JP5278103B2 - Information transmission system, distortion compensation method and distortion compensation control program used in the system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information transmission system in which influences of rotor modulation are suppressed when transmitting transmission data from a shooting helicopter through a relaying helicopter to a ground station. <P>SOLUTION: Pilot symbols ps<SB>1</SB>, ..., ps<SB>M</SB>of reception data ra are extracted by PS extraction sections 42<SB>1</SB>, ..., 42<SB>M</SB>in a distortion compensation means (e.g., data radio unit 28). Channel estimation data cp<SB>1</SB>, ..., cp<SB>M</SB>are acquired in channel estimation sections 43<SB>1</SB>, ..., 43<SB>M</SB>. Non-distorted channel estimation data nd and distorted channel estimation data yd are output by a selective combination unit 44. In a fading compensation unit 45, fading compensation is performed using the non-distorted estimation data nd, and reception data fa are acquired. In a rotor distortion estimation unit 46, a distortion component di of rotor modulation is estimated on the basis of the distorted channel estimation data yd. In a rotor modulation compensation unit 47, compensated reception data ma are acquired. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an information transmission system, a distortion compensation method and a distortion compensation control program used in the system, and in particular, for relaying transmission data such as video information from a shooting helicopter via a directional antenna. The present invention relates to an information transmission system suitable for use in transmission to a helicopter (rotary wing aircraft) and further transmission from the relay helicopter to a ground station or the like in real time, a distortion compensation method used in the system, and a distortion compensation control program.

  In the event of a disaster such as a sudden earthquake or fire, as a first response by a private news agency or government agency, the site is photographed by a camera installed in a helicopter (photographing helicopter), and the captured video information is quickly real-time Is transmitted to the ground station. When transmitting images to a ground station using a single helicopter, the coverage area of the imaging helicopter is in the range of a few tens of kilometers from the ground fixed station. It is necessary to deploy ground mobile stations such as cars in the coverage area. In addition, in the event of a disaster such as a sudden earthquake, emergency response is required, so it is not possible to spend time deploying relay vehicles, and it is also assumed that relay vehicles cannot be used due to road collapses. The For this reason, an apparatus may be used in which video information transmitted from the transmission unit of the imaging helicopter is relayed by another helicopter (relay helicopter) and transmitted to the ground receiving station. In this type of device, since the direction control of the antenna is performed by performing arithmetic processing based on the own device information and the counterpart device information, the coordinates and altitude information of each other are used using UHF (Ultra High Frequency) band carriers. Bidirectional wireless communication is performed.

  In this case, since the directivity control between the two helicopters is performed by coordinate tracking based on the calculation result of the calculation process, data transmission for transmitting the own machine information and the partner machine information is important. However, many data errors are detected even though the reception electric field of the UHF band carrier that performs this data transmission is high. The cause of this data error is considered to be the influence of fading distortion on the propagation path of the carrier. On the other hand, if the received electric field of the carrier is subjected to frequency analysis by FFT (Fast Fourier Transform), the rotor period of the helicopter Since the same frequency component is detected, another possible cause is rotor modulation due to the carrier wave being blocked by the rotor blades.

As a countermeasure against this rotor modulation, there is a method of transmitting data avoiding the rotor cycle on the transmission side. However, in transmission between helicopters, rotor modulation with different timing occurs in the helicopter on the reception side. Even if it copes, the effect is not enough.
In addition, there is a method of transmitting the same information multiple times and selecting information that was not affected by rotor modulation, but the information to be transmitted is information with a high update rate including the position of the helicopter, the attitude of the aircraft, etc. Since sending the latest information while sending the same information a plurality of times is advantageous for the directional control, the effect is not sufficient.

As this type of related technology, for example, there is an OFDM communication apparatus described in Patent Document 1.
In this OFDM (Orthogonal Frequency Division Multiplexing) communication apparatus, the transmission unit includes a quality determination information adding unit that adds quality determination information to information to be transmitted. The receiving unit includes a transmission channel estimation unit, a transmission channel compensation unit, an error correction unit, an error detection unit, and a re-encoding unit. The transmission path compensation unit compensates transmission path distortion of the received signal using the transmission path estimation value. The error correction unit performs error correction processing on the signal whose transmission path distortion is compensated. The error detection unit performs error detection on the error-corrected signal based on the quality determination information, and outputs an error detection signal indicating the presence or absence of an error. The re-encoding unit performs re-encoding processing on the error-corrected signal. The transmission path estimator obtains a transmission path estimation value based on the pilot symbol, performs transmission path estimation based on the re-encoded signal, and only when the error detection signal indicates that there is no error. The channel estimation value based on the re-encoded signal corresponding to is output instead of the one based on the pilot symbol.

  Further, in the receiver described in Patent Document 2, pilot symbols and data symbols are extracted from a received signal input through a filter by a despreading unit. The channel estimation unit performs channel estimation using a pilot symbol having a block length corresponding to the fading period measured by the fading period measurement unit. The queuing memory makes the data symbols wait for the time required for channel estimation, and the reverse rotation unit reversely rotates the data by the amount corresponding to the reverse rotation vector of the pilot symbol, and the decoding result is obtained and synthesized by the signal synthesis circuit.

JP 2004-072251 A JP 2004-140561 A

However, the related technology has the following problems.
That is, in the OFDM communication apparatus described in Patent Document 1, it is possible to prevent deterioration of reception characteristics, but it does not correspond to a system that transmits transmission data from a shooting helicopter to a ground station via a relay helicopter. The above problems are not improved.

