JP2002107448A - Doppler navigation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a Doppler navigation device that avoids the arrival of the radio waves far away and maintaining the output of the speed information even if a large attitude change of an airplane happens until the transmitting and receiving beam is directed to, near the horizontal line. SOLUTION: A beam direction control unit compares the attitude angle of an airplane detected by an attitude angle sensor with a threshold of airplane attitude angle at which the beam transmitted from an antenna will arrive far way, and in the case of the attitude angel of airplane within a range less than the threshold of a threshold setting unit, the beam control signal for changing the beam direction is not outputted. In the case of the attitude angle of airplane more than the threshold value, the beam control signal for changing the beam direction to a direction except the horizontal direction is transmitted to a beam direction selector unit. The beam direction selector unit selects the transmission beam in a direction indicated by the beam control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave mounted on an aircraft, transmitting a radio wave toward the ground surface, and detecting a reflected wave from the ground surface, that is, a Doppler shift frequency corresponding to the speed of the aircraft contained in the received radio wave. The present invention relates to an improvement of a Doppler navigation device that obtains information and supplies speed information to an upper-level device of an aircraft or a pilot as navigation information to be used for operation of an aircraft.

[0002]

2. Description of the Related Art There are various types of navigation devices that provide flight status such as attitudes such as pitch angle and roll angle of the aircraft, azimuth of the nose, flight altitude, etc., to an upper navigation device or a pilot of the aircraft. One of them is a Doppler navigation device that provides aircraft speed information. The Doppler navigation device is a device that transmits radio waves from an aircraft to the ground surface, detects a Doppler frequency shift corresponding to the speed of the aircraft included in the reflected wave, and calculates the speed.

FIG. 7 relates to the principle of this device. 1 is an aircraft, 2 is a conventional Doppler navigation device, 3 is a transmission / reception beam of radio waves transmitted and received by the Doppler navigation device 2, and 4 is a ground surface. The velocity vector of the aircraft is V, and the angle between the velocity vector V of the aircraft and the transmission / reception beam 3 is Γ. At this time, assuming that the transmission frequency of the transmitting and receiving beam 3 is ft and the radio wave propagation velocity is c, the Doppler frequency shift fd included in the reflected wave due to the Doppler effect is expressed by the following equation (1).
The speed V is given by the following equation (2).

[0004]

(Equation 1)

[0005]

(Equation 2)

Therefore, the speed V of the aircraft can be obtained by detecting the Doppler frequency shift included in the received radio wave. The Doppler navigation device is a device that obtains the speed of an aircraft based on such a principle. In an actual device, since the speed of the aircraft needs to be decomposed into three-dimensional information orthogonal to each other and provided to a higher-order navigation device or pilot, the transmission and reception beams from the Doppler navigation device must be at least three.
Need more than direction.

FIG. 8 is a diagram showing the configuration of a conventional Doppler navigation system. In the figure, 2 is the same as FIG. 7, 5 is an antenna composed of a transmitting antenna 5a and a receiving antenna 5b, 6 is a frequency tracking system having a transmitting / receiving function and a frequency tracking function of the Doppler navigation system, and 6a is a transmission reference signal. , A receiver for amplifying the received signal, 6c
Is a mixer that outputs the difference between the frequency of the transmission reference signal and the received signal, that is, the Doppler shift frequency, 6d is a frequency tracker that tracks the Doppler shift frequency and outputs a tracking value, 7 is a speed calculator that calculates the aircraft speed It is.

FIG. 9 shows, as an example of a conventional Doppler navigation system, a Doppler navigation system for transmitting at least three required beams to the ground surface, based on the coordinate system of the Doppler navigation system. FIG. 4 shows a relationship between a velocity vector of the airframe and a transmission / reception angle of a beam.

In the figure, reference numerals 1 and 2 denote the same coordinate system as in FIG. 7, and the coordinate system is based on a Doppler navigation system mounted on the bottom surface of the aircraft 1 and has a reference as a reference. In the navigation system, the T axis, L axis, and V axis correspond to the mutually orthogonal planes of the aircraft 1, the T axis is the nose plane plane, the L axis is the starboard plane plane, and the V axis is the downward plane plane. Matches. Va is the velocity vector of the aircraft, and its components VT, VL, and VV are the projections of Va on the T axis, L axis, and V axis, respectively. Indicate the direction of the transmitted / received beam, the angle formed by each beam with each of the T, L, and V axes is constant, the angle formed with the T axis is γ, the angle formed with the L axis is σ, V
The angle formed by the axis is ψ, and the angles formed by the transmission and reception beams directed to are denoted by γ1, σ1, and ψ1, for example.

