Data flow control method for navigation differential data and GNSS receiver

Abstract

The present invention discloses a data stream control method for navigation differential data and a GNSS receiver. The data stream control method includes: the GNSS receiver acquires navigation differential data; determines whether the amount of navigation differential data is greater than a congestion threshold, and if so, acquires the observation data in the navigation differential data, where the congestion threshold is obtained according to the theoretical transmission amount within each differential data update interval; deletes at least one satellite system observation data in the observation data in a preset order; and transmits the navigation differential data after deleting the satellite system observation data to a data transmission radio station. The present invention can ensure the stability of the receiver when broadcasting data in a specific differential data format by radio, and provides an active data stream control scheme for navigation differential data in view of the hardware limitations of the radio station, enabling users to stably and efficiently receive differential data for high-precision positioning when using it.

Description

Technical Field

[0001] The present invention relates to a GNSS receiver, and particularly to a data flow control method for navigation differential data and a GNSS receiver. Background Art

[0002] Based on decades of development of GNSS-based engineering surveying technology, it has evolved from centering measurement to the widely used tilt measurement today. In recent years, the release of GNSS integrated navigation systems has provided a new vane for engineering surveying technology.

[0003] In an embedded system development environment, for data transmitted to a peripheral device, its data timeliness and robustness are always restricted by the performance of the peripheral device itself. In many cases, data transmission is subject to high latency or large deviation due to the performance of the peripheral device. For example, during RTK (Real-Time Kinematic) in the surveying and mapping industry, if differential data broadcast via a radio is delayed or packet lost due to predicted bandwidth issues, unacceptable deviation will occur in measurement accuracy.

[0004] Due to the differences in radio air baud rate and transmission protocols, the amount of data that can be serially transmitted in real time by a radio varies. If a large amount of data is sent to the radio in a brute-force manner, data loss will occur, affecting real-time positioning accuracy. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defect that data loss occurs in the communication between a GNSS receiver and a radio in the prior art, resulting in reduced positioning accuracy, and to provide a data flow control method for navigation differential data and a GNSS receiver that can ensure the stability of the receiver when broadcasting data in a specific differential data format via the radio, enabling users to stably and efficiently receive differential data for high-precision positioning during use.

[0006] The present invention solves the above technical problem by the following technical solutions:

[0007] A data flow control method for navigation differential data, characterized in that the data flow control method includes:

[0008] The GNSS receiver acquires navigation differential data;

[0009] Determine whether the amount of navigation differential data is greater than the congestion threshold. If so, acquire the observation data in the navigation differential data, where the congestion threshold is obtained based on the theoretical transmission amount within each differential data update interval;

[0010] Delete at least one satellite system observation data in the observation data in a preset order;

[0011] Transmit the navigation differential data after deleting the satellite system observation data to the data transmission radio station.

[0012] Preferably, the GNSS receiver is provided with at least two congestion thresholds, and the data flow control method includes:

[0013] Judge whether the amount of navigation differential data is greater than any congestion threshold. If so, obtain the closest target congestion threshold that the amount of navigation differential data is greater than.

[0014] Delete the satellite system observation data of the target number in the observation data in a preset order. The target number is obtained according to the target congestion threshold. The larger the target congestion threshold, the more the target number.

[0015] Preferably, the congestion thresholds include a first congestion threshold aM, a second congestion threshold bM, and a third congestion threshold cM. The value range of a is (0.9, 1), the value range of b is 1.2, and the value range of c is (1.9, 2). M is the theoretical transmission amount within each differential data update interval.

[0016] Preferably, the step of deleting the satellite system observation data of the target number in the observation data in a preset order includes:

[0017] Obtain the RTCM3.X format data in the observation data;

[0018] Sort the RTCM3.X format data according to the satellite system, and the satellite system sorting is arranged in a circular permutation;

[0019] For the navigation differential data of a target epoch, judge whether the amount of navigation differential data is greater than the congestion threshold. If so, obtain the satellite system observation data deleted by the adjacent navigation differential data of the target epoch, where the adjacent navigation differential data is the previous navigation differential data greater than the congestion threshold of the target epoch;

[0020] Obtain the next satellite system of the satellite system observation data deleted by the adjacent navigation differential data in the satellite system sorting;

[0021] For the navigation differential data of the target epoch, delete the satellite system observation data of the next satellite system.

[0022] Preferably, the types of satellite system sorting include one or more of single-system sorting, dual-system sorting, and triple-system sorting. The data flow control method includes:

[0023] Select the type of satellite system sorting according to the target number;

[0024] Delete the satellite system observation data of the target number in the observation data in the order of the selected satellite system sorting.

