JPH05264713A - Position deciding apparatus in hyperbolic navigation system - Google Patents

Abstract

PURPOSE:To enhance the position deciding accuracy of a position deciding apparatus by a method wherein the error of a radio-wave propagation speed is reduced regarding the position deciding apparatus wherein the user's receiver of a hyperbolic navigation system utilizing the propagation of ground radio waves decides coordinates of the position of the receiver. CONSTITUTION:A lane value computation means 13 subdivides a utilization area in prescribed shape units; topographical data which indicates a topographical situation, a latitude and a longitude at each divided area is stored in advance; a topographical ratio is found from related topographical data and from a bearing angle on the basis of a transformed output from a coordinate transformation part 12. Then, the weighted average value of radio-wave propagation speeds according to geographical features is computed from the topographical ratio. Then, a lane value corresponding to the transformed output from the coordinate transformation part 12 is computed by using the radio-wave propagation speeds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position determining device in a hyperbolic navigation system, and more particularly to a position determining device for a user receiver of a hyperbolic navigation system using surface radio wave propagation to determine its receiver position coordinates. Regarding

In a hyperbolic navigation system utilizing surface radio wave propagation, radio waves from two different stations are received by a user receiver, and a locus having a constant phase difference and time difference between the received radio waves is a hyperbolic group whose focus is on each station. Then, the position coordinates (latitude, longitude) of the user receiver are determined.

The errors in such a hyperbolic navigation system are generally classified into system errors (bias errors) and random errors (random errors). The latter random error includes an error due to random changes in the propagation speed of radio waves due to atmospheric conditions, etc., and a phase fluctuation error in the received radio waves caused by the inclusion of spatial waves in the surface wave. The error can be reduced to some extent by applying the method of least squares to the value, but it cannot be made zero because the error occurs accidentally and is not reproducible.

On the other hand, the former system error is
Geometric accuracy of position line, error due to intersection angle of position line,
There are errors due to the radio wave propagation speed, errors due to the frequency stability of the emitted radio waves of the master station and slave stations, errors due to phase synchronization between the master station and slave stations, and errors caused by the proficiency level and personal habits of the measurer.

Among these errors, the above-mentioned errors and are used to increase the frequency stability by using a cesium atomic oscillator,
Further, at night, it can be corrected by using a phase synchronizer (Japanese Patent Publication No. 63-63071). However, the above error occurs because the pattern of the position line is a hyperbola, and it is a geometric error due to an increase in deviation as the position moves away from the baseline. Is difficult, and the error of is the geometrical error due to the smaller narrow angle of the position line,
Is difficult to remove as well.

On the other hand, the error due to the radio wave propagation speed is caused by the radio wave propagation path from the transmitting station to the receiving point, and is an error due to an inaccurate assumed average value of the radio wave propagation speed for obtaining the lane value. Therefore, it is possible to make some correction.

The factors, features, and means for removing the errors described above are summarized in the following table.

[0008]

[Table 1]

Therefore, in order to reduce the total error in the hyperbolic navigation system and perform accurate position determination, it is necessary to correct the system error, particularly the error due to the radio wave propagation velocity.

[0010]

2. Description of the Related Art FIG. 8 shows a positional relationship between a transmitting station and a user receiver of a general hyperbolic navigation system. Master station M, slave station S
1 and S2 are fixed stations on the ground, which are a master station M and a slave station S, respectively.
1 and the distance B _S1 between the master station M and the slave station S2.
_{Each S2} is known (constant). These master station M and slave station S1
And S2 respectively transmit a predetermined single frequency f in the same phase by time division.

The user receiver, which is a moving body, is located at point P.
Distance L from the main station M _M, Slaves S1 and S
Distance between 2 and L respectively_S1And L_S2And these distances
The user receiver is separated from the lane number (called the pattern number
Sometimes, it is obtained by calculating.

