Meteorological observation image transmission method based on Beidou communication

Abstract

The invention discloses a meteorological observation image transmission method based on Beidou communication, and relates to the field of image transmission, and the method employs an H.266 video compression algorithm to compress meteorological observation images, and carries out the intra-frame compression of a first meteorological observation image and the intra-frame compression of a second meteorological observation image. Inter-frame compression is performed on the basis of the stored reference compression frame from the second meteorological observation image, and the meteorological center station can decode the meteorological observation image only by transmitting the difference data between the meteorological observation image and the reference compression frame and the image identifier of the corresponding reference compression frame to the meteorological center station. Therefore, the data transmission quantity of each meteorological observation image is greatly reduced, the time consumed for transmitting the meteorological observation image to the meteorological center station through the Beidou communication technology is reduced, and the transmission efficiency of the meteorological observation image is improved.

Description

Technical Field

[0001] This application relates to the field of image transmission, and in particular to a method for transmitting meteorological observation images based on BeiDou communication. Background Technology

[0002] An automatic weather station is a device that can automatically observe and store meteorological data. Automatic weather stations installed in the field need to take meteorological observation images at regular intervals according to observation needs and upload the meteorological observation images to a remote server for unified monitoring.

[0003] When automatic weather stations are installed in uninhabited environments such as deserts, 4G communication is often unavailable. In such cases, BeiDou short message communication can be considered for transmitting meteorological observation images. However, BeiDou communication transmits images at a frequency of only one minute, typically once per minute, with each transmission carrying a maximum of several hundred bytes. For example, the latest civilian BeiDou communication transmits a maximum of 240 bytes per transmission. A meteorological observation image stored in JPEG format with a resolution of 1920*1080p typically occupies 1000KB. Even with the most advanced image compression algorithms, the compressed image, while maintaining legibility, is only about 40KB to 90KB. Transmitting this image via BeiDou short message communication would still take 200 to 500 minutes, resulting in low transmission efficiency. Summary of the Invention

[0004] This application addresses the aforementioned problems and technical requirements by proposing a meteorological observation image transmission method based on BeiDou communication. The technical solution of this application is as follows: A meteorological observation image transmission method based on BeiDou communication, the meteorological observation image transmission method includes: Automatic weather station acquires the i-th meteorological observation image S i The initial value of the integer parameter i is 1; When i=1, the automatic weather station uses the intra-frame compression mechanism in the H.266 video compression algorithm to compress the i-th meteorological observation image S. i Compressed frame data K is obtained by compression encoding. i And the currently obtained compressed frame data K i Directly used as the i-th compressed frame F i With the i-th meteorological observation image S i The image identifiers are stored accordingly; the automatic weather station encapsulates the i-th set of data to be transmitted into a BeiDou data packet and transmits it to the meteorological center station via BeiDou communication technology. The i-th set of data to be transmitted carries the i-th meteorological observation image S. i Image identifiers and compressed frame data K i The meteorological center station decodes the received BeiDou data packets to obtain the i-th meteorological observation image S.i ; When i>1, the automatic weather station uses the inter-frame compression mechanism in the H.266 video compression algorithm based on the i-th meteorological observation image S. i Reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i Compressed frame data K i Characterizing the i-th meteorological observation image S i Compared with its reference compressed frame S i_ref The data differences between them can be referenced in compressed frame S. i_ref It is the i-1 compressed frames that are already stored and the i-th meteorological observation image S. i The acquisition status is matched and the i-th meteorological observation image S i The compressed frame obtained through compression encoding occupies the fewest bytes; the automatic weather station also utilizes the inter-frame compression mechanism in the H.266 video compression algorithm to compress the frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i And the i-th meteorological observation image S i The image identifiers are stored accordingly. The automatic weather station encapsulates the i-th set of data to be transmitted into a BeiDou data packet and transmits it to the meteorological center station via BeiDou communication technology. The i-th set of data to be transmitted carries the i-th meteorological observation image S. i Image identifier, reference compressed frame S i_ref Image identifiers and compressed frame data K i The meteorological center station decodes the received BeiDou data packets to obtain the i-th meteorological observation image S. i .

[0005] A further technical solution involves utilizing the inter-frame compression mechanism in the H.266 video compression algorithm based on the reference compressed frame S. i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i include: Select the image that matches the i-th meteorological observation image S from the stored i-1 compressed frames. i Several compressed frames that match the acquisition status are used as candidate frames; When there is only one candidate frame, the selected candidate frame is directly used as the reference compressed frame S. i_ref And using the inter-frame compression mechanism in the H.266 video compression algorithm based on the reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i ; When there are multiple candidate frames, the inter-frame compression mechanism in the H.266 video compression algorithm is used to compress the i-th meteorological observation image S based on each candidate frame. i Compression encoding yields multiple candidate results. The candidate frame with the fewest bytes is selected as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i .

[0006] Its further technical solution is that any i-th meteorological observation image S i Image identifiers are used to identify the i-th meteorological observation image S. i The collection timestamp includes the collection date (Day). i And the time of collection within the natural day of the collection date. i ; Select the image that matches the i-th meteorological observation image S from the stored i-1 compressed frames. i Several compressed frames matched to the acquisition status are selected as candidate frames, including: The acquisition timestamp of each compressed frame is determined based on the image identifier corresponding to each stored compressed frame. The acquisition date and the corresponding meteorological observation image S are then selected from the (i-1) stored compressed frames. i Collection date Day i The interval does not exceed the maximum natural day interval, and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i Consistent compressed frames are used as candidate frames; If the collected date and the i-th meteorological observation image S are not present in the already stored i-1 compressed frames i Collection date Day i The interval does not exceed the maximum natural day interval and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i When compressing frames consistently, select the i-th meteorological observation image S. i The compressed frames from the most recent acquisition times preceding the acquisition time are used as candidate frames.

[0007] A further technical solution is to obtain a reference compressed frame S when there are multiple candidate frames. i_ref And compressed frame data K i include: Using the inter-frame compression mechanism in the H.266 video compression algorithm, the i-th meteorological observation image S is compressed based on each candidate frame. i Compression encoding is performed to obtain P-frame candidate results, which represent the i-th meteorological observation image S. i The data difference between the current frame and the corresponding candidate frame; Multiple candidate frames are combined pairwise to obtain several candidate frame combinations. Then, the inter-frame compression mechanism in the H.266 video compression algorithm is used to compress the i-th meteorological observation image S based on each candidate frame combination. i Compression encoding is performed to obtain B-frame candidate results, which represent the i-th meteorological observation image S. i The data difference between the two candidate frames in the corresponding candidate frame combination; The candidate frame corresponding to the candidate result with the fewest bytes among all P-frame candidate results and all B-frame candidate results is used as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i When the candidate result with the fewest bytes belongs to the P-frame candidate results, the obtained reference compressed frame S is... i_ref This includes a candidate frame corresponding to the P-frame candidate result; when the candidate result with the fewest bytes belongs to the B-frame candidate result, the resulting reference compressed frame S is... i_ref This includes two candidate frames from a candidate frame combination corresponding to the B-frame candidate result.

