JPH0260989B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention is a method for determining a navigation position by converting the intersection of two position lines obtained as the output of a navigation device such as a Loran receiver into latitude and longitude information. This relates to navigation equipment.

(b) Conventional technology The output of the Loran receiver, which is a typical example of navigation equipment, is position line information of the current ship position, which is the measurement point.
It is necessary to use a longitude conversion device. Navigation devices using Loran receivers have a built-in latitude and longitude converter, and are now in widespread use as a means of further automating hyperbolic navigation using Loran receivers.

(c) Problems to be solved by the invention By the way, in order to determine the current position of a ship using hyperbolic navigation, the intersection of two position lines is found, but for geometrical reasons it is necessary to find the intersection of two position lines. As the distance between adjacent position lines increases, the ambiguity of the position lines increases, and the error in the determined ship position increases. Furthermore, as the intersection angle θ between the two position lines becomes smaller, the error in the ship's position similarly becomes larger. This will be explained with reference to FIG. If the two position lines L ₁ and L ₂ are orthogonal at the intersection point P, then the figure B shows the two position lines L ₁ and L _2.
Indicates the case where they intersect at the intersection point P at the intersection angle θ,
ΔL ₁ and ΔL ₂ indicate the error range caused by ambiguity in the position line, ie, variations in radio wave propagation. This error range increases as the divergence increases. Therefore, from this figure, the shaded areas A and B indicate the total error range of the ship's position, including radio wave propagation causes and geometric causes. The smaller the intersection angle of the lines, the larger the area of the shaded area.
It can be seen that the error in the desired ship position becomes larger.

As described above, the present invention provides a navigation method that allows an operator to easily determine that the accuracy of the obtained latitude and longitude is insufficient when the divergence of position lines is large or when the angle of intersection between two position lines is small. It provides equipment.

(d) Means for solving the problem The present invention calculates the information per unit time deviation of each position line from two position line information received from navigation equipment such as a Loran receiver and station position information such as a Loran station. The present invention is characterized by comprising means for obtaining a coordinate transformation coefficient representing a change in latitude and longitude of , and means for displaying this coordinate transformation coefficient.

Further, when the magnitude of the coordinate transformation coefficient is equal to or greater than a certain value, a means is provided for switching the position line information from the navigation equipment being received at that time to the position line information from another navigation equipment. .

(e) Effect First, the principle of determining the accuracy of the navigation device according to the present invention will be explained with reference to FIG.

In the figure, L ₁ and L ₂ indicate the currently used position lines.

Now, regarding the two position lines L ₁ and L ₂ , if one position line is fixed and the other position line is shifted by a unit time, the intersection point P ₁ (or _{P 2} ) represents the degree of divergence of the shifted position line and the degree of intersection between the two position lines before shifting. If the divergence of the position lines is large, the length between the original position line and the shifted position line becomes long, and the magnitude of the movement vector becomes large. Also, when the intersection angle is θ, the size of the shift vector is 1/1/2 the length between the original position line and the shifted position line.
Since it becomes the size multiplied by sin θ, the smaller the intersection angle θ, the larger the size becomes.

Therefore, it can be determined that the larger the magnitude of the movement vector, the greater the divergence or the smaller the intersection angle.
If L ₁ and L ₂ are calculated respectively, it is possible to determine whether the accuracy of the latitude and longitude obtained at the position of the intersection point is good or bad. That is,
As the magnitude of the above-mentioned movement vector obtained by calculation increases, the error range of the position of the intersection at that time increases, so it can be determined that the accuracy of latitude and longitude becomes worse. It can be determined that the accuracy of latitude and longitude improves as the value decreases.

The above movement vector can be easily determined geometrically if the Loran station position is known. Generally, the value of this movement vector is expressed as a coordinate conversion coefficient representing a change in latitude and longitude per unit time shift of a position line, and has been conventionally used to determine latitude and longitude.

