CN108089172A - A kind of double-view field signal processing method of laser radar - Google Patents

Abstract

The invention discloses a dual-field laser radar signal processing method, comprising the following steps: performing distance square calibration on the original signal of the double-view field; confirming whether splicing is performed by calculating the Pearson correlation coefficient of window data; dynamically changing the splicing The splicing position is determined by the window position and the window length; the splicing coefficient is calculated according to the above splicing position; the dynamic splicing process is performed on the dual-field-of-view signal according to the above coefficient to obtain the spliced signal. The invention has the advantages of large detection range, small blind area and the like.

Description

A signal processing method for dual-field lidar

technical field

The invention belongs to laser radar, and in particular relates to a signal processing method of a dual-field laser radar.

Background technique

Lidar is an important technical means to detect the temporal and spatial distribution of atmospheric particles and clouds. The data it detects are of great significance to the study of the vertical distribution, migration and diffusion process of aerosols, cloud structure, atmospheric boundary layer and its temporal and spatial evolution characteristics. .

In the current particle monitoring, the most mature and widely used is the meter scattering lidar. The height profile of the local extinction coefficient at that time can be obtained by inverting the LiDAR meter scattering echo signal by using the US standard atmosphere, which can be used for related research. However, when only the far-field detection module is used, the blind area of the signal is large, which will cause more data near the ground to be inaccurate; and when only the near-field optical path is used for detection, the effective detection height is low, and it is impossible to obtain a larger dynamic range. data.

Contents of the invention

In order to overcome the defects existing in the prior art, the present invention provides a dual-field-of-view laser radar processing method, which acquires spliced signals with a large detection range and small blind area, and effectively improves the data quality of the laser radar near the ground.

The purpose of the present invention is achieved through the following technical solutions:

A dual-field of view laser radar signal processing method, the dual-field of view laser radar signal processing method comprises the following steps:

(A1) Using laser radar to obtain the original signal P _B (z) of the far-field optical path and the original signal P _S (z) of the near-field optical path;

(A2) Obtain the background noise according to the baseline of the original signal, and then subtract the background noise on the basis of the original signal to obtain the effective signal corresponding to the dual-field optical path, which are recorded as E _B (z) and _ES (z) respectively;

(A3) Perform distance square correction on the effective signal corresponding to the dual-field optical path, that is, PRR _B (z) = E _B (z) z ² , PRR _s (z) = E _s (z) z ² ;

(A4) According to the distance square correction signal PRR _B (z) corresponding to the far-field optical path, set the default height range of splicing, the starting height is H _start , the ending height is H _end , and the data window length W of the selected splicing point is preset, The initial position of the preset window is H _start ;

(A5) Starting from the initial position of the window, select data with a length of W at the corresponding positions of PRR _B (z) and PRR _s (z); calculate the Pearson correlation coefficient for the two sets of data, if the Pearson correlation coefficient is greater than the threshold, the window is located The height is the joining point Z _R , and step (A6) is executed; otherwise, step (A7) is executed;

(A6) Use the least square method to fit the near-field optical path PRR _s (Z _R ) to the telescope PRR _B (Z _R ) with the data in the window, and after obtaining the stitching coefficient, apply the stitching coefficient to the PRR before the window position _s , z<Z _R , get PRR′ _S , and replace PRR _B with this part of data, z<Z _R , get the final PRR;

(A7) Judging that the window position is out of bounds, if not, then move the window position to the H _end direction, and return to step (A5); if yes, then perform step (A8);

(A8) reduce the window length, and determine whether the current window length is valid; if so, restore the window position to the initial position, and return to step (A5); otherwise, set the splicing point to the initial position, and perform step (A6) .

According to the above-mentioned zero-blind-spot lidar, preferably, the threshold is 0.9.

According to the above-mentioned zero-blind spot laser radar, preferably, the method of obtaining the splicing coefficient is: using the least square method to combine the near-field optical path PRR _s (Z _R ) and the far-field optical path PRR _B (Z _R ) according to the formula PRR _B (Z _R )= a*PRR _s (Z _R )+b for fitting to obtain splicing coefficients a and b.

According to the above-mentioned zero-blind zone laser radar, preferably, the stitching coefficient is applied to the PRR _s before the window position, z<Z _R , and PRR' _S =a*PRR _s +b is obtained.

According to the above-mentioned zero-blind-spot lidar, preferably, the lidar is a meter-scattering lidar.

Compared with the prior art, the present invention has the following beneficial effects:

Combining the advantages of near and far field of view detection, using the meter scattering lidar with a dual field of view detection module, through dynamic splicing of the original data, it can obtain signals with small blind spots and large detection ranges, which effectively improves the performance of the laser radar near the ground. data quality, as shown in Figure 2.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

FIG. 1 is a schematic flow chart of a dual-field-of-view lidar signal processing method according to an embodiment of the present invention;

Fig. 2 is a processing effect diagram according to an embodiment of the present invention.

Detailed ways

The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in different instances. This repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. It should be noted that components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and processes are omitted herein to avoid unnecessarily limiting the present invention.

