JP3956024B2 - GP path prediction method for ILS glide path apparatus - Google Patents

Description

  The present invention relates to a GP path prediction method for monitoring a spatial error caused by snow on a GP path of a glide path device in an instrument landing device (hereinafter referred to as ILS), and more particularly to a GP path prediction method for CAT3. It is.

  ILS is a landing system used in the case of poor visibility, a glide path device (hereinafter simply referred to as GP) that gives vertical approach course information, a localizer device that gives horizontal approach course information, and an airport. It is comprised with three marker apparatuses which give the distance information.

  Among them, the GP uses a reflected wave from the ground to create a GP path that gives horizontal and vertical information to the aircraft. Therefore, if the reflectance of the ground reflection changes, the GP path also changes. Therefore, at an airport in a snowfall area, the reflectance varies due to snow accumulated on the GP reflecting surface, and the GP path changes accordingly.

For example, as shown in FIG. 16, GP approach course 90 is formed by utilizing the reflected waves from three reflection points set on the Fresnel reflecting surface 83 to 300m ahead of GP antenna (not shown) However, when snow accumulates on the Fresnel reflection surface 83, the reflection point changes, and the GP approach course 90 changes in a complex manner due to multiple reflections of radio waves transmitted through the snow layer.

  On the other hand, there is a field monitor 80 related to GP path monitoring. In this field monitor 80, a field monitor antenna 82 is installed at a position 75 m ahead of the GP antenna 81, receives a monitor signal, and monitors a change in GP path angle (3 degrees), a modulation degree, and an electric field strength. is doing. As described above, the field monitor 80 monitors whether or not the GP transmitter (not shown) has failed, and does not consider the influence of snow on the Fresnel reflecting surface 83. The change of the GP approach course 90 due to snow on the Fresnel reflecting surface 83 is not monitored at all.

  That is, in the GP field monitor 80, in order to make the seasonal variation of the ground reflection coefficient constant, a radio wave reflection wire mesh (not shown) is laid between the GP antenna 81 and the field monitor antenna 82, and on this wire mesh. A monitor reflector 84 laid with 5 cm thick asphalt pavement is installed. However, when the snow accumulated on the monitor reflecting plate 84 melts, the monitor indication value fluctuates greatly due to the synergistic effect of the proximity phase effect of the wide aperture GP antenna 81 and the field monitor antenna 82. There is. For this reason, the field monitor 80 frequently removes snow from the monitor reflector 84 to eliminate the influence of snow. Reference numeral 88 denotes a GP reflecting surface center line.

  The actual change in the GP approach course due to actual snow cover is that there is no way to monitor other than flight inspection, but the flight inspection also has poor visibility under winter weather conditions, and is in visual flight. There is a problem that it is difficult to carry out a flight inspection that requires flying at the airport.

  For this reason, at snowy airports, as a countermeasure, the snow depth on the GP reflecting surface (Fresnel reflecting surface) 83 is reduced or removed from the GP antenna 81 by 300 m, and the snow depth is 30 cm or less. In order to prevent the GP approach course from deviating from the reference value, a stepped snow structure is provided in which the inclined surface 86 inclined from the pressure snow surface 85 in the 30 cm region 85a is connected to the natural snow surface 87. We are striving to However, during snowfall in winter, the amount of snowfall changes from moment to moment, and the snow depth fluctuates. Therefore, the cost and labor involved in the snow pressure removal and snow removal work in the 30 cm region 85a are heavy, and in the result of the flight inspection, GP radio waves are reflected in the inclined surface 86 region, multiple reflection occurs, and the path width of the approach course is increased. There is a problem of spreading.

  Thus, an effective method for monitoring changes in the GP approach course due to snow accumulation has not yet been established. Furthermore, there is a growing need for advanced operation of the current ILS at airports in snowy areas. Considering the above, it is an urgent task to develop a technique for predicting a GP approach course by snow.

  ILS CAT1 (Category 1) used at current airports stipulates that the snow removal standard for GP reflective surfaces is 30 cm or less, so the snow removal standard for GP reflective surfaces is always 30 cm or less during snowfall. As described above, the snow is removed by the snow removal vehicle. As described above, in CAT1, a snow removal standard using only the snow depth of snow is used. For this purpose, it is necessary to accurately measure the snow quality of snow (dielectric constant varies depending on snow quality) and snow depth.

  Accordingly, the inventors have an object to provide a prediction system for predicting a change in the GP approach course at the time of snowfall. As means for solving this problem, the dielectric constant of the snow cover such as the Fresnel reflecting surface 83 and the snow depth at that time. An invention relating to a method and apparatus for predicting a high-accuracy GP approach course by obtaining a change in the path angle due to the above has already been filed.

  As shown in FIG. 17, first, the snow reflecting surface that influences the GP approach course is a GP having a stepped snow structure that is connected from a compressed snow surface having a constant snow depth to a natural snow surface through an inclined surface. A reflection surface and a front terrain reflection surface formed by a front terrain located in front of the GP reflection surface. Therefore, the snow depth between the GP reflecting surface and the front terrain reflecting surface is measured by the snow depth measuring device 115 installed on the GP reflecting surface.

  On the other hand, the shape data representing the staircase snow cover structure is created by the staircase snow cover shape data generation unit 116, and the created shape data is stored in the data file. Further, the front topography data 111 of the front topography located in front of the GP reflecting surface is created by the front topography data generation unit 117, and the created front topography data is stored in the data file.

  Next, a typical dielectric constant of the snow that forms the stepped snow structure is measured by the dielectric constant generator 114, and the measured dielectric constant is stored in a data file and each dielectric constant stored in the data file is also measured. Each snow depth at the time of each measurement is measured by the snow depth measuring device 115, and the height data of the GP antenna 81 of the glide path is input to the prediction calculating device 118, and the obtained shape data, forward terrain data, and representative The dielectric constant and the snow depth at this time are read from the data file and input to the prediction calculation device.