  In the receiver described in Patent Document 2, the reception performance is improved, but it does not correspond to data transmission between the imaging helicopter and the relay helicopter, and the above-described problems are not improved.

  The present invention has been made in view of the above circumstances, and an information transmission system in which the influence of rotor modulation is suppressed when transmission data is transmitted from a shooting helicopter to a ground station via a relay helicopter, and the system It is an object of the present invention to provide a distortion compensation method and a distortion compensation control program used in the above.

  In order to solve the above-described problems, a first configuration of the present invention includes an information transmission device that is mounted on a first rotary wing machine and that transmits transmission data via a first directional antenna, and a second rotation A relay transmitter mounted on a wing machine, receiving the transmission data transmitted from the information transmitter via a second directional antenna, and relaying the data to another receiver station; The transmission device generates first state information indicating a flight state of the first rotary wing aircraft, transmits the first state information to the second rotary wing aircraft via the first transmission path, and transmits the second rotary wing aircraft. Second state information representing a flight state of the second rotary wing aircraft is acquired from the aircraft, and adaptively based on the first state information and the second state information, the first directional antenna A first antenna control means for controlling directivity, wherein the relay transmission device includes the second antenna The state information is generated and transmitted to the first rotary wing machine via the second transmission path, and the first state information is acquired from the first rotary wing machine, and the second state information and According to an information transmission system having second antenna control means for adaptively controlling directivity characteristics of the second directional antenna based on first state information, the first antenna control means includes The first pilot symbol for distortion detection is inserted into one state information, and the second antenna control means is configured to insert a second pilot symbol for distortion detection into the second state information. And the first antenna control means analyzes the second pilot symbol inserted in the second state information, and based on the analysis result, the distortion of the second transmission path is analyzed. First distortion compensation means for compensating is provided. The second antenna control means analyzes the first pilot symbol inserted in the first state information, and compensates for distortion of the first transmission path based on the analysis result. A second distortion compensation means is provided.

  According to a second configuration of the present invention, the information transmission device is mounted on the first rotary wing aircraft and transmits the transmission data via the first directional antenna. The information transmission device is mounted on the second rotary wing aircraft. A relay transmitting device that receives the transmission data transmitted from the transmitting device via a second directional antenna and relays the data to another receiving station; and the information transmitting device includes: First state information representing a flight state of the rotary wing aircraft is generated and transmitted to the second rotary wing aircraft via a first transmission path, and the second rotary wing aircraft from the second rotary wing aircraft. First state information is acquired for acquiring second state information representing a flight state of the aircraft, and adaptively controls directivity characteristics of the first directional antenna based on the first state information and the second state information. An antenna control means, wherein the relay transmitting device generates the second state information to generate a second transmission signal. Transmitting to the first rotorcraft via the road, acquiring the first state information from the first rotorcraft, and adapting based on the second state information and the first state information In particular, according to a distortion compensation method used in an information transmission system having second antenna control means for controlling directivity characteristics of the second directional antenna, the first antenna control means includes the first state information. A first pilot symbol for distortion detection is inserted, and the second antenna control means inserts a second pilot symbol for distortion detection into the second state information, and the first antenna The control means analyzes the second pilot symbol inserted in the second state information, and performs a first distortion compensation process for compensating for the distortion of the second transmission path based on the analysis result. And the second antenna control hand Performs a second distortion compensation process for analyzing the first pilot symbol inserted in the first state information and compensating for the distortion of the first transmission path based on the analysis result. It is characterized by.

  According to the configuration of the present invention, data errors caused by distortion due to rotor modulation by the first rotary wing machine and the second rotary wing machine are reduced, and the first rotary wing machine and the second rotary wing machine are It is possible to stably perform antenna directivity control between the two.

It is a figure which shows an example of the environment where the information transmission system which is one Embodiment of this invention is used. It is a block diagram which shows the electric constitution of the principal part of the information transmitter mounted in the imaging device 1 in FIG. It is a block diagram which shows the electric constitution of the principal part of the transmission apparatus for relay mounted in the repeater 2 in FIG. It is a schematic diagram which shows the pilot symbol inserted in the imaging | photography machine data sa by the data radio | wireless part 17 in FIG. It is a block diagram which shows the electrical constitution of the principal part of the data radio | wireless part 28 in FIG. It is a figure which shows the timing of the rotor modulation | alteration by the imaging device 1 and the relay machine 2. FIG.

  The first transmission path is configured using a first carrier wave in a predetermined frequency band, and the second transmission path is configured using a second carrier wave in a predetermined frequency band, and the information transmitting apparatus Transmits the first status information to the relay transmission device via the first transmission path and receives the second status information from the relay transmission device via the second transmission path. And the relay transmission device receives the first state information from the information transmission device via the first transmission path, and the second state information. An information transmission system having a second omnidirectional antenna for transmitting to the information transmitting apparatus via the second transmission path.

  In a preferred form of the invention, the first antenna control means is configured to insert a predetermined number of the first pilot symbols for each frame of the first state information, and the second distortion. The compensating means performs fading compensation of the first transmission path based on the first pilot symbols inserted for each frame of the first state information, and then performs the first rotorcraft and The rotor modulation distortion is estimated by performing the rotor modulation distortion estimation by the second rotorcraft, and the second antenna control means has a predetermined number of frames for each frame of the second state information. The second pilot symbol is inserted, and the first distortion compensation means is configured to insert each second pilot symbol inserted for each frame of the second state information. After performing fading compensation of the second transmission path based on Bol, the rotor modulation distortion is compensated by estimating the rotor modulation distortion by the second rotary wing machine and the first rotary wing machine. It is configured.

