JPH04119407A - Antenna tracking device - Google Patents

Abstract

PURPOSE:To eliminate magnetization components from FGC(flux gate compass) output without turning a moving body by using the azimuth of the moving body for turning-on of a carrier detection signal (CD) to obtain magnetization components. CONSTITUTION:The FGC system to detect components in a horizontal plane of terrestrial magnetism is adopted. Magnetization components of the moving body are included in these components detected by the FGC system. The FGC system is provided with a CD method centripetal means 158 to eliminate magnetization components of the moving body. Magnetization components of the moving body are obtained by this means 158 based on the initial value of components in the horizontal plane of terrestrial magnetism, the direction of the moving body for generation of the CD, and components in the horizontal plane of terrestrial magnetism. Obtained magnetization components of the moving body are eliminated from components in the horizontal plane of terrestrial magnetism by a terrestrial magnetism direction calculating means 130 to obtain the azimuth of terrestrial magnetism. Thus, magnetization components due to magnetization are eliminated without turning the moving body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an antenna tracking device that is mounted on a moving object such as a vehicle or a ship and that tracks and receives satellites.

[Prior Art] Antenna tracking devices are known for use in receiving satellite broadcasts on trains and for maritime satellite communications. That is, in a moving object, the direction of the satellite (satellite azimuth) as seen from the main body of the moving object changes due to its movement.

Therefore, in order to receive signals from a satellite and supply them to a satellite communication/satellite broadcasting receiver mounted on a mobile object, it is necessary to offset changes in orientation due to movement of the mounted mobile object by controlling the orientation of the antenna. There is. The antenna tracking device is
This is an antenna device that enables such operations.

As mentioned above, the main uses of antenna tracking devices are:
There is satellite broadcast reception on trains and maritime satellite communications.

In the former, the tracking principle is generally a monopulse method. In this method, a sum-difference signal for tracking is generated and the antenna is driven using this sum-difference signal. Therefore, the tracking performance is said to be relatively good.

The latter method uses a device that generates an azimuth reference, such as a gyro compass, and uses its output to cancel out changes in relative satellite orientation due to course changes and turns of the ship.

[Problems to be Solved by the Invention] However, the conventional antenna tracking device has the following problems.

First, in the monopulse method, the configuration of an antenna system, high frequency circuit, intermediate frequency circuit, etc. is complicated to generate the sum-difference signal, and the cost is high. There is also the problem that the antenna may wander if the radio waves from the satellite are lost due to temporary blocking by obstacles such as mountains, buildings, or standing trees. Furthermore, in recent years, satellite systems using burst signals that transmit accumulated data in batches have been increasing in order to make effective use of the satellite's transmission power. It is difficult to use the bust signal as a tracking signal in the monopulse method.

Additionally, in small ships and land vehicles weighing less than 100 tons, it is generally not possible to install a device that generates a highly reliable azimuth reference, such as a gyro compass, due to equipment costs, so the output of the gyro compass, etc. is used instead. method cannot be used.

The applicant has previously proposed a tracking antenna device that solves these problems (Japanese Patent Application No. 2-175014).
issue). That is, we are proposing an inexpensive tracking antenna device that can be installed on small ships and land mobile bodies that do not have highly reliable devices such as a gyro compass, and that can accurately track the antenna using burst signals without causing wandering.

In this device, means for detecting the turning angular velocity of the moving body, such as a rate sensor, is used. The rate sensor is a sensor that detects the turning angular velocity of the moving body, and the turning angle of the moving body is determined by integrating its output (by using values over a certain period of time). On the other hand, if the azimuth of the moving body at the previous point in time (mobile azimuth) is given, by adding this turning angle to the azimuth of the moving body, the azimuth of the moving body can be determined while being updated one by one. The determined mobile object azimuth is subtracted from the current satellite azimuth, and as a result of this subtraction, the antenna azimuth control target (antenna command angle) is determined. The antenna is servo-controlled according to the antenna command angle.

However, since the rate sensor is accompanied by a DC offset and a drift due to its temperature, it is necessary to keep the ambient temperature constant in order to obtain a turning angular velocity with good accuracy. for example,
If it is heated to about 70 to 80'C, relatively good detection can be expected.

Another effective method is to attach a temperature sensor and correct the turning angular velocity by calculation (Japanese Patent Application No. 2-175 cited above).
(See No. 014).

Although such temperature measures may cause the device configuration to become larger and more complicated, it is actually preferable to make the configuration as simple as possible. For this purpose, a rate sensor that is less unstable with respect to temperature may be used. For example, there are various types of rate sensors such as vibration gyros, gas rate sensors, and optical fiber gyros, but optical fiber gyros are more stable against temperature or are extremely expensive than vibration gyros and gas rate sensors. be.

However, since the price of a rate sensor generally increases depending on its detection accuracy and temperature stability, the requirement to ensure good temperature stability runs counter to the requirement to reduce the cost of the antenna tracking device.

In order to resolve this contradiction, a so-called fluxgate compass (FCC) may be used. F.C.C.
is a means for detecting the horizontal component of geomagnetism. This horizontal component of the earth's magnetism indicates the orientation of the mobile object with respect to magnetic north, so if the FCC output is used and changes in the orientation of the mobile object are determined from the output of rate sensing, the orientation of the mobile object can be determined more accurately. Therefore, the instability of the output due to the temperature characteristics of the rate sensor can be compensated for by the FCC output, and it is possible to obtain a good moving object orientation while using an inexpensive rate sensor.

On the other hand, when using FCC, a magnetization component due to the magnetization of a moving body is included in the star detected as a horizontal component of the earth's magnetism by FCC. Therefore, in order to ensure the detection accuracy of FCC, it is necessary to remove the magnetization component.

Conventionally, various methods have been proposed as methods for removing the influence of magnetization. For example, in the method described in Japanese Unexamined Patent Publication No. 56-6169, which was previously proposed by the applicant of the present application, detection is performed while changing the direction of a device for detecting a magnetic field vector. For example, when the device is loaded on a vehicle, the vehicle is turned. Connecting the tips of the detected magnetic field vectors forms a circle or arc. By finding the center of this circle or arc, we obtain a vector j·le that remains unchanged despite changes in the geomagnetic orientation relative to the device. This vector can be regarded as a vector of magnetization components due to magnetization. Therefore,
By vector subtracting the magnetization component obtained in this way from the magnetic field vector, the influence of magnetization is eliminated.

However, when such a method is applied to an antenna tracking device, the moving object must be turned by a predetermined angle or more. Such a turn is not necessarily carried out by the operator of the moving object, and it is not preferable to require the moving object to turn.

The present invention was made with the aim of solving these problems, and eliminates the influence of the magnetization component due to magnetization without turning the moving object, making it possible to calculate the direction of the moving object using FCC output. The purpose of the present invention is to provide an antenna tracking device that achieves the following.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides an antenna that is rotatably supported in at least one axis, and an antenna servo that servo-controls the antenna direction according to an antenna command angle. system, a second adder that calculates the antenna command angle from the satellite orientation and the mobile object orientation, a satellite orientation system that calculates the satellite orientation from the current latitude/light information and the satellite longitude, and the rotation angle of the mobile object and the geomagnetic field. a second adder that calculates the orientation of the moving object from the azimuth; a rate sensor system that detects the turning angle of the moving object by detecting the turning angular velocity of the moving object and performs low-pass filtering; and a rate sensor system that detects the horizontal plane component of the geomagnetic field. an FGC system that removes a moving body magnetization component to determine the geomagnetic direction; a reception system that receives radio waves with an antenna, detects a carrier when the antenna direction is close to the satellite direction, and outputs a carrier detection signal; In an antenna tracking device mounted on a moving body such as a ship, vehicle, or ship, the FGC system detects the initial value of the horizontal plane component of the geomagnetic field, the direction of the moving body when a carrier detection signal is generated, and the geomagnetic field. The present invention is characterized by comprising a CD method centripetal means for determining a moving body magnetization component based on a horizontal plane component of the earth's magnetic field, and a geomagnetic azimuth calculating means for calculating a geomagnetic direction by removing the moving body magnetization component from the horizontal plane component of the earth's magnetism.

