CN103199868A - Data compression method for locating information transmission - Google Patents

Abstract

The invention relates to a data compression method for locating information transmission. According to the invention, the data compression of locating information requires five main steps including evenly spaced selection, format conversion, position prediction and predicted error calculation, movement status judgment of users and massage content generation. The data compression method for locating information transmission has the advantages of being suitable for compression treatment of locating information of various navigation locating systems; and greatly improving the locating information transmission capability of the massage service no matter which state users are in, so that the effectiveness and real-time property of position record are improved greatly.

Description

A data compression method for positioning information transmission

technical field

The invention relates to a data compression method for positioning information transmission. The method utilizes the characteristics of less sudden changes in the target's motion state to predict the user's position, and compresses the location information losslessly by calculating and comparing prediction errors. Therefore, the message can contain more positioning compressed data within a limited length, which improves the utilization rate of the message and the real-time performance of the position report.

Background technique

With the development of navigation and positioning technology, its application technology in related fields is also blooming everywhere. To process and utilize the positioning information, the user first needs to send its positioning information to the management center in a certain way. The combination of GPS/GSM positioning communication has been widely used in remote alarm and target monitoring, but the limitation of mobile communication network coverage leads to its application blind spots. The end users of the Beidou satellite navigation system have both fast positioning and two-way communication functions, which are expected to make up for the shortcomings of the GSM network.

Since the formats of positioning information output by different navigation systems are different, to effectively compress the positioning information of multi-mode receivers, the format must first be unified into a standard data format. In addition, whether it is the GSM network or the Beidou communication link, it either charges fees based on the number of messages sent by the user, or limits the frequency of communication and the length of the message. This makes it necessary for the user to transmit multiple positioning information within a communication interval through one message communication, thus generating a demand for compressing the positioning information.

The data compression method for positioning information transmission involved in the invention is an effective technical means for improving the utilization rate of short messages. This method takes advantage of the characteristics of less sudden changes in the motion state of the target. The positioning information at the first two moments is used to predict the positioning information at the next moment. Likely big.

Contents of the invention

The invention proposes a data compression method suitable for multi-mode receiver positioning information transmission. It performs equal interval selection, format conversion, position prediction, prediction error calculation, and motion state judgment on a large number of positioning information in different formats within the message communication interval, and finally generates message data containing multiple pieces of positioning information.

First, select all positioning data at equal intervals within the message sending time interval, so that the compressed time information only needs to retain an initial time, and the user's location changes will be clearer. Afterwards, the format of all positioning information data received by the multimode receiver is converted into a unified format. Secondly, according to the characteristics of high correlation of adjacent position information and less mutation of target motion state, the first two positioning information are used to predict the positioning information of the next moment. Afterwards, after comparing the prediction error value with the positioning data difference, it is judged whether the user is in a "regular motion state" or an "irregular motion state". When the user is in a regular motion state, the prediction error is selected as the transmission content; when the user is in an irregular motion state, the positioning information difference is selected as the transmission content. Finally, generate compressed message data according to the requirements of the message format.

The invention realizes the effective compression of positioning information, enables the message to contain more positioning information data within a limited length, thereby improving the utilization rate of the message and the real-time performance of position reporting.

The advantages of the present invention are:

1. Greatly improved the positioning information transmission capability of the message service;

2. Regardless of the user's motion state, this method can achieve a large compression rate;

3. It is suitable for compression processing of positioning information of various or multi-mode navigation and positioning systems;

Description of drawings

Figure 1 is a block diagram of the compression method.

Figure 2 is the specific data format of the message.

Detailed ways

The present invention will be further described in detail below. The present invention sequentially performs five-step processing for multiple positioning information within the message communication time interval, including equal interval selection, format conversion, position prediction and prediction error calculation, motion state judgment, and message content generation. The principle block diagram is shown in FIG. 1 .

