JP2008304329A - Measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly determine reliability of a measured result in a measuring device such as a Doppler radar. <P>SOLUTION: An amplitude measuring part 141 in the measuring device measures an amplitude at a peak time of a reflection wave 502 received by a receiving part 113. In a reference value measurement mode, an amplitude storing part 151 stores the amplitude of the reflection wave 502 measured by the amplitude measuring part 141. In an altitude and speed measurement mode, an amplitude determining part 155 compares the amplitude of the reflection wave 502 measured by the amplitude measuring part 141 with the amplitude of the reflection wave 502 stored by the amplitude storing part 151 to determine whether a difference between the amplitudes is within an allowable range. When the amplitude determining part 155 determines that the difference between the amplitudes is within the allowable range, a reliability output part 156 outputs a signal showing that reliability of the measured result calculated by a state calculation part 130 is high, and outputs a signal showing that the reliability of the measured result is low when the amplitude determining part 155 determines that the difference between the amplitudes is out of the allowable range. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measuring apparatus such as a Doppler radar that is mounted on an aircraft and measures altitude and speed of the mounted aircraft.

In order to guide an aircraft or the like, it is necessary to measure the altitude or speed of the aircraft or the like.
Since Doppler radar can measure altitude and speed without external support such as GPS satellites, external support such as drone landing support in disaster areas and autonomous navigation of planetary probes is not possible. It can be used even in situations where it cannot be expected.
Myron Kayton, Walter R .; Fried “Avionics Navigation Systems” John Wiley & Sons, Inc. 1997, pp. 449-502.

When a measuring device such as a Doppler radar is used in this way, it is important to determine whether the measurement result is reliable.
The present invention has been made, for example, in order to solve the above-described problems, and it is an object of the present invention to correctly determine the reliability of a measurement result in a measurement apparatus that measures altitude and speed, such as Doppler radar.

The measuring apparatus according to the present invention is
A transmitter for transmitting radio waves,
A receiving unit for receiving a reflected wave reflected by the radio wave transmitted by the transmitting unit hitting the target; and
A reflected wave measuring unit for measuring at least one of a delay time and a frequency shift of the reflected wave received by the receiving unit;
Based on at least one of the delay time and frequency shift measured by the reflected wave measurement unit, a state calculation unit that calculates at least one of the distance to the target and the relative velocity;
An amplitude measuring unit for measuring the amplitude of the reflected wave received by the receiving unit;
An amplitude determination unit that determines whether the amplitude measured by the amplitude measurement unit is within a predetermined range;
If the amplitude measured by the amplitude measuring unit is not within a predetermined range, the amplitude determining unit determines that the reliability is low for at least one of the distance and the relative speed calculated by the state calculating unit. And a reliability output unit that outputs a signal.

  According to the measuring apparatus of the present invention, when the amplitude of the reflected wave is outside the predetermined range, the reliability output unit outputs a signal indicating that the reliability is low, so the radio wave transmitted by the transmission unit is assumed. When a reflected wave reflected by an external object is observed, it can be excluded as abnormal data, and the reliability of the measurement result can be correctly determined.

Embodiment 1 FIG.
Embodiment 1 will be described with reference to FIG.

FIG. 1 is a block configuration diagram showing an example of the overall configuration of the altitude speed measuring apparatus 100 in this embodiment.
The altitude speed measuring device 100 (measuring device) is a device mounted on an aircraft or the like. The altitude velocity measuring apparatus 100 transmits a radio wave (transmission wave 501) toward the ground surface 400 (target), receives the reflected wave 502 reflected by the transmitted radio wave hitting the ground surface 400, and measures the transmission time and frequency shift. By doing so, the altitude and speed of an aircraft or the like on which the altitude speed measuring apparatus 100 is mounted are measured.

  The altitude speed measurement apparatus 100 includes a transmission unit 111, an antenna 112, a reception unit 113, a reflected wave measurement unit 120, a state calculation unit 130, an amplitude measurement unit 141, a reliability determination unit 150, an attitude information input unit 171, and a speed output unit 181. And a distance output unit 182.

  The transmitter 111 generates a pulse-modulated signal having a predetermined frequency (for example, a microwave band or a millimeter wave band). This is a case where the altitude speed measurement method is a pulse method, and a different method may be used. For example, in the case of FM-CW (Frequency Modulated Continuous Wave), the transmission unit 111 generates a frequency-modulated signal. In the case of the spread spectrum system, the transmission unit 111 generates a signal that is spread-modulated with a pseudo-random code.

The antenna 112 receives the signal generated by the transmission unit 111 and transmits the input signal as a transmission wave 501 in a predetermined direction.
The antenna 112 is an active array antenna, for example, and can transmit a radio wave by forming a desired beam in an arbitrary direction. Alternatively, the antenna 112 may be a mechanical antenna, and may transmit radio waves in a desired direction by mechanically moving the direction of the antenna 112. The antenna 112 may be a plurality of antennas having different directivities, and may transmit radio waves in a desired direction by switching the antennas.

The transmission wave 501 transmitted by the antenna 112 propagates at the speed of light and reaches the ground surface 400 (target). The transmission wave 501 hits the ground surface 400 and is reflected to become a reflected wave 502. The frequency of the reflected wave 502 is shifted due to the Doppler shift caused by the relative velocity between the antenna 112 and the ground surface 400. The reflected wave 502 propagates at the speed of light and reaches the antenna 112. The antenna 112 receives the reflected wave 502.
Note that the transmitting antenna and the receiving antenna may be different.

