JPH07294620A - Doppler position-measuring apparatus - Google Patents

Abstract

PURPOSE:To provide a means for measuring a position with high accuracy by automatically updating a height input by a user in a position-measuring apparatus based on the Doppler effect. CONSTITUTION:The apparatus is provided with a storing means 1 for storing three or more measured results of positions, an average-calculating means 2 for obtaining an average position from the stored positions, and a dispersion- calculating means 3 for obtaining a dispersion of the measured results. A height- updating means 4 of the apparatus obtains an updated value of a height. Although two, namely, a positive and a negative values are obtained as the updated value of the height, the correct) one is calculated by calculating a measured position again and determining one that has a smaller difference of a measured value and a calculated value of a range rate from a standard deviation as a true position. Therefore, while updating he height of the measuring point by the dispersion of three or more measured results, the position is highly accurately measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Doppler positioning device based on Doppler.

[0002]

2. Description of the Related Art A positioning method based on Doppler is NN
SS (Navy Navigation Satell)
There is a positioning method represented by Doppler count (integrated value of Doppler) typified by "ite System" and a positioning method based on instantaneous Doppler frequency. Here, regarding the conventional positioning method based on the instantaneous Doppler frequency,
chmid & Lynn "Satellite Dop"
pler-Data Processing Usin
ga Microcomputer ”, IEEE T
rans. It will be described with reference to GE-16.

Now, when a transmission signal of a satellite having a known frequency is received from a certain reception point, the reception frequency is measured, and the transmission frequency is subtracted, the Doppler frequency is obtained. Due to the Doppler effect, this Doppler frequency is measured as a positive frequency when the satellite approaches the receiving point, and as a negative frequency when the satellite moves away. Positioning based on this Doppler frequency is positioning by Doppler. The rate of change in the distance between the receiving point and the satellite is called the range rate R ', and the relationship between the range rate R'and the Doppler frequency f is expressed by (Equation 1).

[0004]

[Equation 1]

As can be seen from (Equation 1), if the Doppler frequency can be measured, the range rate can be obtained. Since the range rate of (Equation 1) is obtained from the measured Doppler frequency, it will be referred to as a range rate measurement value R ′ _m . When the range rate is known, the position of the receiving point can be known. This will be described with reference to the geometrical relationship diagram of the conventional positioning method shown in FIG.

[0006] Now, the range rate at the position S ₁ of the satellites in a satellite orbit Q R _'1, the range rate at the position S ₂ of the satellite R' and _2. Range rate R 'certain aspects, since the velocity v of the satellite is a conical surface which is the rotation axis, the range rate R' with respect to ₁ i, draw a cone like b with respect to the range rate R _'2, received The point is somewhere on the line of intersection C. Here, when the reference ellipsoid K is determined, P ₁ and P ₂ are obtained as the intersections of the intersection line C and the reference ellipsoid K, and the true reception point is either of the _two intersections P ₁ and P _2. .

Since the range rate R'is a function of the receiving position of the position, the receiving position can be obtained by measuring the range rates by an unknown number and solving their simultaneous equations. However, since the range rate and the reception position have a non-linear relationship, they cannot be solved easily. The usual method of solving a nonlinear equation is to make it linear by Taylor expansion.
Now, it is assumed that the range rate is a function of the latitude φ, the longitude λ, and the bias B of the receiving point. Here, the bias B is an offset term that corrects the deviation of the reference frequency in the receiver.
Taylor range expansion of the range rate R ′, which is a function of these three variables, gives (Equation 2).

[0008]

[Equation 2]

Here, φ ₀ , λ ₀ , and B ₀ are the current estimated latitude, estimated longitude, and offset bias, respectively,
φ, λ, and B are the updated estimated latitude, estimated longitude, and offset bias, respectively. Also, (Equation 2) is
It can be rewritten as in (Equation 3).

[0010]

[Equation 3]

Here, ΔR ′, Δφ, Δλ, and ΔB are represented by (Equation 4).

[0012]

[Equation 4]

Further, R _'C, the position of the terminal (phi _0, lambda
It is a range rate obtained from ( ₀ ) and is given by (Equation 5).

[0014]

[Equation 5]

Since this is the range rate calculated from the estimated reception position, not the measured value, it will be called the calculated value of the range rate.

In the positioning by Doppler, first, the estimated initial position is obtained, and the initial position is converged to the true reception position by using the relational expression (Equation 3), the successive approximation method, and the least squares method. Since there are three unknowns: latitude, longitude, and bias, the number of Doppler measurement points may be three, but in reality, measurement data of four or more points are optimized using the least squares method and converted into three equations. Latitude / longitude bias is calculated by three equations. In the least squares method, simultaneous measurement equations are established by adding each measurement data as shown in (Equation 6).