[0008] A further technical solution involves encapsulating the i-th group of data to be transmitted into a BeiDou data packet, including: When i=1, the data packet type of the i-th group of data to be transmitted is determined to be a keyframe type; when i>1 and the i-th group of data to be transmitted carries compressed frame data K... i When it belongs to the P-frame candidate results, the data packet type of the i-th group of data to be transmitted is determined to be a non-critical P-frame type; when i>1 and the i-th group of data to be transmitted carries compressed frame data K i When the result belongs to the B-frame candidate result, the data packet type of the i-th group of data to be transmitted is determined to be a non-critical B-frame type. According to the data packet format matching the data packet type of the i-th group of data to be transmitted, and based on the maximum number of bytes transmitted in a single transmission using BeiDou communication technology, the i-th group of data to be transmitted is divided into packets and encapsulated to obtain multiple BeiDou data packets.

[0009] A further technical solution is that when the data packet type of the i-th group of data to be transmitted is a keyframe type, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the keyframe type includes, in sequence, a type field, a frame identifier field, a packet number field, a total packet number field, and a data field, wherein: the type field carries the type identifier corresponding to the keyframe type, and the frame identifier field carries the i-th meteorological observation image S i The image identifier, packet number field carries the packet number of the BeiDou data packet, total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and data field carries the compressed frame data K. iA corresponding local data segment; When the data packet type of the i-th group of data to be transmitted is a non-critical frame type of P-frame, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the non-critical frame type of P-frame includes, in sequence, a type field, a current frame identifier field, a reference identifier field, a packet number field, a total packet number field, and a data field. Among them, the type field carries the type identifier corresponding to the non-critical frame type of P-frame, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the reference identifier field carries the reference compressed frame S i_ref The image identifier, packet number field carries the packet number of the BeiDou data packet, total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and data field carries the compressed frame data K. i A corresponding local data segment; When the data packet type of the i-th group of data to be transmitted is a non-critical frame type of B-frame, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the non-critical frame type of B-frame includes, in sequence, a type field, a current frame identifier field, a first reference identifier field, a second reference identifier field, a packet number field, a total packet number field, and a data field. The type field carries the type identifier corresponding to the non-critical frame type of B-frame, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the first reference identifier field carries a reference compressed frame S i_ref The image identifier, the second reference identifier field carries another reference compressed frame S i_ref The image identifier, packet number field carries the packet number of the BeiDou data packet, total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and data field carries the compressed frame data K. i A corresponding local data segment.

[0010] A further technical solution involves the meteorological center station decoding the received BeiDou data packets to obtain the i-th meteorological observation image S. i ,include: The received BeiDou data packets are parsed to obtain the type identifier carried in the type field, and the data packet type corresponding to the type identifier is determined. When the data packet type corresponding to the type identifier is determined to be a keyframe type, the received BeiDou data packet is parsed according to the data packet format matching the keyframe type to obtain the i-th meteorological observation image S. i The image identifier, the packet number of the BeiDou data packet, the total number of BeiDou data packets, and the local data segments are used to carry the i-th meteorological observation image S. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers.i The compressed frame data K i Directly used as the i-th compressed frame F i For the i-th compressed frame F i Decoding yields the i-th meteorological observation image S i And compress the i-th frame F i With the i-th meteorological observation image S i The image identifier is stored accordingly; When the data packet type corresponding to the type identifier is determined to be either a P-frame non-critical frame type or a B-frame non-critical frame type, the received BeiDou data packet is parsed according to the data packet format matching the data packet type to obtain the i-th meteorological observation image S. i The image identifier, the image identifier of the reference compressed frame, the packet number of the BeiDou data packet, the total number of BeiDou data packets, and the local data segments are used to carry the i-th meteorological observation image S. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers. i ; Retrieve the compressed frame corresponding to the image identifier of the reference compressed frame from the already stored compressed frames as the reference compressed frame S. i_ref Using the inter-frame compression mechanism in the H.266 video compression algorithm, based on the compressed frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i For the i-th compressed frame F i Decoding yields the i-th meteorological observation image S i And compress the i-th frame F i With the i-th meteorological observation image S i The image identifier is stored accordingly.

[0011] A further technical solution involves dividing and encapsulating the i-th group of data to be transmitted into multiple BeiDou data packets based on the data packet type matching the data packet format of the i-th group of data to be transmitted and the maximum number of bytes transmitted in a single transmission using BeiDou communication technology. These packets include: Based on the number of bytes occupied by fields other than the data field in the data packet format that match the data packet type of the i-th group of data to be transmitted, the number of bytes occupied by the data field is determined according to the maximum number of bytes transmitted in a single transmission using BeiDou communication technology. The compressed frame data K is then compressed according to the number of bytes occupied by the data field. i The data is divided into multiple local data segments, and each local data segment is sequentially encapsulated into different BeiDou data packets according to the packet number. In the data packet format for keyframe type matching, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; in the data packet format for non-keyframe P-frames, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the reference identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; in the data packet format for non-keyframe B-frames, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the first reference identifier field occupies 26 bits, the second reference identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; and the image identifier for each meteorological observation image is the number of minutes between the meteorological observation image acquisition timestamp and the predetermined start timestamp.

[0012] Further technical solutions include: the meteorological observation image transmission method also includes: The meteorological center station receives the i-th meteorological observation image S within the predetermined time period. i When the number of BeiDou data packets identified by the image identifier does not reach the total number of BeiDou data packets, a meteorological observation image S carrying the i-th image is sent to the automatic weather station. i The image identification supplementary transmission instruction shall not exceed the maximum number of bytes transmitted in a single transmission using BeiDou communication technology. The automatic weather station will carry the i-th meteorological observation image S according to the received retransmission command. i The BeiDou data packet obtained by encapsulating the i-th group of data to be transmitted from the image identifier is resent to the meteorological center station.

[0013] A further technical solution is that the retransmission command includes a command type field, a current frame identifier field, a total packet digital field, and a data field. The command type field carries the retransmission command identifier, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the total packet digital field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data packets to be transmitted, and the data field carries a binary receive status code stream. The total number of bits in the receive status code stream is consistent with the total number of packets. When any m-th bit in the receive status code stream is 1, it indicates that the BeiDou data packet with the m-th packet number obtained by encapsulating the i-th group of data packets to be transmitted has been received. When any m-th bit in the receive status code stream is 0, it indicates that the BeiDou data packet with the m-th packet number obtained by encapsulating the i-th group of data packets to be transmitted has not been received. The automatic weather station will carry the i-th meteorological observation image S according to the received retransmission command. i The BeiDou data packet obtained by encapsulating the i-th group of data to be transmitted from the image identifier and resending it to the meteorological center station includes: Parsing the retransmission command yields the retransmission command identifier and the i-th meteorological observation image S. i The image identifier and total number of packets are used to parse the received status code stream based on the total number of packets, and the i-th meteorological observation image S is then used. i In the BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted from the image identifier, the BeiDou data packet containing the packet number corresponding to the bit that is 0 in the receiving status code stream is resent to the meteorological center station.

[0014] The beneficial technical effects of this application are: This application discloses a meteorological observation image transmission method based on BeiDou communication. This method uses the H.266 video compression algorithm for image compression. Intra-frame compression is performed on the first meteorological observation image, and inter-frame compression is performed based on the stored reference compressed frames starting from the second meteorological observation image. Only the difference data between the meteorological observation image and the reference compressed frame and the image identifier of the corresponding reference compressed frame need to be transmitted to the meteorological center station. The meteorological center station can then decode the meteorological observation image. Therefore, the amount of data transmitted for each meteorological observation image is greatly reduced, the time spent transmitting meteorological observation images to the meteorological center station via BeiDou communication technology is reduced, and the transmission efficiency of meteorological observation images is improved.