Further, claim (2) of the present invention provides that the FGC system removes a component that changes with the rotation of the mobile body from the horizontal plane component of the geomagnetic field obtained by the rotation of the mobile body, and transfers the remaining component to the horizontal plane component of the geomagnetic field obtained by the rotation of the mobile body. It includes an AB method centripetal means for obtaining a magnetization component, and a centripetal method switching means for selectively switching and supplying the moving body magnetization component obtained by either the AB method centripetal means or the CD method centripetal means to the geomagnetic azimuth calculation means. It is characterized by

Claim (3) of the present invention provides that the satellite orientation system is at the current latitude and
It is characterized by having means for determining the declination of magnetic north with respect to true north from longitude information and correcting the satellite direction to the magnetic north reference.

Further, claim (4) of the present invention provides that the rate sensor system includes a low-pass filter that integrates the turning angle of the moving body, and
The GC system is characterized in that it includes a low-pass filter having a transfer function complementary to the rate sensor system.

Claim (5) of the present invention provides that when the moving object magnetization component is obtained by the CD method centripetal means, the movement obtained by the second adder is body orientation, in other cases satellite orientation,
It is characterized by comprising a step track control circuit for correcting.

[Operations] In the antenna tracking device of the present invention, the turning angular velocity of the moving body is detected by the rate sensor system and low-pass filtered. As a result, the turning angle of the moving body is determined. On the other hand, the FGC system detects the horizontal component of the earth's magnetism, and determines the earth's magnetic direction. The turning angle and geomagnetic azimuth of the moving body thus determined are supplied to a second adder, and the moving body azimuth is calculated by this second adder.

The determined moving object orientation is supplied to a first adder.

The first adder calculates the antenna command angle from the satellite azimuth and the mobile object azimuth. The satellite orientation is calculated using the satellite orientation system from the current latitude and longitude information and the satellite longitude.

According to the antenna command angle obtained in this way, servo control of the antenna direction is performed by the antenna servo system, and the satellite is tracked by the antenna.

Furthermore, the present invention employs an FGC system that detects the horizontal component of earth's magnetism. The horizontal plane component of the earth's magnetism detected by the FGC system includes a moving body magnetization component. In order to remove this moving body magnetization component, the FGC system uses C
Equipped with D-method centripetal means.

That is, the CD method centripetal means determines the magnetization component of the moving body based on the initial value of the horizontal plane component of the earth's magnetism, the moving body direction when the carrier detection signal (CD) is generated, and the horizontal plane component of the earth's magnetism. CD is emitted from the receiving system when the antenna orientation is close to the satellite orientation.

Furthermore, the obtained moving body magnetization component is removed from the horizontal plane component of the geomagnetism by the geomagnetic azimuth calculation means, and the geomagnetic azimuth is determined.

As a result, in the present invention, the magnetization component due to magnetization is removed without rotating the moving body.

Moreover, in claim (2) of the present invention, it is determined by either the moving body magnetization component, the AB method centripetal means, or the CD method centripetal means. For example, when the moving object turns to satisfy a predetermined condition, the moving object magnetization component calculated by the AB method centripetal means is used, and in other cases, the moving object magnetization component calculated by the CD method centripetal means is used. It is switched by the centrality switching means and supplied to the geomagnetic azimuth calculation means. In addition,
The AB method centripetal means detects the magnetization component of the moving body using a conventional method based on the horizontal plane component of the earth's magnetism obtained by the rotation of the moving body.

As a result, for example, if the turning angle of the moving object is sufficient, AB
Tracking is carried out using an appropriate centripetal means depending on the case, such as a CD centripetal means or, if insufficient, a CD centripetal means.

In claim (3), the declination angle of magnetic north with respect to true north is determined from current latitude and longitude information using a satellite orientation system,
The satellite orientation is corrected to the magnetic north reference.

As a result, the standard is unified with the FGC system that determines the geomagnetic direction using the magnetic north reference, and errors caused by deviations are prevented.

Next, in claim (4), the rate sensor group and F
Since it is equipped with a GC system or a complementary filter, a more accurate calculation of the moving body direction is performed by eliminating the difference in characteristics between the two.

That is, the turning angular velocity of the moving object is low-pass filtered, that is, incompletely integrated, by the low-pass filter of the rate sensor system, and high-frequency noise is therefore removed. On the other hand, F.G.C.
A low-pass filter in the system removes the moving object vibration component included in the geomagnetic direction. In this way, the rate sensor system including the low-pass filter and the FG including the low-pass filter
Since the C system and the C system have transfer functions that are complementary to each other, that is, the sum becomes 1, it becomes possible to compensate for the offset of the rate sensor and its temperature drift by the FGC system.

In claim (5), the step track control circuit corrects the satellite azimuth or the mobile object azimuth so that the reception level in the reception system becomes the highest, and more accurate tracking and centripeting are performed.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

(1) Actual configuration of embodiment] 5 FIG. 1 shows the configuration of an antenna tracking device according to an embodiment of the present invention. In particular, FIG. 1(a) shows a perspective view, and FIG. 1(b) shows a side view.

This device includes an antenna 10 supported at a predetermined angle so as to be rotatable in a horizontal plane.

The antenna 10 is, for example, a parabolic antenna, a phased array antenna, or the like, and is shown as a flat antenna in this figure. This antenna 1
0 is designed to be able to receive radio waves from a satellite to be tracked, and is covered by a bowl-shaped radome 11.

The antenna 10 is connected to an azimuth axis motor 12 through a gear, and is rotated by the drive of this azimuth axis motor 12. Rotation of the antenna 10 is detected as a change in its angle by a rotary encoder 14 connected to the axis of the antenna 10 by a belt.

A receiver 16 is disposed at the neck portion of the antenna 10. This receiver 16 processes the signal from the satellite received by the antenna 10 and outputs it as an intermediate frequency signal (hereinafter referred to as an IF multiplied signal) of a predetermined frequency.

Around the antenna 10 are a rate sensor] 8, a flux gate compass (FCC) 20. An electronics unit 22 and a power supply device 24 are also provided. The rate sensor 18 is a sensor that detects the angular velocity related to the turning of a moving body such as a vehicle or a small boat on which this device is mounted, that is, a turning angular velocity. The FCC 20 is a sensor that detects the horizontal plane component of the earth's magnetism and obtains the earth's magnetic direction θVM['.

The electronics unit 22 is a unit that houses the circuits that constitute this embodiment, and the power supply device 24 is a device that supplies power to each of these components.

(2) Overall circuit configuration of the embodiment FIG. 2 shows the overall circuit of the embodiment, 7 components, mainly the configuration built in the electronics unit 22.

In this embodiment, the antenna]0 is servo-controlled by an antenna tracking device 26. That is, antenna 1
The angle of 0 (antenna orientation) is the antenna command angle θAVC
controlled with the goal of

The antenna command angle θAVC is calculated by the adder 28 from the satellite azimuth 08M and the moving object azimuth θ■8.

That is, the adder 28 subtracts the mobile object azimuth θVM also based on the magnetic north from the satellite azimuth 08M based on the magnetic north to obtain the antenna command angle θAVC. Expressed in the formula, it is as follows.

θAVC"'θSM-θVM-(1)
The satellite orientation θ8M is 1 and is determined by the satellite orientation system 30. The satellite orientation system 30 calculates the satellite orientation 08N based on true north based on the latitude/longitude information indicating where the mobile object carrying the device is currently located and the satellite longitude, and further corrects this to the magnetic north reference. Then, the satellite orientation θ88 is determined. The relationship between the magnetic north reference and true north reference will be explained later.

The moving body orientation θVM is obtained by the adder 32. The adder 32 receives the geomagnetic direction θ supplied from the FGC system 34.
4■8. and the moving body turning angle θ supplied from the rate sensor system 36 to determine the moving body force position θVM. That is, θ■8−θV)IP+θVR (2). This is because the geomagnetic direction θVMF corresponds to the magnetic north-based moving body direction detected by the FGC 20, and the turning angle θ2 corresponds to the change in the moving body direction due to turning. In particular, as will be described later, the outputs of the FGC system 34 and the rate sensor system 36 pass through complementary filters, and the filters for the rate sensor]8, which is a non-localization type sensor, are reset and the outputs of both systems 34 and 36 are By adapting the behavior.

