JP7347553B2 - Laser ranging device, method, program - Google Patents

Description

The present invention relates to a laser ranging device, method, and program, and particularly to a laser ranging device, method, and program suitable for inter-satellite ranging.

As a related technology for measuring the distance between satellites, for example, Patent Document 1 describes a small laser ranging device that can measure the distance between satellites with sufficient accuracy and in real time, as shown in FIG. is disclosed. Note that FIGS. 10A and 10B are diagrams corresponding to FIGS. 1 and 3 of Patent Document 1, respectively. However, in FIGS. 10(A) and 10(B), the reference numerals and the like of each element have been changed from those in Patent Document 1.

In FIG. 10(A), the light receiving unit 205 receives a laser beam sent from the other party's artificial satellite (opposing satellite). The light receiving unit 205 branches a part of the laser beam from the opposing satellite, and identifies the direction of the opposing satellite using the pointing detection visual field sensor based on the branched laser beam. The discriminator 206 detects the signal received by the ranging light receiving element of the light receiving unit 205 and converts it into a trigger signal for time reading. The event timer 207 is a timer that accurately determines the time inside the artificial satellite (its own satellite).

The pointing section 203 is driven by the pointing drive section 204 and adjusts the laser transmission direction according to information detected by the coarse adjustment pointing sensor and the fine adjustment pointing sensor of the light receiving section 205. The control unit 208 records the time when the laser was sent to the opposing satellite and the time when the laser was received from the opposing satellite, and calculates the distance to the opposing satellite from these times. The interface 209 is an interface between the laser distance measuring device and an external device (not shown). The power supply unit 210 supplies power to each part of the laser distance measuring device.

In the light receiving unit 205, as shown in FIG. 10(B), about 10% of the received light (laser light) split by the first beam splitter 301 is focused by the first condensing lens 302 and used for coarse adjustment. The light is sent to the pointing sensor 303, and the coarse adjustment pointing sensor 303 detects the direction of the oncoming satellite that sent out the laser in real time, coarsely and with a wide field of view, from the amount of light detected by a four-part Si (silicon) photodiode. Furthermore, about 10% of the received light (laser light) split by the second beam splitter 304 is focused by the second condensing lens 305 and sent to the fine adjustment pointing sensor 306. The direction of the oncoming satellite is detected in real time with a narrow field of view based on the amount of light detected by a 4-part Si (silicon) photodiode, and about 80% of the received light (laser light) is focused by the third condensing lens 307. , and is sent to a ranging photodetector 308 made of silicon (Si)-APD (avalanche photodiode).

U.S. Pat. No. 5,005,003, which uses a device other than a photon counting device, includes an optical signal transmitted by a TOF (Time of Flight) camera system and an array of pixel sensors in an image sensor of the TOF camera system. determining a phase difference between a reflected light signal received by the at least one pixel sensor of the TOF camera system; determining the amplitude of the reflected light signal received by the at least one pixel sensor; the at least one pixel by combining the amplitude and the phase difference into a combined signal parameter for the at least one pixel sensor; and filtering the combined signal parameter for the at least one pixel sensor. - A method is disclosed comprising the step of denoising said coupled signal parameters for a sensor.

In Patent Document 2, filtering is performed by parameterizing a change in the phase of a received signal with respect to a transmitted signal that is modulated for each pixel of an array sensor.

JP2005-91286A Patent No. 6367827

Accurately determining the distance between satellites is expected to improve positioning accuracy on the ground in satellite groups that carry out positioning missions using constellations such as GPS (Global Positioning System) satellites and Japanese quasi-zenith satellites. has been done.

Various studies are being conducted on methods to directly measure the distance between satellites, but none have been put into practical use at this time. One of the next-generation positioning technologies is improving the accuracy of inter-satellite ranging. For example, there is hope for technology that can accurately measure distances between satellites from several hundred kilometers (kilometers) to more than 50,000 kilometers. If RF (Radio Frequency) (radio waves) is used for distance measurement, there is a concern about radio wave interference from satellites of other countries. For this reason, optical ranging between satellites has become promising.

In Patent Document 1 mentioned above, in order to cancel errors in the clocks of each satellite, two Data needs to be compared. Furthermore, since there is an error in the predicted orbits of each satellite, it is necessary to use a part of the received light for the ranging signal for pointing detection in order to accurately match the beam pointing. As a result, in order to ensure a signal to noise ratio (SNR) of the ranging signal, a large laser transmission power is required, leading to an increase in the size of the device. Furthermore, since separate detectors are required for distance measurement and pointing, the apparatus becomes complicated.

Regarding the standardization of distance measurement and communication in order to realize miniaturization of devices, a distance measurement method using communication signals is also considered. When inter-satellite optical communication is used for distance measurement, a pointing mechanism that can control the beam on the order of, for example, several μrad (microradian) is required in order to accurately input the received signal into the fiber core. There is a problem that the device becomes complicated and large in size because it detects the pointing of communication signal light or beacon light and performs feedback control.