The figure shows the intersection point when the unit time lag is 10 μs.
It shows that the amount of movement of P ₀ is expressed by the distance ΔD and the direction θ. The distance ΔD is the magnitude of the movement vector. ΔD ₁ and θ ₁ are fixed position line L ₂ and position line L ₁
ΔD ₂ and θ ₂ represent the amount of movement when position line L ₁ is fixed and position line L ₂ is shifted by 10 μs.

As described above, by finding the coordinate conversion coefficients that represent changes in latitude and longitude per unit time shift of each position line and displaying those coefficients, the operator can determine whether the accuracy of latitude and longitude is good or bad from the display contents. can be determined. Additionally, if the magnitude of the coordinate transformation coefficient determined is greater than a certain value, an alarm can be issued, and in that case, it is also possible to switch the position line information to be used from other navigation equipment. It is.

For example, if the position line information to be used is
and C, the accuracy of latitude and longitude may be improved compared to the case where position line information of only Loran C is used. This case will be explained with reference to FIG. 6 as follows.

In the figure, the intersection point P ₁ of time difference lines L ₁ and L ₂ is the own ship position. When the time difference line L ₂ includes an error Δt ₂ , the intersection of the time difference lines L ₁ and L ₂ varies within the range of P ₂ to P ₃ .

That is, for an error Δt ₂ of the time difference line L ₂ , the time difference line L ₁ fluctuates by Δt ₁ .

The amount of variation t ₁ on the time difference line L ₁ is determined by Δt ₁ =Δt ₂ /sinθ.

Now, if we adopt Loran A for time difference line L ₂ ,
The nominal accuracy of Loran A is 1 μsec.

Therefore, the amount of variation Δt ₁ A in the time difference line L ₁ direction is Δt ₁ A=1/1=1 (μsec).

In other words, if the time difference lines are approximately perpendicular to each other, the measurement error will be 1 μsec when measuring Loran A and C in combination.

Next, if the time difference lines L ₁ and L ₂ are both Loran C,
Since the nominal accuracy of Loran C is 0.1 μsec, the error Δt _1c in the time difference line L ₁ direction is Δt _1c =0.1/sinθ.

The time difference line L ₁ when this error Δt _1c becomes equal to the error 1 μsec in the combination of Loran A and C
When calculating the intersection angle θ _between

As is clear from this, when position measurement is performed using Loran C on time difference lines L ₁ and L ₂ , when the intersection angle of the time difference lines becomes 5.7°, Loran A is used on time difference line L ₂ .
It is equal to the error when performing positioning with the time difference lines L ₁ and L ₂ orthogonal using .

In other words, when the angle of intersection between time difference lines L ₁ and L ₂ is 5.7° or less, it is more accurate to perform positioning with the combination of Loran C and A, whose time difference lines are orthogonal to each other, than with the combination of Loran C. , it can be said that.

In the following example, Loran A and C receivers that output position line information of different geodetic systems are used as navigation equipment, and even if the two position line information are from Loran A and C, the latitude of the intersection, A navigation device is exemplified in which the longitude is determined and an alarm is issued when the calculated travel amount exceeds a predetermined allowable range. Such a device makes it easy to select a position line that provides high accuracy at any point covered by the Loran A and C chains.

(f) Embodiment FIG. 3 is a block diagram of a navigation device using a Loran receiver, which is an embodiment of the present invention.

In the figure, a Loran A receiver 1 and a Loran C receiver 2 are each configured independently, and are each capable of outputting a plurality of position line information. A position line selection circuit 4 is connected to the Loran A and C receivers 1 and 2, which selects two predetermined position line information based on the set position of the selection switch 3 from among the position line information output from them. The circuit 4 calculates the latitude of the intersection point based on the selected position line information,
A latitude/longitude conversion circuit 5 for calculating longitude is connected. In this latitude/longitude conversion circuit 5, when one of the position lines selected by the selection switch 3 and the position line selection circuit 4 is the position line information of Loran C, the station data serving as the reference for the position line is converted. First, the coordinate data is converted to Bethel system coordinate data, and latitude and longitude are determined from the converted values. For this reason,
Correction values for the above conversion are stored in advance in a geodetic system conversion table 6 composed of ROM, and the latitude/longitude conversion circuit 5 is configured to refer to the stored contents of the table 6 as appropriate. Further, although the details will be described later, the latitude/longitude conversion circuit 5 further obtains a coordinate conversion coefficient C representing a change in latitude/longitude per unit time shift of the position line, and based on this coefficient C, the It is designed to judge the accuracy of latitude and longitude. The alarm circuit 8 is a notification circuit that is activated when the result of this accuracy determination is defective, and is composed of an LED display and its auxiliary circuits.