  Then, the prediction calculation device 118 sequentially obtains the reflection coefficient on the compressed snow surface and the inclined surface of the stepped snow accumulation structure while changing the distance from the GP antenna 81 to the reception point, and reflects each of the obtained reflection coefficients. The electric field strength of the wave is obtained, and similarly, the wave of the radio wave from the frontal topography is obtained sequentially, and the electric field strength of each of the obtained diffracted waves is obtained. Further, the direct wave at the receiving point is transmitted from the GP antenna to the receiving point. Are obtained sequentially while changing the distance, and the electric field strength of each of the obtained direct waves is obtained.

In the predictive calculation device 118, the path angle is calculated from the height data of the GP antenna 81, the reflected waves obtained by changing the distance from the GP antenna to the reception point, the direct waves, and the electric field strengths of the diffracted waves. The glide path GP approach course 108 is predicted by obtaining the change and the change in the path width.
JP 2003-085699 A

In the invention previously filed by the inventors, the snow removal method of CAT1 is adopted. This is because the snow depth of the GP reflecting surface is monitored by a snow depth meter (six in the embodiment) of a plurality of snow depth measuring devices standing on the GP reflecting surface, and the snow surface is replaced with a complete conductor reflection model. The snow depth is measured by averaging the data from the snow depth gauge. However, when the snow removal vehicle travels so that the snow removal standard of the GP reflecting surface is 30 cm or less, it travels so as not to tilt the snow depth meter. Therefore, as shown in FIG. In the vicinity of the snow depth gauge, there are residual snow areas with different snow depths. Therefore, the vertical section of the snow cover has a two-layer to three-layer structure in which fresh snow accumulates on the surface layer. Therefore, the GP path prediction method that calculates by replacing the snow surface with a complete conductor reflection model has a low prediction accuracy and does not match the flight experiment results. Therefore, development of a highly accurate GP path prediction method is desired.

  Furthermore, since the dielectric constant of snow is measured by a reflection method or a transmission method, the measurement antenna becomes large, and therefore the dielectric constant measurement device becomes large. Since such a large dielectric constant measuring device is installed on the GP reflection surface, there is a problem that it is difficult to measure the dielectric constant by a reflection method or a transmission method. There has been a demand for a smaller dielectric constant measuring apparatus.

  Even in heavy snowfall areas such as Aomori Airport, CAT3 (snow removal standards are defined as 10 cm or less) is scheduled in the near future. However, in CAT3, it will switch to an advanced operation method that uses automatic landing as the basic mode. Therefore, the deviation of the GP path due to snow accumulation may lead to a serious accident. Is one of the factors that cause a decrease in the GP path, and monitoring the GP path is an important issue.

  The deviation of the GP path during snow accumulation depends on the snow accumulation state of the GP reflecting surface. Therefore, in order to monitor the GP path, it is necessary to monitor the snow accumulation state and perform snow removal work according to the snow removal standard. However, in heavy snowfall areas such as Aomori Airport, when operating CAT3 in the winter, it is possible to remove snow of 10 cm, which is the current CAT1 snow removal standard, and 30 cm, which is the current CAT1 snow removal standard. Since snow removal will not be in time, there is a demand for significant relaxation of snow removal standards.

  In order to make ILS CAT3 in such a heavy snowfall area, it is necessary to relax the snow removal standard to about 30 cm which is the standard of the current CAT1, and further, the GP path becomes the specified value due to the snow on the GP reflecting surface. The purpose was to solve the two problems that it was necessary to monitor the GP path and predict the GP path during the snowfall period so as not to deviate and reduce the reliability of the ILS.

  The invention according to claim 1 includes forward terrain data formed by forward terrain located in front of the GP reflecting surface, snow data of a constant snow depth that forms a layer structure in which the GP reflection points are removed at the same height, and GP GP path prediction of the ILS glide path device storing the snow data of unequal snow depth, which forms a layered structure where snow is removed at uneven heights of reflection points, as basic snow shape data of the GP reflecting surface, respectively, in a data file In the method, at least the antenna height of the three elements of the upper element, the middle element, and the low element, the offset amount of the GP antenna from the runway are set, the basic snow shape data, the transverse gradient data of the GP reflecting surface, the longitudinal gradient data, In addition to reading from the data file, the GP reflection surface is converted to a mesh data string, and the permittivity of the snow cover at a constant or uneven snow depth is measured. In addition to measuring with a resonance type sensor, each snow depth at the time of measuring each dielectric constant is measured with a snow depth meter, and the measured dielectric constant, the snow depth at the time of measuring this dielectric constant, and a constant snow cover from the data file The following (1) to (5), in which at least three points of the mesh data string in the longitudinal direction of the depth or uneven snow depth and the height data of the GP antenna are read and the distance from the GP antenna to the receiving point is variable. ) Is repeated, (1) the reflection point is estimated from the mesh data string, (2) the propagation path from the reflection point, the GP antenna virtual image and the reception point is obtained, (3) the reflection coefficient of snow is obtained, 4) A direct wave is obtained, and (5) a diffracted wave of the front terrain is obtained from the front terrain data formed by the front terrain located in front of the GP reflecting surface, and the direct wave and the reflection of each of the two frequencies thus obtained are obtained. wave By adding the diffracted wave, obtains an input signal ILS receiver, in which was set to determine the received instruction value DDM airborne receiver from the ILS input signal.

  The invention according to claim 2 is the GP path error calculation based on at least the GP path characteristic, the GP path width characteristic, the snow depth and the snow quality error, and the predicted snowfall amount in the graphic display unit in the invention according to claim 1. The figure shows the basic snow cover shape.

  According to a third aspect of the present invention, in the first and second aspects of the present invention, the dielectric constant measurement sensor for measuring the dielectric constant is measured using a resonance type sensor arranged in the snow depth direction. Is.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the dielectric constant measurement sensor for measuring the dielectric constant is measured using a resonance type sensor having a structure installed on the ground plane. It is a thing.

