not the ephemeris data of the stored incomplete subframe, the complete ephemeris data of the subframe is stored into the ephemeris storage area. In the corresponding subframe; if the ephemeris data in the navigation message data is the ephemeris data of the incomplete subframe that has been stored, the complete subframe is synthesized by combining the stored ephemeris data, thereby obtaining the complete first and the first Ephemeris data for 2 and 3rd subframes.

In a specific implementation process, the method further includes: after acquiring the ephemeris parameters of the three or four satellites in step S5, calculating the satellite position and velocity, and combining the time and information of the pseudorange and Doppler measurement, The receiver position information is calculated, and the cold start of the navigation satellite signal receiver is completed to the first positioning process.

In a specific implementation process, the method further includes: checking the validity of the local clock of the receiver before receiving the navigation message data, and reading the valid time limit of the ephemeris stored in the receiver and the local clock if the local clock is valid. For comparison, if the ephemeris stored in the receiver is within the valid time limit, the hot start mode is entered; if the ephemeris stored in the receiver exceeds the valid time limit, the valid time limit of reading the almanac stored in the receiver is compared with the local clock. If the local almanac is within the valid time limit, enter the warm start mode; if the receiver local clock time is invalid, or the ephemeris and almanac stored in the receiver exceed their respective valid time limits, the receiver enters the cold start mode.

In a specific implementation process, the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite signal receiver.

In the cold start method of the navigation satellite signal receiver in this embodiment, after the frame synchronization is successful, all the collected navigation message data bits before the completion of the frame synchronization are reserved, and the data is effectively utilized, which saves time and improves the cold start of the receiver. speed.

Example 2

As shown in FIG. 1, a navigation satellite signal receiver includes:

Receiving channel: The number of receiving channels is multiple. Each receiving channel is used to receive navigation message data of different navigation satellites, and perform bit synchronization and frame synchronization on the navigation message data. After completing frame synchronization, obtain the TOW of the current subframe. And the subframe number;

a data processing unit: configured to determine a subframe number of the previous subframe according to the current subframe number, and if the subframe number of the previous subframe is 1, 2, or 3, perform reverse search on the data of the previous subframe. Part of the ephemeris data is stored in the ephemeris storage area, and the ephemeris data in the subsequently received navigation message data is stored in the ephemeris storage area until the complete first, second and third sub-frame stars are obtained Calendar data

The solving unit is configured to decode the ephemeris data according to the obtained ephemeris data of the complete first, second and third sub-frames, and obtain all ephemeris parameters, And according to the ephemeris parameters to calculate the satellite position and speed, combined with the pseudorange, Doppler measurement time and information, solve the position information of the navigation satellite signal receiver.

In a specific implementation process, the method further includes: after acquiring the ephemeris parameters of the three or four satellites in step S5, calculating the satellite position and velocity, and combining the time and information of the pseudorange and Doppler measurement, The receiver position information is calculated, and the cold start of the navigation satellite signal receiver is completed to the first positioning process.

In a specific implementation process, the number of the ephemeris storage areas is multiple, and is correspondingly disposed in each receiving channel.

In a specific implementation process, the ephemeris storage area includes a TOW storage area, a subframe data area, and a subframe marking area;

The TOW storage area stores a TOW;

The subframe data area stores ephemeris data of the first, second, and third subframes, respectively;

The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe.

In a specific implementation process, the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite signal receiver.

In a specific implementation process, the navigation satellite signal receiver further includes an output unit, and the output unit is configured to output the decoded navigation satellite signal receiver positioning result and related information.

The navigation satellite signal receiver of this embodiment is the basis for implementing the cold start method of Embodiment 1. The navigation satellite signal receiver and the cold start method of the present invention combine to realize rapid cold start of the navigation satellite signal receiver.

Example 3

This embodiment combines the cold start method of Embodiment 1 and the navigation satellite signal receiver of Embodiment 2 to provide an embodiment of a rapid cold start of a navigation satellite signal receiver.