That is, the user receiver is a master station M and a slave station S.
Which lane (hyperbola) of the hyperbolic group whose focal points are the two transmitting stations M and S1 in which the phase difference is constant between the two stations
And to which lane of the hyperbolic group having the two transmitting stations M and S2 as a focus, the phase difference between the two stations, the master station M and the slave station S2, is constant. Can identify your position.

The user receiver measures the above lanes by first reading a preset radio wave propagation velocity from a read only memory (ROM) as shown in FIG. 9 (step
201), and then calculate the lane value based on the following formula.

[0014]

[Equation 1]

However, in the above equation, λ is a wavelength represented by C / f (f is a used frequency, C is a radio wave propagation velocity), and L is a wavelength.
_M (m) is the distance between the master station M and the user, L _S (m) is the slave station S
1 or S2 is the distance between the users and B _S (m) is the distance between the master station M and the slave station S1 or S2.
L _M , L _S , B _S , and f are constant, but C changes depending on the state of each propagation path.

[0016]

However, in the prior art, the above
A constant value was used for the radio wave propagation speed C of each chain
Therefore, as shown in FIG.
Distance L from S1 on land _S1L， At sea L_S1SPosition of
And the land distance L from the slave S2_S2L,Sea
Distance L_S2SFrom the sea at the position of land as shown by P '
If you move to another area, even within the same chain
Since the radio wave propagation path changes significantly, the radio wave propagation speed C
Change significantly and there is an error in the calculated lane value.
I will. I think it's accurate in most areas of the chain
Even if it can be set to the radio wave propagation speed, the topography, buildings, etc.
Due to the effect, the radio wave propagation speed is distorted and fixed in a certain area
There are some margins of error.

The present invention has been made in view of the above points,
An object of the present invention is to provide a position determining device in a hyperbolic navigation system that solves the above problems by variably setting propagation speeds of radio waves transmitted from a master station and slave stations according to the terrain.

[0018]

FIG. 1 shows a block diagram of the principle of the present invention. In the figure, the lane value receiving unit 11 receives the radio wave from the transmitting station, processes the received signal, and obtains the current lane value. The coordinate conversion unit 12 converts the input lane value into latitude and longitude in Cartesian coordinates and outputs the latitude and longitude of the current position.

The lane value calculating means 13 subdivides the use area into predetermined shape units, stores the topographical data indicating the topographical condition and the latitude and longitude for each divided area in advance, and outputs the converted data from the coordinate conversion section 12. Based on the stored terrain data selected based on and the azimuth angle at which the user looks at the user from each transmitting station (between the main station and the user), (between the slave station and the user), and (between the main station and the slave station) After calculating the weighted average value of, the lane value corresponding to the converted output from the coordinate conversion unit 12 is calculated using the radio wave propagation velocity.

The comparator 14 compares whether the error of the lane value calculated by the lane value calculating means 13 with respect to the lane value from the lane value receiving unit 11 is within the allowable range, and the error is within the allowable range. If not, the calculated lane value is corrected and input to the coordinate conversion unit 12.

Further, the lane value calculation means 13 has a memory 13
a and a lane value calculation circuit 13b. Memory 13a
Stores in advance the terrain data in which the terrain condition and the latitude and longitude are paired for each region having a predetermined shape in which the use region is subdivided, or the radio wave propagation speed corresponding to the terrain condition. The lane value calculation circuit 13b uses the terrain data from the memory 13a or the radio wave propagation speed to obtain the latitude from the coordinate conversion unit 12,
Calculate longitude to lane value.