[0015] To address the characteristics of meteorological observation images collected by automatic weather stations, which exhibit minimal changes and significant acquisition intervals, this method adaptively designs the selection of reference compression frames. It uniformly selects previously stored compressed frames under the same acquisition state as reference compression frames, avoiding decoding delays caused by selecting frames from later periods. In practical implementation, considering the similarity of background scenes and illumination levels within the same time period and at the same acquisition time, the method uses the acquisition timestamp as a filtering criterion to initially screen candidate frames with the same acquisition state. Further calculations determine the reference compression frame and the compressed frame data that achieve the optimal compression effect, further optimizing compression efficiency and improving data transmission efficiency.

[0016] The meteorological center station can retransmit data by sending retransmission commands. These commands use different bit values ​​in the received status code stream to indicate the reception status of different BeiDou data packets. This allows automatic weather stations to retransmit only the BeiDou data packets that failed to be received, improving retransmission efficiency. Since the retransmission command does not exceed the maximum number of bytes in a single transmission, packetized transmission is unnecessary, enabling the meteorological center station to handle BeiDou image transmissions from dozens of automatic weather stations.

[0017] Automatic weather stations do not require specialized image encoding chips such as GPUs; they only need to use CPUs for calculations. This allows them to be used on low-end ARM processors, reducing energy consumption requirements and enabling their application in outdoor solar-powered scenarios. They are therefore very suitable for automatic weather station applications. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a meteorological observation image transmission method in one embodiment of this application.

[0019] Figure 2 This is a flowchart of a method for obtaining compressed frame data in one embodiment.

[0020] Figure 3 This is a diagram illustrating the fields included in the data packet format for matching different data packet types.

[0021] Figure 4 This is a diagram illustrating the fields included in the retransmission instruction. Detailed Implementation

[0022] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0023] To improve the data transmission efficiency of meteorological observation images reported by automatic weather stations based on BeiDou communication technology, this application provides a meteorological observation image transmission method based on BeiDou communication, including the following steps, please refer to... Figure 1 The flowchart shown: Step 110: The automatic weather station acquires the i-th meteorological observation image S. i The initial value of the integer parameter i is 1. This application targets an automatic weather station installed in the field that transmits data with a meteorological center station based on BeiDou communication technology. The installed automatic weather station takes meteorological observation images at regular intervals facing a fixed direction, and its image acquisition has the following characteristics: (1) The meteorological observation images collected by automatic weather stations are mainly used to monitor changes in the field environment. Therefore, the differences between the collected meteorological observation images are not too great. Usually, there are changes such as changes in light, water ripples, slight swaying of tree branches, and moving objects, while fixed objects such as valleys and fields will not change much.

[0024] (2) Automatic weather stations do not acquire meteorological observation images at the same frequency as other monitoring scenarios. In traditional security scenarios, the frame rate may reach 24 frames per second or even higher, but automatic weather stations acquire meteorological observation images at a very low frequency, usually only acquiring one meteorological observation image every few hours.

[0025] To improve the transmission efficiency of meteorological observation images, this application applies the H.266 video compression algorithm from the video field to the application scenario for image compression. H.266 is a new generation of video coding standard, also known as VVC (Versatile Video Coding), which has higher compression efficiency than the previous H.265 / HEVC.

[0026] Step 120: When i=1, that is, for the first meteorological observation image S1, the automatic weather station uses the intra-frame compression mechanism in the H.266 video compression algorithm to compress the i-th meteorological observation image S1. i Compressed frame data K is obtained by compression encoding. i The method used in this step to compress and encode the first meteorological observation image S1 using an intra-frame compression mechanism is the same as the method used by the H.266 video compression algorithm to obtain I-frames, and will not be described in detail here.

[0027] The automatic weather station obtains compressed frame data K of the first meteorological observation image S1. i On the one hand, the currently obtained compressed frame data K i Directly used as the i-th compressed frame F i And compress the i-th frame F i With the i-th meteorological observation image S i The image identifiers are stored for use in subsequent image compression processes. On the other hand, the automatic weather station stores the i-th meteorological observation image S. i Image identifiers and compressed frame data K i The data is packaged into the i-th group to be transmitted, and then encapsulated into a BeiDou data packet before being transmitted to the meteorological center station via BeiDou communication technology. The meteorological center station decodes the received BeiDou data packet to obtain the i-th meteorological observation image S. i .

[0028] Step 130: When i > 1, that is, starting from the second meteorological observation image, the automatic weather station has already stored the first i-1 compressed frames. The automatic weather station uses the inter-frame compression mechanism in the H.266 video compression algorithm based on the i-th meteorological observation image S. i Reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i .

[0029] Among them, the compressed frame data K i It does not include the i-th meteorological observation image S i The full dataset, but only used to characterize the i-th meteorological observation image S. i Compared with its reference compressed frame S i_refDue to the data differences between the images, inter-frame compression is more efficient than intra-frame compression. In this application, intra-frame compression is used only for the first meteorological observation image, while inter-frame compression is used for subsequent meteorological observation images to ensure high compression efficiency. In one embodiment, the compressed frame data obtained by intra-frame compression of the first meteorological observation image occupies 40K~90K bytes, while the compressed frame data obtained by inter-frame compression of the other i-th meteorological observation images occupies 4K~20K bytes. Starting from the second meteorological observation image, the data size of the compressed frame data is greatly reduced, thereby improving transmission efficiency. The specific implementation of the intra-frame compression mechanism and inter-frame compression mechanism is based on the algorithm principle of H.266 video compression. The data differences here include motion vectors and prediction errors, which will not be elaborated on in this application.

[0030] When i>1, obtain the compressed frame data K. i Subsequently, the automatic weather station, on the one hand, invokes the inter-frame compression mechanism in the H.266 video compression algorithm, based on the compressed frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i Then, in the automatic weather station, the i-th compressed frame F i With the i-th meteorological observation image S i The image identifiers are stored for subsequent image compression. On the other hand, the automatic weather station stores the corresponding identifiers for the i-th meteorological observation image S. i Image identifier, reference compressed frame S i_ref Image identifiers, compressed frame data K i The i-th group of data to be transmitted is packaged and encapsulated into a BeiDou data packet, which is then transmitted to the meteorological center station via BeiDou communication technology. The meteorological center station decodes the received BeiDou data packet to obtain the i-th meteorological observation image S. i .

[0031] As can be seen from the above, the first meteorological observation image can only be compressed intra-frame, so the compressible space is relatively limited. Therefore, the compressed frame data K obtained after compressing and encoding the first meteorological observation image is... i The amount of data is still relatively large. Starting with the second meteorological observation image, inter-frame compression can be used. However, different reference compression frames result in different compressed frame data, leading to varying compression effects on the second meteorological observation image. Therefore, to maximize compression efficiency and thus improve data transmission efficiency, this application selects the i-th meteorological observation image S... i Reference compressed frame S i_ref It is among the i-1 compressed frames already stored in the automatic weather station that make the compressed frame data K i The compression effect achieves optimal compressed frames.

[0032] The classic H.266 video compression algorithm employs two inter-frame compression mechanisms. These mechanisms compress and encode the current video frame into P-frames (Predicted Frames) and B-frames (Bi-directionally Predicted Frames) based on reference frames. In the video domain, the method for selecting reference frames in these two inter-frame compression mechanisms is as follows: when defining a P-frame, the most recent I-frame or P-frame preceding the current video frame is used as the reference frame. When defining a B-frame, the I-frame or P-frame preceding the current video frame plus the I-frame or P-frame following the current video frame are used as the two reference frames.