  The receiving unit 113 receives the reflected wave 502 received by the antenna 112 and converts the frequency to an intermediate frequency. The receiving unit 113 detects the in-phase component and the quadrature component of the frequency-converted signal, performs analog-digital conversion, and generates an in-phase (I) signal and a quadrature (Q) signal. The receiving unit 113 outputs the generated in-phase signal and quadrature signal.

Based on the in-phase signal and the quadrature signal output from the reception unit 113, the reflected wave measurement unit 120 determines the delay time of the reflected wave 502 (the time from when the antenna 112 transmits the transmission wave 501 until it receives the reflected wave 502. ) And frequency shift (difference between the frequency of the transmission wave 501 and the frequency of the reflected wave 502).
The reflected wave measurement unit 120 includes a Fourier transform unit 121, a peak frequency calculation unit 122, a pulse integration unit 124, a peak detection unit 125, and a response time calculation unit 126.

  The Fourier transform unit 121 inputs the in-phase signal and the quadrature signal output from the reception unit 113. The Fourier transform unit 121 calculates the frequency component (the intensity of the reflected wave 502 in the frequency domain) by performing Fourier exchange (for example, fast Fourier transform (FFT)) on the input in-phase signal and quadrature signal. The Fourier transform unit 121 outputs a signal representing the calculated frequency component.

  The peak frequency calculation unit 122 receives the signal output from the Fourier transform unit 121. The peak frequency calculation unit 122 calculates a frequency (peak frequency) having the strongest frequency component based on the input signal. The peak frequency calculation unit 122 outputs a signal representing the calculated peak frequency.

  The pulse integrating unit 124 inputs the in-phase signal and the quadrature signal output from the receiving unit 113. Based on the input signal, the pulse integration unit 124 calculates and integrates the amplitude of the reflected wave 502 with respect to a predetermined number of pulses of the transmission wave 501 transmitted by the transmission unit 111. Thereby, a signal noise ratio (S / N) improves. The pulse integrator 124 outputs a signal representing the integrated amplitude of the reflected wave 502.

  The peak detection unit 125 receives the signal output from the pulse integration unit 124. The peak detection unit 125 calculates a time (peak time) when the amplitude of the reflected wave 502 is largest based on the input signal. The peak detector 125 outputs a signal representing the calculated peak time.

  The response time calculation unit 126 receives the signal output from the peak detection unit 125. The response time calculation unit 126 calculates the delay time (peak slant range response time) of the reflected wave 502 based on the input signal. The response time calculation unit 126 outputs a signal representing the calculated delay time.

  The posture information input unit 171 inputs posture information. The attitude information is, for example, information indicating the nose direction (an angle in the horizontal plane (heading) and an angle in the vertical direction (pitch)) of an aircraft or the like on which the altitude speed measuring device 100 is mounted. This information is necessary for converting the coordinate system into an absolute coordinate system. For example, the altitude speed measuring apparatus 100 is based on information such as acceleration measured by an acceleration sensor mounted on the altitude speed measuring apparatus 100 or an image obtained by photographing a target whose direction is known in advance (for example, a constellation). The other installed system calculates the posture information. The posture information may be calculated based on information such as altitude and speed measured by the altitude speed measuring apparatus 100. Posture information input unit 171 outputs a signal representing the input posture information.

The state calculation unit 130 calculates the altitude and speed of an aircraft or the like equipped with the altitude speed measurement device 100 based on the delay time or frequency shift measured by the reflected wave measurement unit 120.
The state calculation unit 130 includes a speed calculation unit 131 and a distance calculation unit 132.

The speed calculator 131 receives a signal representing the peak frequency output from the peak frequency calculator 122. Since the frequency shift of the reflected wave 502 is due to Doppler shift, it is proportional to the relative speed (ground speed) between the antenna 112 and the ground surface 400 (target) in the propagation direction (range direction) of the transmission wave 501 and the reflected wave 502.
In order to obtain a three-dimensional velocity vector of an aircraft or the like equipped with the altitude velocity measuring apparatus 100, the antenna 112 transmits a transmission wave 501 in three or more mutually independent directions. The speed calculation unit 131 calculates a speed vector (own machine speed) of an aircraft or the like equipped with the altitude speed measurement apparatus 100 based on the peak frequency in each direction (physical quantity conversion process).
Here, since the direction in which the antenna 112 transmits the transmission wave 501 is based on an aircraft or the like on which the altitude speed measuring device 100 is mounted, the speed vector calculated by the speed calculating unit 131 is also used by the altitude speed measuring device 100. It is expressed in a coordinate system based on the mounted aircraft.
The speed calculation unit 131 inputs a signal representing the posture information output from the posture information input unit 171. The speed calculation unit 131 performs coordinate system conversion on the calculated speed vector based on the input signal, and calculates a speed vector in the absolute coordinate system.

The distance calculation unit 132 receives a signal representing the delay time output from the response time calculation unit 126. Since the transmission wave 501 and the reflected wave 502 propagate at the speed of light, the distance from the reflection point is proportional to the delay time.
The distance calculation unit 132 calculates the distance from the ground surface 400 based on the delay time of the reflected wave 502. The distance calculation unit 132 outputs a signal representing the calculated distance from the ground surface 400.