[0022]

In the present invention, the lane value calculation means 13 calculates the radio wave propagation speed based on the topographical ratio of the radio wave propagation path between the main station and the user, between the slave station and the user, and between the main station and the slave station. Therefore, as compared with the conventional device in which the radio wave propagation speed is fixed, the calculation can be performed until the lane value calculation converges based on the radio wave propagation speed that is more practically approximated.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention is shown in FIG.
3a is a read only memory (ROM), and the current lane value received and processed by the lane value receiving unit 11 is fetched by the comparator 14 and then converged seven times. It is a composition. Therefore, the current lane value, which changes momentarily with the movement of the user receiver, is corrected seven times by the circuit unit including the comparator 14, the coordinate conversion unit 12, the memory 13a, and the lane value calculation circuit 13b. The calculation results are sequentially compared with each other, and the error of the calculation lane value is set within an allowable range. In other words, the received current lane value is held while the lane value calculation circuit 13b calculates the lane value seven times, and then the next current lane value is held again and the comparator 14 holds the seven calculated lanes. The comparison with the value is repeated.

The present invention is characterized by the processing operation of the lane value calculating means 13, and an embodiment of the operation will be described with reference to FIG. In the figure, the lane value calculation circuit 13b first obtains the terrain ratio (step 101). Since the earth is not a perfect conductor, the propagation velocity of surface waves is slower than the propagation velocity in free space and shows different values depending on the terrain. Therefore, the terrain ratio of the radio propagation path determines the accurate radio propagation velocity. Because it is necessary for

There are various examples of how to obtain the topographical ratio, which will be described later, and the ROM 13a stores the topographical data indicating the topographical features together with the latitude and longitude.
There is a method of reading from a and using it.

Subsequently, the radio wave propagation velocity C is calculated by the lane value calculation circuit 13b. Since a general radio wave propagation route is considered to be a route in which various terrain ratios are mixed, the radio wave propagation speed can be obtained by taking a weighted average of the propagation velocities of the respective terrain parts from the above terrain ratio.

Therefore, as the propagation velocity for each terrain,
For example, in the case of a mountainous area over 1000 m, C ₁, From a hundred meters
In case of high altitude up to about 1000m C₂, Hills around 100 m
In case of C₃， C in the plain_Four， C at sea_FiveThen,
The radio wave propagation velocity C is calculated as a weighted average value of the following equation.

[0028]

[Equation 2]

However, in the above equation, d ₁ is the proportion of the mountainous area, and d ₂
Is the proportion of highlands, d ₃ is the proportion of hills, d ₄ is the proportion of plains, and d ₅ is the proportion of the sea. So, for example, 10
Propagation velocity C when a 0-kHz continuous wave is propagated on a terrain with a ratio of "2" in the mountains, "3" in the hills, and "4" in the plains is d ₁ = 2, d ₃ = 3, d ₄ = 4, d ₂
= D ₅ = 0, C ₁ ≈ 297.4 (km / msec), C ₂ ≈ 298.1
(Km / msec), C ₃ ≈ 298.7 (km / msec), C ₄ ≈ 298.
9 (km / msec) and C ₅ ≈ 299.7 (km / msec) respectively (2)
It is obtained by substituting it in the equation and can be calculated as about 298.5 km / msec.

Here, the radio wave propagation speed C obtained in the above step 102 is the radio wave propagation in the three propagation paths between the master station and the user (receiver), between the slave station and the user, and between the master station and the slave station. It is a weighted average value of speed. Finally, the radio wave propagation velocity C close to the true surface wave propagation velocity thus obtained is
The lane value (lane number) is calculated by substituting it into the equation (1) (step 103).

Next, each embodiment of the lane value calculation means 13 will be described. FIG. 3 shows an explanatory diagram of the first embodiment of the lane value calculation means 13. The use area of a specific range (for example, one chain) in which the transmission station Q of one of the master station M and the two slave stations S1 and S2 and the user reception station R are located respectively,
What kind of topography (mountains, highlands, hills, etc.) for each of the subdivided cells (divided areas)
Data indicating whether the area is plain or sea) is paired with the latitude and longitude of the grid to generate numerical or symbolized terrain data, which is stored in the memory 13a in advance.

