A data transmission system

Abstract

The embodiment of the present application provides a data transmission system, comprising: a receiver and a handset; the handset is used for sending an application image data packet to the receiver; the application image data packet comprises: a camera number, a received serial number and a receiving window; the receiver extracts a plurality of images corresponding to the camera number according to the camera number, and generates a corresponding image data packet according to each extracted image; the image data packet is provided with a serial number; for each image data packet, if the serial number is less than the received serial number or greater than the sum of the received serial number and the receiving window, the image data packet is not sent; otherwise, the image data packet is sent to the handset; after receiving each image data packet, the handset takes the serial number of the image data packet as an updated received serial number, and generates an application image data packet again according to the updated received serial number and sends the application image data packet to the receiver. Through the implementation of the present application, the phenomena of network congestion, packet loss and delay during image data transmission can be alleviated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of data transmission, in particular to a data transmission system. BACKGROUND

[0002] The geodetic GNSS receiver is a measuring instrument device, which integrates a GNSS satellite positioning module, an INS sensor and a camera module, and has GNSS direct measurement and setting out, tilt measurement and setting out, photogrammetry and AR setting out functions.

[0003] The hand book is a handheld device used in combination with the receiver, which can be connected to the receiver through Bluetooth or Wi-Fi, and is the main way for the user to operate the receiver.

[0004] In actual measurement process, data transmission needs to be performed between the receiver and the hand book, such as GNSS positioning information, INS attitude information and image information, for transmission and storage. The data processing capacity of the hand book is not strong, and when the receiver transmits image information to the hand book, network congestion, packet loss and data delay may occur. SUMMARY

[0005] The embodiment of the present application provides a data transmission system, which can alleviate the occurrence of network congestion, packet loss and data delay when the receiver transmits image data to the hand book.

[0006] An embodiment of the present application provides a data transmission system, comprising a receiver and a hand book.

[0007] The hand book is configured to send an image data packet to the receiver, wherein the image data packet comprises a camera number, a received serial number and a receiving window. The camera number is used to indicate the camera from which the required image is applied. The received serial number is the serial number of the last image data packet received by the hand book. Initially, the received serial number is 0. The receiving window is the maximum number of images set for image flow control.

[0008] The receiver is configured to extract a plurality of images corresponding to the camera number according to the camera number, and generate a corresponding image data packet for each extracted image. The image data packet is provided with a serial number. Initially, the serial number of the image data packet is 1. The serial number of the image data packet is increased by 1 each time the receiver successfully sends an image data packet.

[0009] For each image data packet, if the serial number is less than the received serial number or greater than the sum of the received serial number and the receiving window, the image data packet is not sent. Otherwise, the image data packet is sent to the hand book.

[0010] The hand book is configured to, after receiving each image data packet, take the sequence number of the image data packet as an updated received sequence number, and according to the updated received sequence number, re-generate an application image data packet and send the application image data packet to the receiver.

[0011] Further, the hand book is further configured to monitor signal strength, packet loss rate, transmission delay, CPU usage rate of itself, and memory occupation rate of itself in real time.

[0012] In a case where a change rate of any one of the signal strength, the packet loss rate, the transmission delay, the CPU usage rate of itself, and the memory occupation rate of itself exceeds a corresponding preset threshold value, a first window adjustment value is generated according to the monitored signal strength, the packet loss rate, the transmission delay, the CPU usage rate of itself, and the memory occupation rate of itself, and the first window adjustment value, the transmission delay, the signal strength, and the packet loss rate are added to the application image data packet.

[0013] The receiver is further configured to, in a case where the first window adjustment value is set in the application image data packet, generate a second window adjustment value according to the received packet loss rate, transmission delay, signal strength, and CPU usage rate and memory occupation rate of itself.

[0014] In a case where window adjustment directions indicated by the first window adjustment value and the second window adjustment value are inconsistent, adjustment of the receiving window is rejected, wherein the window adjustment directions include increasing the receiving window and decreasing the receiving window.

[0015] In a case where window adjustment directions indicated by the first window adjustment value and the second window adjustment value are consistent, a window adjustment average value is calculated according to the first window adjustment value and the second window adjustment value.

[0016] The receiving window is adjusted according to the window adjustment average value.

[0017] Further, the receiver is further configured to extract GPS coordinates attached in images successfully sent in a preset time period.

[0018] Each GPS coordinate is converted into a plane coordinate by UTMT projection, and the corresponding plane coordinate is sorted according to an image acquisition time of each image to generate a continuous path point set.

[0019] A direction angle of each sub-path formed by adjacent path points in the continuous path point set is calculated, and a difference value of adjacent direction angles is calculated.