  According to a fifth aspect of the present invention, in the inventions according to the first to fourth aspects of the present invention, the difference in snow quality of the snow is obtained by using a measured value of dielectric constant.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein after removing snow to a constant snow depth, the snow depth at a reflection point of any one of the three-element antennas is measured by a snow depth meter. It is to be measured.

  The invention according to claim 7 is the invention according to any one of claims 1 to 5, wherein when removing snow at an unequal snow depth, snow removal with different heights is performed on the snow surface of each reflection point of the three-element antenna. A cap is inserted.

  Since the invention according to claim 1 is configured as described above, the reflected wave can be analyzed on the snow surface of the GP reflecting surface even in the three-dimensional snow surface shape in the longitudinal direction and the transverse direction, which is higher than the conventional method. The GP path can be accurately monitored and predicted.

  Since the invention according to claim 2 is configured as described above in the invention according to claim 1, at least the GP path characteristics, the GP path width characteristics, the snow depth and snow quality errors and predictions are displayed on the graphic display unit. Since the error calculation diagram of the GP path based on the amount of snowfall and the basic snow cover shape are displayed, necessary data can be clearly displayed.

  Since the invention according to claim 3 is configured as described above in the invention according to claims 1 and 2, the effect of the invention according to claims 1 and 2 is obtained, and the dielectric constant is measured. As a device to perform, it can be much smaller and lighter than conventional measuring devices. In addition, the conventional sensor suffered from metal fatigue due to snow expansion and contraction due to being buried in the ground, and there was a problem for long-term use. However, the resonance type sensors are arranged in the snow depth direction. Since it is not necessary to embed in the ground as in the prior art, it is durable even for long-term use. In addition, the amount of snow on the resonant sensor can be minimized, and a hollow portion like eaves due to snow is not formed below the resonant sensor, so an accurate dielectric constant must be measured. I can do it. Also, it does not get in the way of the snowplow and it is not necessary to calibrate complicated measuring equipment.

  Since the invention according to claim 4 is configured as described above in the invention according to claims 1 and 2, the same effect as the invention according to claim 2 is obtained. Furthermore, since the snowplow can run on the resonance sensor installed on the ground, it does not interfere with the snow removal work. In addition, there is no occurrence of residual snow portions having different snow depths.

  Since the invention according to claim 5 is configured as described above in the invention according to claims 1 to 4 in the invention described in the above, the snow quality of snow, that is, sleet snow, hail, etc. Since the difference in the snow quality is the difference in the dielectric constant, the difference in the snow quality can be introduced into the GP path prediction calculation by using the measured value of the dielectric constant.

  Since the invention which concerns on Claim 6 was comprised as mentioned above in the invention of Claims 1-5, it is easy to remove snow, and it does not generate | occur | produce the residual snow cover part from which snow cover depth differs. . Further, since changes in snow depth and dielectric constant are made uniform, the measurement result at one point can be represented as the snow quality of the reflecting surface.

  Since the invention which concerns on Claim 7 was comprised as mentioned above in the invention of Claims 1-5, since it can remove snow as a mark at the time of snow removal, snow removal work is easy. Furthermore, since the snowplow can pass over the snow removal cap, there is no occurrence of residual snow accumulation portions having different snow accumulation depths.

  Set at least the antenna height of the upper element, middle element, and low element, the offset amount of the GP antenna from the runway, and the basic snow shape data, the cross slope data of the GP reflecting surface, and the longitudinal gradient data from the data file At the same time, the GP reflection surface is converted into a mesh data string, and the dielectric constant of snow with a constant snow depth or uneven snow depth is measured by a resonance sensor as a dielectric constant measurement sensor, and at the time of measuring each dielectric constant Each snow depth is measured with a snow depth meter, the measured dielectric constant, the snow depth at the time of measurement of this dielectric constant, the mesh data string in the longitudinal direction of constant snow depth or uneven snow depth from the data file, and GP At least three points of antenna height data are read.

  Next, the following (1) to (5) in which the distance from the GP antenna to the reception point is made variable are repeatedly processed, (1) the reflection point is estimated from the mesh data string, and (2) the reflection point and the GP antenna virtual image. And the propagation path from the receiving point, (3) the snow reflection coefficient, (4) the direct wave, and (5) the front terrain from the front terrain data formed by the front terrain located in front of the GP reflecting surface. The diffracted wave is obtained, and the direct wave, the reflected wave and the diffracted wave of the two frequencies obtained in this way are added to obtain the input signal of the ILS receiver, and the on-board receiver receives the signal from the ILS input signal. The indication value DDM is obtained, and at least the GP path characteristics, the GP path width characteristics, the snow depth and snow quality errors, the GP path error calculation chart based on the predicted snowfall amount, and the basic snow cover shape are displayed on the graphic display unit.

An embodiment of the present invention will be described in detail with reference to FIGS.
FIGS. 1b to 1c are models of the basic snow depth shape of the GP reflecting surface, and FIG. 1b is a GP reflecting surface (hereinafter referred to as a “slave depth”) having a layer structure in which the GP reflecting points are removed at the same height. Fig. 1c shows the GP reflecting surface of the unequal snow depth (hereinafter, simply referred to as the unequal snow depth) that forms a layer structure in which the snow is removed to a non-uniform height at the GP reflection point. ing.

  FIG. 2 is a configuration diagram of a dielectric constant measuring device for measuring the dielectric constant of snow, FIGS. 3a to 3b are perspective views of the snow removal cap 7, and FIG. 3a is a snow depth of 30 cm installed near the reflection point of the middle element antenna. The snow removal cap 7a, FIG. 3b is a snow removal cap 7b having a snow depth of 10 cm installed near the reflection point of the upper element antenna and the low element antenna. FIG. 4 is a layout diagram of the snow removal cap 7, and FIG. 5 is a configuration diagram of the prediction calculation unit 8.

