KR20190116834A - Gps reflected wave analysis system for road surface freeze detection - Google Patents

Abstract

Disclosed is a GPS reflected wave measuring and analyzing system for detecting road surface. The present disclosure provides a GPS reflected wave analyzing system for minimizing multipath effects and signal noise patterns. Specifically, by measuring the signal strength and phase by the microwave GPS reflected wave and analyzing measured data, various surface media information caused by various physical properties of the surface can be accurately grasped.

Description

GPS REFLECTED WAVE ANALYSIS SYSTEM FOR ROAD SURFACE FREEZE DETECTION

The present disclosure relates to a GPS reflected wave measurement and analysis system for detecting road frost detection. Specifically, the present disclosure is configured to continuously and precisely detect physical characteristics of a surface medium on which a GPS signal is reflected to prevent an accident caused by road frost in winter. The present invention relates to a high accuracy GPS echo measurement and analysis system using a remote data transmission method.

Unless otherwise indicated herein, the contents described in this section are not prior art to the claims of this application, and inclusion in this section is not admitted to be prior art.

Black ice is a road freezing phenomenon where snow melts on the road and freezes back into thin ice when temperatures drop sharply. Black ice is not black ice, but transparent ice that covers the asphalt as if it were coated, so the driver's eyes appear dry (black) with no ice on the road.

Even if rain falls at the temperature of the image, if the ground temperature is below zero and the road's surface temperature drops to two or three degrees below zero, the rain freezes on the floor. Specifically, the raindrops are frozen below the freezing point as they fall below the freezing point and fall to the surface. That is, even if the air temperature is near 0 ° C, if the surface temperature of the road is zero, raindrops easily stick and freeze.

On the other hand, the surface of the road is low in the morning and high in the day before the air temperature. Therefore, freezing rain usually occurs between dawn and morning, and freezing rain frequently occurs on piers on the same road. Areas such as piers are due to the high heat loss on the surface.

In order to detect road frost conditions caused by black ice, conventionally, (1) an existing road surface temperature was analyzed to predict road conditions. The technology for predicting road conditions through road surface temperature analysis is an indirect prediction method based on the road surface prediction model, which detects approaching freezing point and temperature change rather than detecting ice that is actually generated. Have

In addition, conventionally, (2) the road road frost state was detected through infrared and laser scattering reflection analysis. Infrared and laser scattering reflection analysis technology detects by infrared and laser scattering and reflection characteristic analysis. It is a relatively expensive imported product of about 10 million won per one product, and this method is limited to a short distance of about 10m. The disadvantage is that it is effective.

In addition, the conventional technology for predicting road conditions through image analysis (3) is that the restriction due to weather and brightness is relatively large, and it is difficult to secure a field of vision at night when clouds or fog are applied or when the day is dark. There is a problem.

1. Korea Patent Registration No. 10-1124888 (2012.02.29)

The present disclosure provides a GPS echo measurement and analysis system that minimizes multipath effects and signal noise patterns. Specifically, by measuring the signal strength and phase by the microwave GPS reflected wave, and by analyzing the measured data, it is possible to more accurately grasp the various surface medium information due to various physical properties of the surface.

GPS reflected wave measurement and analysis system for road surface freezing detection according to an embodiment stores the road surface freezing detection information including the phase information, GPS satellite positioning information, road surface location information, GPS signal information of the GPS (Global Positioning System) signal A data logger; GPS observation, RHCP (Right Hand Circular Polarization), which is the GPS signal observed on the road surface, which is the GPS observation point, phase and unique number of the GPS signal, and the target observation point, and LHCP (Left Hand Circular Polarization), which is the reflection signal for the GPS signal. Receiving module for receiving the GPS reflection signal and the temperature and humidity change data of the time zone measured the reflection signal, and visualizes the GPS reflection signal according to the signal strength; And an analysis server for determining a freezing state of the road surface based on the strength of the GPS reflection signal collected by the receiving module, the phase information of the GPS signal, and the satellite arrangement information. It includes.