[0020] A current operation mode is determined according to the difference value of the adjacent direction angles.

[0021] A predicted coordinate of a geographical area corresponding to an image to be applied by the hand book is generated according to the current operation mode.

[0022] According to the predicted coordinates, images of corresponding geographical areas are collected and stored in advance.

[0023] Further, the receiver determines the current operation mode according to the difference between each adjacent direction angle, including:

[0024] If the difference between all adjacent direction angles is less than a preset angle value, the current operation mode is determined to be a straight-line operation mode.

[0025] If there are more than a preset number of 90° turns in the difference between adjacent direction angles, the current operation mode is a grid operation mode.

[0026] Further, the receiver generates predicted coordinates of the geographical area corresponding to the image to be applied according to the current operation mode, including:

[0027] In the case of a straight-line operation mode, a straight-line path is generated by straight-line fitting according to the path point set; and the predicted coordinates are determined according to the average moving distance along the direction of the straight-line path.

[0028] In the case of a grid operation mode, the next target grid is determined according to the traversal order of the grid and the current grid according to the traversal order of the grid when the path point set is collected; and the center coordinates of the next target grid are taken as the predicted coordinates.

[0029] Further, the receiver is also configured to feed back a response image data packet to the handbook after receiving each application image data packet; and the response image data packet is set with the sequence number of the last image data packet successfully sent by the receiver.

[0030] The handbook is also configured to update the received sequence number to the sequence number of the last image data packet successfully sent by the receiver in the response image data packet.

[0031] Further, the handbook is also configured to send an application message data packet to the receiver; and the application message data packet is set with a message type to be applied, including positioning information or attitude information.

[0032] The receiver is also configured to extract corresponding information according to the message type, generate a message data packet according to the extracted information, and transmit the message data packet to the handbook.

[0033] Further, the handbook is also configured to send a query characteristic data packet to the receiver before sending the application image data packet to the receiver.

[0034] The receiver is further configured to feed back a response query characteristic data packet to the hand book after receiving the query characteristic data packet, wherein the response query characteristic data packet is provided with a camera number of the camera provided in the receiver.

[0035] Further, the hand book is further configured to extract, after receiving the image data packet, a camera number corresponding to the image, an image acquisition time, an image width, an image height, an image encoding, a display angle corresponding to the image, and an image data size from the image data packet.

[0036] An image storage data packet is generated according to the camera number, the image acquisition time, the image width, the image height, the image encoding, the display angle corresponding to the image, and the image data size, and the image storage data packet is stored.

[0037] Further, the hand book is further configured to determine a message type in the message data packet after receiving the message data packet.

[0038] If the message type is posture information, an acquisition time of the posture information, a posture angle, and a posture angle evaluation error are extracted from the message data packet.

[0039] An overall machine posture storage data packet is generated according to the acquisition time of the posture information, the posture angle, and the posture angle evaluation error, and the overall machine posture storage data packet is stored.

[0040] If the message type is positioning information, an acquisition time of the positioning information, a phase center coordinate, a coordinate evaluation error, and a solution state are extracted from the message data packet.

[0041] A positioning information storage data packet is generated according to the acquisition time of the positioning information, the phase center coordinate, the coordinate evaluation error, and the solution state, and the positioning information storage data packet is stored.

[0042] By implementing the embodiments of the present application, the following beneficial effects can be achieved:

[0043] The embodiment of the present application provides a data transmission system, the system is provided with a receiver and a handset, the handset sends an application image data packet to the receiver; the application image data packet is provided with a camera number, a received serial number and a receiving window; the camera number is used for indicating a camera from which an image to be applied is derived, the received serial number is a serial number of a last image data packet received by the handset, the received serial number is 0 initially, and the receiving window is a maximum image quantity set when image flow control is performed; the receiver extracts a plurality of images corresponding to the camera number according to the camera number, and generates a corresponding image data packet according to each extracted image; the image data packet is provided with a serial number; the serial number of the image data packet is 1 initially, and the serial number of the image data packet is increased by 1 every time the receiver successfully sends an image data packet; for each image data packet, the image data packet is not sent when the serial number is less than the received serial number or greater than a sum of the received serial number and the receiving window; otherwise, the image data packet is sent to the handset; and the handset takes the serial number of the image data packet as an updated received serial number after receiving the image data packet, and generates an application image data packet again according to the updated received serial number and sends the application image data packet to the receiver. Compared with the prior art, the receiving window and the dynamic received serial number are set in the application image data packet sent by the handset to the receiver, the receiving window sets the maximum image quantity set when image flow control is performed; when the receiver sends the image data packet, if the serial number of the image data packet is less than the received serial number or greater than a sum of the received serial number and the receiving window, the image data packet is not sent, otherwise, the image data packet is sent, so that flow control during image data sending is realized, and network congestion, packet loss and data delay and other phenomena are alleviated. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 FIG. 1 is a system architecture diagram of a data transmission system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0046] As shown in FIG. 1, an embodiment of the present application provides a data transmission system, which comprises a receiver and a handset. Figure 1