In array sensor lidars (light detection and ranging) that use photon counting devices, such as Geiger mode APDs, erroneous distance measurements due to dark counts are a problem. Photon counting devices cannot perform filtering using intensity modulation because they cannot recognize the intensity data of the received signal. Therefore, an effective noise removal method is required.

Furthermore, when RF (radio wave) communication is used for distance measurement, there are problems such as radio wave interference with other satellites in orbit and poor distance measurement accuracy compared to optical.

The present disclosure has been devised in view of the above-mentioned problems, and its purpose is to suppress the complexity and size of the device, to realize a more compact device configuration, and to provide a laser measurement system suitable for inter-satellite ranging. Its purpose is to provide distance measuring devices, methods, and programs.

According to one aspect of the present disclosure, a laser ranging device that measures the distance between a target device that transmits and receives laser beams and the own device includes:
a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitted laser toward the target device based on the laser received from the target device;
a photodetector including an array sensor in which a plurality of sensing elements are arranged in an array;
Equipped with
The array sensor of the photodetector performs signal detection for distance measurement and pointing detection in one,
moreover,
The apparatus includes means for calculating a distance between the own apparatus and the target apparatus based on the transmission timing of the transmission laser and the reception timing of the laser received from the target apparatus.

According to another aspect of the present disclosure, a laser section that outputs a transmission laser;
a pointing unit that directs the emission direction of the transmitting laser toward the target device based on the laser received from the target device that transmits and receives the laser;
a photodetector including an array sensor in which a plurality of elements are arranged in an array;
A laser distance measuring method for measuring the distance between a self-device including a laser distance measuring device and the target device includes:
(a) The array sensor of the photodetector performs signal detection for ranging and pointing detection with one;
(b) calculating the distance between the self-device and the target device based on the transmission timing of the transmission laser and the reception timing of the laser received from the target device;
(c) applying a temporal gate and a spatial gate to the signal detected by the array sensor to remove noise data;
(d) time-modulating the transmission timing of the transmission laser pulse in the laser unit and superimposing communication data on the ranging transmission laser pulse;
Of these,
The above (a) and the above (b),
Said (a), said (b), and said (c),
(a), (b), (d),
(a), (b), (c), and (d);
Do any combination of these.

According to another aspect of the present disclosure, there is provided a laser ranging device that measures a distance between a target device that transmits and receives a laser, and includes:
a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitted laser toward the target device based on the laser received from the target device;
a photodetector including an array sensor in which a plurality of elements are arranged in an array;
In the array sensor of the photodetector, a computer constituting the own device includes a laser ranging device that detects signals for ranging and pointing detection in one;
(a) a process of calculating the distance between the self-device and the target device based on the transmission timing of the transmission laser and the reception timing of the laser received from the target device;
(b) processing of applying a temporal gate and a spatial gate to the signal detected by the array sensor to remove noise data;
(c) a process of time modulating the transmission timing of the transmission laser pulse in the laser unit and superimposing communication data on the ranging transmission laser pulse;
Of these,
(a) above;
Above (a) and above (b)
Said (a), said (b), and said (c),
A program is provided that causes processing of any combination of these to be performed. Furthermore, according to the present disclosure, a semiconductor storage such as a computer readable recording medium (for example, RAM (Random Access Memory), ROM (Read Only Memory), or EEPROM (Electrically Erasable and Programmable ROM)) storing the program; HDD (Hard Disk Drive), SSD (Solid State Drive), CD (Compact Disc), and DVD (Digital Versatile Disc) are provided.

According to the present invention, it is possible to suppress the complexity and size of the device, to realize a more compact device configuration, and to provide a laser ranging device suitable for inter-satellite ranging.

FIG. 1 is a diagram illustrating an example of a configuration of an embodiment of the present invention. (A) and (B) are diagrams illustrating an array sensor of a photodetector, an APD, and an ROIC in an embodiment of the present invention. FIG. 3 is a diagram illustrating a timing/angle measuring section in an embodiment of the present invention. FIG. 3 is a diagram illustrating a data processing/control unit in an embodiment of the present invention. (A), (B), and (C) are diagrams illustrating one embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an embodiment of the present invention. FIG. 1 is a diagram illustrating an example of a configuration of an embodiment of the present invention. (A) and (B) are diagrams illustrating a configuration example of related technology.

In the following, an overview of the present invention will first be described, and then embodiments will be described.

In one form of the present invention, a laser ranging device (inter-satellite ranging device) measures the distance between satellites, for example from several hundred kilometers to more than 50,000 kilometers, by measuring the propagation time of laser light. By receiving the laser beam output from the other satellite (opposing satellite) and comparing the transmission and reception times of both the own satellite and the opposing satellite, the error between the clocks of the own satellite and the opposing satellite is canceled, and the The distance between the satellites is calculated from the propagation time of the laser beam between the opposing satellites.