The FGC system 34 uses the output of the FCC 20 to determine the geomagnetic direction θ.
The rate sensor system 36 is a circuit that calculates the VMF, and the rate sensor system 36 is a circuit that calculates the turning angle θ2 of the moving body based on the output of the rate sensor]8.

Further, the antenna ] 0 is connected to the receiving system 38 .

The receiving system 38 detects a carrier from the radio waves received by the antenna 0 and generates a carrier detection signal (CD). This CD is emitted when the antenna bearing is close enough to the satellite bearing (when the satellite bearing is within the beam of the anti]9 and 10). moreover,
The reception system 38 receives a reception level signal (RE
CLE V).

The CD is supplied to the FGC system 34. That is, F.G.C.
The system 34 performs a centripetal operation (operation for determining the magnetization component) in response to CD. This centripetal method using CD (CD method) is a technique related to the characteristics of the present invention, and will be explained in detail later.

Also, CD and RECLEV are step track type 4
0. The step track system 40 generates a step angle in predetermined increments when CD is generated, and R
The antenna command angle θAVC is adjusted so that the reception level indicated by ECLEV is the highest.

Note that the rate sensor system 36 is supplied with a search flag from the FGC system 34 in order to be reset at the time of direction search.

(3) Antenna servo system and reception system FIG. 3 shows the configuration of the antenna servo system 26 and reception system 38.

(3,1) Antenna servo system The antenna servo system 26 includes an azimuth axis motor 12 that rotates the antenna 0, a rotary encoder 14 that detects the rotation angle of the antenna 0, and an antenna angle register 4.
2. Antenna command angle register 44, adder 46, error register 48, D/A converter 50, and servo drive circuit 52
Contains.

That is, when the antenna 10 is rotated by the azimuth axis motor] 2 and the angle related to the rotation of the antenna 10 is detected by the rotary encoder 14, the detection result is stored in the antenna angle register 42. The antenna angle register 42 outputs the antenna angle θAV.

On the other hand, the antenna command angle register 44 is supplied with the antenna command angle θAVC from the adder 28, and the adder 46 subtracts the antenna angle θ 2 from the antenna command angle θAVC and outputs the servo error θAEV. This servo error θAE is the error register 4
8 and then converted into an analog value by a D/A converter 50. The servo drive circuit 52 drives the azimuth axis motor 12 based on the D/A converted servo error θAE, and rotates the antenna 10.

As a result of such operation of the antenna servo system 26, the angle of the antenna 10 is servo-controlled to match the antenna command angle θAVC.

(3, 2) Receiving system Further, a receiving system 38 including a receiver 16 is connected to the antenna 10. That is, the receiver ] 6 is the antenna 1
0 is converted into a signal of a predetermined frequency multiplied by IF.

Further, the reception system 38 includes a demodulator 54 and a reception level detector 56.

The demodulator 54 performs IF multiplied signal demodulation and carrier detection. Carrier detection in the demodulator 54 is one of the basic techniques in a general demodulator, and many methods have been developed or put into practical use, such as a method using PLL, for example. A carrier detection signal (CD) written as a result of carrier detection is a signal indicating whether a desired signal can be received at a certain level or higher.

The reception level detector 56 estimates C/No (carrier-to-noise ratio) from the level of the carrier included in the F-fold signal, etc.
A reception level signal (RECLEV) is generated. For example, RECLEV is generated so that its value monotonically increases with respect to C/No.

These CDs and RECLEV are step track type 4
Used in 0. Further, the CD is used for centripetal control in the FGC system 34 using the CD method.

(4) Satellite heading system and step track system Figure 4 shows the following:
The configuration of a satellite orientation system 30 and a step track system 40 is shown.

(4,1) Satellite bearing system First, the satellite bearing system 30 includes latitude/longitude input means 58. The latitude/longitude input means 58 inputs the position (latitude) of the moving body using, for example, a GPS receiver or the like.

This is a means of inputting the longitude.

A satellite azimuth calculator 6 is provided after the latitude/longitude input means 58.
0 or connected. The satellite azimuth calculator 60 is a device that takes in the latitude and longitude from the latitude/longitude input means 58, and also takes in the current satellite longitude and calculates the satellite azimuth θSN. That is, since the orbital data of the satellite is known in advance, the satellite orientation 08N can be determined using data related to the position of the satellite and data related to the position of the moving object.

Satellite orientation 08N determined by satellite orientation calculator 60
is stored in the satellite orientation register (true north) 62. Since the calculation is performed by the satellite azimuth calculator 60 or based on the latitude, longitude, and longitude of the satellite, the satellite azimuth 08N is a true north reference value with the North Pole as the northernmost point.

On the other hand, a ROM 64 is connected downstream of the latitude/longitude manual means 58 in parallel with the satellite azimuth calculator 60 . This R
In the OM 64, a declination angle 08N indicating the difference between true north and magnetic north at each point on the earth is stored as a declination table in association with the position.

Here, the concept of declination will be explained.

At each point on the earth, true north and magnetic north do not necessarily match, but have a predetermined difference (declination).

The declination changes depending on the position coordinates expressed by latitude and longitude, or changes over time. Since the change over time is a slight change due to the passage of a long period of time, for example, on a yearly basis, it can be said that the declination angle is determined by latitude and mildness.

Therefore, if a declination table that associates latitude/longitude and declination angle is created in advance, the declination angle θMN can be determined by referring to this declination table by latitude and longitude.

FIG. 5 shows part of the contents of the argument table stored in the ROM 64.

For example, the declination angle θMN at a point of 62 degrees 01 minutes north latitude and 129 degrees 43 minutes east longitude is 19 degrees 28.9 minutes westward. When the latitude and longitude input from the latitude and longitude input means 58 are 62 degrees 01 minutes north latitude and 129 degrees 43 minutes east longitude,
The corresponding declination angle θ, 9, is 19 degrees 28.9 minutes westward.

A declination register 66 is connected after the ROM 64. The argument register 66 is a register that temporarily stores the argument θMN output from the ROM 64.

The satellite orientation 08N based on true north stored in the satellite orientation register (true north) 62 is input to the adder 68. The adder 68 also receives the argument 08N stored in the argument register 66.

The adder 68 subtracts the declination θMN from the satellite orientation 08N,
Output as satellite azimuth θ88 based on magnetic north.

FIG. 6 shows the relationship between the satellite azimuth 08N based on true north and the satellite azimuth θ88 based on magnetic north.

In this figure, N means true north and MN means magnetic north. Further, ■ is the moving object direction, A is the antenna direction, and S is the satellite direction.

As shown in this figure, true north N and magnetic north MN have a declination angle θ
The only difference is This declination 08N corresponds to the difference from the azimuth of the satellite based on true N north N, that is, the azimuth of the satellite based on θSN"' magnetization, that is, 08M. Therefore, in the adder 68, the following equation By performing calculations based on , the satellite orientation 08M based on magnetic north can be determined.

θsM−〇SN−θMN”・(
3) Satellite bearing 08 based on magnetic north calculated in this way
M is the satellite orientation register (magnetic north) via switch 70
The signal is temporarily stored in 72 and further supplied to adder 28 via switch 74. In the adder 28, the mobile object azimuth θVM is subtracted from this satellite azimuth 08M, and as shown in FIG. 6, an antenna command angle 0AVC indicating the difference in the azimuths between the mobile object and the satellite is obtained.

The satellite orientation system 30 also includes a satellite orientation θ based on magnetic north.
A memo 76 is provided to store the initial value θSMO. This memory 76 is backed up by a battery 78 and is a writable nonvolatile memory.

