JPH0147748B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the speed of polarized flow such as tidal currents.

Most of the conventional methods of measuring drift velocity are to calculate it directly from the difference between ground speed and water speed, or to divide the difference between water movement and ground movement by the measurement time. I am trying to find it depending on the situation. Normally, speed over water and amount of movement over water are measured using an ultrasonic water speed meter or electromagnetic log, and speed over ground and amount of movement over water are measured using an ultrasonic ground speed meter, Loran, or NNSS.
Each is measured by a receiver, etc.

However, since the ultrasonic ground speed meter can only measure depths of 2 to 300 meters, it has the disadvantage that it cannot be used in sea areas deeper than that, and it is also difficult to measure ground speed and ground movement. When using a Loran or NNSS receiver, the measurement system is completely different from the water speedometer, and each operates completely independently, so it takes a relatively long time to determine the eccentric speed. However, when acceleration is applied to the ship, overshooting or hunting of the tracking point occurs, resulting in a large error in the calculated drift velocity.

The purpose of this invention is to eliminate the above-mentioned drawbacks, and by directly inputting information from a ship's water speed and heading device into a hyperbolic navigation device such as a Loran device or an Omega device, it is possible to determine drift speed and its hyperbolic navigation. The present invention provides a method for measuring drift velocity according to the requirements of the device.

To summarize this invention, most of the sampling timing movement speed during tracking can be estimated from the water speed and the output of the course detection device.
Focusing on the fact that the difference between the estimated movement speed and the actual movement speed obtained by correcting it, that is, the amount of correction of the estimated movement speed corresponds to the drift speed, the sampling timing can be adjusted. The contents of the speed register that stores the moving speed are set to be the correction value of the estimated moving speed obtained from the water speed and the output of the course detecting device, and the drifting speed is calculated from the correction amount. This is a characteristic feature.

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, a case where the tracking signal is a Loran C signal will be explained.

FIG. 1 is a diagram for explaining the principle of the drift velocity measuring method according to the present invention.

In Figure 1, as the ship moves, the signal changes to speed Vl.
If the tracking point moves from position A to position B, the sampling timing Tm of the first tracking point must be changed to Tm'. Now put this speed in the speed register
Assuming that Vl has been stored, the new timing Tm' is given by a function of velocity Vl. This speed Vl is due to the movement of the ship,
If you know the ship's ground moving speed (speed including course information) with respect to the station position, you can calculate the above speed from the ship's moving speed, the measured current position, and the station position.
Vl will be required immediately.

However, if the actual moving speed of the ship is defined as the speed relative to the water, that speed is different from the speed relative to the ground, so in order to perform tracking, the speed relative to the water must be corrected. On the other hand, if this moving speed relative to water is corrected to make the content of the speed register the actual sampling timing moving speed, the amount of correction of the moving speed relative to water will correspond to the drift velocity.

Therefore, if tracking is performed while setting the contents of the speed register to a value corrected by the estimated movement speed at the sampling timing obtained from the ship's movement speed with respect to water,
The drift velocity can be determined from the correction amount.
V shown in the figure represents this estimated moving speed, and Vc represents its correction amount.

By the way, if you correct the estimated movement speed in this way, you can perform tracking and measurement of the drift speed, but the correction method is the same as the conventional tracking method, by predicting the tracking point and setting the speed register. An automatic correction method is used that increases or decreases content.

Figure 2 A, B, and C show the principle of correcting the sampling timing movement speed.

Figure A shows a state in which the signal tracking point is captured at timing Tm. If the ship moves in this state, the sampling timing will be changed based on its speed relative to the water, but if there is a drift at that time, the situation will be as shown in B or C in the figure. In the state shown in B of the figure, the tracking point and sampling timing do not match because the timing movement speed stored in the speed register is too fast, and in the state C in the same figure, the timing movement speed stored in the speed register is too slow. The tracking point and sampling timing do not match. Therefore, in B, the unit amount is subtracted from the speed register, and in C, the unit amount is added to the speed register, and by performing these operations until the state in A is reached, the sampling timing movement speed is corrected. I can do it.