[0033] If this application directly uses the method of selecting reference frames in the above video scene to select the i-th meteorological observation image S i Reference compressed frame S i_ref This would present the following problem: Since only the first compressed frame in this application is an I-frame, as the acquisition process progresses, the i-th meteorological observation image S... i The time interval between the acquisition timestamp of the first image and the acquisition timestamp of the first compressed frame will become increasingly larger. This larger time interval will cause the i-th meteorological observation image S to... i Significant data discrepancies can arise from acquisition conditions completely different from the first compressed frame. For example, the first compressed frame was acquired in summer, while the i-th meteorological observation image S... i The data was collected in winter, and due to seasonal changes, there would be snow cover, resulting in the i-th meteorological observation image S being... i The data differs significantly from that in the first compressed frame. In reality, because the acquisition time interval between two adjacent meteorological observation images in this application scenario is typically large, the i-th meteorological observation image S... i The previous meteorological image is also relatively large, for example, there will be an interval of several hours. This time interval will also affect the i-th meteorological image S. i The data differs significantly from the previous meteorological observation image due to different acquisition conditions; for example, the i-th meteorological observation image S... i The image was captured at night, but the previous meteorological observation image was captured during the day. The difference in illumination caused by the change in time will also lead to a large difference in the captured pixels. Therefore, the practice of always selecting the nearest I-frame or P-frame in traditional video scenarios is not applicable in this application scenario.

[0034] Furthermore, the H.266 video compression algorithm, when used in video scenarios, selects reference frames before and after the current video frame when defining B-frames. This means that after receiving a B-frame, the receiving end must wait for the subsequent reference frames to arrive before decoding. Since the video frame rate is high (e.g., 24 images captured per second), this delay might only be 1 / 24 of a second, imperceptible to the human eye, and therefore has no impact on visual presentation. However, in the scenario described in this application, the acquisition frequency of meteorological observation images is low. Combined with the time required for each meteorological observation image to be transmitted to the meteorological center station via BeiDou communication technology, this delay can last for several hours, making it unsuitable for use as in video scenarios.

[0035] Therefore, in order to adapt to the application scenario of this application, the following two adaptive modifications were made when applying the H.266 video compression algorithm to the meteorological observation image compression encoding scenario of this application: (1) In the i-th meteorological observation image S i Select the reference compressed frame S from the previously obtained i-1 compressed frames. i_ref (2) It does not always default to selecting the i-th meteorological observation image S. i Instead of using the most recent I-frame or P-frame as the reference compressed frame, the reference compressed frame and the compressed frame data K are determined based on specific calculation results. i .

[0036] Therefore, it is necessary to calculate the compression effect when different compressed frames are selected as reference compressed frames. In order to improve the efficiency of this process, the following step 210 is performed first: Step 210: Select the image that matches the i-th meteorological observation image S from the (i-1)-th compressed frame that is already stored. i Several compressed frames matching the acquisition status are used as candidate frames. Please combine them with... Figure 2 The flowchart shown.

[0037] That is, the (i-1) already stored compressed frames are initially screened to identify the compressed frames that may result in better compression performance as candidate frames. As mentioned above, to ensure that the reference compressed frame has a good compression effect, the i-th meteorological observation image S should be compressed as much as possible. i The background difference between the image and the reference compressed frame is small, but a larger date span can lead to greater background differences due to seasonal changes and building alterations. Variations in illumination at different times within the same day can also cause significant pixel differences in a fixed background. Therefore, based on the above analysis, the following method is used to filter out images with similar backgrounds to the i-th meteorological observation image S. i Several candidate frames matching the acquisition state include: (1) Determine the i-th meteorological observation image S i The collection timestamp includes the collection date (Day).i And the time of collection within the natural day of the collection date. i For example, in one instance, the i-th meteorological observation image S i The data collection timestamp is 18:00 on October 1, 2025, then the data collection date is Day. i The data collection time is October 1, 2025. i It is 18:00.

[0038] (2) In addition, in this embodiment, any i-th meteorological observation image S is defined. i The image identifier is used to identify the i-th meteorological observation image S. i If the data collection timestamp is obtained, the automatic weather station can determine the collection timestamp of each compressed frame by querying the image identifiers of the stored i-1 compressed frames. Then, it can filter out the meteorological observation image S with the collection date from the stored i-1 compressed frames. i Collection date Day i The interval does not exceed the maximum natural day interval, and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i Consistent compressed frames are used as candidate frames.

[0039] The maximum natural day interval here can be customized, generally set to 10-15 days to ensure that the time span is not too large, while the same collection time ensures similar illumination. For example, when the maximum natural day interval is set to 15 days, based on the above example, compressed frames collected at 18:00 within 15 natural days before October 1, 2025 are selected as candidate frames.

[0040] (3) When the collected date and the i-th meteorological observation image S do not exist in the i-1 compressed frames that have already been stored i Collection date Day i The interval does not exceed the maximum natural day interval, and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i When there is consistent frame compression, such as in the first few days of data collection, the i-th meteorological observation image S is selected. i The candidate frames are the compressed frames from the most recent acquisition times preceding the acquisition time. That is, this application prioritizes the compressed frames from the same acquisition time on adjacent natural days as candidate frames, and then selects the compressed frames from the most recent acquisition times as candidate frames.

[0041] In this case, when the i-th meteorological observation image S iWhen there is only one compressed frame from a previous acquisition time, i.e., when the i-th meteorological observation image is the second meteorological observation image acquired at the second acquisition time on the first acquisition date, the first meteorological observation image is directly selected as the candidate frame. However, when the i-th meteorological observation image S... i When there are multiple compressed frames from previous acquisition times, that is, starting from the third meteorological observation image acquired at the third acquisition time of the first acquisition date, the i-th meteorological observation image S is selected. i The most recent compressed frames from the acquisition time before the acquisition time are used as candidate frames, and the specific number of candidate frames can be customized.

[0042] Step 220: When there is only one candidate frame, the selected candidate frame is directly used as the reference compressed frame S. i_ref And using the inter-frame compression mechanism in the H.266 video compression algorithm based on this reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i In a single reference compressed frame S i_ref At that time, compression encoding is performed according to the inter-frame compression mechanism of P-frames defined by the H.266 video compression algorithm. The specific encoding principle will not be elaborated here.

[0043] Step 230: When there are multiple candidate frames, it is necessary to specifically determine which one or two candidate frames to select as the reference compressed frame S. i_ref First, the inter-frame compression mechanism in the H.266 video compression algorithm is used to compress the i-th meteorological observation image S based on each candidate frame. i Compressed encoding is performed to obtain candidate results, and then the candidate frame with the fewest bytes is used as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i The reference compressed frame S selected in this way i_ref This refers to the compressed frame that achieves the optimal compression effect, and the corresponding compressed frame data K. i It refers to the compressed frame data with the best compression effect.

[0044] As mentioned above, the H.266 video compression algorithm has two inter-frame compression mechanisms to produce P-frames and B-frames respectively. Both inter-frame compression mechanisms are applicable when there are at least two candidate frames, therefore including: (1) Using the inter-frame compression mechanism of P-frame defined in the H.266 video compression algorithm, the i-th meteorological observation image S is compressed based on each candidate frame. i Compression encoding is performed to obtain P-frame candidate results, which represent the i-th meteorological observation image S.i The data difference between the corresponding candidate frame and the frame.