In addition, when calculating | requiring altitude (self-machine altitude), such as an aircraft carrying the altitude speed measuring apparatus 100, the antenna 112 needs to transmit the transmission wave 501 in the downward direction.
Therefore, the antenna 112 forms a relatively wide range of beams expected to include the direct downward direction, and transmits the transmission wave 501. Assuming that the ground surface 400 has no undulations or slopes and is flat and horizontal, the ground surface 400 in the downward direction when viewed from the antenna 112 is closest to the antenna 112. Therefore, the reflected wave 502 from the ground surface 400 in the downward direction returns to the antenna 112 earliest. Moreover, since the distance is the shortest, the amplitude of the reflected wave 502 is the largest. As a result, the altitude of an aircraft or the like equipped with the altitude speed measuring device 100 can be calculated even if the downward direction is not accurately known.

  It is to be noted that the altitude velocity measuring device is determined by determining which direction is directly below based on the attitude information input by the attitude information input unit 171 and transmitting the transmission wave 501 by the antenna 112 toward the determined directly downward direction. The altitude of an aircraft equipped with 100 may be calculated.

  As described above, the transmission pattern (transmission direction, pulse period, etc.) of the transmission wave 501 transmitted by the antenna 112 is different between when the speed is desired and when the distance is desired. Generally, since the measurement accuracy of speed and the measurement accuracy of distance tend to contradict each other, the altitude speed measurement apparatus 100 inputs a signal indicating, for example, a speed measurement mode or a distance (altitude) measurement mode from the outside. The transmission pattern of the transmission wave 501 transmitted by the antenna 112 may be determined based on the input signal. Alternatively, the speed measurement mode and the distance (altitude) measurement mode may be alternately repeated at a predetermined cycle.

The amplitude measuring unit 141 measures the amplitude of the reflected wave 502 at the peak time.
Amplitude measuring section 141 receives a signal representing the amplitude of reflected wave 502 output from pulse integrating section 124 (the intensity of reflected wave 502 in the time domain) and a signal representing the peak time output from peak detecting section 125. The amplitude measuring unit 141 calculates the amplitude of the reflected wave 502 at the peak time based on the input signal. The amplitude measuring unit 141 outputs a signal representing the calculated amplitude of the reflected wave 502.

The reliability determination unit 150 determines whether or not the distance and speed calculated by the state calculation unit 130 are reliable based on the amplitude of the reflected wave 502 at the peak time measured by the amplitude measurement unit 141.
The reliability determination unit 150 (target information identification unit) includes an amplitude storage unit 151, an amplitude determination unit 155 (threshold determination unit), and a reliability output unit 156.

  The amplitude storage unit 151 receives the signal output from the amplitude measurement unit 141. The amplitude storage unit 151 temporarily stores the amplitude of the reflected wave 502 measured by the amplitude measurement unit 141 represented by the input signal.

The amplitude determination unit 155 receives the signal output from the amplitude measurement unit 141. The amplitude determination unit 155 compares the amplitude of the reflected wave 502 measured by the amplitude measurement unit 141 represented by the input signal with the amplitude of the reflected wave 502 previously stored by the amplitude storage unit 151.
The amplitude determination unit 155 determines whether or not the difference in amplitude is within a preset allowable range, and outputs a signal representing the determination result.

  The reliability output unit 156 receives the signal output from the amplitude determination unit 155. When the amplitude determination unit 155 determines that the difference in amplitude is within the allowable range based on the input signal, the reliability output unit 156 has reliability such as the distance and speed calculated by the state calculation unit 130. A signal indicating high is output to the outside. When the amplitude determination unit 155 determines that the amplitude difference is outside the allowable range, the reliability output unit 156 indicates that the reliability such as the distance and speed calculated by the state calculation unit 130 is low. Is output to the outside.

The speed output unit 181 outputs a signal representing the speed vector calculated by the speed calculation unit 131 to the outside.
The distance output unit 182 outputs a signal representing the distance calculated by the distance calculation unit 132 to the outside.

  The signals output from the speed output unit 181 and the distance output unit 182 are input by, for example, an inertial navigation system (navigation guidance control unit) and used to estimate the current position and altitude of an aircraft equipped with the altitude speed measuring device 100. To do. At that time, after determining the reliability based on the signal output by the reliability output unit 156, the distance and speed represented by the signal input by the inertial navigation system are used. For example, when the signal output from the reliability output unit 156 indicates that the reliability is low, the inertial navigation system does not use the distance or speed indicated by the signal input at that timing. Alternatively, when the reliability is low, the data may be used with a lighter weight than data with high reliability.

Next, the principle of reliability determination in this embodiment will be described.
The amplitude of the reflected wave 502 is inversely proportional to the fourth power of the distance to the reflection point, and is proportional to the radar cross section (RCS) at the reflection point. Therefore, when the amplitude of the reflected wave 502 changes significantly, either the distance to the reflection point (slant length) has changed significantly, or the radar cross-sectional area (scattering characteristic) at the reflection point has changed significantly.