Then, in order to obtain the terrain ratio, as shown in FIG. 4, the terrain at the point P ₁ which is 1/2 box in the direction of the user position R from the transmitting station Q in the longitude is read, and then 1 block in the longitude ( Distance L) The operation of reading the terrain at the advanced point P ₂ is repeated up to the user position R. The terrain information of each point thus obtained is collected for each same terrain, and the distance for each terrain is obtained.
At this time, the azimuth angle θi when the user position R is seen from the transmitting station Q to be used can be expressed by the following equation, for example.

[0033]

[Equation 3]

However, i is M when the transmitting station Q is the main station M,
The subscripts are S1 and S2 when the slave stations are S1 and S2. Further, φ _M , φ _S1 , φ _S2 : Geographic latitude of each transmitting station λ _M , λ _S1 , λ _S2 : Geographical longitude of each transmitting station φ _P ′, λ _P ': Latitude / longitude of estimated receiving position φ _i : Latitude f of each transmitting station and estimated receiving position: Flatness of the earth In the present embodiment, when calculating the lane value, between the main station and the user based on the above terrain data and the azimuth angle θ _{i at} which the user sees the user from each transmitting station. , After calculating the distance between the slave station and the user, and between the master station and the slave station, the weighted average value of each radio wave propagation velocity is calculated based on the geographical ratio.

FIG. 5 is an explanatory view of the second embodiment of the lane value calculation means 13. In this embodiment, as shown in FIG. 5, the usage area is subdivided into trapezoidal or fan-shaped cells centered on the transmitting station Q, and for each subdivided cell, the type of topography and the latitude and longitude are set. Topographic data consisting of pairs is created and stored in the memory 13a in advance. However, in this embodiment, the topographical data to be stored in the memory 13a is required for each of the three transmitting stations. Therefore, the memory capacity is about 2 to 3 times that of the first embodiment, but the radio wave propagation speed is The calculation speed is improved because the calculation is simple.

Then, in order to obtain the terrain ratio, as shown in FIG. 6, the transmitter station Q is used from the azimuth angle θ from the transmitter station Q looking at the user position R and the terrain data of the points P _{1 to} P _3, etc. Find the distance between each person for each topographical situation. This distance is similarly calculated between the master station and the slave stations. After that, the radio wave propagation velocity is calculated based on the topographical ratio between the master station and the slave station, between the master station and the user, and between the slave station and the user, and the weighted average value thereof is further calculated. This weighted average value is used as C in equation (1) to obtain the lane value.

In this embodiment, the closer the mesh is to the transmitting station, the smaller the area is. Therefore, it is not a problem in practice to thin one out every few meshes. In addition, the location of geometrically inaccurate determined by the arrangement of the transmitting station (for example, on the base line extension of each transmitting station,
Even if the method of dividing the grid in a place far away from each transmitting station) is rough, it does not affect the positioning accuracy.

FIG. 7 shows an explanatory view of the third embodiment of the lane value calculating means. In this embodiment, as in the first embodiment, the use area is subdivided into cells as shown in FIG. 7, and the radio wave propagation speed corresponding to the topography of each cell is calculated for each transmitting station and stored in the memory 13a in advance. I'll do it.

That is, in this embodiment, the radio wave propagation speed is not calculated each time by the movement of the user, but the radio wave propagation speed value corresponding to all the cells of the chain in use (variation is expected rather than all digits is expected). Only the lower digits of the range are acceptable, the symbol,
A numerical value may be calculated) and stored in the memory 13a together with the position address (latitude, longitude) of the grid as shown in the following table.

[0040]

[Table 2]

The above table is created for each chain and
In one chain, the radio wave propagation speed (unit: km / msec) from the two transmitting stations Q ₁ and Q ₂ to the user position R is shown.
In this embodiment, the radio wave propagation speed is called from the memory 13a and used when the user calculates the lane value as the user moves. Of course, the memory 13a is not limited to the ROM but may be a RAM or the like.

[0042]

As described above, according to the present invention, since the lane value can be calculated based on the radio wave propagation speed that is more practically approximated than the conventional device, the system error due to the radio wave propagation speed can be reduced. It has features such as being able to do so.