In the specific implementation process, as shown in FIG. 2, after the receiver is powered on, the validity of the internal local clock is checked first. If the local clock is valid, the effective time limit of reading the ephemeris stored in the receiver is compared with the local clock. If the ephemeris stored in the receiver is within the valid time limit, enter the hot start mode; if the ephemeris stored in the receiver exceeds the valid time limit, the valid time limit of reading the almanac stored in the receiver is compared with the local clock, if local The almanac enters the warm start mode within the valid time limit; if the receiver local clock time is invalid, or the ephemeris and almanac stored in the receiver exceed their respective valid time limits, the receiver enters the cold start mode.

If the cold start mode is entered, the receiving channel starts the bit synchronization operation of the satellite navigation message data from the signal acquisition into the signal tracking phase, that is, the data bit edge of the satellite navigation message is found from the satellite signal, and then the data bit is continuously collected to find the location. The fixed sync code of the header of the sub-frame determines the edge of the sub-frame to complete the frame synchronization. The purpose of collecting the satellite navigation message is to obtain ephemeris message data from it to predict the orbit, position and other parameters of the satellite. The subframe synchronization code of GPS is 10001011, and the subframe synchronization code of Beidou is 11100010010. After the frame synchronization is completed, the subframe edge of the navigation message can be determined. Further, the data bits received next are divided into words of every 30 groups.

As shown in FIG. 3, after the navigation satellite signal receiver enters the cold start mode, taking one of the receiver receiving channels as an example, after the receiver channel bit synchronization is successful, the navigation message data before the frame synchronization is completed is stored. Go to the message temporary storage area. The receiving channel needs to continue to accept the navigation message data to the message temporary storage area until the TOW and the subframe number in the week of the subframe are obtained. Taking GPS as an example, before the frame synchronization is completed, the receiving channel has received the current subframe. With an 8-bit subframe sync code, the receive channel continues to receive 44 data bits. The 31st to 47th data bits of the sub-frame are read from the message temporary storage area, 31 bits are the highest bit of the TOW in the truncated week, and 47 bits are the lowest bit of the TOW in the truncated week, and will be read. The obtained TOW is stored in the TOW area of the ephemeris storage area during the week. The 50th to 52th data bits of the subframe are read from the message temporary storage area, 50 bits are the highest bit of the subframe number, and 52 bits are the lowest bits of the subframe number.

After the sub-frame number of the current sub-frame is read from the temporary message storage area, the corresponding position of all data in the e-mail temporary storage area in the ephemeris storage area can be determined. Specifically, the message data of the message temporary storage area is reversely searched according to the current subframe number, and the subframe number and the position of the subframe corresponding to the navigation message data saved before the frame synchronization is completed are determined. Taking GPS as an example, if the current subframe number is 2, that is, the current subframe is the second subframe, the message data collected before the frame synchronization is completed belongs to the first subframe, and the message data bit of the second subframe is The subframe end of the first subframe, that is, the 300th data bit of the subframe 1, and so on, can determine the subframe number to which all the data bits received before the frame synchronization is completed and the position within the subframe.

Continue to read the navigation message data. If the current subframe is the 2nd, 3rd, and 4th subframes, perform a reverse search on the message temporary storage area, and store the navigation message data saved before the frame synchronization is completed into the corresponding child of the ephemeris storage area. Within the frame, the sub-frame number of the part of the data is marked as M, and the part of the data in the temporary storage area is cleared; if not, the data of all non-current sub-frames in the data temporary storage area is directly cleared.

If the current subframe is an M subframe, according to the stored data of the ephemeris storage area, the data bits missing in the current subframe are collected, and the complete 1, 2, and 3 subframes can be obtained, and the ephemeris subframe decoding can be performed; If the current subframe is not an M subframe, continue to collect the complete current subframe, and then determine whether the complete 1, 2, and 3 subframes have been collected. If the collection is complete, the ephemeris subframe decoding can be performed. If the collection is not complete, it needs to continue. The message data is collected until a new subframe number is obtained, and it is further determined whether the current subframe is an M subframe.

In this embodiment, if the receiver acquires more than three sets of satellite signals and the complete ephemeris parameters of the corresponding satellite through the receiving channel, the receiver can be positioned and solved to obtain the position and navigation information of the receiver, thereby completing the cold start. .