Unlike a laser ranging device that receives the reflected pulse of the transmitted laser and measures the round trip time from the transmission time and reception time to measure the distance, the intersatellite ranging device of this embodiment calculates the propagation time in one direction. Measurements are taken by each satellite (own satellite and opposing satellite).

The laser ranging device of each satellite (own satellite and opposing satellite) is equipped with an array sensor (photon counting image sensor) and has the function of simultaneously detecting timing measurement and pointing of the received beam.

The array sensor can secure a frequency band by suppressing the capacitance component as a single element, and can widen the detection surface by using multiple elements. Therefore, it is possible to detect high-speed laser pulses with a pulse width on the order of picoseconds with a wide receiving field of view.

In a laser ranging device (inter-satellite ranging device) according to one embodiment of the present invention, by using an array type sensor (photon counting device), it is possible to measure a distance for a received signal of several photons.

In inter-satellite optical communications, the beam divergence of the transmitted beam is usually narrowed down to the order of several microrads (microradians) in order to ensure signal levels.

In contrast, in one embodiment of the present invention, even when the spread angle of the transmission beam is expanded to, for example, about 1 mrad (miliradian), the transmission beam can be received even at a distance of, for example, 50,000 km. This beam spread covers the predicted orbit error of the oncoming satellite and the angle setting accuracy of the pointing mechanism. Therefore, according to one embodiment of the present invention, there is no need to search for an oncoming satellite or constantly monitor received signals and feed them back to the pointing mechanism.

According to one embodiment of the present invention, it is possible to continue to emit a beam from the own satellite to the opposing satellite, and also to receive the beam.

Generally, photon counting devices cause false positives due to dark counts. According to one embodiment of the present invention, the present invention has a function of eliminating noise data and making it possible to detect only received signals (received data) by temporally and spatially gate processing.

According to one embodiment of the present invention, furthermore, by modulating the transmission timing of the laser pulse, it is possible to perform both distance measurement and communication. By transmitting the transmission/reception time of one satellite and the orbit information of the other satellite regarding the own satellite and the opposing satellite, it is possible to communicate with the other satellite through communication with the ground or with other communication equipment. The processing results of bidirectional distance measurement data, which could not be obtained without preparing a system, can now be processed using only the distance measurement device, making it possible to minimize the number of distance measurement/communication transceivers.

In the related technology, separate devices are used for a sensor for laser ranging and a sensor for detecting beam pointing. Recently, avalanche photodiodes (APDs) that operate in array-type Geiger mode have been increasingly used in space, and can also be used for inter-satellite ranging. In Geiger mode, the diode is operated at a voltage slightly higher than its breakdown voltage, and a pair of electrons and holes generated by photon absorption and thermal fluctuations act as a trigger, causing a strong avalanche phenomenon. By installing the sensor surface on the focal plane of the receiving optical system, the array sensor can identify the direction in which the beam is incident based on the position of the pixel on the array sensor, which is a three-dimensional (3D) sensor. It is used in distance image sensors (LiDAR: Light Detection And Ranging), etc. As an array sensor, a space device with a pixel count of 128x128 has been developed, and a device with a pixel size of, for example, 100 μm (micro-meter) can be used (the array element size is 12.8 mm x 12.8 mm).

As described above, in one embodiment of the present invention, by using a Geiger mode APD array sensor, it is possible to perform distance measurement and pointing detection, and to realize an inter-satellite ranging device with simplified device configuration and control.

That is, according to one embodiment of the present invention, in order to perform ranging and pointing detection with one array sensor (one type), a laser ranging sensor (308 in FIG. 10(B)) and beam pointing are detected. There is no need for two types of sensors (303 and 306 in FIG. 10(B)).

APDs operating in Geiger mode are used for photon detection, and although they are highly sensitive, they also generate noise called dark counts at a certain rate. That is, in an APD operating in Geiger mode, single photon detection is achieved by biasing the APD at a voltage higher than its breakdown voltage. The APD remains metastable until a photon arrives and an avalanche occurs; however, when the APD is in a metastable state, an avalanche may be triggered spontaneously. The number of avalanche counts that are randomly and naturally induced is called the dark count rate.

In one form of the present invention, noise data due to this dark count is eliminated by temporal and spatial gate processing, and only received signal data is extracted. The temporal and spatial gating processes are coordinated with each other, and the predicted orbit of the oncoming satellite and the modulation pattern of the timing of the received signal are used to identify the received signal data.

According to one aspect of the present invention, it is determined that a received signal in a region that takes into account prediction errors in time and space, and that the timing and spatial position of the signal form a modulation pattern in a continuous time series. and the received signal data can be identified.

In one form of the present invention, the distance measurement signal itself can be used for communication for exchanging orbit information and distance measurement data between the own satellite and the opposing satellite.