[0047] ​The hand book is used for sending an application image data packet to the receiver; wherein the application image data packet comprises a camera number, a received serial number and a receiving window; the camera number is used for indicating a camera from which an image to be applied is derived, the received serial number is a serial number of a last image data packet received by the hand book, and the received serial number is 0 initially; and the receiving window is a maximum number of images set when image flow control is performed.

[0048] The receiver is used for extracting a plurality of images corresponding to the camera number, and generating a corresponding image data packet according to each of the extracted images; the image data packet is provided with a serial number; wherein the serial number of the image data packet is 1 initially, and the serial number of the image data packet is increased by 1 each time the receiver successfully sends an image data packet.

[0049] For each image data packet, if the serial number is less than the received serial number or greater than a sum of the received serial number and the receiving window, the image data packet is not sent; otherwise, the image data packet is sent to the hand book.

[0050] The hand book is used for, after receiving each image data packet, taking the serial number of the image data packet as an updated received serial number, and generating an application image data packet according to the updated received serial number and sending the application image data packet to the receiver.

[0051] In a preferred embodiment, the hand book is further used for, before sending the application image data packet to the receiver, sending an inquiry characteristic data packet to the receiver.

[0052] The receiver is further used for, after receiving the inquiry characteristic data packet, feeding back a response inquiry characteristic data packet to the hand book, wherein the response inquiry characteristic data packet is provided with a camera number of a camera set in the receiver.

[0053] Illustratively, a specific image data transmission process is as follows:

[0054] 1. The receiver first enables a Wi-Fi hotspot and listens to a TCP 8201 port.

[0055] 2. The hand book connects to the hotspot opened by the receiver, and then connects to the TCP 8201 port of the receiver.

[0056] 3. The hand book sends an inquiry characteristic data packet "Ox0001" to the receiver, and sets up a "current serial number" variable, and the initial value of the "current serial number" variable is 0; the message content in the inquiry characteristic data packet "Ox0001" is empty. It should be noted that the basic format of all data packets in the present application is consistent, and is shown in Table 1, and the message content in different data packets is different:

[0057] Item Type Description Prefix uint16_t Fixed to 0xA4A5 Check uint16_t CRC16 check Length uint32_t Number of bytes in the whole packet Protocol version uint16_t Incremented after each modification of the protocol Message type uint16_t Determines the definition of the message content Sequence number uint32_t Incremented at sending, original value returned at response Message content uint8_t[N] Defined according to the message type

[0058] Table 1

[0059] 4. The receiver feeds back a query characteristic data packet "0x0002" to the handset, wherein the camera number of all cameras set in the receiver is set in the query characteristic data packet "0x0002", and the subsequent user can select the corresponding camera through the handset according to the camera number fed back, and then acquire the data of the corresponding camera.

[0060] 5. After the user selects the camera according to the camera number, the handset sends an image application data packet "0x0101" to the receiver to apply for the image; the message content of the image application data packet "0x0101" is set with the camera number, the received serial number and the receiving window; the set camera number is used to determine which camera of the receiver needs to acquire the image in this data transmission, the received serial number indicates the serial number of the last image data packet received by the handset, and the specific value is filled with the current value of the variable "current serial number", which is initially 0, i.e. when the handset sends the image application data packet "0x0101" for the first time, the value in the received serial number is 0; the receiving window is the maximum number of images set for image flow control, and the specific value can be set according to the actual situation, for example, it can be 10, 8, etc. In other preferred embodiments, the message content of the image application data packet "0x0101" can also be set with the data item "image maximum interval" to control the time interval when the receiver sends the image. Illustratively, the specific content of the message in the image application data packet "0x0101" can be as shown in Table 2:

[0061]

[0062] Table 2

[0063] 6、the receiver receives the application image data packet "0x0101", extracts a number of images collected by the corresponding camera according to the camera number in the "0x0101" message content, and generates a corresponding image data packet "0x0103" according to each image; and sets the sequence number of the image data packet "0x0103" according to the image data packet that has been successfully sent, the basic format of all data packets in the application is shown in Table 1, as can be seen from Table 1, each data packet has the item of "sequence number", and the sequence number of each type of data packet that is successfully sent is monotonically increasing in the form of interval 1, for example, the sequence number of the first successfully sent image data packet is 1, the sequence number of the second successfully sent image data packet is 2, the sequence number of the third successfully sent image data packet is 3, and so on. Next, the receiver compares the sequence number of the image data packet "0x0103" that needs to be sent at present with the received sequence number in the application image data packet "0x0101" and the receiving window, if the sequence number of the image data packet "0x0103" that needs to be sent at present is greater than the received sequence number in the application image data packet "0x0101" and less than or equal to the sum of the received sequence number and the receiving window, the image data packet "0x0103" is sent to the handset, otherwise, it is not sent and waits.