[0017]

[Equation 6]

[0018]

NNSS is known as a positioning method based on Doppler. The NNSS needs to assume that the receiver is on a predetermined reference ellipsoid or enter the altitude by the user when performing the positioning calculation. This restriction has no problem in use on the sea where the altitude is 0 m, but when used on land where there is an altitude, a positioning error occurs because the altitude is not required. However, the conventional method has a problem that the altitude is not required because only two-dimensional positioning is possible.

Therefore, an object of the present invention is to provide a Doppler positioning device capable of highly accurate positioning by self-updating the altitude input by the user.

[0020]

In order to solve the above problems, the present invention provides a positioning result storage means for storing three or more positioning results and an average of the positioning results stored in the positioning result storage means. A positioning result average calculating unit, a positioning result dispersion calculating unit that calculates a dispersion of the positioning results with respect to the average value from the positioning results stored in the positioning result storage unit and the average value calculated from the positioning result average calculating unit, and a positioning result dispersion An altitude updating unit that increases and decreases the assumed altitude of the receiver based on the variance calculated from the calculating unit, and a positioning recalculating unit that performs positioning calculation again using the two altitudes calculated from the altitude updating unit. And the true position determining means for determining the true position from the two measured positions obtained by the positioning recalculating means.

[0021]

In the above structure, a positioning result storage means for storing three or more positioning results, a positioning result distribution calculating means for obtaining an average value and a dispersion of the positioning results, and an altitude updating means for updating the altitude based on the dispersion. By correcting the altitude of the receiver from the positioning recalculation means that performs positioning again from the two updated altitudes, highly accurate positioning can be performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings.
Will be explained. FIG. 1 shows a dop according to an embodiment of the present invention.
FIG. 3 is a block diagram of a camera positioning device. In the figure, 1 is the positioning result
Positioning result average calculation means described below as a storage means
2 and 3 or more measurements used by the positioning result distributed calculation means 3
Stores the rank result. The position currently stored is (x ₀ ，
y₀ , Z₀ ), (X₁ , Y₁ , Z₁ ), (X₂ , Y₂ ，
z₂ ) 3 points. 2 is stored in the positioning result storage means 1.
With the positioning result average calculation means for obtaining the average of the determined positioning results
is there. The average position is (x_m , Y_m , Z_m ), Then (number
7).

[0023]

[Equation 7]

Reference numeral 3 denotes a positioning result distribution calculating means for calculating the dispersion of the positioning results from the positioning results stored in the positioning result storage means 1 and the average position calculated by the positioning result average calculating means 2. When the variance is (x _v , y _v , z _v ), (Equation 8) is obtained.

[0025]

[Equation 8]

Numeral 4 is an altitude updating means, and the updated amount h is obtained from the positioning result dispersion calculating means 3 and
Becomes

[0027]

[Equation 9]

Numeral 5 is a positioning recalculating means composed of two positioning calculating means 5A and 5B, and recalculates the positioning using the altitude updated by the altitude updating means 4. Is that obtained from this block, the measured value R _'m positioning result and range rate
It is the standard deviation of the difference between (Equation 1) and the calculated value R ′ _c (Equation 5). Since the positioning recalculation is performed twice, two are obtained. Reference numeral 6 is a true position determining means. As a criterion for determining the true position, there is a method in which the smaller positioning result of the positions S ₁ and S ₂ is used as the true value. Therefore, according to the positioning method of the present embodiment, it is possible to perform highly accurate positioning by dispersing three or more positioning results and updating the altitude of the positioning point.

[0029]

As described above, according to the present invention, the Doppler positioning device comprises the positioning result storage means, the positioning result average calculation means, the positioning result distribution calculation means, the altitude update means, the positioning recalculation means, and the true position determination means. Therefore, the altitude of the positioning point can be updated by distributing the positioning results of three or more, and highly accurate positioning can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram of a Doppler positioning device according to an embodiment of the present invention.

FIG. 2 is a geometrical relationship diagram of a conventional positioning method.

[Explanation of symbols]

 1 Positioning Result Storage Means 2 Positioning Result Average Calculating Means 3 Positioning Result Dispersion Calculating Means 4 Altitude Updating Means 5 Positioning Recalculating Means 6 True Position Judging Means

Claims (2)

[Claims] 1. A positioning result storage means for storing three or more positioning results, a positioning result average calculation means for obtaining an average of the positioning results stored in the positioning result storage means, and a positioning result storage means for storing the positioning result average calculation means. Positioning result dispersion calculating means for calculating the dispersion of the positioning results with respect to the average value from the positioning results and the average value calculated by the positioning result average calculating means, and the assumption of the receiver based on the dispersion calculated by the positioning result dispersion calculating means The altitude renewing means for renewing by increasing and decreasing the altitude, the recalculating means for repositioning using the two altitudes obtained from this altitude renewing means, and the two recalculating means. A Doppler positioning device, comprising: a true position determining means for determining a true position from two measured positions. 2. The Doppler positioning device according to claim 1, wherein the positioning recalculating means calculates a standard deviation of a difference between the positioning result and the measured value of the range rate and the calculated value.