The first step of the compression method is to select the positioning information at equal intervals in the communication time interval, the purpose of which is to compress the data volume of the time dimension in the state vector. If a message can contain n pieces of positioning information, and t _i+1 -t _i =Δt=T/n=constant. Wherein, T is a message communication time interval. Therefore, in this way, the user only needs to send the time t ₁ corresponding to the first positioning information, and the receiving end can restore the time t _i of all positioning information, t _i =t ₁ +△t*(i-1) .

t表示时间；j表示精度；w表示纬度；h表示高度。The second step in the compression method is the conversion of the standard positioning format. For multi-mode receivers, the positioning information output formats of different navigation systems are different, so the positioning information can only be compressed if the selected positioning information is converted into a unified format. The state of the target at a certain moment can be represented by time, longitude, latitude, altitude, speed, and direction. Among them, the speed and direction of the target can be obtained from the position and time of two adjacent moments. Therefore, the state vector of the memorable object at a certain moment is

t represents time; j represents precision; w represents latitude; h represents height.

已知，相邻状态矢量差值表示为

i∈（1,2，……，n-1）。由于上文已对等间隔选取做了相关说明，所以在后面的论述中将忽略时间维数据。对

的预测量表示为

预测误差定义为

The third step of the compression method is the calculation of position prediction and prediction error. The basic idea of prediction is to use the first two state vector data to linearly predict the state vector at the next moment in the time domain, and calculate the amount of prediction error. The details are as follows. Assuming that a message contains n positioning information, the state vector converted to the standard format can be expressed as The linear prediction method is as follows,

It is known that the difference between adjacent state vectors is expressed as

i ∈ (1,2,...,n−1). Since the selection of equal intervals has been explained above, the time dimension data will be ignored in the following discussion. right

The predicted amount is expressed as

The prediction error is defined as

的大小关系。若

用户处于“不规则运动状态”，则取作为（i+2）时刻定位信息在报文中对应的传输内容；若用户处于“规则运动状态”，则取δ_i+2作为报文传输内容。即，报文内容中（i+2）时刻的定位信息压缩数据，是（i+2）时刻、（i+1）时刻之间状态向量差值

与预测误差值δ_i+2中较小的一个。这种方法克服了目标运动方向和速度同时大幅改变所造成的预测误差比差值大的情况，使得用户不论处于何种运动状态均可保持较高的压缩效率。The fourth step of the compression method is to judge the motion state, compare δ _i+2 with

size relationship. like

If the user is in an "irregular motion state", then take As the transmission content corresponding to the positioning information at (i+2) time in the message; if If the user is in the "regular motion state", δ _i+2 is taken as the message transmission content. That is, the compressed data of the positioning information at (i+2) time in the message content is the state vector difference between (i+2) time and (i+1) time

and the smaller one of the prediction error value δi ₊₂ . This method overcomes the situation that the prediction error is larger than the difference caused by the large change of the target's motion direction and speed at the same time, so that the user can maintain high compression efficiency no matter what motion state the user is in.

报文的第二数据块应对应第二时刻与第一时刻状态矢量差值

其它数据块对应定位信息压缩数据。报文的具体数据格式，参见图2。The final step in the compression method is message content generation. Still assuming that a message contains n pieces of location information, the message is divided into n data blocks, and each data block corresponds to one piece of location information compressed data. The first data block of the message must correspond to the positioning information in the standard format containing the time dimension data, that is, the state vector is

The second data block of the message should correspond to the state vector difference between the second moment and the first moment

The other data blocks correspond to the positioning information compressed data. For the specific data format of the message, see Figure 2.

Claims (2)

1. A data compression method for positioning information transmission. Compressing the positioning information requires five main steps: format conversion, positioning information prediction, prediction error calculation, user motion state judgment, and message content generation. 2. The positioning information data compression method according to claim 1, characterized in that: a large amount of positioning information within the communication interval is selected at equal intervals. A standard positioning information format is ordered for the positioning information of multi-mode receivers. Use the first two positioning information to predict the positioning information at the next moment. By comparing the prediction error value with the positioning information difference, the motion state of the user is judged. The one with the smaller difference between the prediction error and the positioning information is selected as the message transmission data. Generate message content according to the customized message format.

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