  Further, the first antenna control means is set for each frame of the first state information based on the rotor rotation period of the first rotorcraft and the transmission speed of the first state information. The first pilot symbol is inserted, and the second antenna control means includes a rotor rotation period of the second rotorcraft and a second second state information frame for each frame of the second state information. A number of the second pilot symbols set based on the transmission rate of the state information is inserted.

  Further, the second distortion compensation means includes a plurality of first pilot symbol extraction units that extract the first pilot symbols inserted for each frame of the first state information; First channel estimation data representing an estimated value of a transfer function of a channel corresponding to each frame of the first transmission path is obtained based on each first pilot symbol extracted by the pilot symbol extraction unit Among the plurality of first channel estimation units and each of the first channel estimation data acquired by each of the first channel estimation units, to obtain an addition average value of the first channel estimation data having substantially the same value First selective combination that outputs first channel estimation data having different values and outputs the first distortion estimation channel estimation data as first distortion-free channel estimation data. And fading compensation is performed on the first state information using the first undistorted channel estimation data to obtain received data for each rotor rotation period of the first rotorcraft. A fading compensation unit, and a first rotor distortion estimation unit that estimates a distortion component of rotor modulation by the first rotary blade machine and the second rotary blade machine based on the first strained channel estimation data By removing the distortion component estimated by the first rotor distortion estimation unit from the reception data for each rotor rotation period of the first rotorcraft acquired by the first fading compensation unit, A first rotor modulation compensator for acquiring first compensated received data subjected to rotor modulation compensation, wherein the first distortion compensation means includes the second state information. Based on a plurality of second pilot symbol extraction units that extract the second pilot symbols inserted for each frame, and the second pilot symbols extracted by the second pilot symbol extraction units. A plurality of second channel estimation units for acquiring second channel estimation data representing (estimated value of transfer function) of a channel corresponding to each frame of the second transmission path; Among the second channel estimation data acquired by the channel estimation unit, an addition average value of second channel estimation data having substantially the same value is obtained and output as second undistorted channel estimation data, while different values are obtained. A second selection / synthesis unit that extracts the second channel estimation data and outputs the second channel estimation data as second distorted channel estimation data; and Based on the second distorted channel estimation data, a second fading compensation unit that performs fading compensation using the channel estimation data and obtains reception data for each rotor rotation period of the second rotorcraft, The second rotor blade obtained by the second rotor blade estimator, the second rotor strain estimator for estimating the distortion component of the rotor modulation by the first rotor blade, and the second fading compensator The second compensated received data subjected to the rotor modulation compensation is obtained by removing the distortion component estimated by the second rotor distortion estimating unit from the received data for each rotor rotation period of the machine. 2 rotor modulation compensators.

Embodiment

FIG. 1 is a diagram showing an example of an environment in which an information transmission system according to an embodiment of the present invention is used.
In the environment of this example, as shown in the figure, a photographing machine (photographing helicopter) 1, a repeater (relay helicopter) 2, and a ground station 3 are provided. The photographing machine 1 is equipped with an information transmission device (not shown) that constitutes an information transmission system. The information transmission device transmits, for example, video captured by the camera 1 and collected sound as transmission data by a wireless signal wd through a directional antenna (not shown). Further, the relay device 2 is equipped with a relay transmission device (not shown) that constitutes an information transmission system. The relay transmission device receives a radio signal wd of transmission data transmitted from the information transmission device via a directional antenna (not shown), and relays the radio signal yd to the ground station 3 in real time.

  In addition, the information transmission device of the camera 1 and the relay transmission device of the relay device 2 are also provided with an antenna for data transmission. Aircraft data sc including photographing machine data sa and relay machine data sb is transmitted to the ground station 3 from the relay transmission device of the relay machine 2. The photographing machine data sa is obtained from the current position information (airframe coordinates) of the photographing machine 1, the body posture, the body height, the heading, the separation distance from the repeater 2, and the flight motion prediction value by a predetermined flight motion prediction calculation program. It is configured. The relay machine data sb is based on the current position information (airframe coordinates) of the relay machine 2, the body posture, the body height, the heading, the separation distance from the camera 1, the reception level of the transmission data, and the flight motion prediction calculation program It consists of flight motion prediction values.

FIG. 2 is a block diagram showing an electrical configuration of a main part of the information transmitting apparatus mounted on the photographing machine 1 in FIG.
As shown in FIG. 2, the information transmission device 10 includes a camera device 11, a transmission unit 12, an antenna 13, an airframe information acquisition unit 14, a GPS (Global Positioning System) 15, The antenna 16 includes a data radio unit 17, a calculation unit 18, and a drive unit 19. The camera device 11 outputs video data vd corresponding to the shot video. The transmission unit 12 performs encoding, modulation, up-conversion to a predetermined frequency band and amplification processing on the video data vd output from the camera device 11 to generate an RF signal, and the RF signal is transmitted as transmission data. In addition to outputting to the antenna 13 as sd, the output level na of the transmission data sd is output to the computing unit 18.