Road surface freezing detection method of the GPS reflection wave measurement and analysis system including a receiving module and the analysis server according to another embodiment (A) phase information of the GPS (Global Positioning System) signal to the data logger of the receiving module, GPS satellite positioning information Storing road surface freezing detection information including road surface location information and GPS signal information; (B) GPS signal, satellite observation information including GPS signal phase and unique number and RHCP (Right Hand Circular Polarization), which is the GPS signal observed on the road surface of the target observation point, Receiving temperature and humidity change data of a GPS reflection signal including a left hand circular polarization (LHCP) and a time zone when the reflection signal is measured; (C) visualizing the GPS reflected signal according to the signal strength in the receiving module; And (D) determining the freezing state of the road surface based on the GPS signal information and the GPS reflected wave strength collected by the receiving module in the analysis server. It includes.

GPS reflected wave measurement and analysis system for detecting the road surface freezing according to the embodiment is able to observe the GPS reflected wave at night or even cloudy or cloudy weather can accurately grasp the road surface state information even when the weather is bad.

In addition, the GPS echo method is passive and can be used to measure GPS echoes over a relatively wide range and distance with low maintenance costs.

It is possible to adjust the height, inclination, direction, etc. of the antenna and measuring unit provided in the receiving module, and it can monitor the GPS reflected wave stably for a long time by using the holder for waterproofing, power supply, low temperature overcome function, and ground fixing.

The effects of the present invention are not limited to the above-described effects, but should be understood to include all the effects deduced from the configuration of the invention described in the detailed description or claims of the present invention.

1A is a diagram illustrating a GPS reflected wave measurement and analysis system according to an embodiment.
1B is a diagram illustrating a GPS reflected wave measurement and analysis system for detecting road frost according to an embodiment.
2 is a diagram illustrating a data processing configuration of a receiving module 100 according to an embodiment.
3 is a diagram illustrating a data processing block of an analysis server 200 according to an embodiment.
4a is a diagram illustrating a process of collecting satellite information and GPS reflected waves for detecting road frost by installing a receiving module 100 directly on a road.
4b is a diagram illustrating an embodiment in which collected satellite information and GPS reflected waves are analyzed;
5 is a signal flow diagram of a GPS echo wave analysis system for detecting road surface ice according to an embodiment.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments of the present invention make the disclosure of the present invention complete and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present disclosure, when it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted. Terms to be described below are terms defined in consideration of functions in the embodiments of the present invention, and may vary according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present disclosure relates to a GPS reflected wave measurement and analysis system including a GPS reflected wave receiving module of a remote data transmission method for detecting road freezing. The analysis system according to the embodiment enables remote data transmission for road surface freezing detection and minimizes multipath and GPS signal noise through data preprocessing.

1A is a diagram illustrating a GPS reflected wave measurement and analysis system according to an embodiment.

 In the GPS reflected wave measurement and analysis system according to the embodiment, when the signals transmitted from several GPS satellites are reflected on the ground surfaces A and B, the reflected wave signals are collected. The cloud-based data storage device calculates and stores the time of measuring the reflected signal as well as the reflected signal for each location, the intensity of the reflected signal, and stores the signal strength, signal phase, satellite information, and photographed image of the generated GPS signal. It stores the GPS signal information and the temperature and humidity information of the ground surface is reflected GPS signal. The analysis server 20 receives the GPS signal information and the reflected signal data and the temperature and humidity information of the ground surface from the data storage device and analyzes the received data to analyze the properties of the ground reflective surface. For example, the analysis server 200 converts a reflection signal characteristic including a delay, a Doppler shift, a power strength, and polarization of a GPS reflection signal into a reflection coefficient. The freezing state of the road surface can be determined according to the converted reflection coefficient. Specifically, when the delay coefficient exceeds the first set value and the coefficient representing the energy level is less than the second set value, the road surface state may be determined to be a snow state. As another example, when the reflection signal analysis results in the polarization coefficient and the attenuation ratio of the energy magnitude is less than a predetermined ratio, the road surface state may be determined to be a dry state. Such a criterion may construct experimental data and store it in advance in the analysis server 200 or communicate with other servers in which reflected signal data and data analysis data are stored, and determine the road surface state in the analysis server 200.

FIG. 1B is a diagram illustrating a GPS reflected wave measurement and analysis system for detecting road surface freezing according to an embodiment.