Example:

Fig. 1 schematically provides a flow chart of a dual-view laser radar signal processing method according to an embodiment of the present invention. As shown in Fig. 1 , the dual-view laser radar signal processing method includes the following steps:

The laser radar equation corresponding to the backscattered echo signal of the m-scattering lidar is:

Among them: P(z) is the backscatter echo signal received by the lidar at height z (unit, W); c is the laser radar system constant (unit, W km3 sr), β(z) is height z The total backscatter coefficient at (unit km-1 sr-1), α(z) is the total extinction coefficient at distance z (unit, km-1);

(A1) Obtain the original signal P _B (z) of the far-field optical path and the original signal P _S (z) of the near-field optical path by using the dual-field meter scattering lidar;

(A2) Obtain the background noise according to the baseline of the original signal, and then subtract the background noise on the basis of the original signal to obtain the effective signal corresponding to the dual-field optical path, which are recorded as E _B (z) and _ES (z) respectively;

(A3) Perform distance square correction on the effective signal corresponding to the dual-field optical path, that is, PRR _B (z) = E _B (z) z ² , PRR _s (z) = E _s (z) z ² ;

(A4) According to the distance square correction signal PRR _B (z) corresponding to the far-field optical path, set the default height range of splicing. The starting height is H _start , such as 0.05km, and the ending height is H _end , such as 0.5km. The default selection The length W of the data window of the splicing point, if the initial value is set to 50, the default initial position of the window is H _start ;

(A5) Starting from the initial position of the window, select data with a length of W at the corresponding positions of PRR _B (Z) and PRR _s (z); calculate the Pearson correlation coefficient for the two sets of data, if the Pearson correlation coefficient is greater than the threshold value, such as 0.9, Then the height where the window is located is the splicing point Z _R , and step (A6) is executed; otherwise, step (A7) is executed;

(A6) Use the least square method to fit the near-field optical path PRR _s (Z _R ) to the telescope PRR _B (Z _R ) with the data in the window, such as PRR _B (Z _R )＝a*PRR _s (Z _R )+ b. After obtaining the stitching coefficients a and b, apply the stitching coefficient to the PRR _s before the window position, z<Z _R , get PRR' _S =a*PRR _s + b, and replace PRR _B with this part of the data, z < Z _R , get the final PRR;

(A7) Judging that the window position is out of bounds, if not, then move the window position to the H _end direction, and return to step (A5); if yes, then perform step (A8);

(A8) reduce the window length, and determine whether the current window length is valid; if so, restore the window position to the initial position, and return to step (A5); otherwise, set the splicing point to the initial position, and perform step (A6) .

Although the example embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims. For other examples, those of ordinary skill in the art will readily understand that the order of process steps may be varied while remaining within the scope of the present invention.

Claims (5)

1. a kind of double-view field signal processing method of laser radar, it is characterised in that：The double-view field laser radar signal processing side Method comprises the following steps：

(A1) far field light path original signal P is obtained using laser radar_B(z), near field light path original signal P_S(z)；

(A2) ambient noise, and then the background correction noise on the basis of original signal are obtained according to original signal baseline, obtained double The corresponding useful signal of visual field light path, is recorded as E respectively_B(z), E_S(z)；

(A3) square distance correction, i.e. PRR are carried out to the corresponding useful signal of double-view field light path_B(z)=E_B(z)·z²,PRR_s(z) =E_s(z)·z²；

(A4) according to the corresponding square distance correction signal PRR of far field light path_B(z), the default height section of splicing is set, is originated Highly it is H_start, it is H to terminate height_end, the data window length W for choosing splice point is preset, preset window initial position is H_start；

(A5) since window initial position, in PRR_B(z) and PRR_s(z) correspondence position chooses the data that length is W；To two Group data calculate Pearson correlation coefficient, if Pearson correlation coefficient is more than threshold value, height where window is splice point Z_R, and perform step (A6)；Otherwise, then step (A7) is performed；

(A6) by the data in window, using least square method by near field light path PRR_s(Z_R) fitting arrival telescope PRR_B(Z_R), After obtaining splicing coefficient, by the splicing coefficient applied to the PRR before the window's position_s, z<Z_R, obtain PRR '_S, and with the portion Divided data replaces PRR_B, z<Z_R, obtain final PRR；

(A7) it is to cross the border to judge the window's position, if it is not, then by the window's position to H_endDirection is moved, and return to step (A5)；It is then Perform step (A8)；

(A8) reduce length of window, and judge whether current window length is effective；If so, the window's position is reverted into initial bit It puts, and return to step (A5)；Otherwise, splice point is arranged to initial position, and performs step (A6).

2. double-view field signal processing method of laser radar according to claim 1, it is characterised in that：The threshold value is 0.9.

3. double-view field signal processing method of laser radar according to claim 1, it is characterised in that：The splicing coefficient Acquisition pattern is：Using least square method by near field light path PRR_s(Z_R) and far field light path PRR_B(Z_R) press formula PRR_B(Z_R)=a* PRR_s(Z_R)+b is fitted, obtain splicing coefficient a and b.

4. double-view field signal processing method of laser radar according to claim 3, it is characterised in that：By the splicing coefficient Applied to the PRR before the window's position_s, z<Z_R, obtain PRR '_S=a*PRR_s+b。

5. double-view field signal processing method of laser radar according to claim 1, it is characterised in that：The laser radar is Mie scattering lidar.