  The shape of the GP reflecting surface has a great influence on the formation of the GP path of the GP. For example, the GP reflecting surface of Aomori Airport, which the inventors have experimented, has a cross slope of 1.5% and 0 for both the constant snow depth shown in FIG. 1b and the unequal snow depth shown in FIG. 1c. It has a vertical gradient of 15%, and the snow quality of the vertical section of the snow has lower fresh snow and upper fresh snow. Furthermore, the surface is fresh snow.

  1b to 1c, 1 is a GP antenna, 2 is a snow depth meter, and 3 is a GP reflection point. In this embodiment, three points are measured. Reference numeral 4 denotes a dielectric constant measuring sensor, and in this embodiment, a resonant sensor 4a arranged in the snow depth direction and a resonant sensor 4b having a structure installed on the ground are used. 5 is a snowplow.

  Note that the resonance type sensor 4b having a structure installed on the ground as the dielectric constant measurement sensor 4 is destroyed even when the snowplow 5 travels in a place where the resonance type sensor 4b is buried during snow removal work. There will be no residual snow.

  In FIG. 2, a plurality of resonance sensors 4 a and 4 b as the dielectric constant measurement sensor 4 are arranged along the support pillars 10 standing in the snow depth direction for measuring the snow quality of the middle layer and the surface layer. The resonance type sensor 4a and the resonance type sensor 4b having a large ground installation structure are used for measuring snow quality of the lower layer snow. The resonant sensors 4a and 4b have a half-wave electrical length consisting of two parallel or three wires incorporated in a corrosion-resistant dielectric plate such as PTFE (trade name: Teflon (registered trademark)). Alternatively, there is a distributed line type resonator having a quarter wavelength shape, which resonates freely in the UHF band (near 1 GHz).

  The dielectric constant measuring device 6 includes a dielectric constant measuring sensor 4, a network analyzer 11 for measuring resonance characteristics, a coaxial switch and driving unit 12 for multi-port coaxial switching, a sensor resonant line 13, a personal computer for measuring instrument control and data storage ( (Hereinafter referred to as PC) 14.

  The dielectric constant measurement sensor 4 and the network analyzer 11 are connected by a pair of coaxial cables (2 ports), and the control of the coaxial switch 12 for sequentially switching the connection with each sensor 4 is controlled from the PC 14 side by the RS232C interface 16. Is done through.

  In the measurement of the complex permittivity of snow, a part of the resonant electromagnetic field along the sensor resonance line 13 leaks out of the dielectric plate, so that it depends on the complex permittivity of the snow in the vicinity that interacts with this in the air. Changes in the sensor resonance characteristics. Therefore, the complex dielectric constant can be estimated by comparing the measured values of the resonance frequency and the load Q (resonance frequency / resonance bandwidth) with values stored in the air in advance. The free resonance frequency of the sensor is designed in the UHF band where the shape and size are reasonable, and the measurement result of the dielectric constant is converted into the target GP frequency (330 MHz) band.

The network analyzer is controlled by an automatic measurement control program on the PC 14 at regular intervals via the GPIB interface, and the coaxial switch 12 is also controlled at regular intervals by this automatic measurement control program on the PC 14. . The measured dielectric constant profile data is displayed on the display 15 on the PC 14 together with the measurement time, and can be stored in the PC 14 at the same time.

Next, a method for removing snow from the GP reflecting surface will be described.
First, as shown in FIG. 1b, a case where snow is removed to a constant snow depth will be described. If snow removal with a constant snow depth is performed, changes in snow depth and dielectric constant depending on the location of the GP reflecting surface are made uniform. Therefore, it is possible to apply a dielectric constant measuring device of a type in which a dielectric constant measuring sensor is inserted into snow. The dielectric constant can represent the measurement result at one location as the snow quality of the GP reflecting surface.

  Therefore, as shown in FIG. 1b, a case where snow is removed to a constant snow depth will be described first. Snow removal was performed at a constant snow depth, and the snow layer structure was two-layer structure (lower layer and surface layer), and GP path prediction calculation was performed. The prediction calculation results are shown in FIGS. In FIG. 6, the lower layer snow depth Dsw1 = 5 cm and ε1 = 1.8−j0.004, and in FIG. 7, the lower layer snow depth Dsw1 = 10 cm and ε1 = 1.8−j0.004. The snow depth of the surface layer was set at 10 cm intervals, and the dielectric constant was variable in the range of 1.0 <ε1 ≦ 1.3 by simulating snow melting as shown on the horizontal axis of FIGS.

  As apparent from FIGS. 6 and 7, when the snow depth is Dsw1 + Dsw2 = 35 cm or 40 cm, the GP path increases rapidly. Therefore, it is necessary to remove snow to a constant snow depth of 5 cm to 15 cm and to carry out snow removal before melting snow when Dsw1 + Dsw2> 35 cm or 40 cm. If such a snow removal system can be implemented, the snow removal standard up to 40 cm can be relaxed.

  FIG. 8 shows a prediction calculation simulating the case where the snow moisture content increases due to warm winter or rain. As is apparent from FIG. 8, the snow is removed to a constant snow depth, the upper snow depth is 30 cm, and the lower snow depth is 30 cm. When the snow depth is 15 cm, the change in the GP path is greatly reduced when the dielectric constant of the lower snow depth is changed from 2 to 10. Therefore, if the change in the dielectric constant is monitored, the Cdi (indicated value on the machine) fluctuates during cold weather, so it is necessary to monitor carefully. However, during the warm winter, the rain and the end of snowfall, Does not occur.

  Next, a case where snow is removed to an uneven snow depth will be described. In the case of the unequal snow depth shown in FIG. 1c, it is difficult to remove snow in this state. Therefore, as shown in FIGS. 3a and 3b, snow removal caps 7 (7a and 7b) having different heights are applied to the snow surface near the reflection point 3 of the three-element antenna, and reflected by the upper element, the middle element, and the low element, respectively. If it is interpolated in the vicinity of the point 3, the snowplow 5 can remove snow to a snow depth (for example, 10 cm, 30 cm, 10 cm) corresponding to the height of the snow removal cap 7 using that as a mark.