Referring to FIG. 1B, the GPS reflected wave measurement and analysis system may include a receiving module 100, an analysis server 200, and a computing device 300. The term 'module', as used herein, should be interpreted to include software, hardware or a combination thereof, depending on the context in which the term is used. For example, the software can be machine language, firmware, embedded code, and application software. As another example, the hardware may be a circuit, a processor, a computer, an integrated circuit, an integrated circuit core, a sensor, a micro-electro-mechanical system (MEMS), a passive device, or a combination thereof.

The receiving module 100 receives the satellite observation information, the GPS reflection signal and the temperature and humidity change data of the time zone in which the reflection signal is measured, and visualizes the GPS reflection signal. For example, the GPS observation information includes a GPS signal generating a reflected signal, a GPS signal generated from the road surface, which is a satellite observation information, and a target observation point, RHCP (Right Hand Circular Polarization), a phase and a unique number of the GPS signal. Information may be included. The GPS reflection signal may include LHCP (Left Hand Circular Polarization), which is a reflection signal of the GPS signal observed on the road surface, which is satellite observation information and a target observation point.

In an embodiment, when the receiving module 100 includes a thermal imaging camera or a temperature sensing camera, the receiving module 100 may monitor the temperature and humidity change data of the time when the GPS reflection signal and the reflection signal are measured.

The data logger stores road road ice detection information including phase information, GPS satellite positioning information, road surface location information, and GPS signal information of a global positioning system (GPS) signal. In an embodiment, the data logger may be included in the receiving module 100 or may be configured as a storage server wirelessly communicating with the receiving module.

The analysis server 200 analyzes the signal strength of the GPS reflection signal collected by the reception module 100, the phase information of the GPS signal, the satellite arrangement information, and the visualization information of the GPS reflection signal to determine the freezing state of the road surface.

2 is a diagram illustrating a data processing configuration of a receiving module 100 according to an embodiment.

Referring to FIG. 2, the reception module 100 includes an upward antenna 10 (RHCP, right hand circular polarization) for receiving a GPS signal, a downward antenna 20 (LHCP, left hand circular polarization) for receiving a GPS reflected wave, and a data collection unit ( 110, the data processor 130, and the data logger 150 may be configured. The data collection unit 110 may include a monitoring unit 111 and a logging unit 113, and the data processing unit 130 may include a visualization unit 131 and a communication unit 133.

The uplink antenna 10 (RHCP) for receiving GPS signals receives satellite observation information. For example, the uplink antenna 10 receives in real time the unique information of the GPS signal such as the GPS signal, the phase of the GPS signal, the unique number, and the like.

The downlink antenna 20 (LHCP) for receiving the GPS reflection wave receives the GPS reflection signal reflected on the road surface.

The monitoring unit 111 of the data collection unit 110 is reflected on the road surface collected from the satellite observation information collected from the uplink antenna 10 (RHCP) for receiving GPS signals and the down antennas 20 (LHCP) for receiving GPS reflected waves. The GPS reflection signal is collected, and the monitoring unit 111 monitors the collected satellite observation information, the GPS reflection signal, and the temperature and humidity change data of the time zone when the reflection signal is measured.

The logging unit 113 collects and stores logging data including signal strength information, phase information, and satellite configuration information of the GPS for each surface medium on which the reflected GPS reflection signal is reflected. The data stored in the logging unit 113 may also include data on a signal measurement period, a reception frequency, a number of channels, and a unit and performance of an input power source described in Table 1.

 Logging data example Performance indicators Measuring cycle Receiving frequency Receive Channels Input power unit second MHz Ch V Implementation performance Within 1 second 1575.42 MHz
GPS L1 2 ~ 4 Ch 5 ~ 12V DC

The visualization unit 131 of the data processor 130 collects GPS reflection signals stored in the logging unit 113 and generates comma-separated values (CSV) data based on the collected signals. CSV is a text data and text file with several fields separated by commas. After generating the CSV file, the visualization unit 131 visualizes the surface of the surface reflecting surface by tracking the first surface reflecting surface position (FFZ; First Fresnel Zone), which changes according to the satellite altitude, based on the installed position of the receiving module. For example, the visualization unit 131 may convert the satellite signal reception intensity (C / N0) graph for each antenna according to the satellite altitude included in the logging data and the first surface reflection surface position change.