The display 7 displays the latitude determined by the conversion circuit 5,
It consists of a digital display that directly displays numerical values of the amount of movement (azimuth and distance) determined from longitude and coordinate conversion coefficients.

Incidentally, the latitude/longitude conversion circuit 5 and the geodetic system conversion table 6 are constituted by a microcomputer.

Next, the operation of this device will be explained.

When the selection switch 3 selects the Loran A chain, the position line selection circuit 4 enables the two position line information from the Loran A receiver 1 and disables the position line information from the Loran C receiver 2. . In other words, the latitude and longitude are determined by the two position line information from the Loran A receiver 1 and the two position line information from the Loran A receiver 1. In this case, the contents of the geodetic system conversion table 6 are not referred to, and therefore the latitude/longitude conversion circuit 5 performs calculations using the two position line information from the Loran A receiver 1 with Bessel system coordinates as a reference.

When the selection switch 3 selects the Loran C chain, contrary to the above, the position line selection circuit 4 validates the two position line information from the Loran C receiver 2 and selects the position from the Loran A receiver 1. Disable line information. That is, the latitude and longitude are determined based on the two position line information from the Loran C receiver 2. In this case, the Loran C chain is configured based on the WGS system coordinates, so when calculating latitude and longitude, the geodetic system conversion table 6 is referred to and the station data is converted to data corresponding to the Betssel system. The latitude and longitude calculations described above are executed from here.

Selection switch 3 is Loran A or Loran C
If chain is selected, latitude and longitude calculations are performed as described above.

Next, the operation when the selection switch 3 selects Loran A and C chains will be described.

In this case, the position line selection circuit 4 selects one position line information from the Loran A receiver 1 and another position line information from the Loran C receiver 2, and invalidates the other position line information of each receiver. Make it. At the same time, the latitude and longitude conversion circuit 5 calculates the latitude and longitude only for the position line information from the Loran C receiver 2 using the geodetic system conversion (WGS system → Betssel system) correction value of the station data. In this way, even if the position line information has different coordinate systems, the station data related to the position line information from one position line information, that is, the position line information from the Loran C receiver 2, can be used as the reference coordinate system for the other position line information, that is, from the Betsu cell. The latitude and longitude of the intersection of both position lines can be found by simply converting to data based on system coordinates.
The reason for this is that the position line information is time difference information, that is, distance information, and if the WGS coordinate position of the reference point (transmitting station) is converted to the Bethel system coordinate position, the position line of the Loran C chain is also the position of the Loran A chain. This is because it can be handled simultaneously with lines.

As will be described later, the calculation of latitude and longitude conversion is performed after calculating the coordinate conversion coefficient C that represents the change in latitude and longitude per unit time shift of the position line. The direction θ and the distance ΔD, which are the amount of movement shown in FIG. 2, can be immediately determined. The above-mentioned accuracy determination is performed based on whether the magnitude of the distance ΔD falls within or exceeds a preset tolerance range, and if it exceeds the tolerance range, the alarm circuit 8 is activated.

Therefore, if you select a position line in Loran A and C chains that does not have an alarm,
The position line can be known as having an accuracy within a preset tolerance range.

Next, the contents of calculations in the above-mentioned stability and longitude conversion circuit 5 will be explained with reference to FIG. 4. This figure shows the calculation procedure for determining latitude and longitude using the microcomputer and determining the accuracy of the determined latitude and longitude.