[0064] 7、the handset updates the value of the sequence number of the image data packet "0x0103" as the updated value of the variable "current sequence number" after receiving each image data packet "0x0103", generates a new application image data packet "0x0101" according to the updated value of the "current sequence number" and sends it to the receiver, the sequence number (i.e. the sequence number in Table 1) in the new application image data packet "0x0101" and the received sequence number in the message content are both the updated value of the "current sequence number", thereby realizing the updating of the sequence number, and cooperating with the receiving window to enable continuous control of image flow.

[0065] In a preferred embodiment, the handset is further configured to monitor the signal strength, packet loss rate, transmission delay, CPU usage and memory occupation rate in real time.

[0066] In a case where the change rate of any one of the signal strength, the packet loss rate, the transmission delay, the CPU usage rate of the hand-held device, and the memory occupation rate of the hand-held device exceeds a corresponding preset threshold, a first window adjustment value is generated according to the monitored signal strength, the packet loss rate, the transmission delay, the CPU usage rate of the hand-held device, and the memory occupation rate of the hand-held device, and the first window adjustment value, the transmission delay, the signal strength, and the packet loss rate are added to the application image data packet;

[0067] The receiver is further configured to, in a case where the first window adjustment value is set in the application image data packet, generate a second window adjustment value according to the received packet loss rate, transmission delay, signal strength, and CPU usage rate and memory occupation rate of the hand-held device;

[0068] In a case where the window adjustment directions indicated by the first window adjustment value and the second window adjustment value are inconsistent, the adjustment of the receiving window is rejected, wherein the window adjustment directions include increasing the receiving window and decreasing the receiving window;

[0069] In a case where the window adjustment directions indicated by the first window adjustment value and the second window adjustment value are consistent, a window adjustment average value is calculated according to the first window adjustment value and the second window adjustment value;

[0070] The receiving window is adjusted according to the window adjustment average value.

[0071] Specifically, in this embodiment, the hand-held device monitors the signal strength, the packet loss rate, the transmission delay, the CPU usage rate of the hand-held device, and the memory occupation rate of the hand-held device, and compares each of the monitored data with the standard signal strength, the standard packet loss rate, the standard transmission delay, the standard CPU usage rate, and the standard memory occupation rate corresponding to the receiving window, to calculate the change rate of each data. If the change rate exceeds the corresponding preset threshold, it indicates that the network environment or the device processing capability of the hand-held device has changed greatly. In this case, a first window adjustment value is generated according to the monitored signal strength, the packet loss rate, the transmission delay, the CPU usage rate of the hand-held device, and the memory occupation rate of the hand-held device. The first window value is used to inform the receiver that the size of the receiving window can be adjusted, so as to increase or decrease the maximum number of image transmissions in the transmission channel according to the current network state or the processing capability of the hand-held device, to further avoid network congestion or to speed up the transmission speed.

[0072] Specifically, first, the change rate of each data is calculated:

[0073] The signal strength change rate is set as S1 for the monitored signal strength at the current time, and S0 for the standard signal strength

[0074] The signal strength change rate is set as S1 for the monitored signal strength at the current time, and S0 for the standard signal strength

[0075] Packet loss rate change rate: assuming the current time monitoring packet loss rate is L1, the standard packet loss rate is L0, then the packet loss rate change rate

[0076] Transmission delay change rate: assuming the current time monitoring transmission delay is D1, the standard transmission delay is D0, then the transmission delay change rate

[0077] CPU usage rate change rate: assuming the current time monitoring CPU usage rate is C1, the standard CPU usage rate is C0, then the CPU usage rate change rate

[0078] Memory occupancy rate change rate: assuming the current time monitoring memory occupancy rate is M1, the standard memory occupancy rate is M0, then the memory occupancy rate change rate

[0079] After determining the change rate of each data, if any change rate exceeds the corresponding preset threshold, for example, 5%, then the window adjustment value is calculated according to the following formula:

[0080] The calculation formula of the first window adjustment value A can be:

[0081] Wherein, A is the first window adjustment value, if A is positive, it can indicate that the window adjustment direction is to increase the receiving window; if it is negative, it can indicate that the window adjustment direction is to reduce the receiving window, and the absolute value size can be used to measure the amplitude of window adjustment; W S is the weight coefficient corresponding to the signal strength change rate, W L is the weight coefficient corresponding to the packet loss rate change rate, W D is the weight coefficient corresponding to the transmission delay change rate, W C is the weight coefficient corresponding to the CPU usage rate change rate, W M is the weight coefficient corresponding to the memory occupancy rate change rate; B is the receiving window.

