JPH0544631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hyperbolic navigation automatic measurement device that automatically calculates the position of a receiving point in hyperbolic navigation such as Loran or Detsuka.

<Background> In hyperbolic navigation, for example Loran C, a main station and multiple slave stations form a pair. For example, as shown in Figure 1, a burst of radio waves of 1 m from the main station is followed by a burst of radio waves from each slave station. Radio waves 1 _s1 , 1 _s2 , 1 _s3
Radio waves of 1 m, 1 _s1 , 1 _s2 ,
1 _S3 is being sent. Radio waves from the master station and radio waves from the slave stations are constantly and repeatedly transmitted.
A receiver and measurement device installed on a ship or aircraft receives the radio waves from Loran-C and transmits the radio waves from the main station.
After receiving 1m, the radio waves from each slave station are 1 _s1 , 1 _s2 ,
1 By measuring the time it takes to receive _s3 , the difference in arrival time between the radio waves from the master station and the radio waves from each slave station to their reception point is measured, and the two of the measured time differences are In other words, the position of the receiving point is calculated using the measurement time difference between two different combinations of transmitting stations.

In such hyperbolic navigation, for example, when a main station M is provided on land 11 and slave stations S ₁ to S ₃ are provided on small islands as shown in _FIG . As mentioned in Figure 1, from the time between receiving the radio wave 1m from the main station M and receiving the radio wave 1 _S1 from the secondary station _S1 , the radio wave 1m from the main station M reaches the receiving point _R1. time and radio wave 1 from slave station S _{1 S1} is receiving point R ₁
Measure the time difference until reaching . In this case, in Figure 2, 1 m of radio waves from transmitting station M is 1 m on land.
It propagates over a distance of l ₁ in part 1, and further travels over the ocean.
It propagates by l ₂ and reaches the receiving point R ₁ . On the other hand, the radio waves from slave station S ₁ mainly propagate over the sea by l ₃ and reach the receiving point.
Reach R ₁ . In addition, in the relationship between the master station M and the slave station _S3 , the state on the propagation path from the master station M to the receiving point _R1 does not change, but from the slave station _S3 , the propagation occurs over the sea, _and then on land, which is the island 12. The signal propagates through l ₅ and further over the sea through l ₆ to reach the receiving point R ₁ .

In this way, the propagation path of radio waves from each transmitting station to the receiving point may include land and sea parts, only land parts, or only sea parts, and the ratio of land and sea parts may be different. It differs depending on the position of the receiving point. The electrical conductivity on land is about 1/1000th that of the sea, and the propagation constant of radio waves differs greatly between the sea and land.

However, each hyperbola corresponding to the time difference in hyperbolic navigation is created on the assumption that the state of the propagation path from the two transmitting stations is the same. Therefore, as described above, if the position of the reception point is calculated based on the time difference measured for radio waves propagated on paths with different propagation conditions, an error will occur. For example, in the past, this has caused a time difference error of up to 4 microseconds. This results in an error of about 1/4 mile.

Conventionally, in order to correct such errors, errors for each point are prepared in advance in a correction table, as shown in the magazine "Ship Science" Vol. The position of the receiving point was calculated from the measured time difference, the error at that position was read from the correction table, the measurement time difference was corrected by this error, and the position was calculated again to find the correct receiving position. .

Such correction tables have been published only in a few of the world's Loran C service areas, and for Loran C service areas for which correction tables have not been published, due to the difference in the conditions of the propagation path. It is not possible to correct errors based on Even in areas where a correction table exists, it is troublesome to manually review the correction table and correct errors in order to utilize it. Considering automatic correction from these points, it is possible to store such a correction table in memory, read the correction table memory from the measured position, and use the read error to perform correction calculations. is proposed. However, in that case, errors would be stored in the memory for each unit area in the entire service area, and the amount of data to be stored would be enormous, making it impractical.

<Summary of the Invention> An object of the present invention is to automatically correct measurement errors due to differences in propagation constants, and to store a relatively small amount of data. An object of the present invention is to provide a hyperbolic navigation automatic measurement device that can automatically correct errors using the device.

According to this invention, for each transmitting station, data indicating the sea section and land section from the transmitting station on the azimuth for each unit angle with respect to the true azimuth is stored in advance in the sea/land discrimination memory, and the data is first received based on the measurement time difference. Calculate the position of the point, calculate the true bearing and distance for each transmitting station used for the measurement from that position, and read out the sea/land discrimination memory for the corresponding transmitting station based on the calculated true bearing. Know the data indicating the land and sea sections from the transmitting station to the receiving point. Using this data, calculate the propagation time error from the previously determined distance from the receiving point to the transmitting station, and then calculate the error in the measured time difference from the calculated propagation time error for the two transmitting stations used for the corresponding time difference measurement. do. The corresponding measurement time difference is corrected using the time difference error, and the position of the receiving point is calculated again using the corrected time difference. This kind of processing is performed automatically.