Next, the operation will be described. In FIG. 8, a transmitter 6a sends a transmission reference signal of a transmission beam to a transmission antenna 5a and a mixer 6c, and a transmission radio wave is transmitted from the antenna 5a. The transmission radio wave of each beam is reflected on the ground surface and received by the antenna 5b, and the reception frequency at that time is the one that has undergone the Doppler frequency shift accompanying the speed of the aircraft. The antenna 5b outputs this received radio wave as a received signal to the receiver 6b, and the receiver 6b amplifies the received signal corresponding to each transmission / reception beam and mixes the received signal with the mixer 6c.
Output to

In the mixer 6c, the signals from the transmitter 6a and the receiver 6b are mixed to extract the frequency difference between the transmission reference signal and the reception signal of the transmission beam, that is, the Doppler shift frequency included in each reception beam. Output to the frequency tracker 6d. The frequency tracker 6d outputs the frequency tracking value to the speed calculator 7 while tracking the input frequency. The speed calculator 7 calculates three-dimensional speed information Va (VT, VL, VV) that coincides with the aircraft axis based on the Doppler shift frequencies of the reception beams in three directions.

Next, the calculation inside the speed calculator 7 will be described. In FIG. 9, the Doppler shift frequencies included in the reflected waves of the transmission beams in three directions are respectively fd1,
If fd2 and fd3, respectively, each Doppler shift frequency is shifted to an axis that coincides with the aircraft axis of the aircraft at the aircraft speed Va because the Doppler shift frequency is due to the contribution of the velocity component when the aircraft velocity is projected onto each transmission / reception beam. Projections VT, VL, VV
Using the angles γ, σ, ψ formed by each axis and each transmission / reception beam, the transmission frequency ft, and the speed c of the radio wave,
Is obtained.

[0013]

(Equation 3)

In Equation 3, the unknowns are VT, VL, VV
By solving Equation 3 as a simultaneous equation, the velocity component along the axis of the aircraft, that is, three-dimensional velocity information can be obtained.

Although the conventional Doppler navigation system in which the transmitting and receiving beam projection directions are three directions has been described as an example, in the case of the conventional Doppler navigation system in which the transmitting and receiving beam projecting directions are four or more, the transmission and reception in Equation (3) are performed. Simultaneous equations equal to the number of beam projection directions are obtained, and three or more arbitrary equations can be simultaneously calculated to calculate three-dimensional velocity information.

[0016]

FIG. 10 is a diagram for explaining a problem to be solved by the invention. In the figure, 8 is the direction of the transmission beam of the aircraft 1. In the conventional Doppler navigation system, for example, as shown in FIG. 10, when the attitude of the aircraft 1 changes greatly until the direction 8 of the transmission / reception beam points near the horizontal line, the angle between the ground surface 4 and the direction 8 of the transmission beam becomes shallower. In addition to not being able to obtain reflections in the direction of aircraft 1, reflections on the ground surface or direct radio wave arrival at a distant place, the presence of aircraft 1 may be known at a distant place by radio wave detection. There is a problem that the confidentiality of the information is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and when a large attitude change of an aircraft occurs until a transmission beam is directed near a horizontal line,
The purpose of the present invention is to obtain a Doppler navigation device having a function of outputting speed information even after a direction change or a cut-off, by avoiding arriving at a distant place by switching or cutting a direction only for a transmission / reception beam directed to a horizontal direction. And

[0018]

According to a first aspect of the present invention, there is provided a Doppler navigation apparatus, comprising: an attitude angle sensor for outputting an attitude angle of an aircraft as airframe attitude angle information; and an airframe attitude angle at which a transmission beam will reach a distant place. A threshold setting device that sets a threshold value of the beam; a beam direction controller that outputs a beam control signal that controls a direction of a transmission / reception beam according to a comparison result of the attitude angle of the attitude angle sensor and a threshold value of the aircraft attitude angle; And a beam direction switch for switching the direction of the transmission / reception beam based on the control signal.