[0082] It should be noted that the specific values of W S , W L , W D , W C and W M can be adjusted according to actual conditions W S +W L +W D +W C +W M =1; illustratively, W S , W L , W D can all be set to 0.2, and W Cis set to 0.3, W M is set to 0.1. It is also to be noted that the above-mentioned standard signal strength, standard packet loss rate, standard transmission delay, standard CPU usage rate and standard memory occupancy rate are the signal strength, packet loss rate, transmission delay, CPU usage rate and memory occupancy rate corresponding to the receiving window. In actual scenarios, the user can test the signal strength, packet loss rate, transmission delay, CPU usage rate and memory occupancy rate corresponding to each size of receiving window by setting different sizes of receiving window; then, under the premise of acceptable signal strength, packet loss rate, transmission delay, CPU usage rate and memory occupancy rate, the corresponding receiving window is selected as the final receiving window, and the signal strength, packet loss rate, transmission delay, CPU usage rate and memory occupancy rate corresponding to the final receiving window are respectively set as the above-mentioned standard signal strength, standard packet loss rate, standard transmission delay, standard CPU usage rate and standard memory occupancy rate.

[0083] After the first window adjustment value is generated, the hand book adds the first window adjustment value, transmission delay, signal strength and packet loss rate to the application image data packet "0x0101"; the receiver calculates the second window adjustment value in the same way as the hand book after receiving the corresponding application image data packet "0x0101"; then the second window adjustment value is compared with the first window adjustment value, if both window adjustment values are positive or negative, it means that the window adjustment directions indicated by the first window adjustment value and the second window adjustment value are consistent, at this time, an average value is calculated according to the first window adjustment value and the second window adjustment value to obtain the above-mentioned window adjustment average value; then the receiving window is adjusted according to the adjustment average value, for example, assuming that the original receiving window is 10, if the window adjustment average value is -2; at this time, the receiving window is reduced and set to 8; if the window adjustment average value is 2, at this time, the receiving window is increased and set to 12.

[0084] In this embodiment, through the dynamic adjustment of the receiving window, on the one hand, network congestion or device overload can be further avoided, when the network quality decreases (such as the packet loss rate rises, the delay increases) or the device load is too high, the receiving window is actively reduced to reduce the data receiving amount, preventing buffer overflow or processing delay; on the other hand, network resources can also be fully utilized, when the network quality improves or the device load decreases, the receiving window is increased to improve the data transmission throughput; in addition, the hand book and the receiver generate adjustment values in both directions and compare the directions, avoiding adjustment failure or oscillation caused by single-sided misjudgment.

[0085] In a preferred embodiment, the receiver is further configured to extract the GPS coordinates attached in the successfully transmitted images in a preset period;

[0086] Converting each GPS coordinate into a plane coordinate by UTMT projection, and sorting the corresponding plane coordinates according to the image acquisition time of each image to generate a continuous path point set;

[0087] Calculating the direction angle of each sub-path formed by each adjacent path point in the continuous path point set, and calculating the difference value of adjacent direction angles;

[0088] Determining the current operation mode according to the difference value of each adjacent direction angle;

[0089] Generating a predicted coordinate of a geographic area corresponding to an image to be applied by the hand book according to the current operation mode;

[0090] According to the predicted coordinate, the image corresponding to the geographic area is collected and stored in advance.

[0091] Preferably, the receiver determines the current operation mode according to the difference value of each adjacent direction angle, including:

[0092] If the difference value of all adjacent direction angles is less than a preset angle value, the current operation mode is determined to be a straight line type operation mode;

[0093] If there are more than a preset number of 90° turns in the difference value of adjacent direction angles, the current operation mode is a grid type operation mode.

[0094] Preferably, the receiver generates a predicted coordinate of a geographic area corresponding to an image to be applied by the hand book according to the current operation mode, including:

[0095] In the case where the current operation mode is a straight line type operation mode, a straight line path is generated by straight line fitting according to the path point set; and the predicted coordinate is determined according to the average moving distance along the direction of the straight line path.

[0096] In the case where the current operation mode is a grid type operation mode, the next target grid is determined according to the traversal order of the grid and the current grid according to the traversal order of the grid when the path point set is used for image acquisition, and the center coordinate of the next target grid is taken as the predicted coordinate.

[0097] In this embodiment, a prediction function is introduced in the receiver, which predicts the area of the hand book during operation in advance to control the corresponding camera to take images and cache in advance before the hand book initiates an image transmission request, further reducing the delay of the hand book receiving images.

[0098] Specifically, the receiver generates GPS coordinates corresponding to the captured images when shooting the images, extracts GPS coordinates of successfully transmitted images in a preset period of time (for example, in the past 3 hours); divides a preset map into grids, projects the GPS coordinates onto the grids through UTM projection, and converts them into plane coordinates (X, Y) on the map;

[0099] Sort the plane coordinates by image collection time to generate a continuous path point set P = {p1, p2,..., pn,...} ; n} ; p n is the nth path point in the continuous path point set.

[0100] For adjacent path points p i and p i+1 , the direction angle θ i = arctan 2 (y i+1 -y i , x i+1 -x i ). The adjacent direction angle difference Δθ i = θ i+1 - θ i . y i+1 is the longitudinal coordinate of the path point p i+1 , x i+1 is the horizontal coordinate of the path point p i+1 , y i is the longitudinal coordinate of the path point p i , and x i is the horizontal coordinate of the path point p i .

[0101] If all Δθ i are less than a preset angle value (such as 5°), it indicates that the path is basically moved along a straight line (such as road and railway survey: along the road axis to collect terrain and topographic data, such as roadbed elevation measurement and slope monitoring), and at this time, it is determined as a straight-line type operation mode;

[0102] If there are more than a preset number of times (such as 4 times) of 90° turning, it meets the grid type surveying and mapping scene (such as farmland surveying and mapping), and at this time, it is determined as a grid type operation mode.

[0103] If it is determined as a straight-line type operation mode, the path point set P is subjected to least square straight line fitting to obtain a straight line equation; then the average moving distance is calculated through the following formula:

[0104] Then, the next coordinate is predicted along the straight line direction according to the distance d (for example, if the current point is p n , then the predicted point p n+1 = p n+ d * (cos θ, sin θ), where θ is the direction angle of the fitted straight line.

[0105] If the grid mode is determined, the traversal order of the grid in the grid mode is determined according to the network corresponding to each path point in the path point set, for example, according to the path point, it is found that it is traversed in the order of rows from left to right and from top to bottom to form a "mouth" shaped path, or the odd rows are traversed from left to right and the even rows are traversed from right to left to form a "Z" shaped path.

[0106] If the traversal order of the network is: traversed in the order of rows from left to right and from top to bottom to form a "mouth" shaped path, if the current point p n is in the grid (i, j), and the i-th row has not been traversed, the next grid is (i, j+1); if the i-th row has been traversed, the next grid is (i+1, 0) (after line change, start from the 0th column).

[0107] If the traversal order of the network is: traversed in the order of rows from left to right and from top to bottom to form a "mouth" shaped path, if the current point p n is in the grid (i, j), and the i-th row has not been traversed, the next grid is (i, j+1); if the i-th row has been traversed, the next grid is (i+1, 0) (after line change, start from the 0th column).

[0108] In a preferred embodiment, the receiver is further configured to feed back a response application image data packet to the hand book after receiving each application image data packet; the response application image data packet is set with the serial number of the last image data packet successfully sent by the receiver.

[0109] The hand book is further configured to update the received serial number to the serial number of the last image data packet successfully sent by the receiver in the response application image data packet in the case of receiving the response application image data packet.

[0110] Specifically, in this embodiment, the receiver feeds back a response application image data packet "0x0102" after receiving an application image data packet 0x0101, and the message content of the response application image data packet "0x0102" is set with the serial number of the last image data packet successfully sent by the receiver and the corresponding camera number, as shown in Table 3.

[0111]

[0112] Table 3

[0113] In the case that the hand book receives the response application image data packet "0x0102", the value of the variable "current serial number" is updated to the value of "last sent image serial number" in the response application image data packet "0x0102", and the value is assigned to the received serial number when a new application image data packet is generated subsequently.

[0114] In a preferred embodiment, the hand book is further configured to send an application message data packet to the receiver, and the application message data packet is provided with a message type indicating a required application, and the message type includes positioning information or attitude information.

[0115] The receiver is further configured to extract corresponding information according to the message type, generate a message data packet according to the extracted information, and transmit the message data packet to the hand book.

[0116] In this embodiment, the receiver further sends a message data packet containing positioning information or attitude information to the hand book to realize transmission of the positioning information or attitude information.

[0117] Specifically, the hand book sends an application message data packet "0x0104" to the receiver, and the message content in the application message data packet "0x0104" is provided with a message type. If the value of the message type is 5, it indicates that attitude information is required. If the value of the message type is 6, it indicates that positioning information is required. In addition, a maximum interval is provided, which is used to control the time interval of the message sent by the receiver.

[0118]

[0119] Table 4

[0120] The receiver extracts corresponding information according to the value in the message type in the application message data packet "0x0104", and then generates a corresponding message data packet "0x0106" and transmits it to the hand book. Specifically, if the message type is attitude information, the message data packet "0x0106" contains extracted attitude information acquisition time, attitude angle, and attitude angle evaluation error. If the message type is positioning information, the message data packet "0x0106" contains positioning information acquisition time, phase center coordinates, coordinate evaluation error, and solution state.

[0121] In a preferred embodiment, the hand book is further configured to extract, after receiving the image data packet, a camera number corresponding to an image, image acquisition time, image width, image height, image encoding, display angle corresponding to the image, and image data size from the image data packet.

[0122] According to the camera number, image collection time, image width, image height, image encoding, image corresponding display angle and image data size, an image storage data packet is generated and stored.

[0123] Specifically, the hand book performs operation and display after receiving the image data packet 0x0103. When data needs to be saved, the camera number corresponding to the image, the image collection time, the image width, the image height, the image encoding, the image corresponding display angle and the image data size are extracted from the image data packet 0x0103, and then the image storage data packet shown in Table 5 is generated and written into a file.

[0124]

[0125] Table 5

[0126] In a preferred embodiment, the hand book is further configured to determine the message type in the message data packet after receiving the message data packet.

[0127] If the message type is attitude information, the attitude information collection time, the attitude angle and the attitude angle evaluation error are extracted from the message data packet.

[0128] According to the attitude information collection time, the attitude angle and the attitude angle evaluation error, a whole machine attitude storage data packet is generated and stored.

[0129] If the message type is positioning information, the positioning information collection time, the phase center coordinates, the coordinate evaluation error and the solution state are extracted from the message data packet.

[0130] According to the positioning information collection time, the phase center coordinates, the coordinate evaluation error and the solution state, a positioning information storage data packet is generated and stored.

[0131] Specifically, the hand book performs operation and display after receiving the application message data packet "0x0106". When data needs to be saved, if the message type is attitude information, the whole machine attitude storage data packet shown in Table 6 is generated according to the attitude information collection time, the attitude angle and the attitude angle evaluation error in the message data packet, and then written into a file.

[0132] Item Type Description Attitude information acquisition time int64_t UNIX milliseconds Attitude angle float[3] Degrees, [X roll, Y pitch, Z heading] Attitude angle evaluation error float[3] Degrees, [X roll, Y pitch, Z heading]

[0133] Table 6

[0134] If the message type is positioning information, the positioning information storage data packet shown in Table 7 is generated according to the positioning information collection time, the phase center coordinates, the coordinate evaluation error and the solution state in the message data packet "0x0106", and then written into a file.

[0135] Item Type Description Position information acquisition time int64_t UNIX milliseconds Phase center coordinates double[3] WGS84, degrees, [latitude, longitude, ellipsoidal height] Coordinate evaluation error float[3] Meters, [north, east, sky] Solution status uint32_t Same as GPGGA

[0136] Table 7

[0137] The above is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements are also considered to be within the scope of the present application.

Claims

1. A data transmission system, characterized by The application comprises: a receiver and a handset; the handset is configured to send an image data packet to the receiver, wherein the image data packet comprises a camera number, a received serial number and a receiving window; the camera number is used to indicate the camera from which the image is obtained; the received serial number is the serial number of the last image data packet received by the handset; the received serial number is 0 initially; the receiving window is the maximum number of images set for image flow control; the receiver is configured to extract the image corresponding to the camera number and generate an image data packet corresponding to each extracted image; the image data packet is provided with a serial number; the serial number of the image data packet is 1 initially; the serial number of the image data packet is increased by 1 each time the receiver successfully sends an image data packet; for each image data packet, if the serial number is less than the received serial number or greater than the sum of the received serial number and the receiving window, the image data packet is not sent; otherwise, the image data packet is sent to the handset; the handset is configured to update the serial number of the image data packet as the updated received serial number after receiving each image data packet, and to generate an image data packet and send it to the receiver according to the updated received serial number.

2. The data transmission system of claim 1, wherein, The handset is also configured to monitor the signal strength, packet loss rate, transmission delay, CPU usage and memory usage in real time; if the change rate of any one of the signal strength, packet loss rate, transmission delay, CPU usage and memory usage exceeds the corresponding preset threshold, a first window adjustment value is generated according to the signal strength, packet loss rate, transmission delay, CPU usage and memory usage, and the first window adjustment value, transmission delay, signal strength and packet loss rate are added to the image data packet; the receiver is also configured to generate a second window adjustment value according to the received packet loss rate, transmission delay, signal strength, CPU usage and memory usage of the receiver when the first window adjustment value is set in the image data packet; if the window adjustment directions indicated by the first window adjustment value and the second window adjustment value are inconsistent, the adjustment of the receiving window is rejected; the window adjustment direction includes increasing the receiving window and decreasing the receiving window; if the window adjustment directions indicated by the first window adjustment value and the second window adjustment value are consistent, a window adjustment average value is calculated according to the first window adjustment value and the second window adjustment value; the receiving window is adjusted according to the window adjustment average value.

3. The data transmission system of claim 2, wherein, The receiver is also configured to extract the GPS coordinates attached to the images successfully sent in a preset period; each GPS coordinate is converted into a plane coordinate by UTM projection, and the corresponding plane coordinates are sorted according to the image acquisition time of each image to generate a set of continuous path points; Calculate the direction angle of each sub-path formed by each adjacent path point in the continuous path point set, and calculate the difference value of adjacent direction angles; Determine the current operation mode according to the difference value of each adjacent direction angle; According to the current operation mode, the predicted coordinates of the geographic area corresponding to the image to be applied by the hand book are generated; According to the predicted coordinates, the image corresponding to the geographic area is collected and stored in advance.

4. The data transmission system of claim 3, wherein, The receiver determines the current operation mode according to the difference value of each adjacent direction angle, including: If the difference value of all adjacent direction angles is less than a preset angle value, the current operation mode is determined to be a straight line type operation mode; If there are more than a preset number of 90° turns in the difference value of adjacent direction angles, the current operation mode is a grid type operation mode.

5. The data transmission system of claim 4, wherein, The receiver generates the predicted coordinates of the geographic area corresponding to the image to be applied by the hand book according to the current operation mode, including: In the case where the current operation mode is a straight line type operation mode, a straight line path is generated by straight line fitting according to the continuous path point set; and the predicted coordinates are determined according to the average moving distance along the direction of the straight line path. In the case where the current operation mode is a grid type operation mode, the next target grid is determined according to the traversal order of the grid when the continuous path point set is collecting images and the current grid, and the center coordinates of the next target grid are taken as the predicted coordinates.

6. The data transmission system of claim 5, wherein, The receiver is also configured to feed back a response image data packet to the hand book after receiving each application image data packet; the response image data packet is provided with the sequence number of the last image data packet successfully sent by the receiver; The hand book is also configured to update the received sequence number to the sequence number of the last image data packet successfully sent by the receiver in the response image data packet after receiving the response image data packet.

7. The data transmission system of claim 6, wherein, The hand book is also configured to send an application message data packet to the receiver; the application message data packet is provided with a message type to be applied, including positioning information or attitude information; The receiver is also configured to extract the corresponding information according to the message type, generate a message data packet according to the extracted information, and transmit the message data packet to the hand book.

8. The data transmission system of claim 7, wherein, The hand book is also configured to send a query characteristic data packet to the receiver before sending the application image data packet to the receiver; The receiver is also configured to feed back a response query characteristic data packet to the hand book after receiving the query characteristic data packet; the response query characteristic data packet is provided with the camera number of the camera provided in the receiver.

9. The data transmission system of claim 8, wherein, The hand book is also configured to extract the camera number corresponding to the image, the image collection time, the image width, the image height, the image encoding, the display angle corresponding to the image, and the image data size from the image data packet after receiving the image data packet; Generate an image storage data packet according to the camera number, the image collection time, the image width, the image height, the image encoding, the display angle corresponding to the image, and the image data size, and store the image storage data packet.

10. The data transmission system of claim 9, wherein, The hand book is also used for determining the message type in the message data packet after receiving the message data packet; If the message type is attitude information, extracting attitude information collection time, attitude angle and attitude angle evaluation error from the message data packet; According to the attitude information collection time, attitude angle and attitude angle evaluation error, generating a whole machine attitude storage data packet, and storing the whole machine attitude storage data packet; If the message type is positioning information, extracting positioning information collection time, phase center coordinates, coordinate evaluation error and solution state from the message data packet; According to the positioning information collection time, phase center coordinates, coordinate evaluation error and solution state, generating a positioning information storage data packet, and storing the positioning information storage data packet.

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