  As shown in FIG. 1c, it is necessary to remove snow by 30 cm higher at the reflection point 3 of the middle element of the GP antenna. As in the case of removing snow to a constant snow depth, the snow layer structure is a two-layer structure (lower layer and surface layer), and as shown in FIG. 9, the lower layer snow depth is Dsw1 = 10 cm or 35 cm (middle element reflection point) ), The dielectric constant of the lower snow depth is ε1 = 1.8−j0.004. As shown in FIG. 10, the lower layer snow depth is Dsw1 = 10 cm or 30 cm (the reflection point of the middle element), and the dielectric constant of the lower layer snow depth is ε1 = 1.8−j0.004. In addition, the snow depth of the surface layer is set at an interval of 10 cm, and the dielectric constant is calculated in the range of 1.0 <ε1 ≦ 1.3 by simulating the snow melting state as shown in the horizontal axis of the figure. .

  As shown in FIGS. 9 and 10, when the snow depth of the two layers (the lower layer and the surface layer) is Dsw1 + Dsw2 ≦ 60 cm or more, the fluctuation of the GP path rapidly increases when the surface snow melts. Therefore, if the height of the snow removal cap 7 is set to 10 cm, 30 cm, and 10 cm, and snow is removed using this as a mark, a significant relaxation up to 60 cm becomes possible.

Next, GP path prediction calculation will be described with reference to FIG.
In FIG. 5, first, at the start of calculation (step 51), at least the antenna height of at least three elements of the upper element, middle element, and low element, and the offset amount of the GP antenna from the runway are input as basic data (step 52). . Further, the front terrain data formed by the front terrain located in front of the GP reflecting surface is read from the data file (step 53). Similarly, basic snow shape data (snow data) of the GP reflecting surface, cross slope data and longitudinal gradient data of the GP reflecting surface are read from the data file (step 53). The GP reflecting surface is converted into a mesh data string (step 55). In this embodiment, the GP reflecting surface is broken down into a 20 cm wide mesh data string.

  In step 52, the snow data read from the data file is a data string in the longitudinal direction of a constant snow depth or an uneven snow depth. While reading these data strings, the dielectric constants ε1, ε2, and ε3 measured by the dielectric constant measuring device and the snow depth meter, the snow depth data Dsw1, Dsw2, Dsw3, and the height data of the GP antenna element (in this embodiment, 4 .32m, 8.63m, 12.95m) is read (step 54).

The coordinate system of the GP antenna is an orthogonal coordinate system having the GP antenna base as an origin. Conventionally, the two-dimensional analysis is performed in consideration of the longitudinal direction of the GP reflecting surface. However, when the remaining snow portion of the snow cover and the unequal snow depth are deformed, the GP reflecting surface may be deformed in three dimensions. Therefore, as shown in FIG. 11 as a schematic diagram for analyzing the reflected wave when the surface shape of the GP reflecting surface is three-dimensional, the runway crossing gradient, longitudinal gradient, and longitudinal snow accumulation on the GP reflecting surface are shown. This is a three-dimensional analysis taking into account the shape change, and the surface shape of the reflecting surface is obtained by equation (1).

  Here, the snow data (Hsnow) of the equation (1) is the snow shape data of the reflection points for uneven snow depth shown in FIGS. 11 and 12, 0.0015 is the longitudinal gradient, and 0.015 is the transverse gradient. . If there is survey data on the GP reflecting surface, the survey data is read and calculated (step 52).

  Next, the following (1) to (5) repetitive processing (Do Loop) for changing the distance from the antenna to the receiving point is executed in the following order (step 55). First, in the iterative process (1), the GP reflection surface is converted into a mesh data string, and the reflection point is estimated from the mesh data string as follows (step 56). Hereinafter, a method for estimating at least three points (upper, middle, and low) of reflection points on the GP reflection surface will be described with reference to the schematic diagram of FIG.

  First, in the iterative process (1), the receiving point of the experimental device is known, a data string in the cross direction of the mesh is selected, and the point at which the horizontal deviation Dho of the receiving point is minimized is calculated. While moving this operation one column at a time in the longitudinal direction, the minimum value of the deviation Dho of each column is estimated at any time. From this column vector, a point at which the deviation Dvo in the height direction of the reception point is minimized is obtained. This point becomes a reflection point of the radio wave (step 56).

  Next, in the iterative process (2), the minimum point of any horizontal deviation Dho is set to (Xf, Yf, Zf), its tangent plane is obtained, and the virtual image (Xi) of the GP antenna that is point-symmetric with respect to this tangent plane , Yi, Zi), the following equation (2) is obtained (step 57).

  Here, (Xo, Yo, Zo) are the coordinates of the intersection of the tangent plane of the minimum point (Xf, Yf, Zf) of the horizontal deviation Dho and the Z axis of the GP antenna. Zox and Zoy indicate the z and y components at the intersection of the tangent plane and the Z axis of the GP antenna.

  Further, the deviation Dvo in the height direction of the reception point is obtained from the straight line connecting the virtual image of the GP antenna and the reflection point obtained by Expression (2), and the deviation Dvo in the height direction is obtained from the column vector in the longitudinal direction. Estimate the point that minimizes. Thus, according to the calculation theory of the deviation Dho in the horizontal direction and the deviation Dvo in the height direction, the reflection point on the GP reflection surface can be searched by the shortest method.

  Next, in the iterative process (3), the reflection coefficient Γsnow is calculated (step 58). The theoretical formula of the reflection coefficient Γsnow = Zte (θ) when the GP digital pattern of the horizontal deviation pattern (TE wave) is incident on the snow surface of the three-layer structure (non-snow depth) at an incident angle θ is It is represented by (3) (step 58).

  Here, Z3 is a recurrence formula of the input impedance of the snow surface of the layer structure, and is calculated from the lower layer to the surface layer in order. Z0 is the characteristic impedance of free space, Zgd is the characteristic impedance due to the dielectric constant of the earth, Zsw3 is the characteristic impedance of each layer, and γsw3 is the propagation constant of each layer.