When performing laser ranging in one direction, errors in the clocks of the own satellite and the opposing satellite become a cause of ranging errors. In order to avoid ranging errors due to errors in the clocks of the own satellite and the opposing satellite, it is necessary to perform offline processing via communication with the ground or directly exchange data between satellites to compare their ranging data. . In related technology, in order to directly exchange data only in orbit (between satellites) without going through the ground, it is necessary to install a communication device in addition to a laser ranging device.

According to one embodiment of the present invention, the device configuration is simplified by superimposing mutual information (data for avoiding ranging errors) on the ranging signal itself.

In one embodiment of the present invention, the modulation of the transmitted laser light serving as the ranging signal is achieved by modulating the emission timing (transmission timing) of the transmitted laser light. For example, when modulating the emission timing (transmission timing) of a repeating laser pulse train of 1 kHz (kilohertz), the distance measurement (time) resolution is 30 cm (centimeter) (≒ speed of light c x 1 ns (nanosecond) = 3 x 10 ⁸ ( m)×10 ^-9 ), in principle, 10 ⁶ times can be identified within a 1 ms (millisecond) time interval, that is, a 1 kHz period, and can be used as a communication signal.

Furthermore, according to one embodiment of the present invention, in the ranging device of one satellite, by modulating the emission timing (transmission timing) of the transmitting laser beam serving as the ranging signal, It transmits information and ranging data to other opposing satellites. As a result, it becomes possible to process inter-satellite ranging data between one satellite and another satellite in orbit (only between satellites) without going through other communication devices or the ground. .

<Embodiment>
FIG. 1 is a diagram illustrating a configuration example of an embodiment of the present invention. FIG. 1 shows an example of the configuration of a laser ranging device (inter-satellite ranging device) 100 mounted on one satellite (self-satellite) 10. The difference from the configuration of Patent Document 1 described above is that FIG. 1 does not include the pointing sensor described with reference to FIG. 10(B). Note that in FIG. 1, the discriminator 206, event timer 207, pointing drive section 204, power supply section 210, etc. of FIG. 10(A) are not shown. In FIG. 1, it is assumed that a satellite (opposing satellite) 20 that opposes one satellite (own satellite) 10 is also equipped with a laser ranging device (inter-satellite ranging device) 100.

In FIG. 1, the pointing unit 109 has a two-axis movable mechanism (pointing mirror drive mechanism) for directing the laser optical axis to the LOS (Line Of Sight) angle of the opposing satellite 20. The pointing mirror drive mechanism corresponds to the pointing drive unit 204 in FIG. 10(A). The angle control of the transmission beam in the mirror drive mechanism is performed by the data processing/control unit 104.

The data processing/control unit 104 controls the angle of the pointing unit 109 by providing predicted orbit information of the opposing satellite 20 in advance.

The data processing/control unit 104 detects LOS angle information of the oncoming satellite 20 from the measurement results of the photodetector 106 and controls the pointing unit 109 .

The laser unit 102 generates short pulse laser light on the picosecond order in synchronization with the trigger signal from the timing/angle measurement unit 103, and outputs a transmission pulse to the opposing satellite 20 via the transmission optical unit 107 and pointing unit 109. .

The receiving optical unit 108 focuses the laser light transmitted from the opposing satellite 20 onto the array sensor surface (not shown) of the photodetector 106.

The photodetector 106 is configured by combining an array sensor (a photon counting sensor that is a multi-pixel Geiger mode APD) and a readout integrated circuit (ROIC) (not shown). For example, it consists of a two-dimensional array of 128×128 elements.

As a non-limiting example of the combination of the array sensor and the ROIC, a configuration may be employed in which the ROIC cell array 70 is provided directly below the APD cell array 60, as schematically illustrated in FIG. In the example of FIG. 2A, an APD cell 61 constituting a sensing element of an array sensor is mounted on a substrate 62 (for example, a silicon substrate), and is connected to the back surface of the substrate 62 via a via hole (not shown) or the like, and is connected to a bump 64, etc. It is connected to the ROIC cell 71 immediately below. The ROIC cells 71 formed on the substrate 63 are arranged in an array corresponding to the arrangement of the APD cells 61 to form a ROIC cell array 70. Note that in FIG. 2(A), an 8×8 cell array is shown for simplicity.

FIG. 2(B) is a diagram showing an example of the configuration of the ROIC cell 71 in FIG. 2(A). The ROIC cell 71 includes a current-voltage converter (OP amplifier) 72 that converts the current output from the APD cell 61 into a voltage, and a voltage comparison between the voltage output from the current-voltage converter (OP amplifier) 72 and a threshold voltage Vth. and a comparator 73 that outputs the comparison result as a digital signal, and a time-digital signal that inputs the comparison result of the comparator 73 and measures the time until the voltage output from the current-voltage converter 72 exceeds the threshold voltage Vth. It includes a converter (Time to Digital Converter: TDC) 74 and an output circuit 75 that outputs the time (digital value) measured by the TDC 74. The TDC 74 is composed of, for example, a counter, and counts the number of clocks (CLK) until the voltage output from the current-voltage converter (OP amplifier) 72 exceeds the threshold voltage Vth. The output circuit 75 may encode the output of the TDC 74 and output it.