The radar cross-sectional area of the ground surface 400 is considered to be substantially constant within a certain region. In addition, if there is no change in altitude of an aircraft or the like equipped with the altitude speed measurement device 100, it is considered that the distance between the antenna 112 and the reflection point on the ground surface 400 does not substantially change.
Accordingly, when the amplitude of the reflected wave 502 changes greatly, an unexpected target enters the beam of the transmission wave 501 and the reflected wave 502 reflected on the target is observed. Alternatively, there is a high possibility that the radar cross-sectional area at the reflection point has changed.
In that case, the distance and speed calculated by measuring the reflected wave 502 are highly likely to be abnormal data, and the reliability is low.

  The altitude velocity measuring apparatus 100 in this embodiment compares the amplitude of the reflected wave 502 measured by the amplitude measuring unit 141 with the amplitude of the reflected wave 502 previously measured and stored, and the difference in amplitude is predetermined. If it is out of the range, it is determined that the reliability such as the distance and speed calculated by the state calculation unit 130 is low. Therefore, in the above case, abnormal data is correctly determined, and the reliability of the entire system is improved. Can be improved.

  In the speed measurement mode that places importance on speed measurement accuracy, the accuracy of the distance to the reflection point calculated by the distance calculation unit 132 may be low. The altitude velocity measuring apparatus 100 in this embodiment does not use the distance calculated by the distance calculation unit 132, and the distance from the reflection point or the radar cross-sectional area at the reflection point changes based on the change in the amplitude of the reflected wave 502. Therefore, even when the accuracy of the distance calculated by the distance calculation unit 132 is low, the reliability can be correctly determined.

Next, the amplitude of the reflected wave 502 compared by the amplitude determination unit 155 will be described.
The amplitude determination unit 155 measures the reflected wave 502 previously received by the antenna 112 by the amplitude measuring unit 141, and uses the amplitude of the reflected wave 502 stored by the amplitude storage unit 151 as a reference, and the reflected wave received immediately before by the antenna 112. 502 is compared with the amplitude of the reflected wave 502 measured by the amplitude measuring unit 141.

For example, before starting the measurement of altitude and speed, the antenna 112 transmits a transmission wave 501 for measuring the reference amplitude (reference value measurement mode), and the amplitude measured by the reflected wave 502 and output from the amplitude measurement unit 141 Is stored in the amplitude storage unit 151 as a reference amplitude.
Thereafter, the antenna 112 transmits a transmission wave 501 for measuring altitude and velocity (altitude / velocity calculation mode), the reflected wave 502 is measured and the amplitude output from the amplitude measuring unit 141, and the amplitude storage unit 151 The amplitude determination unit 155 compares the stored reference amplitude.

Alternatively, the antenna 112 transmits a transmission wave 501 for measuring altitude and speed, the reflected wave 502 is measured, and the amplitude storage unit 151 stores a plurality of amplitudes output from the amplitude measurement unit 141, thereby determining the amplitude. The unit 155 calculates the average value and sets it as the reference amplitude.
Thereafter, the antenna 112 transmits a transmission wave 501 for measuring altitude and speed, measures the reflected wave 502 and outputs the amplitude output by the amplitude measurement unit 141, and the reference amplitude calculated by the amplitude determination unit 155, The amplitude determination unit 155 performs comparison.

  Alternatively, the altitude / speed measurement and the reference amplitude measurement are alternately performed, and the amplitude determination unit 155 may perform comparison based on the most recently measured reference amplitude or an average value of a plurality of reference amplitudes. .

The altitude speed measuring device 100 (measuring device) in this embodiment is:
A transmission unit 111 that transmits radio waves (transmission waves 501);
A receiving unit 113 that receives a reflected wave 502 reflected by the radio wave (transmission wave 501) transmitted by the transmission unit 111 hitting an object (the ground surface 400);
A reflected wave measuring unit 120 that measures at least one of a delay time and a frequency shift of the reflected wave 502 received by the receiving unit 113;
A state calculating unit 130 that calculates at least one of a distance and a relative velocity with respect to the target (the ground surface 400) based on at least one of the delay time and the frequency shift measured by the reflected wave measuring unit 120;
An amplitude measuring unit 141 that measures the amplitude of the reflected wave 502 received by the receiving unit 113;
An amplitude determination unit 155 that determines whether or not the amplitude measured by the amplitude measurement unit 141 is within a predetermined range;
If the amplitude measured by the amplitude measuring unit 141 is not within a predetermined range, and the amplitude determining unit 155 determines that the distance and / or the relative speed calculated by the state calculating unit 130 are low in reliability. And a reliability output unit 156 that outputs a signal indicating the above.

  According to the altitude velocity measuring apparatus 100 in this embodiment, when the amplitude of the reflected wave 502 is out of the predetermined range, the reliability output unit 156 outputs a signal indicating that the reliability is low. When the reflected wave 502 reflected by an unexpected target other than the ground surface 400 is observed, it can be excluded as abnormal data, and the reliability of the measured distance and speed can be increased.

  In this example, the reliability output unit 156 outputs binary data indicating whether the reliability is high or low, but the reliability output unit 156 has an amplitude of the reflected wave 502 outside a predetermined range. In some cases, a signal representing continuously changing reliability may be output based on the degree of deviation from the predetermined range.