<Example> Next, an example will be described in which the hyperbolic navigation automatic measuring device according to the present invention is applied to a Loran C automatic measuring device. FIG. 3 is a diagram functionally showing this embodiment, in which the radio waves of Loran C received from the antenna 14 are received and amplified by the receiver 15, and sampled by the sampling pulse from the reference oscillator 17 in the time difference measuring section 16. The sampling output is integrated in the integrating circuit 19 for each sampling of the radio waves from each station, and further, the tracking unit 21 tracks the sampling point to a desired phase position of the received radio wave using the integrated output. control is performed to
In this way, the specific phase of the radio waves from the master station is tracked, and the radio waves received from each slave station are also tracked, and the difference in reception time between the radio waves from the slave stations and the radio waves from the master station is measured. Ru.

The coordinate conversion unit 22 converts the combination of two transmitting stations with different time differences measured in this manner from a position on hyperbolic coordinates to a position on latitude and longitude coordinates, that is, calculates the latitude and longitude at the receiving point (position calculations are made). This calculation can be performed, for example, on pages 109 to 110 of the above-mentioned document 1 or in the American document LORAN Navigation with a Hand.
Calculator (Copyright 1980 by: THE
SOCITY OF NAVAL ARCHITECTS AND
MARINE ENGINEERS) (hereinafter referred to as Document 2)
This is carried out by the means described on pages 6-1 to 6-7.

Using the data indicating the latitude and longitude of the receiving point position obtained by the converting unit 22, the azimuth distance calculation unit 24 calculates the measurement time difference used for calculating the receiving point position for each of the three transmitting stations emitting radio waves. The true azimuth, that is, the angle θ with respect to north, and the distance x from the receiving point to the transmitting station are calculated. For example, in Fig. 2, for slave station S ₁ , the azimuth angle θ from _{the north direction (1 )} of the line connecting slave station S ₁ reception point R 1 and the distance x between slave station S ₁ and reception point R ₁ are calculated by calculating the azimuth distance. The calculation is performed by the unit 24. This calculation is performed, for example, as follows. The current position of slave station S ₁ is latitude L ₁ and longitude λ ₁
Assuming that the position calculation result of the reception point R ₁ is latitude L ₂ and longitude λ ₂ , the following calculation may be performed as shown on pages 6-7 of the above-mentioned document 2.

θ=180+tan ^-1 (y/x) (1) x=60sin ^-1 (x ² +y ² ) ¹² (2) x=cosL ₂ cos (λ ₂ −λ ₁ ) sinL ₁ −cosL ₁ sinL ₂ (3) y=cosL ₂ sin(λ ₂ −λ ₁ ) (4) The orientation θ obtained in this way in Figure 3
The error calculation unit 25 calculates a time difference error using the distance x and the distance x. In order to calculate this time difference error, the sea/land division memory 26 stores data indicating the sea section and land section on the azimuth for each unit angle for each transmitting station. For example, as shown in FIG.
For 5°, 10°, 15°..., the distance from the transmitting station 27 to the boundary point between the land 11 and the sea in each direction,
In the 0° direction of Fig. 4, the distance to the boundary point P ₁
l ₁ and the distance l ₂ to the next boundary point P ₂ are stored in the land/sea division memory 26.

In order to save memory capacity, the sea/land division memory 26 is preferably stored as follows. In other words, depending on the location, each 5° direction may be a continuous stretch of sea, or some of the consecutive 5° directions may have almost the same topography. Therefore, as shown in FIG. 5, for each direction of each transmitting station, the address where the sea/land division data is recorded is stored in the address storage section 28, and the address storage section is stored according to the transmitting station and the direction θ. 28 is first read out, and the data stored at the address stored in the address storage section 28 is read out from the data storage section 29.

The data storage section 29 stores, for example, data indicating the distance from each transmitting station 27 to the boundary point every 4 bits, and when the first bit is 0, it indicates land, and when the first bit is 8, it indicates sea. For example, in Figure 4
As stored in the first line of the data area 29 in FIG. 5, the 0° azimuth data has the first bit (left end) of 0 indicating land, and the first land/sea boundary from the transmitting station 27. Since the land distance l ₁ to P ₁ is 7F and the next 4 bits are 012F, the transmitting station 2
The distance l ₂ from 7 to the next boundary point P ₂ is 12F,
The difference between 7F and 12F is the sea section, and the last 2-bit FF is the last state that is continuous, that is, in this example
This shows that land is continuous for up to 1000 miles on the side farther from the transmitting station 27 than point _P2 .
This land/sea classification data covers up to 1000 miles in each direction from each transmitting station.