The communication unit 133 collects the logging data including the signal strength, the phase, and the satellite arrangement information of the GPS, and the surface of the reflecting surface of the GPS satellites over time, and transmits them to the analysis server 200.

3 is a view showing a data processing block of the analysis server 200 according to the embodiment.

Referring to FIG. 3, the analysis server 200 according to the embodiment may include a preprocessor 210, an analyzer 220, and a determiner 230.

The analysis server 200 according to the embodiment compares the GPS reflection signal and satellite observation information, and includes a delay, a Doppler shift, a power strength, and polarization of the GPS reflection signal. The reflection signal characteristic is extracted. In the embodiment, the GPS reflectrometry (GPS-R) is collected to extract the reflection signal characteristics. GPS reflected waves show differences in delay, Doppler shift, power strength, and polarization compared to waves coming directly from satellites. In the embodiment, the information on the various surface characteristics such as the freezing state of the ground surface can be obtained through the characteristics of the reflected signal and the difference between the reflected wave and the GPS signal. To this end, the preprocessing unit 210 of the analysis server 200 is a time zone in which the logging data transmitted from the receiving module 100, the surface reflection surface position information, the GPS reflection signal, and the reflection signal are measured to minimize the multipath and the noise pattern. Receive temperature and humidity change data and preprocess the received data.

The analysis unit 220 detects a change in signal strength for each surface medium recorded in the uplink antenna and the down antenna of the GPS reflected wave receiving module from the preprocessed data.

The determination unit 230 may dry, wet, ice, and snow the road surface freezing state according to the signal intensity change and the reflection signal characteristic for each surface medium determined by the analysis unit 220. ) Is judged as one of the states.

4A is a diagram illustrating a process of collecting satellite information and GPS reflected waves for detecting road surface freezing by installing the reception module 100 directly on a road, and FIG. 4B illustrates an embodiment of analyzing collected satellite information and GPS reflected waves. The figure shown.

As shown in FIG. 4A, the reception module 100 is installed near roads and tunnels, and satellite information and GPS reflection data are collected to preprocess the collected data. In an embodiment, the receiving module may include a measuring unit, a jig and a housing, a power supply unit, a control unit, and a preprocessor. The measurement unit collects satellite information through an uplink RHCP single antenna, and measures GPS satellite information and GPS echo signals collected from a downlink RHCP / LHCP dual antenna. The jig and the housing part is a part corresponding to the body of the receiving module, it may be configured to connect the measuring unit, power supply and pre-processing unit to the jig and the housing.

The preprocessor collects GPS echo data and generates a CSV file based on the collected data. Then, visualize the information tracking the first Fresnel Zone (FFZ) which changes according to the satellite altitude based on the receiving module installation position, and receive the satellite signal reception intensity by antenna according to the satellite altitude and FFZ change. / N0) Create a graph.

As shown in FIG. 4B, the pre-processed data is displayed in different aspects of signal reception intensity and reflection signal characteristics according to the road condition, and thus the road freezing state can be identified.

5 is a signal flow diagram of a GPS reflected wave measurement and analysis system for detecting road surface ice according to an embodiment.

In the step S510 monitors the ambient temperature and humidity changes in the satellite signal and GPS reflected signal measurement time zone from the image recording camera and the thermal imaging camera included in the receiving module 100.

In step S520 the reception module 100 logs the satellite signal through the up and down antennas. Thereafter, in step S530, the surface range of each signal reflected by GPS satellites is visualized. For example, in operation S520, a satellite signal reception intensity (C / N0) graph for each antenna may be generated according to the satellite altitude included in the logging data and the first surface reflection surface position change.

In step S540, the receiving module 100 collects and stores signal strength, GPS phase, GPS satellite arrangement information, and the like with respect to each GPS satellite over time.

In step S550 transmits the data collected by the receiving module 100 to the analysis server 200.

In step S560, the analysis server 200 preprocesses the collected reflection signal to minimize the multipath effect and signal noise pattern.

