Data flow control method for navigation differential data and GNSS receiver

Abstract

The present invention discloses a data flow control method for navigation differential data and a GNSS receiver, the data flow control method comprising: 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 observation data in the navigation differential data, wherein the congestion threshold is acquired according to the theoretical transmission amount within each differential data update interval; filters at least one satellite system observation data in the observation data in a preset order; and transmits the navigation differential data after filtering the satellite system observation data to a digital transmission radio station. The present invention can ensure the stability of the receiver when the radio station broadcasts data in a specific differential data format, and provides an active data flow control solution for navigation differential data in view of the radio station hardware limitation, so that users can 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 in particular to a data flow control method for navigation differential data and a GNSS receiver. Background Art

[0002] GNSS-based engineering surveying technology has developed over decades, from centering measurement to the tilt measurement that is widely used today. In recent years, the release of GNSS integrated navigation systems has provided a new direction for engineering surveying technology.

[0003] In the embedded system development environment, the timeliness and robustness of data transmitted to peripherals are always limited by the performance of the peripherals themselves. In many cases, data transmission will have high delays or large deviations due to the performance of the peripherals. For example, when conducting RTK (real-time kinematic positioning) in the surveying and mapping industry, if the differential data broadcasted through the radio station is delayed or lost due to expected bandwidth problems, the measurement accuracy will have unacceptable deviations.

[0004] Due to the differences in the radio's air baud rate and transmission protocol, the amount of data that can be transmitted serially in real time by the radio is also different. If a large amount of data is sent to the radio indiscriminately, it will lead to data loss and affect the real-time positioning accuracy. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of data loss and reduced positioning accuracy in the communication between the GNSS receiver and the radio station in the prior art, and to provide a data flow control method and a GNSS receiver for navigation differential data that can ensure the stability of the receiver when the radio station broadcasts data in a specific differential data format, so that users can stably and efficiently receive differential data for high-precision positioning when using it.

[0006] The present invention solves the above technical problems through the following technical solutions:

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

[0008] The GNSS receiver acquires navigation differential data;

[0009] 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;

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

[0011] The navigation differential data after filtering the satellite system observation data is transmitted to the digital transmission station.

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

[0013] 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;

[0014] The satellite system observation data of the target number in the observation data is screened in a preset order, wherein the target number is obtained according to the target congestion threshold, and the larger the target congestion threshold, the greater 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, where a ranges from (0.9, 1), b ranges from (1.5, 2.5), and c ranges from (1.9, 2), and M is the theoretical transmission volume in each differential data update interval.

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

[0017] Get RTCM3.X format data from observation data;

[0018] Sorting the RTCM3.X format data according to the satellite system, wherein the satellite system is arranged in a circular manner;

[0019] 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 observation data of a satellite system screened by adjacent navigation differential data of the target epoch, and obtain the next satellite system of observation data of a satellite system screened by adjacent navigation differential data in the satellite system sorting, wherein the adjacent navigation differential data is the previous navigation differential data of the target epoch that is greater than the congestion threshold;

[0020] For the navigation differential data of the target epoch, the satellite system observation data of the next satellite system is screened.

[0021] Preferably, the type of satellite system sorting includes one or more of single system sorting, dual system sorting, and triple system sorting, and the data flow control method includes:

[0022] Select the type of satellite system sorting based on the number of targets;

[0023] Filter the satellite system observation data with the target number in the observation data according to the order in which the selected satellite systems are sorted.

[0024] 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 single-system sorting item and the next item of the single-system sorting, and one item in the triple-system sorting is the corresponding single-system sorting item and the next two items of the single-system sorting.

[0025] Preferably, the single-system sorting is a fixed sorting, and the dual-system sorting and triple-system sorting are dynamically generated based on the last screened satellite system observation data and the fixed sorting, and the dynamically generated sorting items are generated using satellite system observation data other than the last screened satellite system observation data.

[0026] Preferably, the step of transmitting the navigation differential data after filtering the satellite system observation data to the data transmission station comprises:

[0027] 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.

[0028] The step of acquiring navigation differential data by the GNSS receiver of the next epoch is performed using the latest congestion threshold.