In this way, in FIG. 3, the azimuth angle θ calculated by the azimuth distance calculation unit 24 is used to read out the data from the land/sea division memory 26, and the error calculation unit 25 calculates the time difference error from the data and the calculated distance x. demand. In other words, the error in the radio wave propagation time from the main station to the receiving point is calculated using the same method as before, depending on the section between the sea area and the land area within the distance x from the receiving point to the receiving main station (see the above-mentioned document Furthermore, the error in the radio wave propagation time from one receiving slave station to the receiving point is determined, and the difference between these radio wave propagation time errors is calculated to calculate the time difference error for the corresponding measurement time difference. . Similarly, time difference errors of measurement time differences for other slave stations are calculated. These calculated time difference errors δy ₁ , δy ₂
The correction calculation unit 31 in FIG. 3 performs correction calculations on the corresponding measurement time differences, and the conversion unit 22 calculates the reception point position for the corrected time differences. The reception point position obtained as a result is displayed on the display 33 through the processing section 32 as a correct calculation result.

Also, if necessary, the reception point position obtained by the conversion section 22 is given to the navigation calculation section 34, and the distance, direction, arrival time, etc. from the reception point position to the destination are calculated and the calculation results are displayed. display on the device 33.
Furthermore, the operation unit 35 allows selection of the time difference to be measured. If necessary, calculate the time difference error as described above, correct the measurement time difference based on the time difference error, calculate the receiving point position in the converter 22 based on the corrected time difference, and further perform the calculation. Similarly, a new correction calculation is performed for the reception point, that is, the azimuth distance calculation unit 24
, the error calculation section 25 performs an error calculation, the previously corrected time difference is further corrected using the error, and the position of the receiving point is calculated using the corrected time difference, thereby obtaining a more accurate position of the receiving point. You may also ask for

As mentioned above, FIG. 3 is a functional block diagram, and in reality, each calculation section is performed by a common microcomputer. That is, for example, as shown in FIG.
6, and a display 33 and an operation unit (i.e., keyboard, etc.) 35 are connected to the microprocessor 36, and programs for the microprocessor 36 to perform various processes are stored.
The ROM 37 is connected, and the sea/land division memory 26 described in FIG. 3 is also connected (this is generally a ROM).
Additionally, read/write RAM used for calculation processing
38 are connected. The RAM 38 is provided with a storage area 38a for storing each measured time difference measured by the time difference measuring section 16, and the like. The microprocessor 36 sequentially reads out the programs in the ROM 37, decodes and executes them, and thereby sequentially performs the processing described with reference to FIG.

<Effects> As described above, according to the hyperbolic navigation automatic measurement device according to the present invention, measurement errors based on propagation errors on the propagation path are automatically calculated and compensated for.
Correct position measurements can be made. Therefore, there is no need for the complexity of manually reading out and calculating the correction table. Moreover, for this purpose, a sea/land classification memory 26 is provided to store sea/land classification data on the azimuth line for each unit azimuth for each transmitting station, thereby storing the entire correction table showing the error for each receiving point in the service area. The amount of stored data is significantly smaller compared to the case where the data is stored, and in particular, as mentioned earlier, by storing the address where the sea/land division data is stored for each direction, the storage capacity is significantly reduced. Can be made smaller.
Therefore, it becomes possible to construct the device at low cost.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the reception sequence of Loran C radio waves, Fig. 2 is a diagram showing various states of sea and land divisions on the propagation path between the Loran transmitting station and the receiving point, and Fig. 3 is a hyperbolic navigation automatic measuring device according to the present invention. A block diagram functionally showing one example, FIG. 4 is a diagram showing an example of land and sea division in each direction with respect to the transmitting station, FIG. 5 is a diagram showing an example of sea and land division memory, and FIG. 1 is a block diagram showing an example of a hyperbolic navigation automatic measuring device. 15: Receiver, 16: Time difference measurement unit, 22: Position calculation conversion unit, 24: Direction and distance calculation unit, 25:
Time difference error calculation unit, 26: sea/land division memory, 3
1: Correction calculation unit, 33: Display unit.

Claims (1)

[Claims] 1. In a hyperbolic navigation automatic measuring device that measures the arrival time difference of radio waves from two transmitting stations for two different combinations of transmitting stations and calculates the position of the receiving point from the two measured time differences, means for calculating the true azimuth angle and distance to the two transmitting stations from the difference in time between the two measurements;
A sea/land discrimination memory that stores data indicating a land section and a sea section from that transmitting station in each unit direction for each transmitting station, and a land/sea discrimination memory for each transmitting station used in the above-mentioned time difference measurement. an error calculating means for reading out data in the calculated azimuth from the above and calculating a propagation time error from the data and the calculated distance to calculate an error of each measurement time difference; and correcting the time difference error for the corresponding measurement time difference. 1. A hyperbolic navigation automatic measurement device comprising means for calculating the position of a receiving point based on the corrected time difference.