Therefore, if you first set the estimated moving speed of the sampling timing obtained from the ship's moving speed in the speed register, and then correct this estimated moving speed as described above, the amount of correction, that is, the actual sampling timing The drift velocity can be determined from the difference between the moving speed and the estimated moving speed.

In addition, to determine whether the sampling timing matches the tracking point, actually, as shown in Figure 2, the timings Tf and Tb are formed before and after the timing Tm, and the sample data of these two timings is used. I try to do this by looking at the In other words, if the two types of sampled data are + and - (Fig. 2 A), it is considered a coincidence state, and if they are + and + (Fig. 2 B) or - and - (Fig. 2 H). ) It is determined that there is a mismatch, and the contents of the speedless jitter are added or subtracted according to each sign.

FIG. 3 is a block diagram of the main parts of a drift measuring device to which the measuring method according to the present invention is applied.

In the figure, a received signal from an antenna 1 passes through a high frequency amplification circuit 2 and a filter 3, is made into a signal of an appropriate level, and is sent to a sampling circuit 4. When the sampling circuit 4 receives the strobe signal from the strobe signal generation circuit 5, it samples and holds the received signal at that timing, digitizes the sample signal with the A/D converter 6, and sends it to the microcomputer 7. The strobe signal generation circuit 5 receives a timing signal from a real-time counter 8 that determines the actual strobe signal generation timing, and upon receiving the timing signal, supplies a pulse with a width of 0.05 μsec to the sampling circuit 4 as a strobe signal. Real time counter 8 is from microcomputer 7
Receives GRI data and data from the master station counter TM and slave station counter TS, which will be described later,
The strobe signal generation timing is determined based on this data. Further, identification data of the chain to be used is sent to the microcomputer 7 from the input key 9, and latitude and longitude data determined by calculation are sent from the microcomputer 7 to the display 10. Furthermore, as external devices, a log 11 that measures the ship's speed relative to the water and a gyroscope 12 that measures the course are connected to the microcomputer 7, and data from these devices is taken in at regular intervals to calculate the station position. The moving speed is calculated.

The microcomputer 7 is composed of a relatively high-speed system consisting of several ordinary chips, and is capable of performing calculations,
The CPU 70 executes control, corresponds to the sampling timing of master and slave station signals, and the setting chain.
A RAM 71 that stores GRI (chain repetition period) etc. and also includes a speed register, a ROM 72 that stores execution procedures for the CPU 70, and an I/O interface 73 that exchanges data with circuits, etc. are used as external devices. The elements of the data bus
DB, address bus AB, control bus CB
It is connected to the. Further, the RAM 71 is backed up by a battery 74 so that the stored contents are retained even when the power is turned off.

As shown in the figure, the RAM 71 includes at least a chain table, a main station, a group of conventional counters, and a speed register, and the speed register is a main register MV that stores the sampling timing estimated movement speed V obtained from the movement speed of the ship. , storing a correction amount of the estimated timing movement speed for each station signal;
It consists of an auxiliary register MVc consisting of multiple registers, and a counter group for the main station that stores the capture and tracking timing of the main station signal.
TM, a slave station counter TS (TS ₁ , TS ₂ , ...TSn) that stores the acquisition and tracking timing of the slave signal, and a tracking counter P that determines the above correction amount.
It consists of M.

The chain table is a table that stores the GRI corresponding to the chain set by the input key 9, and is read out when it is necessary to send the stored data to the counters TM, TS, or the real-time counter 8. Further, the master station counter TM and the slave station counter TS are counters that are read out when sampling the master station signal and when sampling the slave station signal, respectively, and their stored data is sent to the real-time counter 8. In addition,
In addition to the above, the RAM 71 stores position data of each station forming the chain, and also contains conversion coefficients for determining latitude and longitude data from position line data.
Furthermore, another area is provided for storing conversion coefficients and the like for determining the drift speed from the speed stored in the auxiliary register MVc which stores the timing movement speed correction amount for each station signal.