The antenna 13 is formed of a directional antenna such as a parabolic antenna, and transmits the transmission data sd as a radio signal wd with the direction directed to the repeater 2 under the control of the drive unit 19.
The airframe information acquisition unit 14 acquires the airframe posture (roll, pitch, yaw), airframe altitude, and heading of the photographing machine 1 and outputs them as airframe information ma. The GPS 15 acquires the current position information of the photographing machine 1 and outputs the body coordinates ga. The antenna 16 is formed of an omnidirectional antenna.
The data radio unit 17 uses the imaging device data pa output from the calculation unit 18 as the imaging device data sa (first state information) from the aerial line 16 and a carrier wave in a predetermined frequency band (for example, UHF band, Ultra High Frequency). Is transmitted to the repeater 2 through the transmission line (first transmission line) configured by the same as the first transmission line (second transmission line) and the antenna 16 from the repeater 2. Then, relay data sb (second state information) is received and demodulated, and input to the arithmetic unit 18 as relay data pb.

  In particular, in this embodiment, the data radio unit 17 inserts a predetermined number of first pilot symbols for distortion detection for each frame of the camera data sa (first state information), while the repeater data sb ( First distortion compensation means (not shown) for analyzing the second pilot symbol inserted in the second state information) and compensating for distortion of the second transmission path based on the analysis result is provided. Yes. The first distortion compensation means performs fading compensation of the second transmission path based on each second pilot symbol inserted for each frame of the relay data sb (second state information). Then, the rotor modulation distortion is compensated by estimating the rotor modulation distortion by the repeater 2 and the photographing machine 1.

  Based on the relay data sb received by the data wireless unit 17, the calculation unit 18 calculates the separation distance of the photographing device 1 from the relay 2 and the reception level of the transmission data sd (that is, the wireless signal wd), And, the aircraft information ma and the aircraft coordinates ga are inputted, and adaptively based on the current position information (aircraft coordinates), the aircraft attitude, the aircraft altitude, the heading, the separation distance, the reception level, and the flight motion prediction value The half-value angle da (directivity) of the antenna 13 is calculated, and a control signal ca is output to the transmission unit 12 to control the modulation method of the transmission data sd and the output level of the transmission data sd. The drive unit 19 outputs a control signal ea based on the half-value angle da calculated by the calculation unit 18 to control the half-value angle of the antenna 13. In addition, when the drive unit 19 controls the half angle of the antenna 13 to be widened, the calculation unit 18 determines the output level na of the transmission data sd and the relay unit data sb received by the data radio unit 17. Based on this, when a decrease in the reception level of the radio signal wd by the relay transmission device mounted on the relay device 2 is predicted, the transmission unit 12 adaptively modulates the transmission data sd modulation method and the transmission data. Controls the output level of sd.

FIG. 3 is a block diagram showing an electrical configuration of a main part of the relay transmission device mounted on the relay device 2 in FIG.
As shown in FIG. 3, the relay transmitter 20 includes an antenna 21, a receiver 22, a transmitter 23, an antenna 24, an aircraft information acquisition unit 25, a GPS 26, an antenna 27, and a data radio. The unit 28, the calculation unit 29, and the drive unit 30 are configured. The antenna 21 is formed of a directional antenna such as a parabolic antenna, similarly to the antenna 13, receives a radio signal wd with the direction directed to the camera 1 under the control of the drive unit 30, and receives an RF signal via a low noise amplifier (not shown). Output as received data rd.

  The reception unit 22 down-converts the reception data rd to baseband and outputs the reception data td, and outputs the reception level nb of the reception data rd to the calculation unit 29. The transmission unit 23 performs modulation, up-conversion and amplification processing on the reception data td, and outputs transmission data ud using a carrier wave having a frequency different from that of the transmission data sd of the transmission unit 12 of the information transmission apparatus 10. To do. The antenna 24 is composed of an omnidirectional antenna, and transmits the transmission data ud to the ground station 3 as a radio signal yd. The airframe information acquisition unit 25 acquires the airframe posture (roll, pitch, yaw), airframe altitude, and heading of the relay machine 2 and outputs the acquired airframe information mb. The GPS 26 acquires the current position information of the repeater 2 and outputs the machine coordinate gb. The antenna 27 is composed of an omnidirectional antenna.

  The data radio unit 28 is configured with the relay unit data qa output from the calculation unit 29 as a relay unit data sb (second state information) from the antenna 27 and a carrier wave in a predetermined frequency band (for example, UHF band). Is transmitted to the camera 1 through the existing transmission path (second transmission path), and the camera data sa is received from the camera 1 through the first transmission path and the antenna 27 and demodulated. It inputs to the calculating part 29 as qb. In particular, in this embodiment, the data radio unit 28 inserts a predetermined number of second pilot symbols for distortion detection for each frame of the repeater data sb (second state information), while the radio equipment data sa ( Second distortion compensation means (not shown) for analyzing the first pilot symbol inserted in the first state information) and compensating for distortion of the first transmission path based on the analysis result is provided. Yes. The second distortion compensation means performs fading compensation of the first transmission path based on each first pilot symbol inserted for each frame of the camera data sa (first state information). The rotor modulation distortion is compensated by estimating the rotor modulation distortion by the photographing machine 1 and the repeater 2. Further, the aerial line 27 transmits the body data sc including the photographing machine data sa and the relay machine data sb to the ground station 3.

  The calculation unit 29 calculates the separation distance of the relay device 2 from the camera 1 based on the camera data sa received by the data wireless unit 28 and transmits the transmission data sd based on the reception level nb of the reception data rd. (Radio signal wd) reception level is calculated, and adaptively based on current position information (airframe coordinates), airframe attitude, airframe altitude, heading, separation distance, reception level, and flight motion prediction value The half-value angle db of the antenna 21 is calculated, and the control signal cb is output to the receiving unit 22 to control the demodulation method of the reception data td. The drive unit 30 controls the half-value angle of the antenna 21 by outputting a control signal eb based on the half-value angle db calculated by the calculation unit 29.