Individual reception timings of light (photons) input to each APD cell 61 of the APD cell array 60 are output from the ROIC cell 71. The photodetector 106 transmits 128×128 distance measurement data from each element of the array sensor to the timing/angle measurement unit 103 at a laser repetition frequency (for example, 1 kHz).

Further, in the photodetector 106, when the APD cell 61 receives a part of the transmission laser pulse light emitted from the laser section 102 via the half mirror 105, the ROIC cell 71 detects the transmission timing of the transmission laser pulse. and transmits it to the timing/angle measuring section 103.

FIG. 3 is a diagram illustrating an example of the functional configuration of the timing/angle measuring section 103. Referring to FIG. 3, the timing/angle measurement unit 103:
(A) An inter-satellite distance calculation function 103A that calculates the distance between satellites from the transmission timing of the transmission laser pulse and the reception timing of the laser beam transmitted from the opposing satellite 20;
(B) LOS angle detection function 103B that detects the LOS angle;
(C) a transmission timing control (communication data superimposition) function 103C that controls (modulates) the transmission timing of the transmission laser pulse in the laser unit 102 and superimposes communication data;
(D) a noise removal function 103D that performs temporal and spatial gate processing on the data received by the array sensor of the photodetector 106 to remove noise data;
(E) It includes a time information adding function 103E that adds a time tag to all data received by the array sensor of the photodetector 106 and transmits the data to the data processing/control unit 104.

The reference clock 101 outputs a highly stable frequency standard clock signal, a 1PPS (Pulse Per Second) timing signal serving as an epoch timing (a specific time), and a 1PPS time.

FIG. 4 is a diagram illustrating an example of the functional configuration of the data processing/control unit 104. Referring to FIG. 4, the data processing/control unit 104:
(a) a communication function 104A that transmits and receives control information (power control, command telemetry, satellite orbit information, satellite attitude information, etc.) with the satellite bus system 30;
(b) a control function 104B for the attitude and orbit of the own satellite 10;
(c) LOS angle control function 104C of the pointing unit 109 based on orbit information of the oncoming satellite 20;
(d) a communication data generation function 104D to be superimposed on the transmitted laser pulse;
(e) a decoding function 104E that decodes communication data from the reception timing of the laser beam transmitted from the opposing satellite 20 and received by the photodetector 106;
(f) Compare the ranging data of the opposing satellite 20 sent from the opposing satellite 20 and the ranging data of the own satellite 10, and calculate the ranging data with the clock error between the own satellite 10 and the opposing satellite 20 canceled. It has a distance measurement data calculation function 104F that performs calculations, and the like.

Next, the temporal and spatial gate processing performed by the timing and angle measurement unit 103 in this embodiment will be explained.

FIG. 5 is a schematic diagram for explaining temporal gate (range gate) processing, and FIG. 6 is a schematic diagram for explaining spatial gate (spatial gate) processing. A range gate is generally installed in a device (radar or lidar) that detects the timing of a laser pulse.

The timing/angle measurement unit 103 enables appropriate removal of noise data based on range gate processing and spatial gate processing.

In FIGS. 5A to 5C, the horizontal axis represents time, and the dashed box represents the range gate 40. In the two-dimensional plane of FIG. 6, the area surrounded by the broken line represents the space gate 50.

In FIG. 5(A), the reception timing of 1 circled with a circle is the reception timing (see FIG. 8) that corresponds to the laser transmission timing (transmission timing T1 of satellite S1, which will be explained with reference to FIG. 8). This corresponds to the reception timing T1') of the satellite S1, which will be explained in the following. In the example of FIG. 5(A), the received signal at the timing within the range gate 40 corresponds to the signal (photon) received at the pixel indicated by 1 surrounded by a circle in FIG.

In FIG. 5(B), there is no received signal within the range gate 40. In other words, the noise data 2 circled in FIG. 6 (the signal from the sensing element at the bottom left of one line of the received signal 1 circled in FIG. 6) is the noise data 2 circled in FIG. 5(B). It is not included in the range gate 40 corresponding to the reception timing. Therefore, the timing/angle measurement unit 103 can determine that the data is noise data.

Similarly, in FIG. 5C, dark count noise data exists within the range gate 40, but no received signal exists. Further, in FIG. 6, the space gate 50 does not include dark counts (3 circled). Therefore, the timing/angle measurement unit 103 can determine that the data is noise data.