  In the iterative process (2), a transmission / reception point propagation path Xd shown in the following equation (4) is calculated (step 57). The propagation path Xd is calculated from the antenna virtual image, the reflection point, and the reception point (step 57).

  Next, in the iterative process (4), the reflected wave is obtained by the following equation (4) (step 58).

  Here, the propagation path Xd is a path connecting the antenna virtual image, the reflection point, and the reception point. Γsnow is a reflection coefficient from the snow surface when a TE wave (horizontal polarization in GP) is incident on the multilayer snow depth, the incident angle to the snow surface, the snow depth Dsw of each layer structure, and the dielectric constant ε = ε of each layer It is calculated from “−jε”. Note that the snow depth Dsw of the layer structure and the dielectric constant ε = ε′−jε ”of each layer are snow accumulation data measured by a dielectric constant measuring device.

  Next, in the iterative process (4), the diffracted wave by the hill ahead is calculated and the direct wave is calculated (step 59). Thus, in the iterative process shown in FIG. 5, the process from step 56 to step 59 is performed.

  Next, the received signal of the ILS receiver synthesizes the direct wave, the reflected wave and the diffracted wave while changing the antenna height and transmission / reception distance of the three elements, and the receiver instruction value DDM is obtained through the two-frequency signal demodulation processing of the receiver. It is calculated (step 60), and is displayed on the graphic display unit by DDM (step 61).

  In the graphic display area, a GP path characteristic diagram, a GP path width characteristic diagram, a figure of the ground shape and snow layer structure, a snow depth and snow quality error diagram, and a GP path error calculation diagram that gives the expected snowfall amount are displayed. (Step 61), the process ends (Step 62).

  Note that the GP path prediction calculation unit according to the present invention performs an iterative process to vary the distance from the antenna to the reception point, so that the dielectric constant representing the snow quality of the snow from the dielectric constant measuring device input in step 56 is obtained. The calculation of the GP path can also be performed by changing the value of the rate. Therefore, the GP path prediction method according to the present invention can be applied to any snow quality to predict the GP path.

  Next, in order to investigate the influence of the snow cover state in which there is a residual snow cover portion on the GP path angle, the inventors of the present invention at Aomori Airport when there is no snow on the GP reflecting surface or in FIGS. ) A flight experiment was conducted on the snow cover with the layer structure shown in the figure.

  First, a flight experiment was conducted using MuPAL-α (Dornier aircraft) as an experimental aircraft. In addition, this experimental aircraft is equipped with a GPS augmented inertial navigation system (GPS Aided Inertial-Navigation Avionics, abbreviated as GAIA). By receiving GPS correction signals from the ground, the position of the aircraft is 1 m or less in error. Positioning can be performed with accuracy.

  In the flight experiment, the path is intercepted at a distance of 15 km, and then the receiver data of the 3rd GP path is collected. Since the experimental aircraft leaves the GP path due to the wind, the path characteristic (DDM: Difference of Depth of Modulation) is obtained by correcting the path deviation of the aircraft from the ILS receiver output. As a result, the influence of the frontal terrain and the ground structure of the GP antenna was obtained.

  Further, the amount of separation of the aircraft was obtained from positioning data by DGPS using the carrier phase.

Here, the snow accumulation state when the flight experiment was conducted is as follows.
As shown in FIG. 12 (a), the reflection points are generated at 80 m (Hlow), 160 m (Hmid), and 240 m (Hupr) positions at an equal interval of 80 m from the GP antenna. The residual snow depth near the three element reflection points is shown, and residual snow is generated depending on the location after snow removal. (B) to (e) in FIG. 12 show the residual snow layer and the layered structure of snow on the GP reflecting surface. (B) is the snow cover in January 2003, (c) is the Heisei era. The snow condition in February 2015, (d) the figure shows the snow condition on February 3, 2016, and (e) the figure shows the snow condition on February 19, 2016. The snow cover state has a layer structure of two to three layers. The dielectric constant was measured in the vicinity of the reflection point. The value of the dielectric constant shown in the figure shows the average value of the measured values. In addition, since snow removal is performed with a bulldozer, the middle layer and the lower layer of the snow cover surface are hard and rough snow, and the surface layer is in a state where fresh snow has accumulated.

  Here, the ICAO path standard values for the GP reflection surface snow removal standard defined by ICAO and the GP path vertical deviation at that time are the snow removal standard 30 cm or less and the path standard value ± 30 μA for CAT1, respectively. Then, the snow removal standard is 10 cm or less, and the path standard value is ± 25 to ± 30 μA.

  Table 1 summarizes the flight test results during four snowfalls, and the GP path characteristics during snowfall are deviated to the + side or the-side when there is no snow.

  From Table 1, it was found that (1) to (2). (1) When the reproducibility of data is obtained from a plurality of data when flying on the same approach course, the change in GP path is ± 0.02 degrees or less regardless of whether there is snow or not. (2) Compared to when there is no snow, in the case of snow, there are cases where the GP path is deviated to about 0.02 degrees + and cases where it is deviated to about 0.03 degrees-. . As a result, it was found that the deviation of the GP path during snow accumulation is 0.15 degrees at the maximum and 0.05 degrees or less on average.

  FIG. 13 is a graph showing the flight experiment results shown in Table 1. The horizontal axis indicates the distance (km) from the GP antenna to the reception point, and the vertical axis indicates DDM (μA).

  As is clear from FIG. 13, when the distance from the GP antenna is farther than 14 km and nearer than 2 km, the fluctuation of DDM increases rapidly. The cause is considered to be due to the attitude change due to the wind, landing and descent of the aircraft, and the attitude of the meeting stage with the GP pass. In particular, in the vicinity of 2 km, fluctuation occurs due to the influence of the path difference due to the opening surface of the GP antenna. However, in the section from 3 km to 13 km from the GP antenna, the fluctuation of DDM was ± 5 μA or less, and the linearity was also good.