FIG. 4 is a schematic diagram showing pilot symbols inserted into the camera data sa by the data radio section 17 in FIG.
As shown in FIG. 4, this pilot symbol (first pilot symbol) is a rotor of the camera 1 for each frame of the camera data sa (first state information) composed of N data signals. Np pieces set based on the rotation period and the transmission speed of the same camera data sa are inserted. Similarly, the pilot symbol (second pilot symbol) inserted into the repeater data sb (second state information) by the data radio unit 28 in FIG. 3 is also composed of N data signals. Np pieces set based on the rotor rotation period of the repeater 2 and the transmission speed of the repeater data sb are inserted for each frame of the repeater data sb.

FIG. 5 is a block diagram showing the electrical configuration of the main part of the data radio section 28 in FIG. 3, and particularly shows the configuration of the second distortion compensation means.
As shown in FIG. 5, the second distortion compensation means includes an LPF (low-pass filter) 41, PS (pilot symbol) extraction units 42 ₁ , 42 ₂ ,..., 42 _M−1 , 42 _M , a channel From the estimation units 43 ₁ , 43 ₂ ,..., 43 _M−1 , 43 _M , the selection synthesis unit 44, the fading compensation unit 45, the rotor distortion estimation unit 46, the rotor modulation compensation unit 47, and the demodulation unit 48 It is configured. The LPF 41 outputs received data ra in a band necessary for distortion compensation means from the camera data sa input via the antenna 27. PS extractor _{42 1, 42 2, ...,} 42 M-1, 42 M , the received data pilot symbols each first being inserted in each frame of _{ra ps 1, ps 2, ...} , ps M-1, ps _M is extracted.

Channel estimation units 43 ₁ , 43 ₂ ,..., 43 _M−1 , 43 _M are pilot symbols ps ₁ , ps ₂ , ps ₂ , 42 _M−1 , 42 _M extracted by PS extraction units 42 ₁ , 42 ₂ ,. .., Ps _M−1 , ps _M , channel estimation data cp ₁ , cp ₂ ,... Representing channel transfer function estimation values corresponding to each frame of the received data ra on the first transmission path. cp _M-1 and cp _M are acquired. In this case, channel estimation units 43 ₁ , 43 ₂ ,..., 43 _M−1 , 43 _M extract Np · M pilot symbols Np · M from the M frames, and pilots of the same number in each frame. Channel estimation is performed for each symbol, and Np sequences are acquired for (Np + N) · M channel estimation data. In this estimation method, for example, quadratic interpolation in the time domain, zero-sequence insertion in the frequency domain, or the like is used.

Here, basically, the Np sequence channel estimation data has substantially the same value. However, the data sequence estimated using the pilot symbols affected by the rotor modulation is a data sequence different from the estimated sequence not affected by the rotor modulation. Since a plurality of data sequences having substantially the same component are not affected by the rotor modulation of the pilot symbols, the selection combining unit 44 performs addition averaging of the estimated sequences. Selection combining unit 44, a channel estimator _{43 1, 43 2, ...,} 43 M-1, 43 channel estimation data cp ₁ obtained by _M, cp _2, ..., of the cp _M-1, cp _M, approximately An addition average value of channel estimation data having the same value is obtained and output as undistorted channel estimation data nd, while channel estimation data having different values is extracted and output as distorted channel estimation data yd. The fading compensation unit 45 performs fading compensation on the reception data ra using the undistorted channel estimation data nd, and obtains reception data fa for each rotor rotation period of the photographing apparatus 1.

  The rotor distortion estimation unit 46 estimates a distortion component di of rotor modulation by the photographing machine 1 and the repeater 2 based on the distorted channel estimation data yd. The rotor modulation compensator 47 removes the distortion component di estimated by the rotor distortion estimator 46 from the received data fa for each rotor rotation period of the photographing apparatus 1 acquired by the fading compensator 45, thereby performing rotor modulation compensation. The compensated received data ma subjected to the above is acquired. The demodulator 48 demodulates the compensated received data ma and outputs the camera data qb. The second distortion compensation means is controlled by a CPU (Central Processing Unit) as a computer (not shown), and the CPU operates based on a computer-readable distortion compensation control program. Further, the first distortion compensation means provided in the data radio unit 17 is configured in the same manner as the second distortion compensation means, and is similar to the second distortion compensation means for the input repeater data sb. Processing is performed and relay machine data pb is output.

FIG. 6 is a diagram illustrating the timing of rotor modulation by the photographing machine 1 and the relay machine 2.
With reference to this figure, the processing content of the distortion compensation method used for the information transmission system of this form is demonstrated.
In this information transmission system, the data radio unit 17 inserts a first pilot symbol for distortion detection into the camera data sa, and the data radio unit 28 adds a second distortion detection to the repeater data sb. Pilot symbols are inserted. Then, the data radio section 17 analyzes the second pilot symbol inserted in the relay station data sb, and compensates for distortion of the second transmission path based on the analysis result (first distortion compensation). Processing), and the data radio unit 28 analyzes the first pilot symbol inserted into the camera data sa, and compensates for distortion of the first transmission path based on the analysis result (second). Distortion compensation processing).