[0045] (2) Combine multiple candidate frames in pairs to obtain several candidate frame combinations. Use the inter-frame compression mechanism of B-frames defined in the H.266 video compression algorithm to compress the i-th meteorological observation image S based on each candidate frame combination. i Compression encoding is performed to obtain B-frame candidate results, which represent the i-th meteorological observation image S. i The data difference between the two candidate frames in the corresponding candidate frame combination. It should be noted that although the two candidate frames selected in this embodiment are forward compressed frames, which are different from the traditional B-frame definition, the algorithm principle of the inter-frame compression mechanism is similar, and the specific encoding principle will not be elaborated here.

[0046] (3) Take the candidate frame corresponding to the candidate result with the fewest bytes among all P-frame candidate results and all B-frame candidate results as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i .

[0047] The candidate result with the fewest bytes selected in this way may belong to either the P-frame candidate result or the B-frame candidate result: when the candidate result with the fewest bytes belongs to the P-frame candidate result, the obtained reference compressed frame S... i_ref This includes a candidate frame corresponding to a P-frame candidate result. When the candidate result with the fewest bytes belongs to a B-frame candidate result, the resulting reference compressed frame S is... i_ref This includes two candidate frames from a candidate frame combination corresponding to the B-frame candidate result.

[0048] As can be seen from the above introduction, the first meteorological observation image can be decoded without the aid of a reference compressed frame, while from the second meteorological observation image onwards, a reference compressed frame is required for decoding. Based on the different compression encoding methods described above, the i-th meteorological observation image S... i Reference compressed frame S i_ref There are two possibilities: there may be one reference compressed frame or two reference compressed frames. This results in different data contents for the i-th set of data to be transmitted generated for different i-th meteorological observation images. To ensure that the meteorological center station can accurately decode the i-th meteorological observation image S... iCorrespondingly, the data packet format used when encapsulating the i-th group of data to be transmitted into a BeiDou data packet is also different. Therefore, it is necessary to encapsulate the i-th group of data to be transmitted according to the data packet format matching the data packet type of the i-th group of data to be transmitted. However, since the maximum number of bytes that can be transmitted in a single transmission of BeiDou communication technology is very limited, it is unlikely that any group of data to be transmitted can be transmitted using only one BeiDou data packet. Therefore, it is actually necessary to divide and encapsulate the i-th group of data to be transmitted into multiple BeiDou data packets according to the maximum number of bytes that can be transmitted in a single transmission of BeiDou communication technology. In fact, it is necessary to encapsulate the compressed frame data K in the i-th group of data to be transmitted. i The data is divided into multiple local segments, and different local segments are encapsulated into different BeiDou data packets. The different scenarios are described below: (1) When i=1, the i-th set of data to be transmitted generated for the i-th meteorological observation image carries the i-th meteorological observation image S. i Image identifiers and compressed frame data K i In this case, the data packet type of the i-th group of data to be transmitted is determined to be the key frame type.

[0049] In this scenario, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the keyframe type includes, in sequence, a type field, a current frame identifier field, a packet number field, a total packet number field, and a data field, such as... Figure 3 As shown in (a) above. Where: the type field carries the type identifier corresponding to the keyframe type, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, packet number field carries the packet number of each BeiDou data packet obtained from the sub-packet encapsulation, total packet number field carries the total number of BeiDou data packets obtained from the sub-packet encapsulation of the i-th group of data to be transmitted, and data field carries the compressed frame data K. i A corresponding local data segment.

[0050] In the data packet format for keyframe type matching, the number of bytes occupied by fields other than the data field is fixed. Therefore, based on the number of bytes occupied by other fields, the number of bytes occupied by the data field is determined according to the maximum number of bytes transmitted in a single transmission using BeiDou communication technology. Specifically: (a) The type field occupies 4 bits.

[0051] (b) The identifier field of this frame carries the i-th meteorological observation image S iAs mentioned above, the image identifier for each meteorological observation image is used to represent the acquisition timestamp of that meteorological observation image. However, to reduce the number of bits occupied by the image identifier, the acquisition timestamp is not directly used as the image identifier. Instead, the number of minutes between the acquisition timestamp of the meteorological observation image and a predetermined start timestamp is used as the image identifier. The predetermined start timestamp is a user-defined timestamp. Therefore, the image identifier for each meteorological observation image only needs to occupy 26 bits, so the identifier field of this frame occupies 26 bits.

[0052] (c) The package number field occupies 9 bits.

[0053] (d) The total number field occupies 9 bits.

[0054] The maximum number of bytes in each BeiDou data packet represents the maximum number of bytes transmitted in a single BeiDou communication transmission. Excluding the data field, all other fields occupy a total of 48 bits. The remaining bytes can be used to transmit the compressed frame data K. i .

[0055] Then, based on the number of bytes occupied by the data fields, the compressed frame data K is divided. i The data is divided into multiple local data segments, and each local data segment is sequentially encapsulated into different BeiDou data packets according to the packet number. For the multiple BeiDou data packets encapsulated in the i-th group of data to be transmitted, the content of the type field, the current frame identifier field, and the total packet number field are the same, while the packet number field and the data field are different.

[0056] The compressed frame data K of the actual first meteorological observation image i Typically, the data size is between 40K and 90K bytes, while the maximum number of bytes transmitted in a single transmission using BeiDou communication technology is usually around 200. Therefore, it is usually necessary to encapsulate it into approximately 200 to 500 BeiDou data packets.

[0057] (2) When i>1 and the compressed frame data K carried in the i-th group of data to be transmitted i When it belongs to the candidate results of P frames, the i-th group of data to be transmitted carries the i-th meteorological observation image S. i Image identifier, corresponding reference compressed frame S i_ref Image identifiers and compressed frame data K i In this case, the data packet type of the i-th group of data to be transmitted is determined to be a P-frame non-key frame type.

[0058] In one embodiment, the packet format for P-frame non-keyframe type matching includes a type field, a current frame identifier field, a reference identifier field, a packet number field, a total packet number field, and a data field, such as... Figure 3As shown in (b) above. Wherein: the type field carries the type identifier corresponding to the non-keyframe type of frame P, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the reference identifier field is used to carry the reference compressed frame S i_ref The image identifier, packet number field carries the packet number of each BeiDou data packet obtained from the sub-packet encapsulation, total packet number field carries the total number of BeiDou data packets obtained from the sub-packet encapsulation of the i-th group of data to be transmitted, and data field carries the compressed frame data K. i A corresponding local data segment.

[0059] Similarly, in the packet format of P-frame non-key frame type matching, the number of bytes occupied by other fields other than the data field is fixed. Likewise, the number of bytes occupied by each field is as follows: type field occupies 4 bits, current frame identifier field occupies 26 bits, reference identifier field occupies 26 bits, packet number field occupies 9 bits, and total packet number field occupies 9 bits.

[0060] The fields other than the data field occupy a total of 74 bits, and the remaining bytes can be used as the data field to transmit the compressed frame data K. i Then, based on the number of bytes occupied by the data fields, the compressed frame data K will be... i The data is divided into multiple local data segments, and each local data segment is sequentially encapsulated into different BeiDou data packets according to the packet number. For the multiple BeiDou data packets encapsulated in the i-th group of data to be transmitted, the content of the type field, the current frame identifier field, the reference identifier field, and the total packet number field are the same, while the packet number field and the data field are different.