That is, the satellite orientation 08M stored in the satellite orientation register (magnetic north) 72 is sent to the adder 2 via the switch 74.
8 while being written to memory 76. Since the memory 76 is backed up by a battery 78, the contents of the memory 76 are preserved even when the device is powered off. After this, when powering on the device again, the switch 70 is switched to the memory 76 side, and the contents of the memory 76 are transferred and stored in the satellite orientation register (magnetic north) 72 as the initial value θSMO of the satellite orientation θSH. Ru. After this, the satellite orientation register (true north)
When there is an output from 62, switch 74 is activated according to this output.
is switched to the satellite azimuth register (magnetic north) 72 side, and the antenna command angle θAVC calculation according to the operation described above is executed.

(4,2) Step Track System FIG. 4 also shows the configuration of a step track system 4o.

The step track system 40 includes a step track control circuit 80 that generates a step angle according to CD and RECLEV, and a switch 82 that switches and supplies the step angle output from the step track control circuit 80 to the satellite azimuth system 30 and the FGC system 34. It is composed of and. One output end of the switch 82 is connected to the adder 8 of the satellite orientation system 30.
4, an adder 84 adds the step angle to the contents of the satellite orientation register (magnetic north) 72 and switches it to switch 7.
0 to one input terminal.

FIG. 7 shows the configuration of the step track control circuit 80. The step track control circuit 80 shown in this figure controls the satellite orientation θSM' when a CD is occurring.
This is a circuit that generates a step angle to be corrected. This step angle is R obtained by the reception level detector 56.
It is generated to have a sign in a direction that maximizes C/No according to ECLEV.

That is, the step track control circuit 80 controls the received C.
/N o and generates a step angle to optimize this value.

Step track control circuit 80 includes an accumulation register 86 that stores the value of RECLEV. An adder 90 is connected to the input terminal of the accumulation register 86 via a switch 88.
is connected to the adder 90, and RECLEV and the contents of the accumulation register 86 are inputted to the adder 90. That is, when the switch 88 is on, the adder 90
The value of CLEV is sequentially added to the contents of accumulation register 86.

Further, the switch 88 is controlled by the output (addition command pulse) of the addition command pulse generator 92. The addition command pulse generator 92 is configured to generate addition command pulses at regular intervals only when a CD is present. Note that if the CD is an analog signal, it is assumed that it is converted into a digital signal by an A/D converter or the like (not shown). Therefore, cumulative addition of the value of RECLEV to the cumulative register 86 is performed only when a CD is present.

A counter 94 and a minus number circuit 96 are sequentially connected after the addition command pulse generator 92.

The counter 94 receives the addition command pulse from the addition command pulse generator 92 and counts the number of times the addition command pulse is output.

The matching circuit 96 takes in the count result from the counter 94 and compares it with a predetermined value. Namely, this Karan!
- The result indicates the number of cumulative additions in the cumulative register 86, and the minus number circuit 96 determines whether cumulative addition has been performed a predetermined number of times. - If the comparison results in a match, the number circuit 96 outputs a step angle addition command signal and a comparison command signal.

On the other hand, a second accumulation register]-〇〇 is connected to the subsequent stage of the accumulation register 86 via a switch 98. Further, a comparator 102, a step angle generator 104, and a switch 106 are sequentially connected to the subsequent stage of the second accumulation register 100.

That is, when the step angle addition command signal is issued from the minus number circuit 96, the aforementioned cumulative addition has been performed a predetermined number of times, so the switch 98 is closed in response to the step angle addition command signal, and the contents of the cumulative register 86 are The data is transferred and stored in the second accumulation register 100. At this time, the step angle addition command signal is also supplied to the counter 94 and the cumulative register 86, the contents of the counter 94 and the cumulative register 86 are reset, and cumulative addition in the cumulative register 86 is started anew.

Thereafter, when the cumulative addition continues and the count number of the counter 94 reaches a predetermined value again, a comparison command signal is supplied from the minus number circuit 96 to the comparator 102, and the comparator 102 compares the contents of the cumulative register 86 with the second The contents of the accumulation register 100 are compared.

Comparator 102 instructs step angle generator 104 to preserve the sign of the step angle when the former is smaller than the latter as a result of the comparison, and to invert it when it is larger. That is, from the contents of the accumulation register 86, the second accumulation register 100
When the content of is larger, the angle of the antenna 10 can be corrected to improve the C/N.

The sign of the current step angle is saved because it can be assumed that the step angle is being moved in the direction in which the step angle becomes larger. In the opposite case, C/N
Since it can be considered that o has been modified in the direction of decreasing, the sign of the step angle is reversed.

The step angle generator] 04 outputs a step-knob angle of a predetermined magnitude whose sign is imaged in accordance with the instruction from the comparator 102. A switch 106 provided on the output side of the step angle generator 104 is closed in response to a step angle addition command signal from the minus number circuit 96.

This causes the step angle generator 104 to
The step angle is supplied to the switch 82 via the switch 6. The step angle supplied to the switch 82 is supplied to an adder 84 of the satellite azimuth system 30 or an adder (described later) of the FGC system 34 in accordance with the switching of the switch 82.

Table where the step angle is output in this way, antenna 1
The satellite azimuth θ88 or the moving object azimuth θ■8 is corrected so that the C/N o is the best within the beam of 0.
The antenna command angle θ and, in turn, the azimuth of the antenna 10 are adjusted.

In addition, under normal conditions, the switch 82 or the satellite orientation system 30 side,
During centripetal movement using the CD method, it is tilted toward the FGC system 34 side. This improves tracking accuracy under normal conditions, and
This is to improve the centripetal accuracy when centripeting by the CD method.

(5) Rate Sensor System Next, the configuration and operation of the rate sensor system 36 will be explained.

FIG. 8 shows the configuration of the rate sensor system 36.

The rate sensor 18 is a sensor that detects the turning angular velocity of the moving object when the moving object turns.

Further, the rate sensor 18 itself has a differential transfer function. Generally, the rate sensor 18 is cheaper than a gyro compass, etc., but on the other hand, due to its imperfection, it has a DC component (offset), and furthermore, it may cause drift due to environmental factors such as temperature, so countermeasures must be taken. Must be.

For this reason, the above-mentioned Japanese Patent Application No. 2-175014 proposes a method of covering the rate sensor with a heat insulating material and installing a temperature sensor on the side for correction.

However, in the present application, a method is adopted in which compensation is performed using the FCC output by complementary setting of the transfer function of the filter as described below.

First, rate sensor 18 is connected to A/D converter 118. After the A/D converter 118, LPF1
20 and an orientation register 122 are connected in sequence. The output end of the direction register 122 is connected to the input end of the LPF 120, and is also connected to the switch 124.
The output end of the switch] 24 is connected to the adder 32 shown in FIG.
It is connected to the.

That is, the turning angular velocity of the moving object detected by the rate sensor 18 is converted into a digital value by the A/D converter 118. Further, the DC component (offset) and its drift are supplied to the LPF 120 and incompletely integrated.

Therefore, the LPF 120 is configured as a digital filter having a transfer function that performs low-pass filtering on the output of the A/D converter 118. For example, the transfer function is
It can be expressed by the following formula.

Zn=kIXo+ to 2Zo-3, =dt/ (1,0+ωadt) lc =1.0/(1,0+ω (]t)
... (4)a However, X is the input of LPF120, Z is the output, 1
nd
t is the sampling period and ω is the cutoff angular frequency of the filter.

This transfer function, when expressed in the frequency domain using the Laplace operator S, becomes 1/(s+ω). Therefore, when a turning angular velocity is input to the LPF 120, a value obtained by incompletely integrating the turning angular velocity, that is, a turning angle θv2 of the moving body is output from the LPF 20.

The turning angle θVR output from the LPF 120 is temporarily stored in the orientation register 22. The peaks and valleys of the orientation register] 22 are fed back to the input terminal of the LPF 120. In addition, the rate sensor 8 is a non-locating type sensor, and the turning angle θ is determined by incomplete integration from the turning angular velocity output from the rate sensor.
(2) In order to find 7, it is necessary to reset using a search flux at the start of operation.

(G) FGC system FIG. 9 shows the configuration of the FCC system 34 in this embodiment.