  In this case, the first and second transmission lines are affected by fading and affected by the rotor modulation by the photographing device 1 and the repeater 2, and as shown in FIG. 2 is different in the timing of rotor modulation. For this reason, the data radio unit 17 inserts Np first pilot symbols set based on the rotor rotation period of the photographing machine 1 and the transmission speed of the photographing machine data sa for each frame of the photographing machine data sa. After the fading compensation of the first transmission path is performed by the data radio unit 28 based on each first pilot symbol inserted for each frame of the camera data sa, the camera 1 and the relay 2 Thus, the rotor modulation distortion is compensated by the estimation of the rotor modulation distortion. Further, the data radio unit 28 inserts Np second pilot symbols set based on the rotor rotation period of the repeater 2 and the transmission speed of the repeater data sb for each frame of the repeater data sb. After the fading compensation of the second transmission path is performed by the data radio unit 17 based on each second pilot symbol inserted for each frame of the repeater data sb, the repeater 2 and the photographing device 1 The rotor modulation distortion is compensated by performing the rotor modulation distortion estimation.

That is, in the data radio unit 28, the camera data sa input via the antenna 27 is input to the LPF 41, and the reception data ra is output from the LPF 41. The received data ra is input to the PS extraction units 42 ₁ , 42 ₂ ,..., 42 _M−1 , 42 _M, and the first pilot symbols ps ₁ , ps ₂ ,. , Ps _M-1 and ps _M are extracted (first pilot symbol extraction processing). Channel estimation unit _{43 1, 43 2, ...,} 43 M-1, 43 in _M, the pilot symbols ps ₁ extracted, ps _2, ..., based on the ps _M-1, ps _M, the first transmission line Channel estimation data cp ₁ , cp ₂ ,..., Cp _M−1 , cp _M representing channel transfer function estimation values corresponding to each frame of the received data ra are acquired (first channel estimation processing). One of the channel estimation data cp ₁ , cp ₂ ,..., Cp _M−1 , cp _M is output by the selection / combination unit 44 as the undistorted channel estimation data nd. , Channel estimation data having different values are extracted and output as distorted channel estimation data yd (first selective combining process).

  The fading compensation unit 45 performs fading compensation on the reception data ra using the undistorted channel estimation data nd, and obtains reception data fa for each rotor rotation period of the photographing machine 1 (first fading compensation). processing). On the other hand, the rotor distortion estimation unit 46 estimates the distortion component di of the rotor modulation by the photographing device 1 and the repeater 2 based on the distorted channel estimation data yd (first rotor distortion estimation process). In the rotor modulation compensation unit 47, the compensated reception data ma is obtained by removing the distortion component di estimated by the rotor distortion estimation unit 46 from the reception data fa obtained by the fading compensation unit 45 (first). Rotor modulation compensation process). The compensated received data ma is demodulated by the demodulator 48 and output as the camera data qb. Further, the data radio unit 17 performs the same processes as the data radio unit 28 on the input repeater data sb, that is, the second pilot symbol extraction process, the second channel estimation process, and the second selection. The synthesizing process, the second fading compensation process, the second rotor distortion estimation process, and the second rotor modulation compensation process are performed, and the repeater data pb is output.

  As described above, in this embodiment, the data radio unit 17 performs the first distortion compensation process and the data radio unit 28 performs the second distortion compensation process. Data errors caused by distortion due to rotor modulation are reduced, and antenna directivity control between the photographing apparatus 1 and the repeater 2 is stably performed. In addition, since the rotor modulation distortion is estimated after fading compensation of the first and second transmission paths, the rotor modulation distortion is compensated with high accuracy.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiment, and even if there is a design change without departing from the gist of the present invention, Included in the invention.
For example, Np first pilot symbols inserted for each frame of the camera data sa (first state information), and Np second pilot symbols inserted for each frame of the relay device data sb, May be the same or different. Further, the carrier waves constituting the first and second transmission paths are not limited to the UHF band. Further, the data input to the transmission unit 12 is not limited to the video data vd of the camera device 11 and may be arbitrary data such as audio data. In FIG. 1, the ground station 3 is provided as another receiving station, but a mobile receiving station mounted on an automobile or a ship may be used. In addition, GPS is used as position information acquisition means. For example, when “Galileo” planned in Europe and “Quasi-Zenith Satellite” planned in Japan are put into practical use, these are used. May be.

  The present invention can be generally applied to a case where video transmission or the like is performed in real time between two helicopters using a directional antenna.

1 Shooting machine (shooting helicopter) (first rotorcraft)
2 Repeater (relay helicopter) (second rotorcraft)
3 Ground stations (other receiving stations)
13 antenna (first directional antenna)
16 aerial (first omnidirectional aerial)
17 Data radio section (part of first antenna control means, first distortion compensation means)
21 Aerial (second directional antenna)
27 Aerial (second omnidirectional aerial)
28 Data radio unit (part of second antenna control means, second distortion compensation means)
_{42 1, 42 2, ...,} 42 M-1, 42 M PS ( pilot symbol) extracting unit _{43 1, 43 2, ...,} 43 M-1, 43 M channel estimation unit 44 selector and synthesizer 45 fading compensation unit 46 rotor Distortion estimation unit 47 Rotor modulation compensation unit

Claims (11)