The examples shown in FIGS. 5 and 6 are merely theoretical explanations for ease of understanding, and in actual cases, there is also noise data included in both the range gate and the space gate.

In the examples shown in FIGS. 5 and 6, it can be expected that the detected noise data and the original received signal have characteristics in their frequency of occurrence. The timing/angle measuring unit 103 can also identify noise data due to cooperation with the oncoming satellite 20 in FIG. 1 by utilizing the difference in frequency of occurrence.

Furthermore, the timing/angle measurement unit 103 performs pattern matching of the reception timing by programming in advance the modulation pattern of the transmission timing of the laser pulse transmitted from the opposing satellite 20, thereby identifying the reception signal and noise data. You can also do it.

Regarding the spatial gate 50 performed by the timing/angle measurement unit 103, the received signal is determined by spatial pattern matching by comparing the LOS angle control of the pointing unit 109 and the pixel position of the laser signal received by the photodetector 106. identification is possible.

Next, with reference to FIG. 7, the transmission timing control (communication data superimposition) function 103C of the timing/angle measuring section 103 will be described.

As described above, the timing/angle measurement unit 103 of the own satellite 10 controls the timing of laser transmission to the opposing satellite 20. On the opposing satellite 20 side, communication is performed by identifying the reception timing of the laser transmitted from the laser ranging device (inter-satellite ranging device) 100 of the satellite 10 .

In the example of FIG. 7, with a resolution of 10 nsec (nanosecond) (1 data period = 10 nsec) and a time modulation range of 656 μsec (microsecond), 65536 pieces of data (D1-D65536) can be identified. 65,536 (=2 ¹⁶ ) data identifications correspond to a 16-bit data amount.

Depending on where in the data D1-D65536 the ranging signal is placed, 16 bits of information can be transmitted. That is, it is possible to transmit 16 bits of data with one laser ranging signal. If this is operated at a laser repetition frequency of 1kHz (pulse repetition time of 1ms), a communication rate of 16Kbps (Kilo bits per second) can be obtained. Note that a time resolution of 10 nsec corresponds to a measuring distance of approximately 3×10 ⁸ (m)×10×10 ⁻⁹ =3 m. This can be sufficiently identified by a general laser ranging device having a ranging accuracy on the order of mm (millimeter). By increasing the distance measurement accuracy, further improvements in communication rates can be expected. The data superimposition example illustrated in FIG. 7 is just an example, and it is also possible to employ other optical communication systems using pulsed lasers.

FIG. 8A is a schematic diagram for explaining unidirectional distance measurement performed by the distance measurement data calculation function 104F of the timing/angle measurement unit 103. Note that the satellite S1 is the satellite 10 equipped with the inter-satellite ranging device 100 in FIG. 1, and the satellite S2 is the opposite satellite 20 in FIG. ). With reference to FIG. 8, cancellation of the time error in inter-satellite distance measurement in the distance measurement data calculation function 104F of the timing/angle measurement unit 103 will be described.

One-way distance measurement is performed as shown in FIGS. 8(A) and (B).
Time T1 when the laser beam was transmitted from satellite S1,
Time T1' when satellite S1 receives the laser beam from satellite S2,
Time T2 when the laser beam was transmitted by satellite S2,
Time T2' when satellite S2 receives the laser beam from satellite S1
It can be estimated from

Time T1 and time T1' are detected by the photodetector 106 of the inter-satellite ranging device 100 of satellite S1, and time T2 and time T2' are detected by the photodetector 106' of the inter-satellite ranging device 100 of satellite S2. Detected.

If L1 and L2 are unidirectional distance measurements measured by satellites S1 and S2, respectively, and c is the speed of light, then
L1 = (T1' - T1)×c … (1)
L2 = (T2' - T2)×c … (2)

Let 1/2 of the sum of unidirectional ranging L1 and L2 be the inter-satellite distance L.
L = (L1 + L2)/2 … (3)
T1' = T2 + L/c … (4)
T2' = T1 + L/c … (5)

Here, as shown in FIG. 8(B), it is assumed that a time error of δt is included between the reference clocks 101 of each of the satellites S1 and S2. Therefore, even if the satellite S1 and the satellite S2 transmit lasers at the same time according to the reference clock 101, there is a time difference of δt.

T2 = T1 + δt… (6)

Although FIG. 8B shows an example where δt>0, the same calculation method holds true even when δt<0.

By comparing the ranging data acquired by satellite S1 and satellite S2, the time error δt can be canceled from the inter-satellite distance L.

L1 = (T1' - T1)×c
= (T2 + L/c - T1)×c
= (T1 + δt + L/c - T1)×c
= L + δt×c … (7)

L2 = (T2' - T2)×c
= (T1 + L/c - T2)×c
= (T2 - δt + L/c - T2)×c
= L -δt×c … (8)

In the above formula (3), the addition result of the above formulas (7) and (8)
L1＋L2=L+δt×c + L -δt×c =2L … (9)
The time error δt between the satellites S1 and S2 is canceled.