[0025] Preferably, the dual-system sorting and the triple-system sorting correspond one-to-one with each item of the single-system sorting. One item in the dual-system sorting is the corresponding item of the single-system sorting and the next item of the corresponding single-system sorting. One item in the triple-system sorting is the corresponding item of the single-system sorting and the next two items of the corresponding single-system sorting.

[0026] Preferably, the single-system sorting is a fixed sorting, and the dual-system sorting and the triple-system sorting are dynamically generated according to the observation data of the last deleted satellite system and the fixed sorting. The sorted items generated dynamically are generated using the observation data of satellite systems other than the observation data of the last deleted satellite system.

[0027] Preferably, the step of transmitting the navigation differential data after deleting the satellite system observation data to the data transmission radio station includes:

[0028] Obtain the congestion threshold of the navigation differential data for the next epoch according to the actual data volume and the theoretical transmission volume transmitted to the data transmission radio station. The larger the value of the theoretical transmission volume minus the actual data volume, the higher the congestion threshold value;

[0029] Execute the step of obtaining the navigation differential data of the GNSS receiver for the next epoch using the latest congestion threshold.

[0030] Preferably, the step of transmitting the navigation differential data of the deleted satellite system observation data to the data transmission radio station includes:

[0031] According to the data broadcast by the data transmission radio station

[0032] Divide the navigation differential data of one epoch into several parts according to the frequency and send the divided navigation differential data to the data transmission radio station according to the frequency.

[0033] The present invention also provides a GNSS receiver, characterized in that the GNSS receiver is used to implement the data flow control method for navigation differential data as described above.

[0034] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0035] The positive and progressive effects of the present invention are as follows:

[0036] The present invention can ensure the stability of the receiver when broadcasting data in a specific differential data format by the radio station, and provides an active data flow control scheme for navigation differential data in view of the hardware limitations of the radio station, enabling users to receive differential data stably and efficiently for high-precision positioning when using.

[0037] Through testing, it can be known that when the radio data stream is stable, the air delay from the radio sending a packet of data to the other end receiving is about 0.3 s. After adding the flow control method of this application to the system software, it can ensure that the data is transmitted continuously and stably, and there will no longer be packet loss and the air delay exceeding 2 s. Description of the Drawings

[0038] Figure 1 It is a flowchart of the data stream control method according to Embodiment 1 of the present invention. Detailed Embodiment

[0039] The present invention will be further described below by way of embodiments, but the present invention is not limited to the scope of the described embodiments. Embodiment

[0040] This embodiment provides a GNSS receiver system. The GNSS receiver system includes a GNSS receiver and a radio. The GNSS receiver is a reference station and transmits observation data to a rover in real time through a radio.

[0041] The GNSS receiver is used for:

[0042] Obtain navigation differential data;

[0043] Judge whether the amount of navigation differential data is greater than the congestion threshold. If so, obtain the observation data in the navigation differential data, where the congestion threshold is obtained according to the theoretical transmission amount within each differential data update interval;

[0044] Delete at least one satellite system observation data in the observation data in a preset order;

[0045] Transmit the navigation differential data with the satellite system observation data deleted to the data radio.

[0046] In this embodiment, deleting at least one satellite system observation data in the observation data means deleting at least one satellite system observation data in the observation data.

[0047] The GNSS receiver is provided with at least two congestion thresholds. The GNSS receiver is used for:

[0048] Judge whether the amount of navigation differential data is greater than any congestion threshold. If so, obtain the closest target congestion threshold greater than which the amount of navigation differential data is;

[0049] Delete the satellite system observation data of the target number in the observation data in a preset order. The target number is obtained according to the target congestion threshold, and the larger the target congestion threshold, the more the target number.

[0050] Among them, the congestion thresholds include a first congestion threshold aM, a second congestion threshold bM, and a third congestion threshold cM. The value range of a is (0.9, 1), the value range of b is 1.2, and the value range of c is (1.9, 2). M is the theoretical transmission volume within each differential data update interval.

[0051] The GNSS receiver is used for:

[0052] Obtain RTCM3.X format data in the observation data;

[0053] Sort the RTCM3.X format data according to the satellite system, and the satellite system sorting is arranged in a circular permutation;

[0054] For the navigation differential data of a target epoch, determine whether the amount of navigation differential data is greater than the congestion threshold. If so, obtain the satellite system observation data deleted by the adjacent navigation differential data of the target epoch, and obtain the next satellite system of the satellite system observation data deleted by the adjacent navigation differential data in the satellite system sorting, where the adjacent navigation differential data is the previous navigation differential data greater than the congestion threshold of the target epoch;

[0055] For the navigation differential data of the target epoch, delete the satellite system observation data of the next satellite system.