[0029] Preferably, the step of transmitting the navigation differential data of the filtered satellite system observation data to the data transmission station comprises:

[0030] The navigation differential data of one epoch is divided into several parts according to the frequency of data broadcast by the digital radio station, and the divided navigation differential data is sent to the digital radio station according to the frequency.

[0031] The present invention further provides a GNSS receiver, which is characterized in that the GNSS receiver is used to implement the data flow control method for navigation differential data as described above.

[0032] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0033] The positive and progressive effects of the present invention are:

[0034] The present invention can ensure the stability of the receiver when the radio station broadcasts data in a specific differential data format, and provides an active data flow control solution for navigation differential data in view of the radio station hardware limitations, so that users can stably and efficiently receive differential data for high-precision positioning when using it.

[0035] Through testing, it can be learned that when the radio data flow is stable, the air delay from the radio sending a packet of data to the other end receiving it is about 0.3s. After adding the flow control method of this application to the system software, it can ensure the coherent and stable transmission of data, and there will be no packet loss and air delay exceeding 2s. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the data flow control method of embodiment 1 of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples.

[0038] Example 1

[0039] This embodiment provides a GNSS receiver system. The GNSS receiver system includes a GNSS receiver and a radio station. The GNSS receiver is a base station, and the observation data is sent to a mobile station in real time through the radio station.

[0040] GNSS receivers are used for:

[0041] Obtain navigation differential data;

[0042] 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;

[0043] Filter at least one satellite system observation data in the observation data according to a preset order;

[0044] The navigation differential data of the filtered satellite system observation data is transmitted to the digital transmission station.

[0045] In this embodiment, filtering at least one satellite system observation data in the observation data refers to deleting at least one satellite system observation data in the observation data.

[0046] The GNSS receiver is provided with at least two congestion thresholds, and the GNSS receiver is used to:

[0047] 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;

[0048] 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.

[0049] 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 (1.5, 2.5), the value range of c is (1.9, 2), and M is the theoretical transmission amount in each differential data update interval.

[0050] GNSS receivers are used for:

[0051] Get RTCM3.X format data from observation data;

[0052] Sorting the RTCM3.X format data according to the satellite system, wherein the satellite system is arranged in a circular manner;

[0053] 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 observation data of a satellite system screened by adjacent navigation differential data of the target epoch, and obtain the next satellite system of observation data of a satellite system screened by adjacent navigation differential data in the satellite system sorting, wherein the adjacent navigation differential data is the previous navigation differential data of the target epoch that is greater than the congestion threshold;

[0054] For the navigation differential data of the target epoch, the satellite system observation data of the next satellite system is screened.

[0055] During the radio transmission configuration phase, the default generation interval of differential data is first set according to the air baud rate and transmission protocol (differential data includes coordinates and antenna information of fixed frequency + observation data information of adjustable frequency).

[0056] The program sets the internal buffer size, the first congestion threshold and the second congestion threshold, and the first release threshold and the second release threshold. The buffer size is twice the theoretical transmission volume (M) in 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.

[0057] The total bandwidth of the system is dynamically acquired; and a flow control rate is determined according to a relationship between the total bandwidth of the system and the first congestion threshold and the second congestion threshold.

[0058] It is known that RTCM3.X format data contains observation data of satellite systems such as GPS / GLONASS / GALILEO / BEIDOU / QZSS. First, all satellite systems are sorted, and the amount of data written to the buffer in the next epoch is limited based on the theoretical amount of differential data (M) written in this epoch and the amount of residual data in the buffer (S).

[0059] In order to ensure data availability, data is screened in units of satellite systems. The first threshold screens one system, and the second threshold screens two systems, that is, M+S. If the first threshold is triggered, the next epoch data will be removed / restored. The output of observation data of one system will be repeated at most twice. If the second threshold is triggered, the next epoch data will be removed / restored. The output of the differential data (observation value part) of this epoch will be stopped if the third threshold is triggered. The system limit of each epoch is polled according to the satellite system order, that is,

[0060] When only one satellite system is selected: the selection order is GPS+QZSS=>GLONASS=>GALILEO=>BEIDOU;

[0061] When screening two satellite systems: the screening order is gps+qzss+glonass=>glonass+galileo=>galileo+beidou=>beidou+gps+qzss.