FIG. 9 is a diagram illustrating an embodiment of the present invention, in which the functions (processing) of the timing/angle measurement section 103 and the data processing/control section 104 shown in FIG. 1 are implemented in the computer device 400. FIG. Referring to FIG. 9, the computer device 400 includes a processor 401, a semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. (or an HDD (Hard Drive)). A memory 402 (which may be a disk drive, etc.) and an interface 403 (bus interface) are provided. The processor 401 implements the functions of the timing/angle measuring section 103 and the data processing/control section 104 by executing a program stored in the memory 402.

Some effects of this embodiment will be described below.

The device configuration is simplified by using a single array sensor as a distance measurement sensor and a pointing sensor.

By installing a Geiger mode APD array sensor as a photodetector, it can be used as a sensor for detecting laser reception timing and beam pointing of an oncoming satellite. Furthermore, by making it possible to measure distances using a received signal of a few photons, even with a transmitting beam spread of about 1 mrad, it can be received at a distance of approximately 50,000 km. Beams can be sent to and received from oncoming satellites without the need for feedback to the pointing machine.

Noise data removal processing using temporal and spatial gate processing improves the performance of distinguishing between received light and noise.

By coordinating range gates and space gates based on information on predicted trajectories and transmission timing, more accurate noise removal is possible. It is also possible to improve the identification performance by pattern matching using coordination with the opposing satellite and synchronization with the LOS angle control of the pointing unit.

Miniaturization can be achieved by adopting data transmission and reception by modulating the ranging signal.

By modulating the transmission timing of the ranging pulsed laser, it is possible to transmit own satellite information such as transmission time data to the opposing satellite.

Furthermore, it is possible to realize an inter-satellite ranging device specialized for miniaturization and equipped with laser ranging and communication functions.

In the above embodiment, a description has been given of measuring the distance between artificial satellites, but the present invention is not limited to measuring the distance between artificial satellites, but can also be used, for example, to measure the distance between planets. Furthermore, it can be used to measure distances between the ground and satellites, and between moving objects and moving objects (or fixed stations).

The disclosures of Patent Documents 1 and 2 mentioned above are incorporated into this document by reference. Within the framework of the entire disclosure of the present invention (including the claims), changes and adjustments to the embodiments and examples can be made based on the basic technical idea thereof. Further, various combinations and selections of various disclosed elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) are possible within the scope of the claims of the present invention. . That is, it goes without saying that the present invention includes the entire disclosure including the claims and various modifications and modifications that a person skilled in the art would be able to make in accordance with the technical idea.

10 Satellite (own satellite)
20 Opposing satellite 30 Satellite bus system 40 Range gate 50 Space gate 60 APD cell array 61 APD cell 62 Substrate 63 Substrate 64 Bump 70 ROIC cell array 71 ROIC cell 72 Current-voltage converter 73 Comparator 74 Time-to-digital converter (TDC)
75 Output circuit 100 Inter-satellite ranging device 101, 101' Reference clock 102, 102' Laser section 103 Timing/angle measurement section 103A Inter-satellite distance calculation function 103B LOS angle detection function 103C Transmission timing (communication data superimposition) function 103D Noise removal Function 103E Time information assignment function 104 Data processing/control unit 104A Communication function 104B Attitude/orbit control function 104C LOS angle control function 104D Communication data generation function 104E Decoding function 104F Distance data calculation function 105 Half mirror 106, 106' Light detection device 107 transmitting optical section 108 receiving optical section 109 pointing section 201 laser section 202 transmitting optical system 203 pointing section 204 pointing drive section 205 light receiving section 206 discriminator 207 event timer 208 control section 209 interface 210 power supply section 301 first beam splitter 302 First condensing lens 303 Pointing sensor for coarse adjustment 304 Second beam splitter 305 Second condensing lens 306 Pointing sensor for fine adjustment 307 Third condensing lens 308 Light receiving element for distance measurement 400 Computer device 401 Processor 402 Memory 403 Interface

Claims (10)