The altitude speed measuring device 100 (measuring device) in this embodiment further includes:
An amplitude storage unit 151 that stores the amplitude measured by the amplitude measurement unit 141;
The amplitude determination unit 155 compares the amplitude measured by the amplitude measurement unit 141 with the amplitude previously stored by the amplitude storage unit 151 and determines whether or not the difference in amplitude is within a predetermined range. It is characterized by doing.

  According to the altitude velocity measuring apparatus 100 in this embodiment, the amplitude determination unit 155 uses the amplitude previously measured by the amplitude measurement unit 141 as a reference for determining the amplitude of the reflected wave 502, and thus the distance from the reflection point. Even if the radar cross-sectional area at the reflection point is unknown, it is possible to determine whether the data is abnormal data.

The above-described altitude speed measuring apparatus 100 (measuring apparatus) measures a physical quantity such as altitude and speed,
The transmission unit 111 transmits a radio wave (transmission wave 501),
The reception unit 113 receives the reflected wave 502 reflected by the radio wave (transmission wave 501) transmitted by the transmission unit 111 and hitting the target (the ground surface 400),
The reflected wave measuring unit 120 measures at least one of the delay time and the frequency shift of the reflected wave 502 received by the receiving unit 113,
Based on at least one of the delay time and the frequency shift measured by the reflected wave measurement unit 120, the state calculation unit 130 calculates at least one of the distance to the target (the ground surface 400) and the relative velocity,
The amplitude measuring unit 141 measures the amplitude of the reflected wave received by the receiving unit 113,
The amplitude determination unit 155 determines whether the amplitude measured by the amplitude measurement unit 141 is within a predetermined range,
When the amplitude determination unit 155 determines that the amplitude measured by the amplitude measurement unit 141 is not within a predetermined range, the reliability output unit 156 determines at least the distance and the relative speed calculated by the state calculation unit 130. Any one of them indicates that the reliability is low and outputs a signal.

Each functional block of the altitude speed measuring apparatus 100 (measuring apparatus) described above may be configured using hardware or may be configured using software. That is, you may comprise by the computer running the program which implement | achieves each said functional block. The computer includes a processing device (such as a CPU) that processes information, a storage device (such as a memory and a hard disk device) that stores information, an input device (such as operation buttons and a keyboard) that inputs information, and an output device (display) that outputs information. The computer may function as the altitude speed measuring device 100 by the processing device executing the program stored in the storage device.
The same applies to each embodiment described below.

Embodiment 2. FIG.
Embodiment 2 will be described with reference to FIG.

FIG. 2 is a block configuration diagram showing an example of the overall configuration of the altitude speed measuring apparatus 100 in this embodiment.
In addition, the same code | symbol is attached | subjected about the part which is common in the altitude speed measuring apparatus 100 demonstrated in Embodiment 1, and description is abbreviate | omitted here.

  The reliability determination unit 150 (target information identification unit) includes a cross-sectional area calculation unit 152, a cross-sectional area storage unit 153, an amplitude prediction unit 154 (threshold value calculation unit), an amplitude determination unit 155 (threshold value determination unit), and a reliability output unit 156. Have

The cross-sectional area calculation unit 152 inputs a signal representing the amplitude of the reflected wave 502 output from the amplitude measurement unit 141. In addition, the cross-sectional area calculation unit 152 receives a signal representing the distance from the ground surface 400 (target) output from the distance calculation unit 132. The cross-sectional area calculation unit 152 calculates the radar cross-sectional area of the ground surface 400 based on the input signal. As described in the first embodiment, the amplitude of the reflected wave 502 is inversely proportional to the fourth power of the distance to the reflection point and proportional to the radar cross-sectional area of the reflection point. = K · P · r ⁴ (σ is the radar cross-sectional area. K is a proportional constant. P is the amplitude of the reflected wave 502 measured by the amplitude measuring unit 141. r is the reflection point calculated by the distance calculating unit 132. The cross-sectional area of the radar is obtained by calculating the distance. The cross-sectional area calculation unit 152 outputs a signal representing the calculated radar cross-sectional area.

The cross-sectional area storage unit 153 receives the signal output from the cross-sectional area calculation unit 152. The cross-sectional area storage unit 153 stores the radar cross-sectional area represented by the input signal.
The cross-sectional area storage unit 153 (RCS table unit) may store the predicted radar cross-sectional area of the ground surface 400 in advance using a storage device such as a ROM (Read Only Memory). In that case, the cross-sectional area calculation unit 152 may be omitted.

The amplitude prediction unit 154 inputs the radar cross-sectional area previously stored by the cross-sectional area storage unit 153. In addition, the amplitude predicting unit 154 inputs a signal representing the distance from the ground surface 400 output from the distance calculating unit 132. The amplitude prediction unit 154 calculates the expected amplitude of the reflected wave 502 based on the input signal. The amplitude predicting unit 154 is, for example, P ′ = σ ′ / (k · r ⁴ ) (P ′ is the expected amplitude of the reflected wave 502. Σ ′ is the radar cross-sectional area stored in the cross-sectional area storage unit 153. k is a proportional constant, r is the distance to the reflection point calculated by the distance calculation unit 132), and the expected amplitude of the reflected wave 502 is obtained. The amplitude prediction unit 154 outputs a signal representing the calculated expected amplitude of the reflected wave 502.