An information transmission device mounted on the first rotorcraft for transmitting data for transmission via the first directional antenna;
A relay transmitter mounted on a second rotorcraft for receiving the transmission data transmitted from the information transmitter via a second directional antenna and relaying the data to another receiver station; Prepared,
The information transmitting device includes:
First state information representing a flight state of the first rotary wing aircraft is generated and transmitted to the second rotary wing aircraft via a first transmission path, and the second rotary wing aircraft transmits the first state information. The second state information representing the flight state of the second rotorcraft is acquired, and the directivity characteristics of the first directional antenna are adaptively controlled based on the first state information and the second state information. First antenna control means to
The relay transmission device includes:
The second state information is generated and transmitted to the first rotary wing machine via a second transmission path, and the first state information is acquired from the first rotary wing machine, and the second An information transmission system having second antenna control means for adaptively controlling the directivity characteristic of the second directional antenna based on the state information and the first state information,
The first antenna control means includes:
The first state information is configured to insert a first pilot symbol for distortion detection,
The second antenna control means includes
A second pilot symbol for distortion detection is inserted into the second state information; and
The first antenna control means includes:
First distortion compensation means for analyzing the second pilot symbol inserted in the second state information and compensating for distortion of the second transmission path based on the analysis result is provided,
The second antenna control means includes
Second distortion compensation means for analyzing the first pilot symbol inserted in the first state information and compensating for distortion of the first transmission path based on the analysis result is provided. An information transmission system characterized by that. The first transmission line is
Configured with a first carrier wave of a predetermined frequency band,
The second transmission line is
It is configured using a second carrier wave of a predetermined frequency band,
The information transmitting device includes:
The first status information is transmitted to the relay transmission device via the first transmission path, and the second status information is received from the relay transmission device via the second transmission path. Having a first omnidirectional antenna
The relay transmission device includes:
A second state for receiving the first state information from the information transmission device via the first transmission path and transmitting the second state information to the information transmission device via the second transmission line; The information transmission system according to claim 1, further comprising an omnidirectional antenna. The first antenna control means includes:
A predetermined number of the first pilot symbols are inserted for each frame of the first state information;
The second distortion compensation means includes:
After fading compensation of the first transmission path based on the first pilot symbols inserted for each frame of the first state information, the first rotorcraft and the second By estimating the rotor modulation distortion by the rotorcraft, it is configured to compensate for the rotor modulation distortion,
The second antenna control means includes
A predetermined number of the second pilot symbols are inserted for each frame of the second state information;
The first distortion compensation means includes:
After fading compensation of the second transmission path based on the second pilot symbols inserted for each frame of the second state information, the second rotor blade and the first 3. The information transmission system according to claim 1, wherein the rotor modulation distortion is compensated by estimating the rotor modulation distortion by the rotorcraft. The first antenna control means includes:
A configuration in which the number of the first pilot symbols set based on the rotor rotation period of the first rotorcraft and the transmission speed of the first state information is inserted for each frame of the first state information And
The second antenna control means includes
A configuration in which the number of the second pilot symbols set based on the rotor rotation period of the second rotorcraft and the transmission speed of the second state information is inserted for each frame of the second state information The information transmission system according to claim 1, 2, or 3, wherein The second distortion compensation means includes:
A plurality of first pilot symbol extraction units for extracting each of the first pilot symbols inserted for each frame of the first state information;
A first channel representing an estimated value of a transfer function of a channel corresponding to each frame of the first transmission path based on each first pilot symbol extracted by each first pilot symbol extraction unit; A plurality of first channel estimation units for obtaining estimation data;
Among the first channel estimation data acquired by the first channel estimation units, an addition average value of first channel estimation data having substantially the same value is obtained and output as first undistorted channel estimation data On the other hand, a first selective combining unit that extracts first channel estimation data having different values and outputs the first channel estimation data as first distorted channel estimation data;
First fading compensation for performing fading compensation on the first state information using the first undistorted channel estimation data to obtain reception data for each rotor rotation period of the first rotorcraft And
A first rotor distortion estimation unit that estimates a distortion component of rotor modulation by the first rotorcraft and the second rotorcraft based on the first strained channel estimation data;
By removing the distortion component estimated by the first rotor distortion estimation unit from the received data for each rotor rotation period of the first rotorcraft acquired by the first fading compensation unit, the rotor A first rotor modulation compensator for acquiring first compensated received data subjected to modulation compensation;
The first distortion compensation means includes:
A plurality of second pilot symbol extraction units for extracting each second pilot symbol inserted for each frame of the second state information;
Based on each second pilot symbol extracted by each second pilot symbol extraction section, a second (representation value of transfer function) of a channel corresponding to each frame of the second transmission path A plurality of second channel estimation units for acquiring channel estimation data of
Among the second channel estimation data acquired by the second channel estimation units, an addition average value of the second channel estimation data having substantially the same value is obtained and output as second undistorted channel estimation data On the other hand, a second selective combining unit that extracts second channel estimation data having different values and outputs the second channel estimation data as second distorted channel estimation data;
Second fading compensation for performing fading compensation on the second state information using the second undistorted channel estimation data to obtain reception data for each rotor rotation period of the second rotorcraft And
Based on the second strained channel estimation data, a second rotor distortion estimation unit that estimates a distortion component of rotor modulation by the second rotorcraft and the first rotorcraft;
By removing the distortion component estimated by the second rotor distortion estimation unit from the received data for each rotor rotation period of the second rotorcraft acquired by the second fading compensation unit, the rotor 5. The information transmission system according to claim 4, further comprising a second rotor modulation compensator that acquires second compensated received data subjected to modulation compensation. An information transmission device mounted on the first rotorcraft for transmitting data for transmission via the first directional antenna;