A laser ranging device that measures the distance between a target device that transmits and receives a laser and the own device,
a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitted laser toward the target device based on the laser received from the target device;
a photodetector including an array sensor in which a plurality of sensing elements are arranged in an array;
Equipped with
The array sensor of the photodetector performs signal detection for distance measurement and pointing detection in one,
moreover,
decoding means for decoding communication data from the reception timing of the laser transmitted from the target device and received by the photodetector;
comprising means for calculating first ranging data between the self-device and the target device based on the transmission timing of the transmission laser and the reception timing of the laser received from the target device ;
The decoding means obtains second ranging data between the target device and the own device measured by the target device, which is included in the received laser from the target device detected by the photodetector. , calculating the distance between the own device and the target device with the time difference between the target device and the own device canceled by calculation of the first distance measurement data and the second distance measurement data; A laser ranging device equipped with means . Within one cycle corresponding to a predetermined laser repetition frequency, 2 N sections (N is a predetermined positive integer) with a predetermined time resolution are provided, and where in the 2 N sections is the distance measurement performed? Transmission of N bits of information is performed depending on the arrangement of signals, and means for realizing a communication rate determined by the product of the laser repetition frequency and the N bits,
The laser ranging device according to claim 1, wherein the decoding means decodes the communication data by detecting where the ranging signal is arranged in the 2 N sections included in the receiving laser. Device. 3. The laser ranging device according to claim 1, further comprising means for applying a temporal gate and a spatial gate to the signal detected by the array sensor to remove noise data. A laser ranging device that measures the distance between a target device that transmits and receives a laser and the own device,
a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitted laser toward the target device based on the laser received from the target device;
a photodetector including an array sensor in which a plurality of sensing elements are arranged in an array;
Equipped with
The array sensor of the photodetector performs signal detection for distance measurement and pointing detection in one,
Means for modulating the transmission timing of the transmission laser pulse in the laser unit and superimposing communication data on the ranging transmission laser pulse,
Within one cycle corresponding to a predetermined laser repetition frequency, 2 N sections (N is a predetermined positive integer) with a predetermined time resolution are provided, and where in the 2 N sections is the distance measurement performed? means for transmitting N bits of information depending on how signals are arranged, and realizing a communication rate determined by the product of the laser repetition frequency and the N bits by operating at the laser repetition frequency ;
A laser ranging device comprising means for calculating first ranging data between the own device and the target device based on the transmission timing of the transmitting laser and the reception timing of the laser received from the target device. . 5. The laser ranging device according to claim 4, further comprising decoding means for decoding communication data from the reception timing of the laser beam transmitted from the target device and received by the photodetector. The decoding means obtains second ranging data between the target device and the own device measured by the target device, which is included in the received laser from the target device detected by the photodetector. ,
By calculating the first distance measurement data and the second distance measurement data, a distance between the own device and the target device is calculated by canceling a clock error between the own device and the target device. The laser ranging device according to claim 5, further comprising means. 7. The array sensor comprises an APD cell array including APD (Avalanche Photo Diode) cells as the sensing elements , and includes a time measurement circuit for measuring the time when laser is received by each APD cell. The laser ranging device described in . the self-device is a satellite;
The laser ranging device according to any one of claims 1 to 7, wherein the target device is an opposing satellite facing the satellite and equipped with the laser ranging device. a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitting laser toward the target device based on the laser received from the target device that transmits and receives the laser;
a photodetector including an array sensor in which a plurality of elements are arranged in an array;
A laser distance measuring method for measuring a distance between a self-device including a laser distance measuring device and the target device, the method comprising:
(a) The array sensor of the photodetector performs signal detection for ranging and pointing detection with one;
(b) calculating first ranging data between the self-device and the target device based on the transmission timing of the transmission laser and the reception timing of the laser received from the target device;
(c) applying a temporal gate and a spatial gate to the signal detected by the array sensor to remove noise data;
(d) time-modulating the transmission timing of the transmission laser pulse in the laser unit and superimposing communication data on the ranging transmission laser pulse;
( e ) decoding communication data from the reception timing of the laser transmitted from the target device and received by the photodetector, and measuring it with the target device included in the received laser from the target device detected by the photodetector; obtaining second distance measurement data between the target device and the own device;
( f ) By calculating the first distance measurement data and the second distance measurement data, calculate the distance between the own device and the target device with the time difference between the target device and the own device canceled. to calculate,
A laser ranging method that performs A laser ranging device that measures the distance between a target device that transmits and receives laser beams,
a laser section that outputs a transmitting laser;
a pointing unit that directs the emission direction of the transmitted laser toward the target device based on the laser received from the target device;
a photodetector including an array sensor in which a plurality of elements are arranged in an array;
a computer constituting its own device, which is equipped with a laser ranging device that detects signals for distance measurement and pointing detection in one array sensor of the photodetector;
(a) a process of calculating first ranging data between the self-device and the target device based on the transmission timing of the transmission laser and the reception timing of the laser received from the target device;
(b) processing of applying a temporal gate and a spatial gate to the signal detected by the array sensor to remove noise data;
(c) a process of time modulating the transmission timing of the transmission laser pulse in the laser unit and superimposing communication data on the ranging transmission laser pulse;
( d ) Decode communication data from the reception timing of the laser transmitted from the target device and received by the photodetector, and measure it with the target device included in the received laser from the target device detected by the photodetector. a process of acquiring second distance measurement data between the target device and the own device;
( e ) By calculating the first ranging data and the second ranging data, the distance between the own device and the target device is calculated by canceling the time difference between the target device and the own device. Process to calculate,
A program to run.

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