In the specific implementation process, the specific process of collecting the missing data bits of the ephemeris storage area by any one of the receiving channels is as shown in FIG. 4, and the receiving channel first detects whether the current subframe carries the ephemeris parameters.

If the current subframe does not carry the ephemeris parameter, the telegraphic temporary storage area is cleared, and the sub-frame bit counter counts the received new data bits, but does not store to the teletext temporary storage area. When the subframe bit counter reaches the maximum value, for example, the maximum number of bits of the subframe of the GPS is 300, indicating that the current subframe has been broadcasted, and the next data bit is the start bit of the new subframe, and the subframe is at this time. The counter is cleared. When a new data bit is received, it is stored in the teletext buffer, the sub-frame counter, and the current sub-frame number is updated.

If the current subframe carries the ephemeris parameter, first detect whether the ephemeris storage area has a portion of the current subframe, and if so, continue to receive the missing teletext data bits of the current subframe in the ephemeris storage area, and after receiving the complete, The data in the teletext temporary storage area and the ephemeris storage area are jointly combined for parity check; if the ephemeris storage area does not store part of the current sub-frame, the telegram data bit continues to be received and counted by the sub-frame bit counter until the current sub- The frame is received completely, and then the words in the message temporary storage area are parity checked.

After the parity is completed, the words that pass the parity are stored in the ephemeris storage area, and the stored data bits are marked. Then, the ephemeris parameter included in the current subframe is decoded from the ephemeris storage area, and it is checked whether the required ephemeris parameter is complete. If the ephemeris parameter is complete, the orbit of the satellite tracked by the current receiving channel can be solved and predicted. And position; if the ephemeris parameter is not complete, the sub-frame bit counter is cleared, the current sub-frame number is updated, the new data bit is continuously stored to the telegraphic temporary storage area and counted, and the next sub-frame data collection cycle is entered.

The ephemeris storage area in this embodiment is composed of a TOW, a sub-frame data area, and a sub-frame mark area. As shown in FIG. 5, the sub-frame data area is divided into a plurality of peer-to-peer blocks for storing ephemeris data of the first sub-frame, the second sub-frame, and the third sub-frame, respectively; the sub-frame mark area and the sub-frame data. The corresponding area is also divided into equal number of peer blocks to mark the valid data bits and subframe integrity in the corresponding subframe. The sub-frame data block only stores 61~300 bits of data of the complete sub-frame, and the corresponding sub-frame mark block stores 240-bit data, which is used to indicate whether each bit in the sub-frame data area has data. . The TOW of the ephemeris storage area is used to store the TOW extracted from the sub-frame, and only the TOW of the latest sub-frame is stored.

In this embodiment, the telegram data is quantitatively analyzed. Taking GPS as an example, when the ephemeris data is located in 1, 2, and 3 subframes, according to the traditional cold start ephemeris collection strategy, the average ephemeris parameter collection time is 29.402s. According to the method of the present embodiment, the average collection time of the ephemeris parameters is 27.596 s, which is an improvement of about 2 s.

It is apparent that the above-described embodiments of the present invention are merely illustrative of the present invention and are not intended to limit the embodiments of the present invention. Other different forms of changes may also be made based on the above description for those of ordinary skill in the art. Or change. There is no need and no way to exhaust all of the implementations. Any modifications, equivalent substitutions and improvements made within the spirit and scope of the invention are intended to be included within the scope of the appended claims.

Claims (10)