[0056] In the configuration radio transmission stage, according to the air baud rate and transmission protocol, first set the default generation interval of the differential data (the differential data includes the coordinates and antenna information of a fixed frequency + the observation data information of an adjustable frequency).

[0057] The program sets the internal buffer size, sets the first congestion threshold and the second congestion threshold, and sets the first release threshold and the second release threshold. The buffer size is twice the theoretical transmission volume (M) within each differential data update interval. The first congestion threshold is 0.95*M, the second congestion threshold is 1.2*M, the third congestion threshold is 1.99*M, the first release threshold is 0.8*M, and the second release threshold is 0.2*M.

[0058] Dynamically obtain the total system bandwidth; determine the flow control rate according to the relationship between the total system bandwidth and the first congestion threshold and the second congestion threshold.

[0059] It is known that the RTCM3.X format data contains satellite system observation data such as GPS / GLONASS / GALILEO / BEIDOU / QZSS, etc. First, sort all satellite systems, and limit the amount of data written to the buffer in the next epoch based on the theoretical amount (M) of the differential data written in this epoch and the remaining data amount (S) in the buffer.

[0060] To ensure data availability, data deletion is performed on a satellite system basis. The first threshold deletes one system, and the second threshold deletes two systems. That is, if M+S triggers the first threshold, the data for the next epoch will be restricted to removing / restoring the observation data of one system, and this can be repeated at most twice. If the second threshold is triggered, the data for the next epoch will be restricted to removing / restoring the data of two systems. If the third threshold is triggered, the output of the differential data (observation value part) for this epoch will be stopped. The system restrictions for each epoch are polled according to the satellite system sorting, that is

[0061] When only one satellite system is deleted: The deletion order is gps+qzss => glonass => galileo => beidou

[0062] When two satellite systems are deleted: The deletion order is gps+qzss+glonass => glonass+galileo => galileo+beidou => beidou+gps+qzss

[0063] Since the qzss observation values are dependent on gps, these two systems are treated as one system for processing.

[0064] Control the sending of user data according to the described flow control rate.

[0065] Based on the data broadcast frequency of the radio itself, the data in the buffer is sent to the radio at intervals of 0.5 seconds, with the flow rate being half of the actual data transmission amount per second.

[0066] For example, if the theoretical transmission amount is 1000 and the navigation differential data amount for one epoch is 1100, exceeding the first congestion threshold, then the data of one satellite system is deleted. That is, the data originally sent from the GPS / GLONASS / GALILEO / BEIDOU / QZSS systems becomes the data sent from the GLONASS / GALILEO / BEIDOU systems. If the navigation differential data amount for the next epoch exceeds the first congestion threshold again, then the data of the glonass satellite system is deleted according to the preset order (gps+qzss => glonass => galileo => beidou), and so on.

[0067] Furthermore, the types of satellite system sorting include one or more of single-system sorting, double-system sorting, and triple-system sorting. The GNSS receiver is used to:

[0068] Select the type of satellite system sorting according to the target number;

[0069] Delete the satellite system observation data of the target number in the observation data according to the selected satellite system sorting order.

[0070] The dual-system sorting and triple-system sorting correspond one by one to each item in the single-system sorting. One item in the dual-system sorting is one item in the corresponding single-system sorting and the next item in the corresponding single-system sorting. One item in the triple-system sorting is one item in the corresponding single-system sorting and the next two items in the corresponding single-system sorting.

[0071] For example, if the amount of navigation differential data in an epoch is 1100, exceeding the first congestion threshold, the data of one satellite system is deleted. That is, the data originally sent by the GPS / GLONASS / GALILEO / BEIDOU / QZSS systems becomes the data sent by the GLONASS / GALILEO / BEIDOU systems. If the amount of navigation differential data in the next epoch exceeds the second congestion threshold, the data of the GLONASS / GALILEO satellite system is deleted according to the preset order (gps+qzss+glonass=>glonass+galileo=>galileo+beidou=>beidou+gps+qzss) because GLONASS / GALILEO corresponds to GLONASS in the single-system sorting, and so on.

[0072] In other embodiments, the single-system sorting is a fixed sorting, and the dual-system sorting and triple-system sorting are dynamically generated according to the observation data of the satellite system deleted last time and the fixed sorting. The sorted items generated dynamically are generated using the observation data of satellite systems other than the observation data of the satellite system deleted last time. This method can ensure that a satellite system will not be deleted in two consecutive epochs.