[Brief description of drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment of the main part of the present invention.

FIG. 3 is an explanatory diagram of a first embodiment of lane value calculation means.

FIG. 4 is an explanatory diagram of a method of calculating a distance of a terrain.

FIG. 5 is an explanatory diagram of a second embodiment of the lane value calculation means.

FIG. 6 is an explanatory diagram of a method of calculating a distance of topography.

FIG. 7 is an explanatory diagram of a third embodiment of the lane value calculation means.

FIG. 8 is an explanatory diagram of a positional relationship between a transmitting station and a user of the hyperbolic navigation system.

FIG. 9 is a flowchart for explaining an operation of a conventional example.

[Explanation of symbols]

 11 lane value receiving unit 12 coordinate conversion unit 13 lane value calculating means 13a memory 13b lane value calculating circuit 14 comparators 101 to 103 steps

Claims (4)

[Claims] 1. A lane value receiving section (11) for receiving a radio wave from a transmitting station and processing the received signal to obtain a current lane value.
And a coordinate conversion unit (12) that converts the input lane value into latitude and longitude of Cartesian coordinates and outputs the latitude and longitude of the current position, and the usage area is subdivided into predetermined shape units, and the terrain for each divided area Topographical data indicating the situation and latitude and longitude are stored in advance, and based on the stored topographical data selected based on the conversion output from the coordinate conversion unit (12) and the azimuth angle as seen by the user from each transmitting station ( After calculating the weighted average values of the radio wave propagation speeds between the master station and the user), between the slave station and the user, and between the master station and the slave station, the coordinate conversion unit (12) using the radio wave propagation speeds. Lane value calculation means (13) for performing lane value calculation corresponding to the converted output from the lane value and the lane value calculated by the lane value calculation means (13) with respect to the lane value from the lane value receiving section (11). Is the error within the allowable range? And a comparator (14) for correcting the calculated lane value and inputting the corrected lane value to the coordinate conversion unit (12) when the error is not within the allowable range. Positioning device in navigation system. 2. The lane value calculation means (13) subdivides the use area into a grid shape, and topographical data in which a topographical condition and a latitude and a longitude are paired for each grid area is stored in advance. The memory (13a), the terrain data read from the memory (13a) based on the conversion output from the coordinate conversion unit (12), and the azimuth angle as seen by the user from each transmitting station ( Topographic ratios are calculated for the terrain parts (main station and user), (slave station and user), and (main station and slave station), and the weighted average value of the radio wave propagation speed in the terrain part is calculated from the terrain ratio. Lane value calculation circuit (13
The position determining device in the hyperbolic navigation system according to claim 1, characterized in that it comprises b). 3. The lane value calculating means (13) subdivides the utilization area into a trapezoidal or fan-shaped centering on a transmitting station, and pairs the geographical condition and latitude and longitude for each subdivided area. Topography data, which is stored in advance in correspondence with a plurality of the transmission stations, and the topography data read from the memory (13a) based on the conversion output from the coordinate conversion unit (12). , Calculate the terrain ratio for each terrain portion (between master station and user), (between slave station and user) and (between master station and slave station) from the azimuth angle at which the user saw each transmitting station, A lane value calculation circuit (13) for calculating a lane value after calculating a weighted average value of radio wave propagation velocities in the terrain portion from the terrain ratio.
The position determining device in the hyperbolic navigation system according to claim 1, characterized in that it comprises b). 4. The memory (13a) in which the lane value calculation means (13) subdivides the use area into cells and stores in advance radio wave propagation speeds according to topographical conditions for each of the subdivided areas. ), The radio wave propagation speed read from the memory (13a) based on the conversion output from the coordinate conversion unit (12), the azimuth angle at which the user looks at each transmitting station, and the lane where the user is located. 2. The position determining device in a hyperbolic navigation system according to claim 1, further comprising a lane value calculating circuit (13b) for calculating a value.