[0062] Because the qzss observations are dependent on gps, the two systems are treated as one system.

[0063] The sending of user data is controlled according to the flow control rate.

[0064] Based on the frequency of the radio station's own data broadcast, the data in the buffer is sent to the radio station at intervals of 0.5 seconds, with half of the actual data volume that can be transmitted per second as the traffic volume.

[0065] For example, the theoretical transmission volume is 1000, and the amount of navigation differential data in one epoch is 1100, which exceeds the first congestion threshold. Then, the data of one satellite system will be deleted, that is, the data originally sent from the GPS / GLONASS / GALILEO / BEIDOU / QZSS systems will be changed to the data sent from GLONASS / GALILEO / BEIDOU. If the amount of navigation differential data in the next epoch exceeds the first congestion threshold again, the data of the glonass satellite system will be filtered according to the preset order (gps+qzss=>glonass=>galileo=>beidou), and so on.

[0066] Furthermore, the type of satellite system sorting includes one or more of single system sorting, dual system sorting, and triple system sorting, and the GNSS receiver is used for:

[0067] Select the type of satellite system sorting based on the number of targets;

[0068] Filter the satellite system observation data with the target number in the observation data according to the order in which the selected satellite systems are sorted.

[0069] 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.

[0070] For example, the amount of navigation differential data in an epoch is 1100, which exceeds the first congestion threshold. The data of one satellite system will be deleted, that is, the data originally sent from the GPS / GLONASS / GALILEO / BEIDOU / QZSS systems will be changed to the data sent from GLONASS / GALILEO / BEIDOU. If the amount of navigation differential data in the next epoch exceeds the second congestion threshold, the data of the glonass+galileo satellite system will be filtered 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.

[0071] In other embodiments, the single-system ranking is a fixed ranking, and the dual-system ranking and the triple-system ranking are dynamically generated according to the last screened satellite system observation data and the fixed ranking, and the dynamically generated ranking items are generated using satellite system observation data other than the last screened satellite system observation data. This method can ensure that a satellite system will not be screened for two consecutive epochs.

[0072] GNSS receivers are used for:

[0073] 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.

[0074] The step of acquiring navigation differential data by the GNSS receiver of the next epoch is performed using the latest congestion threshold.

[0075] For example, after filtering 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, in the next epoch, theoretically, 1200 data can be transmitted. By adjusting the congestion threshold, the cache utilization rate can be higher.

[0076] GNSS receivers are used for:

[0077] The navigation differential data of one epoch is divided into several parts according to the frequency of data broadcast by the digital radio station, and the divided navigation differential data is sent to the digital radio station according to the frequency.

[0078] See also Figure 1, using the above GNSS receiver, this embodiment also provides a data flow control method for navigation differential data, including:

[0079] Step 100: The GNSS receiver obtains navigation differential data of an epoch.

[0080] Step 101, determine whether the navigation differential data volume is greater than the congestion threshold, if so, execute step 102, if not, execute step 100 again.

[0081] Step 102: Obtain observation data in the navigation differential data, wherein the congestion threshold is obtained according to a theoretical transmission volume in each differential data update interval;

[0082] Step 103, filtering at least one satellite system observation data in the observation data according to a preset order;

[0083] Step 104: Transmit the navigation differential data of the filtered satellite system observation data to the digital transmission station.

[0084] Specifically, step 101 includes:

[0085] Step 1011, determine whether the navigation differential data volume is greater than any congestion threshold, if so, execute step 1012, if not, execute step 100 again.

[0086] Step 1012: Obtain the closest target congestion threshold that the navigation differential data volume is greater than. The closest target congestion threshold is used to determine how many satellite systems to select. For example, if 950 is the first threshold and 1200 is the second threshold, then if the actual data volume is 1300, 1200 is the closest target congestion threshold, and the observation data of two satellite systems that need to be selected are obtained.