[0073] The GNSS receiver is used for:

[0074] Obtaining the congestion threshold of the navigation differential data for the next epoch according to the actual data volume and the theoretical transmission volume transmitted to the data transmission radio. The larger the value obtained by subtracting the actual data volume from the theoretical transmission volume, the higher the congestion threshold value;

[0075] Performing the step of obtaining the navigation differential data of the GNSS receiver for the next epoch using the latest congestion threshold.

[0076] For example, after deleting the satellite system observation data in the first epoch, the data volume is 800, which is 200 less than the theoretical transmission volume of 1000. Then, theoretically, 1200 data volumes can be transmitted in the next epoch, and the cache utilization rate can be made higher by adjusting the congestion threshold.

[0077] The GNSS receiver is used for:

[0078] Dividing the navigation differential data of an epoch into several parts according to the frequency of data broadcast by the data transmission radio and sending the divided navigation differential data to the data transmission radio according to the frequency.

[0079] See Figure 1, using the above GNSS receiver, this embodiment also provides a data flow control method for navigation differential data, including:

[0080] Step 100, the GNSS receiver obtains navigation differential data for one epoch.

[0081] Step 101, determine whether the amount of navigation differential data is greater than the congestion threshold. If so, execute Step 102; if not, execute Step 100 again.

[0082] Step 102, obtain the observation data in the navigation differential data, where the congestion threshold is obtained according to the theoretical transmission amount within each differential data update interval;

[0083] Step 103, delete at least one satellite system's observation data in the observation data in a preset order;

[0084] Step 104, transmit the navigation differential data with the satellite system's observation data deleted to the data radio station.

[0085] Specifically, Step 101 includes:

[0086] Step 1011, determine whether the amount of navigation differential data is greater than any congestion threshold. If so, execute Step 1012; if not, execute Step 100 again.

[0087] Step 1012, obtain the closest target congestion threshold that the amount of navigation differential data is greater than. The closest target congestion threshold is used to determine how many satellite systems to delete. For example, if 950 is the first threshold and 1200 is the second threshold, and the actual data amount is 1300, then 1200 is the closest target congestion threshold, and it is obtained that two satellite systems' observation data need to be deleted.

[0088] Step 103 is specifically:

[0089] Delete the observation data of the target number of satellite systems in the observation data in a preset order, where the target number is obtained according to the target congestion threshold, and the larger the target congestion threshold, the more the target number.

[0090] The congestion threshold includes the first congestion threshold aM, the second congestion threshold bM, and the third congestion threshold cM. The value range of a is (0.9, 1), the value range of b is 1.2, and the value range of c is (1.9, 2), where M is the theoretical transmission amount within each differential data update interval.

[0091] Specifically, the first congestion threshold is 0.95*M, the second congestion threshold is 1.2*M, the third congestion threshold is 1.99*M, the first release threshold is 0.8*M, and the second release threshold is 0.2*M.

[0092] Step 103 includes:

[0093] Obtain RTCM3.X format data in the observation data;

[0094] Sort the RTCM3.X format data according to the satellite system, and the satellite system sorting is in a circular arrangement;

[0095] For the navigation differential data of a target epoch, determine whether the amount of navigation differential data is greater than the congestion threshold. If so, obtain the satellite system observation data deleted by the adjacent navigation differential data of the target epoch, where the adjacent navigation differential data is the previous navigation differential data greater than the congestion threshold of the target epoch;

[0096] Obtain the next satellite system of the satellite system observation data deleted by the adjacent navigation differential data in the satellite system sorting;

[0097] For the navigation differential data of the target epoch, delete the satellite system observation data of the next satellite system.

[0098] The types of the satellite system sorting include one or more of single-system sorting, dual-system sorting, and triple-system sorting. The data flow control method includes:

[0099] Select the type of satellite system sorting according to the target number;

[0100] Delete the satellite system observation data of the target number in the observation data according to the order of the selected satellite system sorting.

[0101] The dual-system sorting and the triple-system sorting correspond one by one to each item of the single-system sorting. One item in the dual-system sorting is the corresponding item of the single-system sorting and the next item of the corresponding single-system sorting. One item in the triple-system sorting is the corresponding item of the single-system sorting and the next two items of the corresponding single-system sorting.

[0102] Step 103 includes:

[0103] Obtain the congestion threshold of the navigation differential data of the next epoch according to the actual data volume transmitted to the data transmission radio and the theoretical transmission volume. The greater the value obtained by subtracting the actual data volume from the theoretical transmission volume, the higher the congestion threshold value;

[0104] Execute the step of obtaining navigation differential data of the next epoch by the GNSS receiver using the latest congestion threshold.