The amplitude determination unit 155 receives a signal representing the amplitude of the reflected wave 502 output from the amplitude measurement unit 141. In addition, the amplitude determination unit 155 receives a signal representing the amplitude of the expected reflected wave 502 output from the amplitude prediction unit 154. The amplitude determination unit 155 compares two amplitudes represented by the input signal and determines whether or not the difference in amplitude is within a predetermined range.
Here, the allowable range of the difference in amplitude may be a predetermined fixed range, or the measurement accuracy is based on the measurement accuracy of the distance expected from the transmission pattern of the transmission wave 501 transmitted by the antenna 112. If the value is high, the allowable range is narrowed, and if the measurement accuracy is low, the allowable range may be widened. In that case, the amplitude prediction unit 154 may calculate the upper and lower limits of the allowable range, or the amplitude determination unit 155 may calculate and determine the allowable range.

As described above, the amplitude of the reflected wave 502 is inversely proportional to the fourth power of the distance to the reflection point. In the first embodiment, the amplitude of the reflected wave 502 is directly compared on the assumption that the distance to the reflection point is substantially constant. However, when the distance to the reflection point changes, the reflected wave 502 is accordingly changed. Therefore, if the amplitude of the reflected wave 502 is compared as it is, it may not be determined correctly.
In this embodiment, using the distance from the reflection point calculated by the distance calculation unit 132, the cross-sectional area calculation unit 152 converts the amplitude of the reflected wave 502 into the radar cross-sectional area at the reflection point. The converted cross-sectional area of the radar is stored in the cross-sectional area storage unit 153, and is predicted from the stored radar cross-sectional area by using the distance to the reflection point calculated by the distance calculation unit 132 during the subsequent observation. The amplitude of the reflected wave 502 is calculated and compared with the amplitude of the reflected wave 502 measured by the amplitude measuring unit 141. Therefore, the element of the distance to the reflection point is canceled out, and a change in the radar cross-sectional area at the reflection point can be detected.

  Further, as described above, the radar cross section used by the amplitude prediction unit 154 to predict the amplitude of the reflected wave 502 is not calculated by the cross section calculation unit 152 based on actual observation data, but is stored in the cross section area storage. What the unit 153 stores in advance may be used. For example, the cross-sectional area storage unit 153 stores in advance radar cross-sectional areas for typical objects such as urban areas, forests, and paddy fields, and for example, determines the type of the ground surface based on an image captured by the camera, The radar cross-sectional area corresponding to the determined type may be selected and used.

  In this way, when the change in the radar cross-sectional area at the reflection point is detected and the radar cross-sectional area is outside the assumed range, the reflected wave 502 reflected on the object other than the ground surface 400 is observed. It is determined that the reliability such as the distance and speed calculated based on the reflected wave 502 is low. Therefore, abnormal data can be correctly determined.

The altitude speed measuring device 100 (measuring device) in this embodiment further includes:
A cross-sectional area calculation unit 152 that calculates a radar cross-sectional area of the target (the ground surface 400) based on the amplitude measured by the amplitude measurement unit 141;
A cross-sectional area storage unit 153 that stores the radar cross-sectional area calculated by the cross-sectional area calculation unit 152;
An amplitude predicting unit 154 that predicts the amplitude of the reflected wave 502 based on the radar cross-sectional area previously stored in the cross-sectional area storage unit 153;
The amplitude determination unit 155 compares the amplitude measured by the amplitude measurement unit 141 with the amplitude predicted by the amplitude prediction unit 154, and determines whether or not the difference in amplitude is within a predetermined range. It is characterized by.

  According to the altitude velocity measuring apparatus 100 in this embodiment, the cross-sectional area calculating unit 152 calculates the radar cross-sectional area of the reflection point from the amplitude of the reflected wave 502 measured by the amplitude measuring unit 141, and the amplitude is calculated from the calculated radar cross-sectional area. Since the amplitude of the reflected wave 502 predicted by the prediction unit 154 and the amplitude of the reflected wave 502 measured by the amplitude measurement unit 141 are compared, even if the distance from the reflection point changes, the change in the radar cross section Can be detected, and it is possible to correctly determine whether or not the data is abnormal data.

  Note that the reliability determination unit 150 further includes the amplitude storage unit 151 described in the first embodiment, and the amplitude of the reflected wave 502 stored in the amplitude storage unit 151 and the amplitude prediction unit 154 predict according to the situation. The amplitude determination unit 155 may select one of the amplitudes of the reflected waves 502 and the amplitude of the reflected waves 502 measured by the amplitude measurement unit 141 may be compared. For example, in a situation where the distance measurement accuracy calculated by the distance calculation unit 132 is low, the amplitude of the reflected wave 502 stored in the amplitude storage unit 151 is used as a reference for comparison, and in a situation where the distance measurement accuracy is high, the amplitude The amplitude of the reflected wave 502 predicted by the prediction unit 154 may be used as a reference for comparison. Alternatively, it is determined from the speed calculated by the speed calculation unit 131 whether or not an aircraft or the like equipped with the altitude speed measuring device 100 is in horizontal flight, and in the case of horizontal flight, the change in the distance from the ground surface 400 is small. The amplitude of the reflected wave 502 stored in the amplitude storage unit 151 is used as a reference for comparison, and when the flight is not horizontal, the change in the distance from the ground surface 400 is large, so the amplitude of the reflected wave 502 predicted by the amplitude prediction unit 154 is compared. It is good also as a standard of.