The FGC system 34 shown in this figure includes, in addition to the FCC 20, a centripetal device 126, an adder 128, and an arctangent front section 130.
Contains.

3, the centripetal device 126 is a device that obtains a magnetization component generated when a moving body is magnetized.

From the FGC output (x,,y,)]
] An adder that removes the magnetization component, and an arctangent calculation unit 130
is a device that calculates the geomagnetic direction I θVMP from the horizontal plane components (u,,v,) of the geomagnetism obtained by the adder 128.

(G, ],) FC Now, the configuration and operation of the FGC 20 will be explained.

FIG. 10 shows the configuration of the FCC 20, and the first
Figure 1 shows the output characteristics of the FCC 20.

The FCC 20 is supported by a two-shaft hinge 32, as shown in FIG.

This two-axis gimbal 132 is a member that supports the core 133 of the FGC 20 so as to be rotatable within a range of (±20°+α).

An X-direction coil 134-X and a Y-direction coil 134-Y are wound around the core 133. On the other hand, core 133
A high frequency coil 136 excited at a frequency fo by an oscillator 136 is wound around the coil. Therefore, the core 133
A signal modulated by the rotational angular velocity of is output.

After the X and Y direction coils 134-X and 134-Y, filters 1.38-X and 138-Y are installed, respectively.
AC amplifier circuits 140-X and 140Y, synchronous rectifier circuit 1
42-X and 142-Y and DC amplifier circuit 144-
X and 1.44-Y are connected sequentially.

That is, X and Y direction coils: 1. ' The outputs in the X and Y directions obtained by 34-X and 1.34-Y are the oscillation frequency f of the oscillator 136. is filtered by filters 138-X and 130-Y that pass frequencies twice as high as . The secondary high frequency obtained by this filtration is subjected to AC amplification, synchronous control, and DC amplification, and the output (x
,,y,). Note that a phase variable circuit 148 and a frequency multiplier circuit 150 are connected to the synchronous rectifier circuit 142X. The output of the oscillator 136 is multiplied by a frequency multiplier 50, synchronized by a phase variable circuit 148, and then used for synchronous rectification.

The output of the FCC 20 obtained in this way (x,, y,
) changes depending on the magnetic direction θV81 of the earth, as shown in FIG. This change is x
, ,y, are each a sine wave with a phase difference of 90°. Therefore, the output of FCC20 (x
,,y,) and perform arctangent calculation on 1 or above, the geomagnetic direction θVMP can be obtained.

(8,2) Centripetal device Next, the configuration of the centripetal device 126 will be explained.

Prior to this explanation, magnetization of a moving body will be explained.

In Fig. 12, when the moving body is magnetized, the FCC2
Included in the output (x,,y,) of 0]
1 magnetization component is shown. Generally, a moving body is magnetized with a certain intensity and in a certain direction due to the influence of a magnetic field, an earth's magnetic field, etc. generated during driving. This phenomenon is called magnetization of the moving body.

This magnetization affects the detection of the horizontal plane component of the earth's magnetism in the FGC 20. For example, if the horizontal plane component of the earth's magnetism that should be truly detected by the FCC 20 is (u,, v,), if the magnetization due to magnetization [1] component exists, the output of the FCC 20 (X,.

Y,) includes an error corresponding to this magnetization component. Therefore, when installing FGC20 on a mobile object,
Unless the influence of the magnetization component is eliminated, it will be difficult to accurately detect the geomagnetic direction.

The adder] 28 shown in FIG.
This is an adder that removes magnetization components etc. from x, , y,) to obtain the horizontal plane components (u, , v,) of the earth's magnetism. ,
d).

(6, 2, 1) AB method centripetal device The centripetal device 126 includes an AB method centripetal device] 52. The AB method centripetal device 52 receives the output (x, ,
y,) and calculate the magnetization component] l (a, b).

The algorithm used in this AB method centripetal device 52 is similar to the algorithm disclosed in, for example, Japanese Patent Laid-Open No. 56-61.69. In other words, when the moving object is turning, the FCC20 at that time
Using the output (x,,y,)J, perform centripetal determination using the least squares method. Next, find the magnetization components (a, b).

Therefore, when the moving object is turning, the magnetization components (a, b) can be determined by the AB method centripetal device 152, and the magnetization components (a, b) determined in this way are the centripetal components described later. A law determination unit 154 and a switch 156 are provided. The AB method centripetal device 152 supplies a centripetal completion flag to the centripetal method determination device 156 when the centripetal completion is completed.

(6, 2, 2) CD method centripetal device In this embodiment, a CD method centripetal device 158 is provided in parallel with the AB method centripetal device 152.

This CD method centripetal device] 58 is a shrine related to the feature of the present invention, and the magnetization component (c, d
). In the following description, symbols (c, d) are used for magnetization components obtained by the CD method in order to distinguish them from magnetization components obtained by the AB method.

In the CD method, the magnetization components (c, d) are calculated by the following calculation.
This is a method to find. In the CD method, the geomagnetic field in the horizontal plane in the area. Requires. This r is stored in the ROM in correspondence with the latitude and longitude, same as the declination angle 08N mentioned above.
It is also possible to store the information in the 64 in advance and read it out and use it as needed. However, in this embodiment, the following method is used.

First, the CD method centripetal device 158 reads the initial values (u o, v o ) of the horizontal plane components of the earth's magnetism from the memory 160 connected after the adder 128 . These initial values (Llo, Vo) are, for example, horizontal plane components (u, , v) obtained by the adder 128 at the previous timing.
, ). Furthermore, the memory 60 stores the data (u,,v,) from the previous operation even when the device is powered off.1) It is backed up by a battery 62.

Memory 160 may include writable non-volatile memory, such as battery-backed RAM, or E
It is preferable to use EFROM.

The CD method centripetal device 158 uses the initial values (u o , V o ) read from the memory 60 to determine the initial value r of the geomagnetic strength. Calculate. This initial value r.

can be determined by the following formula.

r-transport +v2)]/2...(5) As mentioned above, r from (uo, vo).

Instead of calculating the geomagnetic strength r. Create a table that stores the information in association with the position coordinates, refer to this table, and select r. You may also use a method to find .

Next, the CD method centripetal device 158 takes the direction θ of the moving body when the CD is turned on, and calculates the VM
VM (CD) included.

That is, the CD method centripetal device] 58 takes in the mobile object orientation θ from the adder 32 as θ when the CD supplied from the demodulator 54 is turned on as the orientation search progresses. Therefore, when the antenna 10 is oriented in an azimuth close to the satellite azimuth, the CD-seeking VM (CD) center device 58 captures the current moving object azimuth θ. Note that when centripetal movement is performed by the CD method VM (CD) centripetal device 158, the azimuth search is performed by the azimuth search control circuit 164 in advance.

The CD method centripetal device 158 uses r obtained in this way.
and θ (uos, vos) OVM(C
D) Calculate. The calculation formula is as follows.

Llos−±r o/C ■ =±r' j a n 6' VM(CD)/
CO80 C-(], +tan θ )1/2 ・-(
6) VM (CD) However, the sign is determined by the quadrant of (x,,y,). Obtained in this way ( u Os' v O8)
C. The value of (u,,v,) when centripetal movement is performed by the CD method centripetal means 158 can be considered as 1
】 can. Therefore, by the CD method centripetal means 158, the FCC
From the average value of 20 outputs (x,,y,), this (uOs”
By subtracting Os), the magnetization component (c,
d) can be obtained. That is, the magnetization components (c, d) are determined by the formula C=Σx −/N u os d=Σy −/N−Vos − (7), where N is an appropriate natural number.

(G, 2J) Centripetal method switching centripetal device 126 includes a centripetal method determination device 154 that switches between centripetal by AB method centripetal device 152 (i.e., AB method) and centripetal by CD method centripetal device 158 (i.e., CD method). and a switch 156 are provided.

There are several possible methods for switching between the AB method and the CD method. In this embodiment, the following method is adopted.