In step S570, the analysis server 200 determines the change in signal strength for each surface medium recorded in the up / down antennas of the receiving module 100, and in step S580, the freezing state of the road surface is determined according to the change in signal strength. For example, the analysis server 200 converts a reflection signal characteristic including a delay, a Doppler shift, a power strength, and polarization of a GPS reflection signal into a reflection coefficient. The freezing state of the road surface can be determined according to the converted reflection coefficient. Specifically, when the delay coefficient is less than the first predetermined value and the coefficient indicating the energy amount exceeds the second predetermined value, the road surface state may be determined to be a dry state. As another example, when the polarization coefficient is present as a result of the reflection signal analysis and the attenuation ratio of the energy magnitude exceeds a certain ratio, the road surface state may be determined as a wet state. Such a criterion may construct experimental data and store it in advance in the analysis server 200 or communicate with other servers in which reflected signal data and data analysis data are stored, and determine the road surface state in the analysis server 200.

The embodiment provides a high-precision GPS echo wave reception module system that minimizes multipath effects and signal noise patterns caused by the surrounding environment and artifacts to identify physical characteristics of the surface medium on which the GPS signal is reflected. This minimizes noise patterns caused by multipath and road vehicles and improves the performance of the GPS echo preprocessing software.

The disclosed contents are only examples, and various changes can be made by those skilled in the art without departing from the scope of the claims claimed in the claims, and therefore, the protection scope of the disclosed contents may be It is not limited to an Example.

100: receiving module
200: analysis server

Claims (13)