A Doppler navigation system according to a second aspect of the present invention is the Doppler navigation system according to the first aspect of the present invention, in which the attitude angle information of the aircraft is obtained from the system bus data of the aircraft mounted related device instead of the attitude angle sensor. It has a system bus interface.

In the Doppler navigation system according to a third aspect of the present invention, in the beam direction controller, when the body attitude angle exceeds a threshold of the body attitude angle of the threshold value setting device, a beam for switching a direction of a transmission / reception beam. The control signal is output.

The Doppler navigation system according to the fourth invention sets an attitude angle sensor for outputting the attitude angle of the aircraft as airframe attitude angle information and a threshold value of the airframe attitude angle at which the transmission beam will reach a distant place. A threshold setting device for performing the operation, a beam cutoff controller for outputting a beam control signal for controlling the cutoff of the transmission and reception beams, and a beam breaker for cutting off the transmission and reception beams based on the beam control signal.

The Doppler navigation system according to the fifth invention has a third
In the Doppler navigation apparatus according to the invention, a system bus interface is provided instead of the attitude angle sensor in order to obtain attitude angle information of the aircraft from system bus data of an onboard related apparatus.

In the Doppler navigation system according to a sixth aspect of the present invention, in the beam cutoff controller, when the body attitude angle exceeds a threshold value of the body attitude angle of the threshold value setting device, the transmission and reception beams are blocked. This is to output a beam control signal.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention. In the figure, 9
Is a attitude angle sensor that obtains an attitude angle of the aircraft and outputs aircraft attitude angle information; 10 is a beam direction controller that outputs a beam control signal for controlling the direction of the transmitting / receiving beam 3 of the antenna 5;
11 is a beam direction controller 1 for the body attitude angle information.
A threshold value setting device for setting a threshold value at which 0 switches the beam direction;
Reference numeral 12 denotes a beam direction switch for switching the direction of the transmission / reception beam 3 based on the beam control signal, and reference numeral 13 denotes a transmission / reception beam whose direction has been switched.

Embodiment 1 of the present invention is configured as described above, and transmits an electric wave to the ground surface, and obtains three-dimensional speed information of the aircraft from the Doppler shift frequency included in the received electric wave. The operations of the tracking system 6 and the speed calculator 7 are the same as those of the conventional device.

Next, when there is a large change in the attitude of the aircraft until the transmission beam is directed to the vicinity of the horizon, the direction of only the transmission / reception beam directed to the vicinity of the horizon is switched, and thereafter, a function of outputting speed information is added. The operation of the first embodiment of the present invention will be described.

FIG. 2 is a diagram for explaining the operation of the first embodiment. As an example, a Doppler navigation system for transmitting three beams to the ground surface is shown on the basis of the coordinate system of the Doppler navigation system. FIG. 6 is a relationship diagram between the velocity vector of FIG. FIG. 2 shows, by way of example, the direction of each transmitted / received beam when the beam projection point is switched to 'because the beam directed to the beam projection point is directed in the direction near the horizontal line due to the change in the attitude of the aircraft. I have.

In the figure, the beam projection point after the beam switching of the beam projection point is denoted by ', and the angles formed by the switched beam and the respective axes of T, L and V are γ1', σ1 ',
It is the same as FIG. 9 except that it is set to ψ1, and the Doppler shift frequency included in the reflected wave for 'is fd.
1 '.

In FIG. 1, the attitude angle sensor 9 is the aircraft 1
Beam direction controller 10 using the attitude angle of the
To enter. The threshold value setting device 11 is a device for setting in advance a threshold value of the body attitude angle at which the beam transmitted from the antenna 5 will reach a distant place, and the set value is input to the beam direction controller 10. . Beam direction controller 1
At 0, the body attitude angle of attitude angle sensor 9 and threshold value setting device 1
In the range where the attitude angle of the aircraft 1 does not exceed the set value of the threshold value setting unit 11, there is no output of the beam control signal for switching the beam direction from the beam direction controller 10, It operates similarly to a conventional Doppler navigation system.