Embodiment 3 FIG.
A third embodiment will be described with reference to FIG.

FIG. 3 is a block configuration diagram showing an example of the overall configuration of the altitude speed measuring apparatus 100 in this embodiment.
In addition, about the part which is common in the altitude speed measuring apparatus 100 demonstrated in Embodiment 1 and Embodiment 2, the same code | symbol is attached | subjected and description is abbreviate | omitted here.

  The reliability determination unit 150 (slant length information identification unit, peripheral terrain inclination determination unit) further includes a distance prediction unit 161 (expected slant length calculation unit) and a distance determination unit 162 (slant length determination unit).

  The distance prediction unit 161 inputs a signal representing the posture information output from the posture information input unit 171. The distance prediction unit 161 predicts the distance of the reflected wave 502 from the reflection point based on the input signal. The distance predicting unit 161 includes an aircraft equipped with the altitude speed measuring device 100 in which the orientation information represents the direction (the coordinate system based on the aircraft equipped with the altitude speed measuring device 100) in which the antenna 112 transmits the transmission wave 501. The coordinate system is converted based on the nose direction (inclination of the aircraft) and the direction (absolute coordinate system) in which the antenna 112 transmits the transmission wave 501 is obtained. The distance predicting unit 161 predicts the distance to the ground surface 400 in the direction based on the altitude (own altitude) of an aircraft or the like on which the altitude speed measuring apparatus 100 is mounted. For example, based on the assumption that the ground surface 400 is flat and horizontal with no undulations or slopes, the distance prediction unit 161 uses r = h / cos θ (r is the distance from the reflection point. H is the altitude velocity measurement. The altitude of an aircraft or the like equipped with the apparatus 100. θ is an angle formed between the direction in which the antenna 112 transmits the transmission wave 501 and the vertical direction.), And the antenna 112 transmits the transmission wave 501. Predict the distance to the surface 400 in the direction. The distance prediction unit 161 outputs a signal indicating the distance from the predicted reflection point.

  The distance determination unit 162 inputs a signal representing the distance from the ground surface 400 output from the distance calculation unit 132. In addition, the distance determination unit 162 receives a signal representing the distance from the predicted reflection point output from the distance prediction unit 161. The distance determination unit 162 compares the two distances based on the input signal and determines whether or not the difference in distance is within a predetermined range.

  The reliability output unit 156 outputs a signal representing the reliability of the distance and speed calculated by the state calculation unit 130 based on the determination result of the amplitude determination unit 155 and the determination result of the distance determination unit 162 to the outside.

  FIG. 4 is a diagram showing an example of a signal representing the reliability output by the reliability output unit 156 in this embodiment.

  When the amplitude of the reflected wave 502 and the distance to the reflection point are both within the predicted range, the reliability output unit 156 outputs a signal indicating that the altitude and speed calculated by the state calculation unit 130 are both highly reliable. To do.

  When the amplitude of the reflected wave 502 is within the predicted range, but the distance from the reflection point is outside the predicted range, the reliability output unit 156 has low reliability at the altitude calculated by the state calculation unit 130. The speed outputs a signal indicating that the reliability is high. Since the radar cross-sectional area at the reflection point is as expected, it is considered that the reflected wave 502 reflected on the ground surface 400 is detected. However, since the distance from the reflection point is different from the assumption, it is considered that the ground surface 400 has undulations and inclinations. It is done. This is because when the altitude is measured on the assumption that the ground surface 400 is flat and level, the ground surface 400 has undulations and inclinations contrary to the assumption, and the reliability of the measured altitude is reduced. .

  When the amplitude of the reflected wave 502 is out of the predicted range, but the distance to the reflection point is not within the predicted range, the reliability output unit 156 has high reliability calculated by the state calculation unit 130, The speed outputs a signal indicating that the reliability is low. Since the distance to the reflection point is as expected, the assumption that the ground surface 400 is flat and horizontal is considered to be correct. However, since the radar cross-sectional area at the reflection point is different from the assumption, for example, the reflection on the object moving on the ground This is because the reflected wave 502 may be observed, and the reliability of the speed calculated based on the frequency shift becomes low.

  When both the amplitude of the reflected wave 502 and the distance to the reflection point are outside the predicted range, the reliability output unit 156 outputs a signal indicating that the altitude and speed calculated by the state calculation unit 130 are both unreliable. To do.

  Thus, by combining the determination result of the amplitude determination unit 155 and the determination result of the distance determination unit 162, the shape (terrain structure) of the ground surface 400 (target) and the type of the target can be determined.

  Note that the reliability criterion shown here is an example. For example, if the measurement method does not assume that the ground surface 400 is flat and horizontal, the reliability of the measurement result does not decrease because the distance to the reflection point is different from the assumption.

  In addition, the reliability output unit 156 interprets the determination results of the amplitude determination unit 155 and the distance determination unit 162 and does not determine the reliability, but outputs the determination results of the amplitude determination unit 155 and the distance determination unit 162 as they are. It is also possible to leave the determination to an external system. For example, if both the amplitude of the reflected wave 502 and the distance from the reflection point are out of the predicted range, there is an unexpected target, so the inertial navigation system (navigation guidance control unit) is equipped with the altitude speed measurement device 100. It is also possible to take measures such as changing the course of the aircraft that has been used.