GPS Reflective Wave Measurement and Analysis System for Road Ice Detection
A data logger for storing road frost detection information including phase information of GPS (Global Positioning System) signals, GPS satellite positioning information, road surface position information, and GPS signal information;
GPS observation, RHCP (Right Hand Circular Polarization), which is the GPS signal observed on the road surface of the target observation point, and satellite observation information including the GPS signal, phase and unique number of the GPS signal, and LHCP (Left Hand Circular), which is a reflection signal for the GPS signal. A reception module for receiving a GPS reflection signal including polarization) and temperature and humidity change data of a time zone in which the reflection signal is measured, and visualizing the GPS reflection signal according to signal intensity; And
An analysis server for determining a freezing state of the road surface based on the strength of the GPS reflection signal collected by the receiving module, the phase information of the GPS signal, and the satellite arrangement information; GPS reflected wave measurement and analysis system for road surface freezing detection comprising a.
The method of claim 1, wherein the analysis server
Comparing the GPS reflected signal and the GPS signal, extracting and extracting reflected signal characteristics including delay, doppler shift, power strength, and polarization of the GPS reflected signal GPS reflected wave measurement and analysis system for detecting the road surface ice, characterized in that the ground characteristics according to the reflected signal characteristics.
The method of claim 1, wherein the receiving module
A monitoring unit for monitoring temperature and humidity change data of a GPS signal, a GPS reflection signal, and a time zone in which the reflection signal is measured;
A logging unit configured to collect and store logging data including signal strength information, phase information, and satellite configuration information of GPS for each surface medium on which the reflected GPS reflection signal is reflected;
Collect the GPS reflection signal stored in the logging unit, generate CSV (comma-separated values) data based on the collected signal, and the first surface reflection surface position that changes according to the satellite altitude based on the location where the receiving module is installed A visualization unit for tracking the first reflective zone (FFZ) to visualize the surface reflection surface position; And
A communication unit configured to collect logging data including GPS signal strength, phase, and satellite configuration information and the surface reflection surface position information for each GPS satellite, and transmit the collected data to the analysis server; GPS reflected wave measurement and analysis system for road surface freezing detection comprising a.
The method of claim 3, wherein the visualization unit
GPS reflected wave measurement and analysis system for road surface ice detection, characterized in that for generating a satellite signal reception intensity (C / N0) graph for each antenna according to the satellite altitude and the first surface reflection surface position included in the logging data.
The method of claim 1, wherein the analysis server
Receives the logging data, the surface reflection surface position information, the GPS signal, the GPS reflection signal, and the temperature and humidity change data of the time zone when the reflection signal is measured, and pre-processes the received data to transmit multipath and noise patterns. Preprocessing unit to minimize the;
An analysis unit for detecting signal strength change of each surface medium recorded in the uplink antenna and the down antenna of the GPS reflected wave receiving module from the preprocessed data; And
A determination unit which determines one of dry, wet, ice and snow conditions of the road surface according to the change in signal intensity for each surface medium determined by the analysis unit; GPS reflected wave measurement and analysis system for road surface freezing detection comprising a.
The method of claim 2, wherein the analysis server
The reflection signal characteristics including delay, doppler shift, power strength, and polarization of the GPS reflection signal are converted into reflection coefficients and converted into reflection coefficients. GPS reflected wave measurement and analysis system for detecting the road surface ice, characterized in that for determining the freezing state of the road surface according to.
In the road surface freezing detection method of the GPS reflected wave measurement and analysis system comprising a receiving module and the analysis server,
(A) storing road surface ice detection information including phase information, GPS satellite positioning information, road surface position information, and GPS signal information in a data logger of the receiving module;
(B) GPS signal, satellite observation information including GPS signal phase and unique number, and RHCP (Right Hand Circular Polarization), which is the GPS signal observed on the road surface of the target observation point, and reflection on the GPS signal. Receiving a GPS reflection signal including a left hand circular polarization (LHCP) signal and temperature and humidity change data of a time zone in which the reflection signal is measured;
(C) visualizing the GPS reflected signal according to signal strength at the receiving module; And
(D) determining, by the analysis server, the freezing state of the road surface based on the GPS signal information and the GPS reflected wave strength collected by the receiving module; Road surface freezing detection method comprising a.
8. The method of claim 7, further comprising the steps of: determining the freezing state of the road surface; Is
Comparing the GPS reflected signal with the GPS signal to extract a reflected signal characteristic including a delay, a Doppler shift, a power strength, and polarization of the GPS reflected signal; And
Determining an indicator property according to the extracted reflection signal property; Road surface freezing detection method comprising a.
8. The method of claim 7, further comprising: (C) visualizing the GPS reflected signal according to signal strength at the receiving module; Is
Monitoring temperature and humidity change data of a GPS signal, a GPS reflected signal, and a time zone in which the reflected signal is measured;
Collecting and storing logging data including signal strength information, phase information, and satellite configuration information of the GPS for each surface medium on which the reflected GPS reflection signal is reflected;
Collect the GPS reflection signal stored in the logging unit, generate CSV (comma-separated values) data based on the collected signal, and the first surface reflection surface position that changes according to the satellite altitude based on the location where the receiving module is installed Visualizing the surface reflection surface position by tracking a first frequency zone (FFZ); And
Collecting logging data including the signal strength, phase, and satellite configuration information of the GPS and the ground reflection surface position information according to time for each GPS satellite, and transmitting the collected data to the analysis server; Road surface freezing detection method comprising a.
10. The method of claim 9, further comprising: visualizing the surface reflecting surface position; Is
And a satellite signal reception intensity (C / N0) graph for each antenna according to the satellite altitude included in the logging data and the first surface reflection surface position change.
The method of claim 7, further comprising: determining, by the analysis server, the freezing state of the road surface based on the GPS signal information and the GPS reflected wave strength collected by the receiving module; Is
Receives the logging data, the surface reflection surface position information, the GPS signal, the GPS reflection signal, and the temperature and humidity change data of the time zone when the reflection signal is measured, and pre-processes the received data to transmit multipath and noise patterns. Minimizing;
Determining signal intensity changes for each of the surface media recorded in the uplink antenna and the down antenna of the GPS reflecting wave receiving module from the preprocessed data; And
Determining the freezing state of the road surface as one of dry, wet, ice and snow conditions according to the change in signal intensity for each surface medium; Road surface freezing detection method comprising a.
The method of claim 8, further comprising: extracting the reflected signal characteristic;
The reflection signal characteristics including delay, doppler shift, power strength, and polarization of the GPS reflection signal are converted into reflection coefficients and converted into reflection coefficients. GPS reflected wave measurement and analysis system for detecting the road surface ice, characterized in that for determining the freezing state of the road surface according to.
The method of claim 9, further comprising: (D) determining a freezing state of the road surface; Is
The reflection signal characteristics including delay, doppler shift, power strength, and polarization of the GPS reflection signal are converted into reflection coefficients and converted into reflection coefficients. GPS reflected wave measurement and analysis system for detecting the road surface ice, characterized in that for determining the freezing state of the road surface according to.

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