  In addition, 15/1 (measured in January 2003) and 15/2 (measured in February 2003), 16/2/3 (measured on February 3, 2004) and 16/2 / in FIG. 19 (measured on February 19, 2004) is experimental data obtained when one month of the snowfall period has elapsed, and vertical deviations of 5 μA to 10 μA are generated. This is an influence due to the difference in the snow formation process due to the weather, and during the snowfall period, the GP path can be predicted to change vertically depending on the snow cover state of the reflecting surface.

  Next, the inventors performed prediction calculation of the GP path when the snow surface has a layer structure shown in FIGS. 12B to 12E based on the prediction method according to the present invention. FIG. 14 shows the calculation result of the GP path due to snow by the novel GP path prediction method according to the present invention. The horizontal axis represents the distance (km) from the GP antenna to the reception point, and the vertical axis represents DDM (μA). Show.

  As is clear from FIG. 14, the vertical displacement near 40 μA is the same as the result of the flight experiment shown in FIG. 13 in the case of the conventional method in which the complete conductor reflection model is applied to the surface shown as data of January 2015. Although not done, in the method according to the present invention, it coincides with the straight path portion of the section of 3 km to 13 km of the flight experiment result shown in FIG.

  In addition, 15/1 (measured in January 2003) and 15/2 (measured in February 2003), 16/2/3 (measured on February 3, 2004) and 16/2 / in FIG. 19 (measured on February 19, 2004), the vertical deviation with respect to the change in snow condition due to the weather was also changed from 5 μA to 10 μA, which is consistent with the flight test results.

  In FIG. 14, a sharp noise-like fluctuation of about ± 2 μA occurs in the vicinity of 1.2 km at 10 μA or less and from 1.2 km to 5 km. This noise is inversely proportional to the distance to the aircraft. Further, when the surface shape of the GP reflecting surface is calculated as a horizontal plane, the noise disappears completely. As described above, the path error due to the division width of the mesh is different from the influence of the reflected wave from the ground structure and the diffracted wave generated in the frontal landform (for example, a hill). In the case of a reflected wave, the influence of the frontal terrain becomes a gentle path bend due to the parallel movement of the GP path up and down. A pass bend due to the frontal terrain (hill) that overlaps with noise occurs in the vicinity of 1.3 km. Since the signal level of the diffracted wave by the hill is about 4% of the reflected wave, noise near 1 km corresponds to a little less than 3% of the level of the reflected wave. Moreover, it is 2/5 or less compared with the DDM fluctuation (± 5 μA) in the flight section with good linearity, and the linearity is also good.

  Next, the inventors performed a GP path prediction calculation when the snow surface of the layer structure shown in FIGS. First, a GP path prediction calculation was performed for the three-layered snow surface shown in FIG. As shown in FIG. 15b, the horizontal axis represents the dielectric constant, the vertical axis represents the on-machine command value Cdi, the lower layer snow depth (Dsw1) is 5 cm, the middle layer snow depth remains, and the surface layer The snow depth of 5 cm to 15 cm was simulated by snowfall.

  As is apparent from FIG. 15b, it is the change in the dielectric constant of the middle layer that most significantly affects the on-machine instruction value Cdi. When the dielectric constant of this middle layer increases due to an increase in the water content of snow, the GP path tends to drop. However, when 1.9 ≦ ε2 ′ ≦ 2.1, the change in Cdi is as small as 3.5 μA. Further, in the snow covered state shown in FIG. 12 (b), it was found to be 4 μA, and it was found that both of them almost coincided with the flight experiment result (5 μA) shown in Table 1.

  Next, a GP path prediction calculation was performed for the two-layered snow surface shown in FIG. As shown in FIG. 15c, the horizontal axis represents the dielectric constant, the vertical axis represents the on-machine instruction value Cdi, the lower layer snow depth is 5 cm, the middle layer snow depth is the residual state, and the surface layer snow depth is Simulating snowfall, they were 10 cm, 15 cm, and 20 cm.

  As is apparent from FIG. 15c, it is the snow depth of the surface layer that most significantly affects the on-machine instruction value Cdi. The change in the dielectric constant of the lower layer has little effect. Since the snow depth of the surface layer is 15 cm, the indicated value Cdi = −3 μA, which is found to be in good agreement with the flight experiment results (−2 μA to −6 μA) shown in Table 1.

  Similarly, a GP path prediction calculation was performed for the two-layer structure snow surface shown in FIG. As shown in FIG. 15d, the horizontal axis represents the dielectric constant, the vertical axis represents the on-machine instruction value Cdi, and the surface snow depth was 5 cm, 10 cm, and 15 cm.

  As is apparent from FIG. 15d, the snow depth on the surface layer has the most significant effect on the on-machine instruction value Cdi. The change in the dielectric constant of the lower layer has little effect. Since the measured value of the snow depth on the surface layer is 15 cm, the indicated value Cdi = −2 μA, which is found to be in good agreement with the flight experiment results shown in Table 1 (−3 μA to −6 μA).

  Similarly, the GP path prediction calculation was performed for the three-layer structure snow surface shown in FIG. The calculation result is the value shown in FIG. 12 (e), and the snow depth of the middle layer is the residual value described in FIG. 12 (e), and the snow depth of the surface layer is 5 cm, 10 cm, It was 15 cm.

  As is apparent from FIG. 15e, it is the snow depth of the surface layer that most significantly affects the on-machine instruction value Cdi. The influence of the dielectric constant of the middle layer is when the surface snow depth is 5 cm. Since the measured value of the snow depth on the surface layer is 10 cm, the indicated value Cdi = + 7 μA to 10 μA, which is found to be in good agreement with the flight experiment results shown in Table 1 (4 μA to 8 μA).

  The GP path prediction method according to the present invention can be used particularly effectively at airports provided in heavy snowfall areas.