If the attitude angle of the aircraft 1 exceeds the set value of the threshold value setting device 11, the beam direction controller 10 determines, for the beam that will exceed the threshold value, a direction in which the beam does not point in the horizontal direction, for example, the V axis in FIG. A beam control signal for switching to a direction symmetrical with respect to is transmitted to the beam direction switch 12.

The beam direction switching unit 12 performs beam switching, beam scanning, and the like for the antenna 5, and among the transmission / reception beams 3 exceeding the threshold value of the threshold value setting unit 11, only the beam directed near the horizontal line is used as the beam control signal. In addition to switching to the transmission / reception beam 13 in the designated direction, the beam angle information after switching is transmitted to the beam direction controller 10 and the speed calculator 7.

In the velocity calculator 7, for example, as shown in FIG. 2, when the beam projection point is switched from the quadrant on the TL coordinate to the 'in the quadrant on the TL coordinate that is symmetrical with respect to the V axis. Based on the beam angle information γ1 ′, σ1 ′, and ψ1 ′, the simultaneous equation of Equation 3 is changed to Equation 4, and accurate output of velocity information is maintained even after the beam switching.

[0033]

(Equation 4)

According to the present invention, by adding the attitude angle sensor, the beam direction controller, the threshold value setting device, and the beam direction switch to the conventional Doppler navigation system, the aircraft can travel until the transmission beam is directed near the horizon. By switching the direction of only the transmission / reception beam pointing in the vicinity of the horizontal line when there is a large change in attitude, confidentiality regarding the presence of the aircraft can be ensured, and speed information can be output even after the beam switching.

Embodiment 2 FIG. 3 is a block diagram showing Embodiment 2 of the present invention. In the figure, reference numeral 14 denotes a system bus of an aircraft-mounted related device in which aircraft attitude angle information is provided as bus data, and 15 denotes a system bus 1
4 is a system bus interface for acquiring body attitude angle information from the data on 4.

The second embodiment of the present invention is configured as described above, and transmits the aircraft attitude angle information to the beam direction controller 10 from the system bus 14 of the aircraft-related equipment via the system bus interface 15. Except for
By the same operation as in the first embodiment of the present invention, when there is a large attitude change of the aircraft until the transmission beam is directed to the vicinity of the horizon, the direction of only the transmission / reception beam directed to the vicinity of the horizon is switched. Even maintain accurate speed information output.

Embodiment 3 FIG. 4 is a block diagram showing Embodiment 3 of the present invention. In the drawing, the transmitting and receiving beams are projected in four or more directions.

The third embodiment of the present invention is configured as described above. The antenna 5 transmits the radio wave to the ground surface and obtains the three-dimensional speed information of the aircraft from the Doppler shift frequency included in the received radio wave. The operations of the tracking system 6 and the speed calculator 7 are the same as those of the conventional device.

Next, when there is a large attitude change of the aircraft until the transmission beam is directed to the vicinity of the horizon, only the transmission and reception beams directed to the vicinity of the horizon are cut off from the beams projecting in at least four directions. The operation of the third embodiment of the present invention to which a function of outputting speed information is added will be described.

FIG. 5 is a diagram for explaining the operation of the third embodiment. In this third embodiment, since it is necessary to project beams in at least four directions, as an example, four beams are projected onto the ground surface. About the Doppler navigation system to be sent,
FIG. 3 is a diagram illustrating a relationship between a velocity vector of the aircraft and a transmission / reception angle of a transmission / reception beam based on a coordinate system of a Doppler navigation device. In the figure, a projection point is added by setting the beam projection direction to four directions, and a beam directed to this projection point and T,
This is the same as FIG. 9 except that the angles formed with the L and V axes are respectively γ4, σ4, and ψ4, and the Doppler shift frequency included in the reflected wave is fd4.

In FIG. 4, the attitude angle information from the attitude angle sensor 9 and the threshold value of the attitude angle of the airframe from which the beam transmitted from the antenna 5 will reach far from the threshold value setting unit 11. It is input to the beam breaker 16.
In a range where the attitude angle of the aircraft 1 does not exceed the set value of the threshold value setting device 11, the beam cutoff controller 16 does not output a beam control signal for beam cutoff, and operates similarly to the conventional Doppler navigation device. . However, at this time, since the beam projection directions are four directions in the positional relationship of FIG. 5, the simultaneous equations used for the calculation of the speed calculator 7 are not Equation 3, but Equation 5.