A cold start method for a navigation satellite signal receiver, characterized in that the method comprises the following steps: S1: receiving navigation data of a plurality of satellites and performing bit synchronization on the satellites, and storing the navigation message data after the bit synchronization; S2: performing frame synchronization on the navigation message data, and after completing the frame synchronization, acquiring the TOW and the subframe number of the current subframe; S3: determining a subframe number of the previous subframe according to the current subframe number. If the subframe number of the previous subframe is 1, 2, or 3, performing reverse search on the navigation message data of the previous subframe to obtain a partial star. Calendar data, and stored in the ephemeris storage area; S4: Continue to receive the navigation message data, and store the ephemeris data in the navigation message data into the ephemeris storage area, and after obtaining the complete ephemeris data of the first, second, and third sub-frames, perform the ephemeris data. Decode and obtain all ephemeris parameters; S5: After acquiring the ephemeris parameters of the preset number of satellites, the positioning is started. The cold start method of a navigation satellite signal receiver according to claim 1, wherein the ephemeris storage area comprises a TOW storage area, a subframe data area, and a subframe marking area; The TOW storage area stores a TOW; The subframe data area stores ephemeris data of the first, second, and third subframes, respectively; The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe. A cold start method for a navigation satellite signal receiver according to claim 1, wherein said method further comprises: in step S4, obtaining a complete ephemeris data of said first, second and third sub-frames For example, according to the ephemeris data already stored in the ephemeris storage area, the number of missing bits is calibrated, and the navigation message data is continuously received. If the ephemeris data in the navigation message data is not the ephemeris data of the incomplete sub-frame that has been stored, And storing the complete ephemeris data of the subframe into the subframe corresponding to the ephemeris storage area; if the ephemeris data in the navigation message data is the ephemeris data of the stored incomplete subframe, combining the stored ephemeris Data, synthesizing a complete sub-frame, resulting in complete ephemeris data for the first, second, and third sub-frames. The cold start method of the navigation satellite signal receiver according to claim 1, wherein the method further comprises: after acquiring the ephemeris parameters of the three or four satellites in step S5, calculating the satellite position and speed, Combined with the pseudorange, Doppler measurement time and information solution, the receiver position information is obtained, and the cold start of the navigation satellite signal receiver is completed to the first positioning process. A cold start method for a navigation satellite signal receiver according to claim 1, wherein The method further includes: checking the validity of the local clock of the receiver before receiving the navigation message data, and if the local clock is valid, reading the valid time limit of the ephemeris stored in the receiver is compared with the local clock, if the receiver The internally stored ephemeris enters the hot start mode within the valid time limit; if the ephemeris stored in the receiver exceeds the valid time limit, the effective time limit of reading the almanac stored in the receiver is compared with the local clock, if the local almanac is valid Within the time limit, enter the warm start mode; if the receiver local clock time is invalid, or the ephemeris and almanac stored in the receiver exceed their respective valid time limits, the receiver enters the cold start mode. The cold start method of a navigation satellite signal receiver according to claim 1, wherein the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite. Signal receiver. A navigation satellite signal receiver, characterized in that the navigation satellite signal receiver comprises: Receiving channel: The number of receiving channels is multiple. Each receiving channel is used to receive navigation message data of different navigation satellites, and perform bit synchronization and frame synchronization on the navigation message data. After completing frame synchronization, obtain the TOW of the current subframe. And the subframe number; a data processing unit: configured to determine a subframe number of the previous subframe according to the current subframe number, and if the subframe number of the previous subframe is 1, 2, or 3, perform reverse search on the data of the previous subframe. Part of the ephemeris data is stored in the ephemeris storage area, and the ephemeris data in the subsequently received navigation message data is stored in the ephemeris storage area until the complete first, second and third sub-frame stars are obtained Calendar data The solving unit is configured to decode the ephemeris data according to the obtained ephemeris data of the complete first, second and third sub-frames, and obtain all ephemeris parameters, And according to the ephemeris parameters to calculate the satellite position and speed, combined with the pseudorange, Doppler measurement time and information, solve the position information of the navigation satellite signal receiver. The navigation satellite signal receiver according to claim 7, wherein the number of the ephemeris storage areas is plural, and is correspondingly disposed in each receiving channel. The navigation satellite signal receiver according to claim 8, wherein the ephemeris storage area comprises a TOW storage area, a subframe data area, and a subframe marking area; The TOW storage area stores a TOW; The subframe data area stores ephemeris data of the first, second, and third subframes, respectively; The subframe marking area corresponds to the subframe data area, and marks valid data bits and subframe integrity in the corresponding subframe. The navigation satellite signal receiver according to claim 7, wherein the navigation satellite signal receiver is a GPS navigation satellite signal receiver, a Beidou navigation satellite signal receiver or a GPS-Beidou dual-mode navigation satellite signal receiver.