It is a perspective view of GP reflective surface with a residual snow part. 1, showing an embodiment of the present invention, is a perspective view of a GP reflecting surface that has removed snow to a certain snow depth. FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a GP reflecting surface that removes snow at an uneven snow depth, according to an embodiment of the present invention. 1, showing an embodiment of the present invention, is a configuration diagram of a dielectric constant measuring apparatus. FIG. 1, showing an embodiment of the present invention, is a perspective view of a snow removal cap 7 (7a) installed at a reflection point of a middle element antenna. FIG. The Example of this invention is shown and it is a perspective view of the snow removal cap 7 (7b). The Example of this invention is shown and it is a layout view of the snow removal cap 7. The Example of this invention is shown and it is a block diagram of a prediction calculation part. It is a figure which shows the Example of this invention, and shows the prediction calculation result of the GP path | pass of the constant snow depth state when the lower layer snow depth is 5 cm. It is a figure which shows the Example of this invention and shows the prediction calculation result of the GP path | pass of the constant snow depth state when the lower layer snow depth is 10 cm. The Example of this invention is shown and is a figure which shows the GP path deviation by the lower layer moisture content change of a fixed snow depth. The Example of this invention is a figure which shows the prediction calculation result of the GP path | pass of a non-uniform snow depth state when lower layer snow depth is 10 cm, 35 cm, and 10 cm. The Example of this invention is a figure which shows the prediction calculation result of the GP path | pass of a non-uniform snow depth state when lower layer snow depth is 10 cm, 40 cm, and 10 cm. The Example of this invention is shown and it is a schematic diagram for analyzing the reflected wave in case the surface shape of GP reflective surface becomes three-dimensional. FIG. 4A shows an embodiment of the present invention, in which FIG. 5A is a view showing a residual snow cover state near a reflection point of a three-element antenna, FIG. 5B is a view showing a snow cover state in January 2003, FIG. The figure shows the snow condition in February 2003, (d) the figure shows the snow condition on February 3, 2004, and (e) the snow condition on February 19, 2004. FIG. The embodiment of the present invention is shown in a graph showing the flight experiment results shown in Table 1. The horizontal axis indicates the distance (km) from the GP antenna to the receiving point, and the vertical axis indicates DDM (μA). Yes. The embodiment of the present invention shows the calculation result of the GP path due to snow accumulation, the horizontal axis indicates the distance (km) from the GP antenna to the reception point, and the vertical axis indicates DDM (μA). FIG. 4 shows an embodiment of the present invention and is a diagram showing a GP path prediction result in the snowy state of FIG. 4B. FIG. 4 shows an embodiment of the present invention and is a diagram showing a GP path prediction result in the snowy state of FIG. 4c. FIG. 4 shows an embodiment of the present invention and is a diagram showing a GP path prediction result in the snowy state of FIG. 4d. FIG. 4 shows an embodiment of the present invention and is a diagram showing a GP path prediction result in the snowy state of FIG. 4e. It is explanatory drawing which shows a prior art example. It is a block diagram which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 GP antenna 2 Snow depth meter 3 GP reflection point 4 Permittivity measurement sensor 4a, 4b Resonance type sensor 7 (7a, 7b) Snow removal cap 8 Prediction calculation part

Claims (7)

Front terrain data formed by the front terrain located in front of the GP reflection surface, snow data of a constant snow depth that forms a layer structure in which the GP reflection points are removed to the same height, and the GP reflection points are unevenly high In the GP path prediction method of the ILS glide path device, which stores the snow data of the unequal snow depth forming the layer structure removed from the snow as the basic snow shape data of the GP reflecting surface, respectively, in the data file,
Set the antenna height of at least three elements, upper element, middle element, and low element, and the offset amount of the GP antenna from the runway,
The basic snow shape data, the cross slope data of the GP reflection surface, and the longitudinal gradient data are read from the data file, and the GP reflection surface is converted into a mesh data string.
The dielectric constant of the snow of the constant snow depth or the unequal snow depth is measured by a resonance type sensor as a dielectric constant measurement sensor, and each snow depth at the time of measuring each dielectric constant is measured by a snow depth meter,
A measured dielectric constant, a snow depth at the time of measuring the dielectric constant, a mesh data string in the longitudinal direction of the constant snow depth or the unequal snow depth from the data file, and height data of the GP antenna All read at least 3 points,
The following (1) to (5) in which the distance from the GP antenna to the reception point is variable are repeatedly processed, (1) the reflection point is estimated from the mesh data string, (2) the reflection point, the GP antenna virtual image, and The propagation path from the receiving point is obtained, (3) the snow reflection coefficient is obtained, (4) the direct wave is obtained, and (5) the front terrain data formed by the front terrain located in front of the GP reflecting surface is determined. Find the diffracted wave
The input signal of the ILS receiver is obtained by adding the direct wave, the reflected wave and the diffracted wave of each of the two frequencies thus obtained.
A GP path prediction method for an ILS glide path device, characterized in that a reception instruction value DDM of an on-board receiver is obtained from the ILS input signal. 2. The graphic display unit displays at least a GP path characteristic, a GP path width characteristic, a snow depth and snow quality error, a GP path error calculation chart based on an expected snowfall amount, and the basic snow cover shape. The GP path | pass prediction method of the glide path | pass apparatus of ILS. 3. The GP path of the ILS glide path device according to claim 1, wherein the dielectric constant measurement sensor for measuring the dielectric constant is measured using a resonance type sensor arranged in a snow depth direction. Prediction method. 3. The ILS glide path device according to claim 1, wherein the dielectric constant measurement sensor for measuring the dielectric constant is measured using a resonance type sensor having a structure installed on a ground plane. 4. GP path prediction method. 5. The GP path prediction method for an ILS glide path apparatus according to claim 1, wherein a measured value of dielectric constant is used for the difference in snow quality of the snow cover. 6. The ILS glide according to claim 1, wherein after removing snow to the constant snow depth, a snow depth at a reflection point of any one of the three-element antennas is measured by a snow depth meter. GP path monitoring method for pass device. When removing snow at the unequal snow depth, snow removal caps having different heights are inserted into the snow surface of each reflection point of the three-element antenna. A GP path prediction method for an ILS glide path apparatus.