That is, in the AB method in which centripetal determination is performed by the least squares method on the premise that the moving object is turning, the magnetization components (a, b) may not be determined when the power is turned on or the like. In such a case, centering is performed using the CD method on the condition that the carrier detection signal CD is turned on by the azimuth search. During this time, when the moving object is running and the values of the magnetization components (a, b) are determined by the AB method, the magnetization components (a, b) determined by the AB method centripetal device 158 are supplied to the adder 128. , the switch 156 is switched to the AB method centripetal device ] 52 side.

In this way, the magnetization components (a, b) or (c, d) determined by the AB method or the CD method are supplied to the adder 128 while being switched by the centripetal method determining device 154.

(6, 2, 4) Arctangent calculation unit As mentioned above, the output (x-, y-) of the FCC 20 is supplied to the adder 128. The adder 128 is supplied with magnetization components (a, b) or (c, d) determined by the AB method or the CD method from the centripetal device 126. The adder 128 subtracts the latter from the former and obtains the horizontal plane component of the geomagnetic field (U,.

v, ) is calculated. That is, when the AB method is adopted as the centripetal method, the formula U ・ -x, -av, = y, -b, and in the case of the CD method, U, =X, -C v, = y , -d・(
9)] The components in the horizontal plane (u,,v,) are found by the formula 1]
] I can't stand it.

Furthermore, this horizontal plane component (u,,v,) is supplied to the arctangent calculation unit 130. In the arctangent calculation section] 30, θ = tan' (v, /u,) - (]
0) ■MFj11 Based on the formula, the geomagnetic direction θVMFi corresponding to the horizontal plane component (u,,v,) is calculated.

The calculated geomagnetic direction θVMPi is supplied to the LPF 166. The LPF 166 has a transfer function with complementary characteristics to the transfer function of the rate sensor system 36 determined by the LPF 120.

Here, "complementary" means a transfer function s/(s+
This means that the sum of ω ) and the transfer function ω /(S+ω ) a a of the FGC system 34 is 1. That is, the characteristics of the LPF 166 in the time domain can be expressed by the following equation.

Zo−kIXn+1(2Zo−1 to 1−ωad t/(1,0+ω,dt)k2=1.
, Od t/ (1,0+ωadt) However, X is LP
Input to F166, Z represents n output. Note that dt and ω are LPF12
It is a value similar to 0.

The LPF 166 has a function of removing the swing component of the moving body included in the geomagnetic direction θVMF calculated by the arctangent calculation unit]-30.

As mentioned above, the FCC 20 is supported by the device by the two-axis gimbal 132. When the moving body swings, the swing of the core 133 of the FCC 20 is absorbed to some extent by the two-axis gimbal 132, or cannot be completely eliminated. Therefore, the output (x, y-) of the FGC 20 includes a component due to the swing of the moving body as an error. This ingredient is
Geomagnetic direction θ■8. Since this appears as noise, it is removed by the LPF 166 in this embodiment.

A switch 168 is provided after the L PF 1.66. An adder 32 is further connected to the downstream side of the switch 168 via an orientation register 169 and an adder 170. Therefore, the obtained geomagnetic direction θVMP
is added to the turning angle θ of the moving body in the adder 32, and is supplied to the adder 28 as the moving body azimuth θVM.

(6, 2, 5) Direction Search Control Circuit Next, the configuration and operation of the direction search control circuit 164 will be explained.

In this embodiment, the FGC system 34 includes the reset circuit 1
It is equipped with 72.

The reset circuit 172 includes two OR gates 174 and 176 and a timer 78. When a signal indicating power-on or a reset signal is supplied to the OR gate 174, an activation signal is supplied to the azimuth search control circuit 64 via the OR gate 176. Similarly, when the timer] 78 counts up, an activation signal is also supplied to the direction search control circuit 164 via the OR gate [76].

Further, the timer core 8 is reset when the CD is turned on.

Therefore, the reset circuit 172 resets the direction search control circuit 1 in response to power-on or reset, or after a certain period of time has elapsed since the CD was turned off due to blocking or the like.
64 is activated.

In this embodiment, the direction search control circuit 164
It has a configuration as shown in FIG.

In FIG. 13, the direction search control circuit 164 includes an arctangent calculation section 180. The arctangent calculation unit 180 takes in the initial values (u o , v o ) of the components (u, , v,) in the horizontal plane from the memory 160 and calculates the initial value θINIT of the geomagnetic direction θ MP 5 ]. That is, θ −tan”(v/u) −(12)
The INIT OO operation is executed. The initial value θINIT determined in this manner is supplied to the switch 168.

Further, this calculation is performed in response to supply of an activation signal from the reset circuit 172. That is, when turning on the power, etc., it is only possible to use (u,, v,) related to the output (x t , y ] of the FCC 20 due to the need for direction search, which will be described later. Geomagnetic direction θV using the stored initial value (uv)
An initial 0'0 value θINIT of MP is calculated. The initial value θ obtained in this way is determined by the switch 168. The orientation is supplied to the adder 70 via 16 INIT registers.

The activation signal issued by reset circuit 172 is also supplied to timing signal generator 182 . The timing generator 182 generates timing signals T1 to T1 at predetermined timings in response to the activation signal. This timing signal T1T3 is used for the direction search operation.

Next, the direction search operation will be explained.

First, if the CD obtained by the demodulator 54 is off when a start signal is supplied to the azimuth search control circuit 64, the counter A184 of the azimuth search control circuit starts counting time.

That is, the CD supplied from the demodulator 54 is supplied to the counter A] 84 via an AND gate 186. A
The ND gate 186 is supplied with a timing signal T1 from the timing signal generator 182. Therefore, the input timing of CD to the counter A184 is controlled by the timing signal T1.

A coincidence circuit 187 and an AN
A search flip-flop 190 is connected via a D gate 188. The AND gate 188 is supplied with a timing signal T2 generated by the timing signal generator 182, similar to the timing signal T1 described above.

That is, whether the count value of counter A 184 or the coincidence circuit 187
If the predetermined value set in
7 is synchronously outputted to the search flip-flop '1.90 via an AND gate]88.

The output of search flip-flop 190 is AND gate 1
92. The timing signal T3 supplied from the timing signal generator 182 is input to the AND gate]92.

AND gate 192 synchronizes the output from search flip-flop 190 with this timing signal T3 and supplies it to switch 194 as a search flag.

A switch 194 is provided at the output of the search step angle generator 196. The search step angle generator 196 is
This is a device that generates a search step angle Δθ5RCI□ having a predetermined value.

That is, when rotating the antenna 10 in order to search for an azimuth, the rotation needs to be performed in predetermined angle increments. Search step angle generator 196 to switch 194
The search step angle Δθ5RC11 output via
The switch 1 is supplied to the adder 198 shown in FIG.
68 is added to the geomagnetic direction θ'. The MF obtained as a result of the addition is the geomagnetic direction θV8. is C in adder 170.
It is added to the D method offset ΔθVMP and supplied to the adder 30.

As a result, the mobile object orientation θv8 is rotated by the search step angle ΔθSRCH. As a result, the antenna command angle 0AVC changes, and the direction search using the antenna]0 is performed.

Further, in the case of this embodiment, the search flag is issued when the CD is turned off. That is, the orientation of the antenna 10 is relatively far from the satellite orientation, and therefore the antenna 10
A search flag is issued when radio waves from the satellite are not being received well. In other words, the azimuth search is performed until it reaches an azimuth that is close to the azimuth of the antenna 10 or the satellite azimuth.

In this state, when the CD is turned on, the search flip-flop 190 is reset.

That is, the CD supplied from the demodulator 54 is
It is also supplied to the OR gate 200 along with the ND gate 1-1.86. The output terminal of the OR game 1-200 is connected to the reset terminal of the search flip-flop 90, so when the CD is turned on, the search flip-flop 190 is reset. At this time, the output of the search flip-flop]90 is inverted, and the switch is switched accordingly]9
4 is turned off and the search step angle ΔθSl? CI output is cut off.

In this way, when the CD is off, the search step angle Δθ5RCH is output and the direction search is performed by rotating the antenna 10, and when the CD is turned on, this search ends.