Next, the main part of the operating procedure of the Loran receiver having the above configuration will be explained based on the flowchart of FIG.

Figure A shows the flow for measuring the drift speed, and Figure B shows the flow for calculating the estimated moving speed V at the sampling timing from the ship's moving speed.

First _, in step n ₁ (hereinafter step n _x will simply be referred to as n Be changed. That is, the speed register
The sampling timings stored in the counters TM and TS move at a moving speed that is the sum of the stored contents of MV and MVc. The data stored in the main register MV is formed by the flow shown in FIG. 4B, which is executed as appropriate by interrupts. That is, in this flow, the course is input from the gyro 12 and the water speed V ₀ is input from the log 11, and these are measured at n ₂₂ using these V ₀ data, station position data M, and a flow not shown. The estimated moving speed V at the sampling timing is determined from the current position data P. In addition, the auxiliary register MVc
The correction data is set to an appropriate value in the first tracking stage.

Next, the sign check of the sample data obtained at n ₂ is performed at n ₃ , and according to the method explained in Fig. 2, if the sign of the two sample data is +, +, it is determined to be less than or equal to n ₄ . , −, −, branch to n ₈ or less, respectively. n ₄ and n ₅ and n ₈ and n ₉ are steps for determining whether or not the same code data has been sampled T times for each sample, and counters P and M are used, respectively. If the same sign data is sampled T times, the correction data in the auxiliary register MVc is subtracted by a unit amount at _n7 , and the same correction data is added by a unit amount at _n11 . Then, the sampling timing is further changed using the corrected moving speed at _n1 , and the code check of the signal sample data is continued in the same procedure as above. In this way, the moving speed of the sampling timing is increased or decreased based on the correction data, and the sampling timing is converged to the tracking point. Tracking is completed when the sign of the sample data becomes + or -, that is, when it progresses from n ₃ to n ₁₃ .

_n13 is a step executed after it is determined in _n3 that tracking is complete, and the drift velocity V() [velocity in the latitude direction] and V(λ) [velocity in the longitudinal direction] are calculated. These drifting velocities V() and V(λ) are obtained based on the data stored in the auxiliary register MVc as described above, but specifically, they are obtained by calculating the following equation.

V () = αv ₁ + βv ₂ V (λ) = α′v ₁ + β′v ₂ Note that v ₁ and v ₂ track two position lines (tracking the main station signal and two slave signals). represents the moving speed of each position line (determined from the correction data for each station signal stored in the auxiliary register MVc) when
α, β, α′, β′ are V(), V
(λ) is a coefficient calculated independently from the position line data and the ship's speed of movement relative to the water.

As is clear from the above operation details, most of the sampling timing movement speed at n ₁ is
It is given by the result obtained by n ₂₂ , and the correction speed is
Since Vc is based on a stable drift velocity, the responsiveness of the tracking operation is extremely good and the accuracy is high.

In this way, this invention employs a method that directly measures drift velocity from a hyperbolic navigation device, which is completely different from conventional measurement methods. Accurate drift velocity can be determined regardless of depth.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the principle of the drift velocity measuring method according to the present invention, and FIG. 2 is a diagram for explaining the principle of correcting the sampling timing movement velocity. Further, FIG. 3 is a block diagram of a main part of a drift measuring device to which the measuring method according to the present invention is applied, and FIG. 4 is a flowchart showing a main part of the operating procedure of the same device. 4...Sampling circuit, 7...Microcomputer, 11...Log, 12...Gyroscope,
MV...Main register, MVc...Auxiliary register.

Claims (1)

[Scope of Claims] 1. It has a speed register that stores the moving speed at the sampling timing, and corrects the contents of the speed register according to the movement of the received signal to track the received signal and determine the current position of the own ship. In those that use a hyperbolic navigation device, a device to measure the own ship's speed relative to the water, and a device to measure the course, the hyperbolic navigation device An estimated moving speed at a sampling timing is determined, and a drifting speed is determined from the difference between the estimated moving speed and the moving speed at the sampling timing required for a hyperbolic navigation device to track a received signal. Method.