[0042]

(Equation 5)

When the attitude angle of the aircraft 1 exceeds the set value of the threshold setting device 11, the beam cutoff controller 16 sets the threshold setting device 11
A beam control signal for cutting off a beam exceeding the threshold value is sent to the beam breaker 17. The beam breaker 17 cuts off only the beam directed to the vicinity of the horizontal line among the transmission / reception beams 3 exceeding the threshold of the threshold setting unit 11 for the antenna 5, and also cuts off the beam cut off to the beam cutoff controller 16 and the speed calculator 7. Is transmitted. In the speed calculator 7, f2, f3, and f3 for the transmission / reception beams pointing to the remaining three expressions other than the blocked beam in Expression 5, that is, if the transmission / reception beam pointing to the projection point is blocked, are left. The simultaneous output of the equation relating to f4 maintains the output of accurate speed information even after the beam is cut off.

The above description is directed to an example of a Doppler navigation apparatus in which the transmitting and receiving beams are projected in four directions.
If there are six directions, the speed information output can be maintained if transmission and reception beams in at least three directions can be secured, such as blocking in three directions.

According to the present invention, by adding an attitude angle sensor, a beam cutoff controller, a threshold setting device, and a beam cutoff device to a conventional Doppler navigation system that projects transmission and reception beams in four or more directions, the transmission beam can be moved near the horizontal line. When there is a large change in the attitude of the aircraft until the aircraft is oriented, the confidentiality regarding the presence of the aircraft is secured by shutting off only the transmission and reception beams pointing in the vicinity of the horizon, and speed information is output even after the beam is interrupted. can do.

Embodiment 4 FIG. FIG. 6 is a block diagram showing Embodiment 2 of the present invention. In the figure, 2, 3,
5, 6, 7, 11, 16 and 17 are the same as those of the third embodiment,
14 and 15 are the same as in FIG.

Embodiment 4 of the present invention is configured as described above, and transmits the body attitude angle information to the beam cutoff controller 16 from the system bus 14 of the aircraft-related equipment via the system bus interface 15. Except for
According to the same operation as in the third embodiment of the present invention, when there is a large attitude change of the aircraft until the transmission beam is directed to the vicinity of the horizontal line, the transmission and reception of the beam projected at least in four or more directions is directed to the vicinity of the horizontal line. Only the beam is cut off, and accurate speed information output is maintained even after the beam cutoff.

[0048]

As described above, according to the present invention, the following effects can be obtained.

According to the present invention, when there is a large attitude change of the aircraft until the transmission beam is directed to the vicinity of the horizon, the direction of only the transmission / reception beam directed to the vicinity of the horizon is switched to thereby determine the presence of the aircraft. It is possible to secure confidentiality and to output speed information even after beam switching.

According to the present invention, when there is a large attitude change of the aircraft until the transmission beam is directed to the vicinity of the horizon, only the transmission / reception beam directed to the vicinity of the horizon is cut off, thereby concealing the presence of the aircraft. In addition, the speed information can be output even after the beam is cut off.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a relationship between a velocity vector of the aircraft and a transmission / reception angle of each transmission / reception beam according to Embodiment 1 of the present invention.

FIG. 3 is a block diagram of a Doppler navigation device according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a Doppler navigation device according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a speed vector of an aircraft and a transmission / reception angle of each transmission / reception beam according to Embodiment 3 of the present invention.

FIG. 6 is a block diagram of a Doppler navigation device according to a fourth embodiment of the present invention.

FIG. 7 is a diagram illustrating the principle of a Doppler navigation device.

FIG. 8 is a block diagram showing a conventional Doppler navigation device.

FIG. 9 is a diagram illustrating a relationship between a velocity vector of an aircraft and a transmission / reception angle of each transmission / reception beam in the conventional Doppler navigation device.

FIG. 10 is a diagram illustrating a problem of a conventional Doppler navigation device.