[0105] Step 103 includes: Divide the navigation differential data of one epoch into several parts according to the

[0106] frequency of the data transmitted by the data transmission radio and send the divided navigation differential data to the data transmission radio according to the frequency.

[0107] This embodiment can ensure the stability of the receiver when receiving data in a specific differential data format for radio broadcasts, and provides an active data flow control scheme for navigation differential data in view of the hardware limitations of the radio, enabling users to receive differential data stably and efficiently for high-precision positioning when using it.

[0108] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that these are only examples, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A data flow control method for navigation differential data, characterized in that: The data flow control method comprises: The GNSS receiver acquires navigation differential data; Determine whether the amount of navigation differential data is greater than a congestion threshold, and if so, obtain observation data in the navigation differential data, wherein the congestion threshold is obtained according to a theoretical transmission amount within each differential data update interval; Deleting at least one satellite system observation data in the observation data in a preset order; Transmitting the navigation differential data after deleting the satellite system observation data to the data transmission station; The GNSS receiver is provided with at least two congestion thresholds, and the data flow control method comprises: Determine whether the navigation differential data volume is greater than any congestion threshold, and if so, obtain the closest target congestion threshold that the navigation differential data volume is greater than; The satellite system observation data of a target number in the observation data are deleted in a preset order, wherein the target number is obtained according to a target congestion threshold, and the larger the target congestion threshold, the greater the target number.

2. The data flow control method for navigation differential data according to claim 1, characterized in that: The congestion thresholds include a first congestion threshold aM, a second congestion threshold bM, and a third congestion threshold cM, where a is in the range of (0.9, 1), b is in the range of 1.2, and c is in the range of (1.9, 2), and M is the theoretical transmission volume in each differential data update interval.

3. The data flow control method for navigation differential data according to claim 1, characterized in that: The step of deleting the target number of satellite system observation data in the observation data in a preset order includes: Get RTCM3.X format data from observation data; Sorting the RTCM3.X format data according to the satellite system, wherein the satellite system is arranged in a circular manner; For navigation differential data of a target epoch, determine whether the amount of navigation differential data is greater than a congestion threshold, and if so, obtain satellite system observation data deleted by adjacent navigation differential data of the target epoch, wherein the adjacent navigation differential data is the previous navigation differential data of the target epoch that is greater than the congestion threshold; Acquire the next satellite system of the satellite system observation data deleted from the adjacent navigation differential data in the satellite system sorting; For the navigation differential data of the target epoch, the satellite system observation data of the next satellite system is deleted.

4. The data flow control method for navigation differential data according to claim 3, characterized in that: The type of satellite system sorting includes one or more of single system sorting, dual system sorting, and triple system sorting. The data flow control method includes: Select the type of satellite system sorting based on the number of targets; Delete the target number of satellite system observation data in the observation data in the order in which the selected satellite systems are sorted.

5. The data flow control method for navigation differential data according to claim 4, characterized in that: There is a one-to-one correspondence between each item in the dual-system sorting and the triple-system sorting and the single-system sorting. One item in the dual-system sorting is the corresponding item in the single-system sorting and the next item in the single-system sorting. One item in the triple-system sorting is the corresponding item in the single-system sorting and the next two items in the single-system sorting.

6. The data flow control method for navigation differential data according to claim 4, characterized in that: The single-system sorting is a fixed sorting, and the dual-system sorting and triple-system sorting are dynamically generated according to the last deleted satellite system observation data and the fixed sorting. The dynamically generated sorting items are generated using satellite system observation data other than the last deleted satellite system observation data.

7. The data flow control method for navigation differential data according to claim 1, characterized in that: The transmitting of the navigation differential data after deleting the satellite system observation data to the data transmission station comprises: The congestion threshold of the navigation differential data of the next epoch is obtained according to the actual data volume transmitted to the data transmission radio station and the theoretical transmission volume. The larger the value of the theoretical transmission volume minus the actual data volume is, the higher the congestion threshold value is. The step of acquiring navigation differential data by the GNSS receiver of the next epoch is performed using the latest congestion threshold.

8. The data flow control method for navigation differential data according to claim 1, characterized in that: The transmitting of the navigation differential data after deleting the satellite system observation data to the data transmission station comprises: Broadcast data based on digital radio The navigation differential data of one epoch is divided into several parts according to the frequency and the divided navigation differential data are sent to the data transmission radio station according to the frequency.

9. A GNSS receiver, characterized in that: The GNSS receiver is used to implement the data flow control method for navigation differential data as described in any one of claims 1 to 8.

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