[0087] Step 103 is specifically as follows:

[0088] The satellite system observation data of the target number in the observation data is screened in a preset order, wherein the target number is obtained according to the target congestion threshold, and the larger the target congestion threshold, the greater the target number.

[0089] The congestion thresholds include a first congestion threshold aM, a second congestion threshold bM, and a third congestion threshold cM, where a ranges from (0.9, 1), b ranges from (1.5, 2.5), and c ranges from (1.9, 2), and M is a theoretical transmission amount in each differential data update interval.

[0090] 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.

[0091] Step 103 includes:

[0092] Get RTCM3.X format data from observation data;

[0093] Sorting the RTCM3.X format data according to the satellite system, wherein the satellite system is arranged in a circular manner;

[0094] 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 observation data of a satellite system screened by adjacent navigation differential data of the target epoch, and obtain the next satellite system of observation data of a satellite system screened by adjacent navigation differential data in the satellite system sorting, wherein the adjacent navigation differential data is the previous navigation differential data of the target epoch that is greater than the congestion threshold;

[0095] For the navigation differential data of the target epoch, the satellite system observation data of the next satellite system is screened.

[0096] 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:

[0097] Select the type of satellite system sorting based on the number of targets;

[0098] Filter the satellite system observation data with the target number in the observation data according to the order in which the selected satellite systems are sorted.

[0099] 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.

[0100] Step 103 includes:

[0101] 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.

[0102] The step of acquiring navigation differential data by the GNSS receiver of the next epoch is performed using the latest congestion threshold.

[0103] Step 103 includes: dividing the navigation differential data of an epoch into several parts according to the frequency of data broadcasting by the digital radio station and sending the divided navigation differential data to the digital radio station according to the frequency.

[0104] This embodiment can ensure the stability of the receiver when the radio station broadcasts data in a specific differential data format, and provides an active data flow control solution for navigation differential data based on the radio station hardware limitations, so that users can stably and efficiently receive differential data for high-precision positioning when using it.

[0105] Although the specific embodiments of the present invention are 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. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, 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; Filter at least one satellite system observation data in the observation data according to a preset order; The navigation differential data after filtering the satellite system observation data is transmitted to the digital transmission station.

2. The data flow control method for navigation differential data according to claim 1, characterized in that: 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 the target number in the observation data is screened in a preset order, wherein the target number is obtained according to the target congestion threshold, and the larger the target congestion threshold, the greater the target number.

3. The data flow control method for navigation differential data according to claim 2, 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 ranges from (0.9, 1), b ranges from (1.5, 2.5), and c ranges from (1.9, 2), and M is a theoretical transmission amount in each differential data update interval.

4. The data flow control method for navigation differential data according to claim 2, characterized in that: The method of screening the satellite system observation data of the target number 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 observation data of a satellite system screened by adjacent navigation differential data of the target epoch, and obtain the next satellite system of observation data of a satellite system screened by adjacent navigation differential data in the satellite system sorting, wherein the adjacent navigation differential data is the previous navigation differential data of the target epoch that is greater than the congestion threshold; For the navigation differential data of the target epoch, the satellite system observation data of the next satellite system is screened.

5. The data flow control method for navigation differential data according to claim 4, 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; Filter the satellite system observation data with the target number in the observation data according to the order in which the selected satellite systems are sorted.

6. The data flow control method for navigation differential data according to claim 5, 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.

7. The data flow control method for navigation differential data according to claim 5, 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 screened satellite system observation data and the fixed sorting. The dynamically generated sorting items are generated using satellite system observation data other than the last screened satellite system observation data.

8. The data flow control method for navigation differential data according to claim 1, characterized in that: The step of transmitting the navigation differential data after filtering 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.

9. The data flow control method for navigation differential data according to claim 1, characterized in that: The step of transmitting the navigation differential data after filtering the satellite system observation data to the data transmission station comprises: The navigation differential data of one epoch is divided into several parts according to the frequency of data broadcast by the digital radio station, and the divided navigation differential data is sent to the digital radio station according to the frequency.

10. 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 9.

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