A relay transmitter mounted on a second rotorcraft for receiving the transmission data transmitted from the information transmitter via a second directional antenna and relaying the data to another receiver station; Prepared,
The information transmitting device includes:
First state information representing a flight state of the first rotary wing aircraft is generated and transmitted to the second rotary wing aircraft via a first transmission path, and the second rotary wing aircraft transmits the first state information. The second state information representing the flight state of the second rotorcraft is acquired, and the directivity characteristics of the first directional antenna are adaptively controlled based on the first state information and the second state information. First antenna control means to
The relay transmission device includes:
The second state information is generated and transmitted to the first rotary wing machine via a second transmission path, and the first state information is acquired from the first rotary wing machine, and the second A distortion compensation method used in an information transmission system having second antenna control means for adaptively controlling the directivity characteristics of the second directional antenna based on the state information and the first state information,
The first antenna control means inserts a first pilot symbol for distortion detection into the first state information;
The second antenna control means inserts a second pilot symbol for distortion detection into the second state information; and
The first antenna control means analyzes the second pilot symbol inserted in the second state information, and compensates distortion of the second transmission path based on the analysis result. Distortion compensation processing,
The second antenna control means analyzes the first pilot symbol inserted in the first state information, and compensates distortion of the first transmission path based on the analysis result. A distortion compensation method characterized by performing a distortion compensation process. The first transmission line is
Configured with a first carrier wave of a predetermined frequency band,
The second transmission line is
It is configured using a second carrier wave of a predetermined frequency band,
The information transmitting device includes:
The first status information is transmitted to the relay transmission device via the first transmission path, and the second status information is received from the relay transmission device via the second transmission path. Having a first omnidirectional antenna
The relay transmission device includes:
A second state for receiving the first state information from the information transmission device via the first transmission path and transmitting the second state information to the information transmission device via the second transmission line; The distortion compensation method according to claim 6, further comprising: an omnidirectional antenna. The first antenna control means inserts a predetermined number of the first pilot symbols for each frame of the first state information;
After the second distortion compensation means performs fading compensation of the first transmission path based on the first pilot symbols inserted for each frame of the first state information, The rotor modulation distortion is estimated by performing the rotor modulation distortion estimation by the rotary blade machine and the second rotary blade machine,
The second antenna control means inserts a predetermined number of the second pilot symbols for each frame of the second state information;
After the first distortion compensation means performs fading compensation of the second transmission path based on the second pilot symbols inserted for each frame of the second state information, 8. The distortion compensation method according to claim 6, wherein the rotor modulation distortion is compensated by estimating the distortion of the rotor modulation by the first rotary blade aircraft and the first rotary blade aircraft. The number of the first antenna control means set for each frame of the first state information is set based on the rotor rotation period of the first rotorcraft and the transmission speed of the first state information. Insert a first pilot symbol;
The number of the second antenna control means set for each frame of the second state information is set based on the rotor rotation period of the second rotorcraft and the transmission speed of the second state information. 9. The distortion compensation method according to claim 6, 7 or 8, wherein a second pilot symbol is inserted. The second distortion compensation means comprises:
First pilot symbol extraction processing for extracting each first pilot symbol inserted for each frame of the first state information;
A first channel representing an estimated value of a transfer function of a channel corresponding to each frame of the first transmission path based on each first pilot symbol extracted in each first pilot symbol extraction process; A first channel estimation process for obtaining estimation data;
Among the first channel estimation data acquired in the first channel estimation processing, an addition average value of first channel estimation data having substantially the same value is obtained and output as first undistorted channel estimation data On the other hand, a first selective synthesis process for extracting first channel estimation data having different values and outputting the first channel estimation data as first distorted channel estimation data;
First fading compensation for performing fading compensation on the first state information using the first undistorted channel estimation data to obtain reception data for each rotor rotation period of the first rotorcraft Processing,
A first rotor distortion estimation process for estimating a distortion component of rotor modulation by the first rotorcraft and the second rotorcraft based on the first strained channel estimation data;
By removing the distortion component estimated in the first rotor distortion estimation process from the received data for each rotor rotation period of the first rotorcraft acquired in the first fading compensation process, the rotor Performing a first rotor modulation compensation process for obtaining first compensated received data subjected to modulation compensation;
The first distortion compensation means comprises:
A second pilot symbol extraction process for extracting each of the second pilot symbols inserted for each frame of the second state information;
A second channel representing an estimated value of a transfer function of a channel corresponding to each frame of the second transmission path based on each second pilot symbol extracted in each second pilot symbol extraction process; A second channel estimation process for obtaining estimation data;
Among the second channel estimation data acquired in the second channel estimation processing, an addition average value of second channel estimation data having substantially the same value is obtained and output as second undistorted channel estimation data On the other hand, a second selective combining process for extracting second channel estimation data having different values and outputting the second channel estimation data as second distorted channel estimation data;
Second fading compensation for performing fading compensation on the second state information using the second undistorted channel estimation data to obtain reception data for each rotor rotation period of the second rotorcraft Processing,
Based on the second strained channel estimation data, a second rotor distortion estimation process for estimating a distortion component of rotor modulation by the second rotorcraft and the first rotorcraft;
By removing the distortion component estimated in the second rotor distortion estimation process from the received data for each rotor rotation period of the second rotorcraft acquired in the second fading compensation process, the rotor The distortion compensation method according to claim 9, further comprising: performing a second rotor modulation compensation process for obtaining second compensated reception data subjected to modulation compensation.   A computer-readable distortion compensation control program for causing a computer to function as the first distortion compensation means and the second distortion compensation means according to any one of claims 1 to 5.

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