The altitude speed measuring device 100 (measuring device) in this embodiment further includes:
A distance prediction unit 161 that predicts a distance to the target (the ground surface 400);
A distance determination that compares the distance calculated by the state calculation unit 130 (distance calculation unit 132) with the distance predicted by the distance prediction unit 161 and determines whether or not the difference in the distance is within a predetermined range. Part 162,
The reliability output unit 156 further indicates that the reliability of at least one of the distance and the relative speed is low when the distance determination unit 162 determines that the difference in distance is not within a predetermined range. A signal is output.

  According to the altitude speed measuring apparatus 100 in this embodiment, when the distance to the reflection point is outside the assumed range, the reliability output unit 156 outputs a signal indicating that the reliability is low. In the case where a measurement method that greatly depends on the shape or the like is used, the reliability of the measurement result can be correctly determined.

  In this example, the amplitude predicting unit 154 predicts the amplitude of the reflected wave 502 from the radar cross section based on the distance calculated by the distance calculating unit 132, but based on the distance predicted by the distance predicting unit 161. Thus, the amplitude of the reflected wave 502 may be predicted. Alternatively, the amplitude prediction unit 154 may select and use one of the distance calculated by the distance calculation unit 132 and the distance predicted by the distance prediction unit 161 according to the situation. For example, when the distance measurement accuracy is low, the amplitude of the reflected wave 502 is predicted based on the distance predicted by the distance prediction unit 161. When the distance measurement accuracy is high, the distance calculation unit 132 calculates the distance. Based on the above, the amplitude of the reflected wave 502 may be predicted.

1 is a block configuration diagram showing an example of an overall configuration of an altitude speed measuring apparatus 100 according to Embodiment 1. FIG. FIG. 4 is a block configuration diagram showing an example of the overall configuration of an altitude speed measurement apparatus 100 according to a second embodiment. FIG. 5 is a block configuration diagram showing an example of the overall configuration of an altitude speed measurement apparatus 100 according to a third embodiment. 10 is a diagram illustrating an example of a signal representing reliability output by the reliability output unit 156 according to Embodiment 3. FIG.

Explanation of symbols

  100 altitude speed measuring device, 111 transmitting unit, 112 antenna, 113 receiving unit, 120 reflected wave measuring unit, 121 Fourier transform unit, 122 peak frequency calculating unit, 124 pulse integrating unit, 125 peak detecting unit, 126 response time calculating unit, 130 state calculation unit 131 speed calculation unit 132 distance calculation unit 141 amplitude measurement unit 150 reliability determination unit 151 amplitude storage unit 152 cross-sectional area calculation unit 153 cross-sectional area storage unit 154 amplitude prediction unit 155 amplitude Determination unit, 156 Reliability output unit, 161 Distance prediction unit, 162 Distance determination unit, 171 Attitude information input unit, 181 Speed output unit, 182 Distance output unit, 400 Ground surface, 501 Transmission wave, 502 Reflected wave

Claims (4)

A transmitter for transmitting radio waves,
A receiving unit for receiving a reflected wave reflected by the radio wave transmitted by the transmitting unit hitting the target; and
A reflected wave measuring unit for measuring at least one of a delay time and a frequency shift of the reflected wave received by the receiving unit;
Based on at least one of the delay time and frequency shift measured by the reflected wave measurement unit, a state calculation unit that calculates at least one of the distance to the target and the relative velocity;
An amplitude measuring unit for measuring the amplitude of the reflected wave received by the receiving unit;
An amplitude determination unit that determines whether the amplitude measured by the amplitude measurement unit is within a predetermined range;
If the amplitude measured by the amplitude measuring unit is not within a predetermined range, the amplitude determining unit determines that the reliability is low for at least one of the distance and the relative speed calculated by the state calculating unit. And a reliability output unit that outputs a signal. The measuring device further includes:
An amplitude storage unit for storing the amplitude measured by the amplitude measurement unit;
The amplitude determination unit compares the amplitude measured by the amplitude measurement unit with the amplitude previously stored by the amplitude storage unit, and determines whether or not the difference in amplitude is within a predetermined range. The measuring device according to claim 1, wherein The measuring device further includes:
A distance prediction unit that predicts the distance to the target;
A distance determination unit that compares the distance calculated by the state calculation unit with the distance predicted by the distance prediction unit and determines whether or not the difference in the distance is within a predetermined range;
The reliability output unit further outputs a signal indicating that the reliability of at least one of the distance and the relative speed is low when the distance determination unit determines that the difference in distance is not within a predetermined range. The measuring apparatus according to claim 1, wherein the measuring apparatus outputs the data. The measuring device further includes:
Based on the amplitude measured by the amplitude measurement unit, a cross-sectional area calculation unit for calculating the radar cross-sectional area of the target,
A cross-sectional area storage unit for storing the radar cross-sectional area calculated by the cross-sectional area calculation unit;
An amplitude prediction unit that predicts the amplitude of the reflected wave based on the radar cross-section previously stored by the cross-sectional area storage unit;
The amplitude determination unit compares the amplitude measured by the amplitude measurement unit with the amplitude predicted by the amplitude prediction unit, and determines whether or not the difference in amplitude is within a predetermined range. The measuring apparatus according to any one of claims 1 to 3.

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