[0061] (3) When i>1 and the compressed frame data K carried in the i-th group of data to be transmitted i When it belongs to the B-frame candidate results, the i-th group of data to be transmitted carries the i-th meteorological observation image S. i Image identifiers and corresponding two reference compressed frames S i_ref Image identifiers and compressed frame data K i In this case, the data packet type of the i-th group of data to be transmitted is determined to be a B-frame non-key frame type.

[0062] In one embodiment, the packet format for B-frame non-keyframe type matching includes a type field, a current frame identifier field, a first reference identifier field, a second reference identifier field, a packet number field, a total packet number field, and a data field, such as... Figure 3 As shown in (c) above. Wherein: the type field carries the type identifier corresponding to the non-keyframe type of frame B, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the first reference identifier field is used to carry a reference compressed frame S i_refThe image identifier, the second reference identifier field is used to carry another reference compressed frame S i_ref The image identifier, packet number field carries the packet number of each BeiDou data packet obtained from the sub-packet encapsulation, total packet number field carries the total number of BeiDou data packets obtained from the sub-packet encapsulation of the i-th group of data to be transmitted, and data field carries the compressed frame data K. i A corresponding local data segment.

[0063] Similarly, in the data packet format for B-frame non-key frame type matching, the number of bytes occupied by fields other than the data field is fixed. Likewise, the number of bytes occupied by each field is as follows: type field occupies 4 bits, current frame identifier field occupies 26 bits, first reference identifier field occupies 26 bits, second reference identifier field occupies 26 bits, packet number field occupies 9 bits, and total packet number field occupies 9 bits.

[0064] All fields other than the data field occupy a total of 100 bits, and the remaining bytes can be used as the data field to transmit the compressed frame data K. i Then, based on the number of bytes occupied by the data fields, the compressed frame data K will be... i The data is divided into multiple local data segments, and each local data segment is sequentially encapsulated into different BeiDou data packets according to the packet number. For the multiple BeiDou data packets encapsulated in the i-th group of data to be transmitted, the content of the type field, the current frame identifier field, the first reference identifier field, the second reference identifier field, and the total packet number field are the same, while the packet number field and the data field are different.

[0065] Starting from the second meteorological observation image, the compressed frame data K is obtained. i Typically, the data size is between 4K and 20K bytes, while the maximum number of bytes transmitted in a single transmission using BeiDou communication technology is usually 200 bytes. Therefore, it is usually necessary to encapsulate it into approximately 20 to 100 BeiDou data packets.

[0066] After the automatic weather station encapsulates the i-th group of data to be transmitted into multiple BeiDou data packets according to the above method, it sends each BeiDou data packet to the meteorological center station in sequence via BeiDou communication technology. Although the data packet formats matched by different data packet types are different, the first field in all three data packet formats is the type field and occupies 4 bits. Therefore, the meteorological center station can obtain the type identifier carried by the type field by parsing the first 4 bits of each BeiDou data packet received, and determine the data packet type indicated by the type identifier.

[0067] When the meteorological center determines that the data packet type corresponding to the type identifier is a keyframe type, it parses the received BeiDou data packet according to the data packet format matched by the keyframe type to obtain the i-th meteorological observation image S. iThe image identifier, the current BeiDou data packet number, the total number of packets, and the local data segment are then used. Then, the image S carrying the i-th meteorological observation image is processed. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers. i The compressed frame data K i Directly used as the i-th compressed frame F after decoding i For the i-th compressed frame F i Decompression yields the i-th meteorological observation image S i Additionally, the i-th compressed frame F will be... i With the i-th meteorological observation image S i The image identifiers are stored at the meteorological center station for subsequent decoding. For the i-th compressed frame F... i Decompression yields the i-th meteorological observation image S i For specific methods, please refer to existing methods related to the H.266 video compression algorithm; this application will not elaborate further on them.

[0068] When the meteorological center determines that the data packet type of the i-th group of data to be transmitted is a non-critical P-frame or a non-critical B-frame, it parses the received BeiDou data packet according to the data packet format that matches the data packet type to obtain the i-th meteorological observation image S. i Image identifier, reference compressed frame S i_ref The image identifier, the current BeiDou data packet number, the total number of packets, and the local data segment are then used to process the i-th meteorological observation image S. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers. i The meteorological center station retrieves the compressed frame corresponding to the image identifier of the reference compressed frame from the already stored compressed frames as the reference compressed frame S. i_ref Using the inter-frame compression mechanism in the H.266 video compression algorithm, based on the compressed frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i For the i-th compressed frame F i Decompression yields the i-th meteorological observation image S i Similarly, compress the i-th frame F i With the i-th meteorological observation image S i The corresponding image identifiers are stored at the meteorological center station for subsequent decoding.

[0069] During the transmission of BeiDou data packets from automatic weather stations to the meteorological center station, packet loss is inevitable. Therefore, to improve transmission reliability, the meteorological center station determines whether it has received all BeiDou data packets for the i-th group of data to be transmitted, based on the total number of packets in each BeiDou data packet. If the i-th meteorological observation image S is received within the predetermined time period... i If the number of BeiDou data packets identified by the image identifier does not reach the total number of BeiDou data packets, it is determined that all BeiDou data packets of the i-th group of data to be transmitted have not been received. Therefore, a meteorological observation image S carrying the i-th image will be sent to the automatic weather station. i The automatic weather station receives a retransmission instruction for the image identifier and retransmits the BeiDou data packet, encapsulated from the i-th group of data to be transmitted, back to the meteorological center station. The predetermined duration is customizable, for example, 12 hours, and the specific value is set according to actual operational needs.

[0070] The number of bytes occupied by this retransmission instruction does not exceed the maximum number of bytes transmitted in a single transmission using BeiDou communication technology, thus eliminating the need to packetize the retransmission instruction and allowing it to be transmitted in a single transmission. To improve retransmission efficiency, in one embodiment, such as Figure 4 As shown, the retransmission command includes a command type field, a current frame identifier field, a total packet number field, and a data field. The command type field carries the retransmission command identifier and occupies 4 bits. The current frame identifier field carries the i-th meteorological observation image S. i The image identifier occupies 26 bits. The total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted and occupies 9 bits. The data field carries a binary receive status code stream, the total number of bits of which is consistent with the total number of packets. When any m-th bit in the receive status code stream is 1, it indicates that the m-th packet number of the i-th group of data to be transmitted has been received. When any m-th bit in the receive status code stream is 0, it indicates that the m-th packet number of the i-th group of data to be transmitted has not been received. The instruction type field, the current frame identifier field, and the total packet number field occupy a total of 39 bits. Within the maximum number of bytes that can be transmitted in a single transmission of BeiDou communication technology, the remaining bytes can be used to transmit the receive status code stream. If the maximum number of bytes that can be transmitted in a single transmission is 200 bytes, then 195 bytes are left to be used to transmit the receive status code stream.

[0071] To save space, the length of the received status code stream is dynamically adjusted based on the total number of BeiDou data packets obtained from the encapsulation of the i-th group of data to be transmitted. This also dynamically adjusts the length of the entire retransmission instruction. For example, the first group of data to be transmitted has a larger number of bytes, while subsequent groups will have smaller byte counts due to compression. As mentioned above, the first group of data to be transmitted typically encapsulates 200–500 BeiDou data packets, thus occupying 200–500 bits of the received status code stream. Subsequent groups of data to be transmitted typically encapsulate 20–100 BeiDou data packets, occupying 20–100 bits of the received status code stream.