Furthermore, in the above search, if the antenna 10 rotates once, that is, if the geomagnetic direction θVMF stored in the 16 direction registers shown in FIG. )・The action is executed.

That is, the output of the aforementioned AND gate 92 is connected not only to the switch 194 but also to the counter B204. The output of the counter B204 is connected to the matching circuit B206, and the output of the matching circuit B206 is connected to the OR gate 2.
It is connected to the input terminal of 00. Also, ○R game 1-2
The output terminal of 00 is connected to the reset terminal of the above-mentioned search flip-flop 190, as well as the counter A184 and the matching circuit A18.
6. It is also connected to the reset terminal of the counter B 204 and the coincidence circuit 8206.

That is, the output of the AND gate 192 causes the switch 1 to
94 is turned on, the counter B204 counts the number of times the search step angle Δθ5RC11 is supplied by this operation, and the coincidence circuit B206 compares the monthly result obtained by the counter B204 with a predetermined value.

This predetermined value is a value equivalent to one rotation of the geomagnetic direction θVMF. In the matching circuit B206, the counter B2
If it is determined that the counting result of 04 matches this predetermined value, that is, if the geomagnetic direction θVMF has made one rotation, the output of the matching circuit B206 is sent to the counter A64, matching circuit A186, search flip-flop 190, It is supplied to the reset terminals of counter B204 and coincidence circuit B206. As a result, the circuit receiving the signal supplied to the reset terminal performs a reset operation, so that the entire azimuth search control circuit 1.64 is reset.

Note that when the carrier used for the search is a burst signal, the counter A184 [18] is made longer than the maximum bust interval.

(6, 2, 6) Overall operation of FGC system Next, the overall operation of the FGC system 34 described above will be explained.

First, when a start signal is issued from the reset circuit 172 due to power-on or generation of a reset signal, the azimuth search control circuit 164 sets the initial value θIN1 in response to this start signal.
is calculated and supplied to the switch 168. The switch 168 is switched to the azimuth search control circuit 164 side in response to the activation signal, and as a result, the initial value θINIT of the geomagnetic azimuth θVMP is stored in the azimuth register 169. The initial value θIN1. stored in the orientation register 202. is θV
It is supplied to adder 198 as MF.

When the azimuth search control circuit 164 is activated in response to the activation signal, the azimuth search control circuit 164 generates a search flag and outputs a search step angle Δθ5RCH after a predetermined time has elapsed (after the counter A 184 has counted up). .

Moreover, this search step angle ΔθS RCH is calculated by the adder 1
98. In the adder 198, the search step angle Δθ5PCI is added to the geomagnetic azimuth θVMP − output from the azimuth register 202, and the result of this addition is stored in the azimuth register 202 via the switch 168. Note that the switch 168 is turned to the adder 198 side in accordance with the search flag.

The contents of the 16 azimuth registers that are updated sequentially in this way are added as the geomagnetic azimuth θVMP related to the search] 7
0 to the adder 32. As a result, the moving body direction θVM is successively determined by the search step angle Δθ5RC11.
is updated, the antenna command angle θAVC is changed accordingly, and the antenna 1o is rotated.

On the other hand, the search flag output from the azimuth search control circuit 164 is
supplied to

The CD method centripetal device 158 reads the initial value (110, V D ) of the horizontal plane component of the earth's magnetism from the memory 0 backed up by the battery 162, and also takes in the output (x,, y,) of the FCC 20. . Additionally, the moving object orientation θ■8 is also taken in from the adder 32.

The value of the moving object azimuth θVM changes with the operation of the azimuth search control circuit 164. That is, the search step angle Δθ5R
The moving body orientation θ■8 is updated by successive addition of CHs.

However, the mobile body orientation θ■8 in this case is not the mobile body orientation related to detection. This is a numerical value for rotating the antenna 10 until it faces an azimuth that is sufficiently close to the antenna]-0 or the satellite azimuth.

Therefore, when the CD supplied from the demodulator 54 to the CD method centripetal device 158 is turned on, the direction search control circuit 164
The output of the search step angle ΔθS RCH is stopped, and the CD method centripeting is performed using the mobile body orientation θVM, that is, θVM(CD), which is taken in at this time by the CD method centripetal device 158. The resulting magnetization components (c, d) are supplied to a switch 156 and a centripetality determining device 154.

At this time, the AB method centripetal movement is also being executed by the AB method centripetal device. That is, AB method centripetal device]5
2 is the output of the FGC 20 (x.

y, ) to perform centripetal centripetal movement based on the AB method.

The resulting magnetization components (a, b) are supplied to a centripetality determining device 154 and a switch 156.

The centripetality determining device] 54 takes in a completion flag indicating whether or not the centripetal movement by the A and B methods has been completed in the ABB method centripetal device 152. If the completion flag is supplied to the centripetal determination device 154 while the centripetal motion by the CD method is not completed, the centripetal determination device 154 switches the switch 156 to ABB.
It is turned to the modulus center device 152 side, and the magnetization component (ab) obtained by the AB method is supplied to the adder 128.

In addition, magnetization components (c, d) by the CD method centripetal device 158
has been obtained and the completion flag has not yet been issued, the centripetality determination device 154 turns the switch 156 to the CD method centripetal device 158 side. As a result, the magnetization components (c, d) obtained by the CD method centripetal device] 58 are supplied to the adder 128.

In the adder 128, the magnetization components (a b) or (c
, d) are removed in the horizontal plane component (u, ,
v, ) is stored in the memory 160 and supplied to the arctangent calculation unit 130. In the arctangent calculation unit 130, the geomagnetic direction θVMF is calculated based on the components in the horizontal plane (u,,v,)]1, and further, the LP
The moving body oscillation component is removed by F166, and the obtained geomagnetic direction θVMF is supplied to the direction register 169.

In this embodiment, a register 208 is provided to store an offset based on the CD method. The contents of this register 208 are updated sequentially by the step angle issued by the step track control circuit 80.

That is, the contents of the register 208 are sequentially added and updated according to the step angle supplied from the step track control circuit 80 via the switch 82. For this reason, an adder 210 is provided before register 208, and the step angle is added to the contents of register 208 by adder 21.0. The offset ΔθVMP stored in the register 208 is an offset that occurs when the step track control circuit 80 executes step tracking when centripetal alignment is performed by the CD method. That is, as shown in FIG. 14, when centripeting is performed in the CD method centripetal device, step tracking is executed not on the satellite azimuth system 30 side but on the FGC system 34 side. Therefore, the offset ΔθVMP output from the register 208 is supplied to the adder 170 and added to the geomagnetic direction θVMF.

Further, this register 208 is reset by the search flag or completion flag. That is, the FGC system 34 includes an OR game 1-2 that takes in the search flag and the completion flag.
12 is provided, and the output of this OR gate 212 is connected to the reset I terminal of the register 208. When the search flag is issued in the direction search control circuit 164 and the direction search is started, or AB method centripetal device] 52
When the centripetal movement is completed, the contents of register 208 are initialized.

Further, a search flag generated from the azimuth search control circuit 164 is supplied to the LPF 120 and the azimuth register 122 of the rate sensor system 36. That is, when centripetal movement using the CD method is being executed, the rate sensor system 36 is reset.

Furthermore, the reset circuit] 72 is equipped with a timer 178. This timer 178 is provided to avoid starting the azimuth search when the carrier detection signal CD is turned off for a short time due to short-term radio wave blocking (blocking) due to a tree or the like. Therefore, when the CD is turned off for a certain period of time, the timer 78 counts up and supplies an activation signal to the direction search control circuit 164 via the OR gate 176.

(7) Effects of the Example As described above, in this example, centripetal movement is performed by the AB method and the CD method. In the CD method, the moving body force position θVM (.,
), there is no need to rotate the moving body.

Therefore, like FCC20, its output (X, .

Even when using a device in which the magnetization components (c, d) are included in the magnetization components (c, d), the magnetization components (c, d) can be removed without rotating the moving body. Additionally, as a result, the detection accuracy of the FGC system 34 can be ensured,
For example, the present invention can be used in an antenna tracking device without incurring a waiting time during system start-up, which occurs when a device with relatively low accuracy, such as a rate sensor, is kept at a constant temperature. That is, it becomes possible to use an inexpensive rate sensor 8.