Step n ₁ (Hereinafter, step n _x will be simply referred to as n _x )
Then the station code specified on the Loran receiver is input. In n ₂ , the estimated current position of the ship is read. This estimated position may be input from a key not shown, or may be the previous ship position. Next, at _n3 , the location of the station is determined from the station code input at _n1 . The above-mentioned microcomputer has a table memory in which the position of each station is stored in advance in correspondence with each station code, and the position data of the station corresponding to the station code input in _n1 is read from the above-mentioned memory. There is. In this case, if the station code is of the Loran C chain, the latitude/longitude conversion circuit 5 takes in the correction value for converting from the WGS system to the Bessel system from the geodetic system conversion table 6, and converts the station code of the Loran C chain into the Bessel system. The station data is converted to The work of converting the station data related to the position line information from the Loran C receiver described above into station data based on Betssel system coordinates is executed by _n3 .

Next, in _n4 , it is determined whether position line information is input from the Loran receiver, and if there is no input, the process advances to _n5 . At _n5 , a coordinate conversion coefficient C is obtained that represents a change in latitude and longitude (rad: angular dimension) per unit time shift of a position line (μs: time dimension). As is well known, this coefficient C is the estimated position obtained by _n2 .
It is determined geometrically based on the station position data obtained at _n3 . The obtained coefficient C is displayed at n ₆ and is temporarily stored until it is obtained again in this step, and is placed in a state where it can be used at n ₁₂ , which will be described later.

The coordinate conversion coefficient C is a value representing the change in latitude and longitude per unit time shift of the position line, and includes the degree of divergence and intersection angle of the position line described above. Therefore, by displaying this coefficient C as _n6 , it is possible to know the approximate accuracy when using that position line.

In n ₇ , as mentioned above, it is necessary to determine whether the magnitude of the distance ΔD obtained from the coefficient C falls within or exceeds the preset tolerance range, and therefore depends on the position line currently being used. Accuracy judgment is performed. The above tolerance range can be set arbitrarily, and it can be set in advance in the ROM of the microcomputer or
Just write it in RAM. If the magnitude of the distance ΔD obtained from the coefficient C is not within the above-mentioned allowable range, it is determined that the accuracy is poor and the process proceeds to _n8 and an alarm is issued. On the other hand, if it is within the allowable range, the alarm is not reported and the process returns to _n4 , where the position line information from the Loran receiver is input.

If position line information is input at _n4 , the process advances to _n9 , where the position line information is taken in. continue
At n ₁₀ , the position line at the estimated position obtained at n ₂ is determined. This can be done by first finding the distance between the estimated position and the station position obtained by _n3 , and then calculating based on this distance and the radio wave propagation speed.

Next, in n ₁₁ , the current ship position position line obtained in n ₉ and n ₁₀
By finding the difference between the position lines of the estimated position obtained in step _n12 and multiplying this difference by the coefficient C obtained in _n5 , the difference between the current ship position and the estimated position in the angular dimension can be found. Therefore, by adding the estimated position obtained from this difference _n2 to _n13 , the current position can be determined. The result obtained at n ₁₃ is immediately converted to latitude and longitude data after undergoing simple calculations and displayed at n ₁₄ .
Next, at _n15 , the current position obtained at _n13 is used as the estimated position, and the process returns to _n1 . In this case, if the estimated position of n ₂ is too far away from the true current position, an error will occur in the current position determined by n ₁₃ . Therefore, the calculation procedure shown in FIG. 4 is usually repeated several times before completing the calculation.

As a result of the above operation, regardless of whether the two position line information and station data are from Loran A or C receivers, the latitude and longitude of the current ship position can be determined, and the latitude and longitude of the determined latitude and longitude can be determined. If the accuracy is not within a predetermined range, an alarm will be automatically issued.

Therefore, if there is an alarm notification during navigation, by selecting a position line without alarm notification using the selection switch, it is possible to always obtain highly accurate latitude and longitude information with a simple operation.

Note that it takes a relatively long time to calculate the coordinate transformation coefficient C, so if you wait for position line information to be input from the Loran receiver and then calculate the coefficient C, it will take a long time to calculate the latitude and longitude. It takes time. In this embodiment, as is clear from n ₄ and n ₅ in FIG. 4, the timing for calculating the above coefficients is set to the time when position line information is not input. Therefore, there is an advantage that the time from when the position line information is input until the latitude and longitude are displayed can be made very short. In this case, the estimated position, which is the data necessary to find the coefficient C, that is, the current immediately previous ship position (n ₁₅
Even if the coordinates (reference) move somewhat, the change in the coefficient C is negligibly small and does not affect the latitude and longitude that are finally determined.