[0072] In the retransmission command, the number of bytes occupied by the command type field, the current frame identifier field, and the total packet number field are all fixed. Therefore, after receiving the retransmission command, the automatic weather station first parses the retransmission command identifier and the i-th meteorological observation image S according to the pre-set fixed number of bytes. i The image identifier and total number of packets are obtained, and then the data field of the received status code stream can be parsed according to the total number of packets indicating the total number of bits in the received status code stream to obtain the received status code stream. Then, it is only necessary to send the i-th meteorological observation image S to the data field. i In the BeiDou data packets encapsulated from the i-th group of data to be transmitted using the image identifier, the BeiDou data packet containing the packet number corresponding to the bit with a 0 in the receive status code stream is retransmitted to the meteorological center station. This eliminates the need to retransmit all BeiDou data packets, thus improving retransmission efficiency. For example, in one instance, if the parsed receive status code stream is 01111111011111110111, the automatic weather station only needs to retransmit the 1st, 9th, and 17th BeiDou data packets.

[0073] In addition, after receiving all the BeiDou data packets of the i-th group of data to be transmitted, the meteorological center station can also send the i-th meteorological observation image S to the automatic weather station. i The image identifier was successfully responded to.

[0074] The above descriptions are merely preferred embodiments of this application, and this application is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of this application should be considered to be included within the protection scope of this application.

Claims

1. A method for transmitting meteorological observation images based on BeiDou communication, characterized in that, The meteorological observation image transmission method includes: Automatic weather station acquires the i-th meteorological observation image S i The initial value of the integer parameter i is 1; When i=1, the automatic weather station uses the intra-frame compression mechanism in the H.266 video compression algorithm to compress the i-th meteorological observation image S. i Compressed frame data K is obtained by compression encoding. i And the currently obtained compressed frame data K i Directly used as the i-th compressed frame F i With the i-th meteorological observation image S i The image identifiers are stored accordingly; the automatic weather station encapsulates the i-th group of data to be transmitted into a BeiDou data packet and transmits it to the meteorological center station via BeiDou communication technology. The i-th group of data to be transmitted carries the i-th meteorological observation image S. i Image identifiers and compressed frame data K i The meteorological center station decodes the received BeiDou data packets to obtain the i-th meteorological observation image S. i ; When i>1, the automatic weather station uses the inter-frame compression mechanism in the H.266 video compression algorithm based on the i-th meteorological observation image S. i Reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i Compressed frame data K i Characterizing the i-th meteorological observation image S i Compared with its reference compressed frame S i_ref The data differences between them can be referenced in compressed frame S. i_ref It is the i-1 compressed frames that are already stored and the i-th meteorological observation image S. i The acquisition status is matched and the i-th meteorological observation image S i The compressed frame obtained through compression encoding occupies the fewest bytes; the automatic weather station also utilizes the inter-frame compression mechanism in the H.266 video compression algorithm to compress the frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i And the i-th meteorological observation image S i The image identifiers are stored accordingly. The automatic weather station encapsulates the i-th group of data to be transmitted into a BeiDou data packet and transmits it to the meteorological center station via BeiDou communication technology. The i-th group of data to be transmitted carries the i-th meteorological observation image S. i Image identifier, reference compressed frame S i_ref Image identifiers and compressed frame data K i The meteorological center station decodes the received BeiDou data packets to obtain the i-th meteorological observation image S. i .

2. The meteorological observation image transmission method according to claim 1, characterized in that, The inter-frame compression mechanism in the H.266 video compression algorithm is used based on the reference compressed frame S. i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i include: Select the image that matches the i-th meteorological observation image S from the stored i-1 compressed frames. i Several compressed frames that match the acquisition status are used as candidate frames; When there is only one candidate frame, the selected candidate frame is directly used as the reference compressed frame S. i_ref And using the inter-frame compression mechanism in the H.266 video compression algorithm based on the reference compressed frame S i_ref For the i-th meteorological observation image S i Compressed frame data K is obtained by compression encoding. i ; When there are multiple candidate frames, the inter-frame compression mechanism in the H.266 video compression algorithm is used to compress the i-th meteorological observation image S based on each candidate frame. i Compression encoding yields multiple candidate results. The candidate frame with the fewest bytes is selected as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i .

3. The meteorological observation image transmission method according to claim 2, characterized in that, Any i-th meteorological observation image S i Image identifiers are used to identify the i-th meteorological observation image S. i The collection timestamp includes the collection date (Day). i and the time of collection within the natural day of the collection date. i ; Select the image that matches the i-th meteorological observation image S from the stored i-1 compressed frames. i Several compressed frames matched to the acquisition status are selected as candidate frames, including: The acquisition timestamp of each compressed frame is determined based on the image identifier corresponding to each stored compressed frame. The acquisition date and the i-th meteorological observation image S are then selected from the (i-1) stored compressed frames. i Collection date Day i The interval does not exceed the maximum natural day interval, and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i Consistent compressed frames are used as candidate frames; If the collected date and the i-th meteorological observation image S are not present in the already stored i-1 compressed frames i Collection date Day i The interval does not exceed the maximum natural day interval and the acquisition time is the same as that of the i-th meteorological observation image S. i Time of data collection i When compressing frames consistently, select the i-th meteorological observation image S. i The compressed frames from the most recent acquisition times preceding the acquisition time are used as candidate frames.

4. The meteorological observation image transmission method according to claim 2, characterized in that, When there are multiple candidate frames, a reference compressed frame S is obtained. i_ref And compressed frame data K i include: Using the inter-frame compression mechanism in the H.266 video compression algorithm, the i-th meteorological observation image S is compressed based on each candidate frame. i Compression encoding is performed to obtain P-frame candidate results, which represent the i-th meteorological observation image S. i The data difference between the current frame and the corresponding candidate frame; Multiple candidate frames are combined pairwise to obtain several candidate frame combinations. Then, the inter-frame compression mechanism in the H.266 video compression algorithm is used to compress the i-th meteorological observation image S based on each candidate frame combination. i Compression encoding is performed to obtain B-frame candidate results, which represent the i-th meteorological observation image S. i The data difference between the two candidate frames in the corresponding candidate frame combination; The candidate frame corresponding to the candidate result with the fewest bytes among all P-frame candidate results and all B-frame candidate results is used as the reference compressed frame S. i_ref The corresponding candidate results are then used as the compressed frame data K. i When the candidate result with the fewest bytes belongs to the P-frame candidate results, the obtained reference compressed frame S is... i_ref This includes a candidate frame corresponding to the P-frame candidate result; when the candidate result with the fewest bytes belongs to the B-frame candidate result, the resulting reference compressed frame S is... i_ref This includes two candidate frames from a candidate frame combination corresponding to the B-frame candidate result.

5. The meteorological observation image transmission method according to claim 4, characterized in that, The i-th group of data to be transmitted is encapsulated into a BeiDou data packet, including: When i=1, the data packet type of the i-th group of data to be transmitted is determined to be a keyframe type; when i>1 and the i-th group of data to be transmitted carries compressed frame data K... i When it belongs to the P-frame candidate results, the data packet type of the i-th group of data to be transmitted is determined to be a non-critical P-frame type; when i>1 and the i-th group of data to be transmitted carries compressed frame data K i When the result belongs to the B-frame candidate result, the data packet type of the i-th group of data to be transmitted is determined to be a non-critical B-frame type. According to the data packet format matching the data packet type of the i-th group of data to be transmitted, and based on the maximum number of bytes transmitted in a single transmission using BeiDou communication technology, the i-th group of data to be transmitted is divided into packets and encapsulated to obtain multiple BeiDou data packets.

6. The meteorological observation image transmission method according to claim 5, characterized in that, When the data packet type of the i-th group of data to be transmitted is a keyframe type, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the keyframe type includes, in sequence, a type field, a frame identifier field, a packet number field, a total packet number field, and a data field. Among them, the type field carries the type identifier corresponding to the keyframe type, and the frame identifier field carries the i-th meteorological observation image S. i The image identifier, the packet number field carries the packet number of the BeiDou data packet, the total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and the data field carries the compressed frame data K. i A corresponding local data segment; When the data packet type of the i-th group of data to be transmitted is a non-critical frame type of P-frame, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the non-critical frame type of P-frame includes, in sequence, a type field, a current frame identifier field, a reference identifier field, a packet number field, a total packet number field, and a data field. Among them, the type field carries the type identifier corresponding to the non-critical frame type of P-frame, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the reference identifier field carries the reference compressed frame S i_ref The image identifier, the packet number field carries the packet number of the BeiDou data packet, the total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and the data field carries the compressed frame data K. i A corresponding local data segment; When the data packet type of the i-th group of data to be transmitted is a non-critical frame type of B-frame, each BeiDou data packet obtained by packetizing and encapsulating the i-th group of data to be transmitted according to the data packet format matching the non-critical frame type of B-frame includes, in sequence, a type field, a current frame identifier field, a first reference identifier field, a second reference identifier field, a packet number field, a total packet number field, and a data field. The type field carries the type identifier corresponding to the non-critical frame type of B-frame, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the first reference identifier field carries a reference compressed frame S i_ref The image identifier, the second reference identifier field carries another reference compressed frame S i_ref The image identifier, the packet number field carries the packet number of the BeiDou data packet, the total packet number field carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted, and the data field carries the compressed frame data K. i A corresponding local data segment.

7. The meteorological observation image transmission method according to claim 6, characterized in that, The meteorological center station decodes the received BeiDou data packets to obtain the i-th meteorological observation image S. i ,include: The received BeiDou data packets are parsed to obtain the type identifier carried in the type field, and the data packet type corresponding to the type identifier is determined. When the data packet type corresponding to the type identifier is determined to be a keyframe type, the received BeiDou data packet is parsed according to the data packet format matching the keyframe type to obtain the i-th meteorological observation image S. i The image identifier, the packet number of the BeiDou data packet, the total number of BeiDou data packets, and the local data segments are used to carry the i-th meteorological observation image S. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers. i The compressed frame data K i Directly used as the i-th compressed frame F i For the i-th compressed frame F i Decoding yields the i-th meteorological observation image S i And compress the i-th frame F i With the i-th meteorological observation image S i The image identifier is stored accordingly; When the data packet type corresponding to the type identifier is determined to be either a P-frame non-critical frame type or a B-frame non-critical frame type, the received BeiDou data packet is parsed according to the data packet format matching the data packet type to obtain the i-th meteorological observation image S. i The image identifier, the image identifier of the reference compressed frame, the packet number of the BeiDou data packet, the total number of BeiDou data packets, and the local data segments are used to carry the i-th meteorological observation image S. i The compressed frame data K is obtained by sequentially splicing together the local data segments from all BeiDou data packets identified by the image according to their packet numbers. i ; Retrieve the compressed frame corresponding to the image identifier of the reference compressed frame from the already stored compressed frames as the reference compressed frame S. i_ref Using the inter-frame compression mechanism in the H.266 video compression algorithm, based on the compressed frame data K... i and reference compressed frame S i_ref Decoding yields the i-th compressed frame F i For the i-th compressed frame F i Decoding yields the i-th meteorological observation image S i And compress the i-th frame F i With the i-th meteorological observation image S i The image identifier is stored accordingly.

8. The meteorological observation image transmission method according to claim 6, characterized in that, According to the data packet type matching of the i-th group of data to be transmitted, and based on the maximum number of bytes transmitted in a single transmission using BeiDou communication technology, the i-th group of data to be transmitted is divided into multiple BeiDou data packets, including: Based on the number of bytes occupied by fields other than the data field in the data packet format that match the data packet type of the i-th group of data to be transmitted, the number of bytes occupied by the data field is determined according to the maximum number of bytes transmitted in a single transmission using BeiDou communication technology. The compressed frame data K is then compressed according to the number of bytes occupied by the data field. i The data is divided into multiple local data segments, and each local data segment is sequentially encapsulated into different BeiDou data packets according to the packet number. In the data packet format for keyframe type matching, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; in the data packet format for non-keyframe P-frames, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the reference identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; in the data packet format for non-keyframe B-frames, the type field occupies 4 bits, the frame identifier field occupies 26 bits, the first reference identifier field occupies 26 bits, the second reference identifier field occupies 26 bits, the packet number field occupies 9 bits, and the total packet number field occupies 9 bits; and the image identifier for each meteorological observation image is the number of minutes between the acquisition timestamp of the meteorological observation image and the predetermined start timestamp.

9. The meteorological observation image transmission method according to claim 6, characterized in that, The meteorological observation image transmission method also includes: The meteorological center station receives the i-th meteorological observation image S within the predetermined time period. i When the number of BeiDou data packets identified by the image identifier does not reach the total number of BeiDou data packets, a meteorological observation image S carrying the i-th image is sent to the automatic weather station. i The image identifier is a supplementary transmission instruction, and the number of bytes occupied by the supplementary transmission instruction does not exceed the maximum number of bytes transmitted in a single transmission using BeiDou communication technology; The automatic weather station will carry the i-th meteorological observation image S according to the received retransmission command. i The BeiDou data packet obtained by encapsulating the i-th group of data to be transmitted from the image identifier is resent to the meteorological center station.

10. The meteorological observation image transmission method according to claim 9, characterized in that, The retransmission instruction includes an instruction type field, a current frame identifier field, a total packet number field, and a data field. The instruction type field carries a retransmission command identifier, and the current frame identifier field carries the i-th meteorological observation image S. i The image identifier, the total packet digital segment carries the total number of BeiDou data packets obtained by encapsulating the i-th group of data packets to be transmitted, the data field carries a binary receive status code stream, the total number of bits in the receive status code stream is consistent with the total number of packets, when any m-th bit in the receive status code stream is 1, it indicates that the BeiDou data packet with the m-th packet number obtained by encapsulating the i-th group of data packets to be transmitted has been received, when any m-th bit in the receive status code stream is 0, it indicates that the BeiDou data packet with the m-th packet number obtained by encapsulating the i-th group of data packets to be transmitted has not been received; The automatic weather station will carry the i-th meteorological observation image S according to the received retransmission command. i The BeiDou data packet obtained by encapsulating the i-th group of data to be transmitted from the image identifier and resending it to the meteorological center station includes: Parsing the retransmission command yields the retransmission command identifier and the i-th meteorological observation image S. i The image identifier and total number of packets are used to parse the received status code stream based on the total number of packets, and the i-th meteorological observation image S is then used. i In the BeiDou data packets obtained by encapsulating the i-th group of data to be transmitted from the image identifier, the BeiDou data packet containing the packet number corresponding to the bit that is 0 in the receiving status code stream is resent to the meteorological center station.

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