In addition, in this embodiment, A
The magnetization components (a, b) obtained by method B are added to the adder 12.
It is switched and supplied to 8. Therefore, for example, if the magnetization components (a, b) can be obtained by the AB method due to the operating conditions of the moving object, centripetal can be performed by the proven AB method based on the least squares method, which can be expected to have higher accuracy.

Furthermore, FGC system LPF166 and rate sensor system 3
The six LPFs 120 are configured to be complementary to each other.

Therefore, by adding the outputs of both, it is possible to obtain the moving body orientation θ■8. In addition, FCC2 by LPF166
It is possible to remove the moving body swing component included in the output of 0, and therefore the moving body orientation θ is not affected by the moving body swing.
On the other hand, due to the incomplete integration of the LPF 120, that is, the low-pass characteristic, the rate sensor 1
The turning angular velocity output from 8 can be converted into turning angle θVR.

Furthermore, in this embodiment, the output of the satellite azimuth system 30 is corrected to the magnetic north reference in order to match the FGC 20, which is a magnetic north reference sensor. Sunawaji, latitude based on true north,
The satellite orientation 08N based on true north, obtained using the longitude and satellite longitude, can be corrected to the magnetic north reference by referring to the declination θNM stored in the ROM64, and as a result, the satellite orientation is based on true north. This prevents the problem that the moving object orientation is determined based on the magnetic north reference. This prevents the occurrence of errors caused by the deviation θNM.

In this embodiment, memories 76 and 160
are backed up by batteries 78 and 162, respectively, so for example, when the power is turned on, the satellite orientation θ8)4@ is immediately set, and the centripetal and geomagnetic orientation θVM
It becomes possible to start the F calculation.

"Effects of the Invention" As explained above, according to the present invention, the magnetization component is determined by using the orientation of the moving object when the CD is on, so the magnetization component is determined from the FGC output without turning the moving object. It becomes possible to remove.

Further, according to claim (2) of the present invention, the output of either the AB method centripetal means or the CD method centripetal means is selectively used depending on the turning angle of the moving body, and depending on the case, the output of either the AB method or the CD method centripetal means is used. It is possible to eliminate the magnetized component by appropriate means.

Furthermore, according to claim (3), since the reference for the satellite orientation and the mobile object orientation is unified to the magnetic north reference, it is possible to prevent errors caused by deviations between true north and magnetic north, and to perform more accurate antenna tracking. becomes.

Furthermore, according to claim (4), the moving body rocking component included in the output of the FCC is removed, making it possible to calculate the geomagnetic direction without being affected by the rocking of the moving body.

In addition, by incompletely integrating the output of the rate sensor using a low-pass filter, it is possible to remove the offset of the rate sensor and its temperature drift to determine the turning angle, and the rate sensor system determined by this low-pass filter Since the transfer function of the FGC system is configured to be complementary to the transfer function of the FGC system, by adding the outputs of both, a system with excellent frequency response characteristics can be constructed, and the direction of the moving object can be determined with high accuracy. becomes.

According to claim (5), the step track control circuit corrects the satellite orientation or the mobile object orientation, making it possible to perform antenna tracking so that the reception level in the reception system becomes the highest.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the actual configuration of an antenna tracking device according to an embodiment of the present invention, in which FIG. 1(a) is a perspective external view, FIG. 1(b) is a side view, and FIG. is a block diagram showing the overall circuit configuration of this embodiment. Figure 3 is a block diagram showing the configuration of the antenna servo system and reception system. Figure 4 is a block diagram showing the configuration of the satellite azimuth system and step track system. , Figure 5 is a table showing the contents of the declination table, and Figure 6 is a table showing the contents of the argument table.
Figure 7 is a block diagram showing the configuration of the step track control circuit; Figure 8 is a block diagram showing the configuration of the rate sensor system; Figure 9 is a diagram showing the configuration of the flux gate compass system. FIG. 10 is a block diagram showing the configuration of the flux gate compass. FIG. 11 is a diagram showing the characteristics of the flux gate compass. FIG. 12 is a diagram showing the influence of magnetization of the moving body. Figure 13 shows
FIG. 14 is a block diagram showing the configuration of the azimuth search control circuit. FIG. 14 is a table showing differences in operation depending on the centripetal method. 10... Antenna 18... Rate sensor 20... Fluxgate compass 22...
Electronics unit 26... Antenna servo system 28, 32... Adder 30... Satellite direction system 34... Fluxgate compass system 36...
Rate sensor system 38... Receiving system 40... Step track system 64... ROM 68... Adder 80... Step track control circuit] 20...
LPF 126 ... Centripetal device 128 ... Adder 130 ... Arctangent calculation unit] 52 ... AB method centripetal device] 54 ... Centripetal determination device 156 ... Switch 158 ... CD method centripetal device ]64... Orientation search control circuit 166... LPF CD... Carrier detection signal RECLEV - Reception level signal (a. (c. (u.) ... Satellite azimuth deviation based on true north... Satellite based on magnetic north Azimuth... Turning angle y・) "... Fluxgate compass output b)...
Magnetization component by AB method d) ... Magnetization component by CD method, ■,) ... Component of geomagnetism in horizontal plane (vector) ... Geomagnetic direction Component of geomagnetism in horizontal plane Mobile object azimuth Antenna command angle θVMF r o ”' θ...M θAVC"'

Claims (5)

[Claims] (1) An antenna rotatably supported on at least one axis, an antenna servo system that servo-controls the antenna orientation according to the antenna command angle, and a first addition that calculates the antenna command angle from the satellite orientation and the mobile object orientation. a satellite orientation system that calculates the satellite orientation from the current latitude/longitude information and the satellite longitude; a second adder that calculates the mobile orientation from the rotation angle of the mobile object and the geomagnetic orientation; and a rotation angular velocity of the mobile object. A rate sensor system that detects the rotation angle of a moving object by detecting and low-pass filtering it, a flux gate compass system that detects the horizontal component of the earth's magnetism and removes the moving object's magnetization component to determine the earth's magnetic direction, and an antenna. An antenna tracking device mounted on a moving body such as a vehicle or a ship, comprising: a receiving system that receives radio waves, detects a carrier when the antenna orientation is close to the satellite orientation, and outputs a carrier detection signal; a CD method centripetal means for determining a moving body magnetization component based on the initial value of the horizontal plane component of the earth's magnetism, the moving body direction when the carrier detection signal is generated, and the horizontal plane component of the earth's magnetism; An antenna tracking device comprising: a geomagnetic azimuth calculation means for removing a moving body magnetization component from a horizontal plane component of the terrestrial magnetism to obtain a geomagnetic azimuth. (2) In the antenna tracking device according to claim (1), the fluxgate compass system removes, from the horizontal plane component of the geomagnetic field obtained by the turning of the moving object, a component that changes as the moving object turns, and removes the remaining component. AB method centripetal means that obtains the component obtained as a moving body magnetization component, and centripetal method switching that selectively switches and supplies the moving body magnetization component obtained by either the AB method centripetal means or the CD method centripetal means to the geomagnetic azimuth calculation means. An antenna tracking device comprising: means. (3) In the antenna tracking device according to claim (1), the satellite orientation system includes means for determining the declination angle of magnetic north with respect to true north from the current latitude and longitude information and correcting the satellite orientation to the magnetic north reference. Features: Antenna tracking device. (4) In the antenna tracking device according to claim (1), the rate sensor system includes a low-pass filter that low-pass filters the turning angular velocity of the moving body, and the fluxgate compass system is a complementary transmission to the rate sensor system. An antenna tracking device characterized by comprising a low-pass filter having a function. (5) In the antenna tracking device according to claim (2), when the moving body magnetization component is determined by the CD method centripetal means, it is determined by the second adder so that the reception level in the reception system is the highest. 1. An antenna tracking device comprising: a step track control circuit for correcting a moving object orientation that has been detected, or a satellite orientation in other cases.