[Explanation of symbols]

1 aircraft, 5 antennas, 5a transmitting antenna, 5b
Receiving antenna, 6 frequency tracking system, 6a transmitter, 6b
Receiver, 6c mixer, 6d frequency tracker, 7
Speed calculator, 9 attitude angle sensor, 10 beam direction controller, 11 threshold setting device, 12 beam direction switcher, 14
System bus, 15 system bus interface,
16 beam break controller, 17 beam breaker.

Claims (6)

[Claims] An antenna mounted on an aircraft for transmitting radio waves toward the ground surface and receiving reflected waves from the ground surface,
A frequency tracking system that tracks a Doppler shift frequency corresponding to the speed of the aircraft included in the reflected wave or the received radio wave, a speed calculator that obtains three-dimensional speed information from the Doppler shift frequency, Attitude angle sensor that obtains aircraft attitude angle information, threshold setting device that sets a threshold value of the aircraft attitude angle at which the transmitted beam will reach a distant place, threshold value of the aircraft attitude angle of the threshold setting device, and the attitude angle sensor A beam direction controller for outputting a beam control signal for controlling the direction of the transmission / reception beam in accordance with the result of comparison with the aircraft attitude angle, and a beam direction switch for switching the direction of the transmission / reception beam based on the beam control signal. A Doppler navigation device characterized by the above-mentioned. 2. An antenna mounted on an aircraft, transmitting radio waves toward the ground surface, and receiving a reflected wave from the ground surface,
A frequency tracking system that tracks a Doppler shift frequency corresponding to the speed of the aircraft included in the reflected wave or the received radio wave, a speed calculator that obtains three-dimensional speed information from the Doppler shift frequency, A system bus interface for obtaining body attitude angle information from a system bus of an aircraft-related apparatus, a threshold setting unit for setting a threshold of a body attitude angle at which a transmission beam will reach a distance, and a body attitude angle of the threshold setting unit A beam direction controller that outputs a beam control signal for controlling the direction of a transmission / reception beam in accordance with a result of comparison between the threshold value and the aircraft attitude angle from the system bus interface, and switches the direction of the transmission / reception beam based on the beam control signal. A Doppler navigation device comprising a beam direction switch. 3. The beam direction controller according to claim 1, wherein the body attitude angle exceeds a threshold value of the body attitude angle of the threshold value setting device.
3. The Doppler navigation system according to claim 1, wherein a beam control signal for switching a direction of a transmission / reception beam is output. 4. An antenna mounted on an aircraft, transmitting radio waves toward the ground surface, and receiving a reflected wave from the ground surface,
A frequency tracking system that tracks a Doppler shift frequency corresponding to the speed of the aircraft included in the reflected wave or the received radio wave, a speed calculator that obtains three-dimensional speed information from the Doppler shift frequency, Attitude angle sensor that obtains aircraft attitude angle information, threshold setting device that sets a threshold value of the aircraft attitude angle at which the transmitted beam will reach a distant place, threshold value of the aircraft attitude angle of the threshold setting device, and the attitude angle sensor A beam cutoff controller that outputs a beam control signal for controlling cutoff of a transmission / reception beam in accordance with a result of comparison with the aircraft attitude angle, and a beam cutoff that cuts off a transmission / reception beam based on the beam control signal. Features Doppler navigation system. 5. An antenna mounted on an aircraft for transmitting radio waves toward the ground surface and receiving reflected waves from the ground surface,
A frequency tracking system that tracks a Doppler shift frequency corresponding to the speed of the aircraft included in the reflected wave or the received radio wave, a speed calculator that obtains three-dimensional speed information from the Doppler shift frequency, A system bus interface for obtaining body attitude angle information from a system bus of an aircraft-related apparatus, a threshold setting unit for setting a threshold of a body attitude angle at which a transmission beam will reach a distance, and a body attitude angle of the threshold setting unit And a beam cutoff controller that outputs a beam control signal for controlling cutoff of a transmission / reception beam according to a comparison result between the threshold value of the airframe and the aircraft attitude angle from the system bus interface, and a beam that cuts off the transmission / reception beam based on the beam control signal. A Doppler navigation device comprising a circuit breaker. 6. The beam cutoff controller, when the body attitude angle exceeds a threshold value of the body attitude angle of the threshold value setting device,
7. The Doppler navigation device according to claim 5, wherein a beam control signal for controlling interruption of a transmission / reception beam is output.