In the above embodiment, the stored contents of the geodetic system conversion table are correction values for converting station data from the WGS system to the Bessel system, and the calculations for latitude and longitude are performed based on the coordinates of the Bessel system. However, when performing the above calculation based on coordinates in the WGS system, the stored contents of the geodetic system conversion table may be used as correction values for converting station data from the Bessel system to the WGS system. It is also possible to store these correction values together so that the above calculation can be performed using coordinates of either the Bessel system or the WGS geodetic system as a reference. Furthermore, if it is desired to perform the above calculation using the coordinates of another geodetic system as a reference, it is sufficient to change the correction value stored in the geodetic system conversion table for converting into the coordinates.

Note that the correction value for geodetic system conversion is fixed, so by creating station data in advance when converting the geodetic system based on this correction value and storing it, you can effectively convert the geodetic system. A geodetic system conversion table in which conversion correction values are stored is constructed, thereby making it possible to omit the station data conversion work at _n3 .

In this way, by configuring the geodetic system of the position line to be used without constraints, it is possible to obtain the latitude and longitude with high accuracy at any point in the sea area covered by the chain, but this is not possible at present. By automating the accuracy determination of latitude and longitude based on position lines, it will become even more effective. This is because the operator can easily remove position lines that degrade accuracy just by checking whether or not an alarm is notified. Furthermore, if a large number of position lines intersect, the position line that provides the highest accuracy can be selected by looking at the coordinate transformation coefficients.

Furthermore, if the accuracy determination is poor, the position line to be used can be automatically changed. To make such an automatic change, for example, when the accuracy judgment is bad, set the position line selection switch to 1.
All you have to do is switch the steps. Further, the switching operation is continued until the accuracy judgment becomes good.

(g) Effects of the Invention According to the present invention, coordinate conversion coefficients representing changes in latitude and longitude per unit time shift of the position line being used are displayed, so the operator can determine the current latitude and longitude from the display contents. You can easily determine whether the value is accurate or inaccurate. Furthermore, if the accuracy determination is poor, the position line to be used is automatically changed, which has the advantage of always operating with the best accuracy.

[Brief explanation of drawings]

Figure 1 A and B show that the error range for the determined ship position differs depending on how the two position lines intersect.
The figure is a diagram explaining the principle of accuracy determination of the navigation device according to the present invention. Furthermore, FIG. 3 shows a block diagram of a navigation device using a Loran receiver, which is an embodiment of the present invention, and FIG. 4 shows the procedure for determining latitude and longitude in the navigation device, and 3 is a flowchart showing a procedure for determining accuracy.
FIG. 5 is a partial block diagram of another embodiment of the present invention. Furthermore, FIG. 6 is a diagram illustrating a case where accuracy is improved when using the position lines of Loran A and C. 1...Loran A receiver, 2...Loran C receiver, 3...Selection switch, 4...Position line selection circuit, 5...Latitude and longitude conversion circuit, 6...Geodetic system conversion table, 7... alarm circuit.

Claims (1)

[Claims] 1. From two position line information received from navigation equipment such as a Loran receiver and station position information such as a Loran station,
A navigation device comprising: means for determining a coordinate transformation coefficient representing a change in latitude and longitude per unit time shift of each position line; and means for displaying the coordinate transformation coefficient. 2. The navigation device according to claim 1, further comprising means for notifying an alarm when the magnitude of the coordinate transformation coefficient is greater than or equal to a certain magnitude. 3 Expresses changes in latitude and longitude per unit time shift of each position line from two position line information received from multiple navigation devices such as Loran receivers and station position information such as Loran station Means for determining a coordinate transformation coefficient; and means for switching position line information received from a navigation device to position line information from another navigation device when the magnitude of the coordinate transformation coefficient is greater than a certain value. A navigation device characterized by: