JPS5817384A - Signal tracking method in hyperbolic navigation system - Google Patents

Abstract

PURPOSE:To make sure that the tracking point will not be off from the range of a signal that is the object of integration even if the speed of ship is accelerated by seeking the speed of integrated average start timing from the speed of an actual ship. CONSTITUTION:The memory content of counter TM and TS1-TSn in which integrated average start timing is stored are changed based on the memory content of a speed registor MV, and the course from a gyrocompass 12 and the speed relative to water of a log 11 are respectively input. From those data, station position data, an estimated speed of integrated average start timing is sought. With this arrangement the tracking point is not lost even in a weak field strength area tracing with high accuracy can be made.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal tracking system in hyperbolic navigation such as Loran navigation and Omega navigation.

In recent years, hyperbolic navigation devices generally capture and track signals automatically. Of these, signal tracking is performed by moving the tracking timing at an appropriate speed according to the movement of the ship, and the moving speed of this tracking timing is controlled by a speed register provided in the receiver.

In such a hyperbolic III navigation device, in order to improve the tracking performance as much as possible, the conventional signal tracking method always predicts the next tracking point by using the stored contents of the speed register as the previous movement speed of the tracking timing. However, if the speed of the ship suddenly increases, there may be a delay in tracking, so if such a phenomenon occurs in a weak electric field area, tracking will be impossible. Sometimes.

By the way, there is generally a method called a cumulative averaging method as a means of increasing the S/N ratio of weak signals. This method takes advantage of the property that if the signal to be measured has periodicity, random noise components can be removed by synchronously adding the signals, allowing it to accurately measure signals buried in noise. This is the way to do it.

However, since this cumulative averaging method assumes the periodicity of the signal, it cannot be applied in hyperbolic navigation while the ship is moving, that is, during tracking when the signal period changes.

Therefore, in the conventional tracking method described above, even if the tracking point can be predicted in an area with good reception conditions, tracking becomes impossible when entering an area with a weak electric field.

The purpose of this invention is to eliminate the above-mentioned disadvantages, and to obtain the cycle change of the received signal using information from the ship's speed and course detecting device, and to perform synchronous addition based on the rate of change. The purpose of this invention is to provide a signal tracking method that can perform cumulative averaging by determining the timing to achieve the desired signal, that is, can perform sufficient tracking even in weak electric field regions.

In summary, this invention focuses on the fact that the information obtained from the ship's speed and course detecting device is correlated with the moving speed of the tracking timing, and the cumulative averaging start timing of the cumulative averaging means is obtained from the detecting device. It is something.

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 signal tracking system according to the present invention.

In Fig. 1, 0) indicates a received signal including tracking point 1,
(b) shows the cumulative averaging start timing signal given to the cumulative averaging means. Moreover, (c) shows a signal obtained by integrating and averaging the signals shown in (a).

The received signal (see 0 in the same figure) no longer maintains a certain periodicity as the ship moves, but if the cycle of the integrated average start timing changes by the same amount of change as the period that changes as the ship moves, If it is possible to do so, the cumulative average means will always e.
An integrated and averaged signal included in the tracking point T2 shown in i can be obtained. That is, an appropriate value may be set in the speed register so that the moving speed at the cumulative average start timing is the same as the moving speed of the received signal.

By the way, the moving speed of the received signal is based on the actual moving speed of the ship, but if you know the moving speed of the ship relative to the station position (speed including course information), you can calculate the moving speed of the ship, From the measured current position and station position, the moving speed of the above-mentioned received signal can be immediately determined. Therefore, from the moving speed of the ship, the periodic change in the cumulative average start timing, that is, the moving speed, is determined, and that value is used to control the same timing. By setting the speed register to the speed register, it is possible to synchronously add the received signals including the tracking point an arbitrary number of times.In this way, by determining the integration start timing based on the actual moving speed of the ship, the movement of the ship can be Regardless of the state (magnitude of acceleration, etc.), it is possible to specify the cumulative averaging start timing with high precision and excellent response characteristics.In addition, to capture the tracking point Ta from the cumulatively averaged signal, For example, as shown in Figure 1, two timings Tf%1 having appropriate time widths are used, and a predetermined period T is set as a search area, and the position where the sample data at each timing becomes + or - is searched. You should do it.

It is desirable to detect the speed of a ship relative to the ground, but in reality, it is difficult to detect the speed relative to the ground with high accuracy and continuously, and more realistically, the speed relative to the water should be detected. Targeted. Therefore, in this case, the drift becomes a cause of error, and it becomes necessary to correct the speed register accordingly. This correction is performed by, for example, adding or subtracting the speed register number unit amount when the tracking point captured at the two timings Tf%1 moves left or right and is out of the period T as described above. done by. If tracking point 1 still cannot be captured, a unit amount is further added to or subtracted from the speed register so that tracking point - always exists within period T. That is, as far as this correction operation is concerned, a tracking method that refers to the previous history, similar to the conventional one, will be applied.

FIG. 2 is a block diagram of the main parts of a Loran receiver to which the tracking method according to the present invention is applied.

In the figure, a received signal from an antenna 1 passes through a high frequency amplifier circuit 2 and a filter 3, is converted into a signal of an appropriate level, and is sent to an integrating and averaging circuit 4.

When the integrating/averaging circuit 4 receives the strobe signal from the strobe signal generating circuit 5, it sends it to the microcomputer 7 at that timing. 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 when it receives the timing signal, it calculates a pulse with a width of 95 psec as a strobe signal and calculates an integrated average value. 4. The real-time counter 8 receives GRI data from the microcomputer 7 and data from a master station counter TM and a slave station counter TS, which will be described later, and determines the strobe signal generation timing based on the data.

Further, identification data of the chain to be used is sent from the input key 9 to the microcomputer 7, 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 gyro 12 that measures the course are connected to the microcomputer 7, and data from these devices is taken in at regular intervals and calculated based on the circumferential position. The speed of movement of the ship is required.

The microcomputer 7 is composed of a relatively high-speed 8-bit system consisting of several ordinary chips, and includes a CPU 70 that executes arithmetic operations and control, and a GRI (chain repetition control function) that controls the start timing of integrating and averaging the master and slave station signals and the GRI (chain repetition control) that corresponds to the setting chain. RA that stores the period) etc. and also includes the speed register.
M71, RAM711 that stores the execution procedure of the CPU70
It consists of external devices, circuitry, and an I10 interface 73 for receiving and passing data, and these elements are data nodes D and B, address buses A and B, control bus C,
JC connected. In addition, the RAM 71 is connected to the battery 74.
This ensures that the memory contents are retained even when the power is turned off.

The RAM0I has a chain table,
A main register MY that includes at least a main station, a group of counters for slave stations, and a speed register, where the speed register stores the cumulative average start timing estimated movement speed IILv obtained from the ship's movement speed, and correction of the timing estimated movement speed. The counter group includes a master station counter TM% that stores the cumulative average start timing of the master station signal, and a slave station counter that stores the cumulative average start timing of the slave station signal. TS (TS breath, TS
s, -TSn), and counters TF and TB for capturing tracking points from integrated averaged data.

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 and the real-time counter 8. In addition, the master station counter TM1m and the slave station counter TS are outputs that are read out when performing cumulative averaging of the main station signal and cumulative averaging of the slave station signal, respectively, and the stored data is sent to the real-time counter 8. . In addition, RAM711
In addition to the above, this area also stores circumferential position data for each of the chains, and also has another area for storing conversion coefficients and the like for determining latitude and longitude data from position line data.

FIG. 3 shows a block diagram of an example of the integrating and averaging circuit. The received signal is sampled by a sampling circuit 40 using a signal supplied from a sampling control circuit 41, and further digitized by an A/D converter 42.

The adder circuit 43 and the memory 44 accumulate and average the digitized signals at each sample timing and store them in preparation for data acquisition from the microcomputer 7. Therefore, the memory 44 stores data that has been integrated and averaged at each sample timing.

In this embodiment, all the cumulative averaging is performed by hardware, but it goes without saying that part of the work may be performed by the microcomputer 7.

Next, the main part of the operating element of the Loran receiver having the above configuration will be explained based on the flowchart shown in FIG. 1g4.

Figure 6) shows the signal tracking flow, and Figure (b) shows the estimated movement speed of the sampling timing based on the ship's movement speed.
It shows the flow for finding

First, step ni (hereinafter step ml is simply n, and V.
In (c), the contents of the counters TM and TS in which the integrated average start timing is stored in the signal capture stage (not shown) are as follows.
It is changed based on the contents of speed registers MY and MVC. That is, the cumulative average start timings stored in the counters TM and TS move at a moving speed that is the sum of the stored contents of the speed registers MY and MYc. Main register M
The storage data of V is formed by the flow shown in FIG. 4 (b) which is executed as appropriate by an interrupt. That is, in this flow, the course t is input from the gyro 12, and the water velocity Vo is input from the log 11, and these ψ,
Vo data, circumferential position data M, and V1 (not shown)
From the current position data P measured by the flow,
The estimated moving speed (■) at the integrated average start timing is determined. Note that the correction data in the auxiliary register MVc is set to an appropriate value in the first tracking stage.

When the contents of the counters TM and TS are set at nl, cumulative averaging of the received signals is performed for a predetermined period using the counter timing as the start timing, and the averaged data is taken into the microcomputer 7 at nz. Then, from the obtained data, two pieces of data are sampled at timings Tf and Tb to be stored in counters TF and TB, and the signs of these data are checked. As mentioned above, even if you sample all the data while changing the timing within the period T, if + and - data are not obtained at Tf and Tb, then f
The auxiliary register MVc is corrected by i4,nm. The tracking operation is completed when the process proceeds to H@-*@1, and the current position is measured according to a flow (not shown).

As is clear from the above operation details, most of the moving speed of the tracking point is given by the result obtained by n2N, so the cumulative average start timing is extremely accurate, and the signal including the tracking point is always Cumulative averaging can be performed.

In this way, according to the present invention, the moving speed at the integration average start timing is calculated from the actual moving speed of the ship, so even if acceleration is added to the ship's movement, the tracking point can be determined from the range of the signal targeted for integration. There is no possibility that the Vh will come off, so even in a weak electric field area, the tracking point will not be lost, and highly accurate tracking can be performed at all times.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the principle of the signal tracking system according to the present invention. FIG. 2 is a block diagram of main parts of a Motoguchi Run receiver to which the tracking method according to the present invention is applied, FIG. 3 is a block diagram of an example of an integrating averaging circuit, and FIG. 4 is an operation of the Rollan receiver. It is a flowchart which shows the main part of a procedure. a-IR arithmetic averaging circuit, 7... microcomputer,
11-log, 12-gyro, MV, MV c--speed register (main register, auxiliary register). Applicant Furuno Electric Co., Ltd. Agent Patent Attorney Hisao Komori Figure 1

Claims (1)

[Claims] It has an integrated averaging means that integrates and averages received signals for a predetermined period, and tracks from the integrated averaged signal while varying the integrated averaging start timing according to the movement of the ship so that the tracking point is included in the predetermined period. This is a signal tracking method that captures a point, and is equipped with a speed and course detecting device for detecting the speed and course of the ship, and the integrated average start timing is set based on the output of this detecting device. characterized by
Signal tracking method in hyperbolic navigation.