CN111903231B - Method suitable for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signal - Google Patents

Method suitable for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signal Download PDF

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CN111903231B
CN111903231B CN200810078557.1A CN200810078557A CN111903231B CN 111903231 B CN111903231 B CN 111903231B CN 200810078557 A CN200810078557 A CN 200810078557A CN 111903231 B CN111903231 B CN 111903231B
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remote control
signal
image
telemetering
data
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高保生
景志刚
袁旭猛
许瑞生
巩岩
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CETC 54 Research Institute
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CETC 54 Research Institute
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Abstract

The invention discloses a method suitable for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signals, and relates to a technology suitable for an unmanned reconnaissance aircraft measurement and control and information transmission system line-of-sight data link in the field of unmanned aerial vehicle measurement and control and information transmission. The invention designs a line-of-sight data link of a medium-high altitude remote unmanned reconnaissance aircraft measurement and control and information transmission system, realizes the real-time remote control of the flight state of an unmanned aerial vehicle and the working state of airborne equipment, the real-time remote measurement of the flight state of the unmanned aerial vehicle and the state of the airborne equipment, the tracking and positioning of the unmanned aerial vehicle in the line-of-sight, and the real-time transmission of reconnaissance image information of the unmanned aerial vehicle. The system also has the advantages of interference resistance, interception resistance, good multi-channel resistance, high integration level, simple and reliable equipment and the like. The method is particularly suitable for the transmission application of the line-of-sight data link signals in the measurement and control and information transmission system of the medium-high-altitude remote unmanned reconnaissance aircraft.

Description

Method suitable for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signal
Technical Field
The invention relates to a line-of-sight data link signal method suitable for unmanned reconnaissance aircraft measurement and control and information transmission in the field of unmanned aerial vehicle communication measurement and control, in particular to a line-of-sight data link suitable for a remote unmanned reconnaissance aircraft measurement and control and information transmission system.
Background
At present, the line-of-sight data link remote control, remote measurement, image transmission and distance measurement channels of the unmanned reconnaissance aircraft are all carried out by adopting single links, and the single link transmission causes a large number of receiving and transmitting channels, complex equipment and poor reliability. Meanwhile, the method is not suitable for the line-of-sight data link of the remote unmanned reconnaissance aircraft measurement and control and information transmission system.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method suitable for observing and controlling an unmanned reconnaissance aircraft and transmitting a line-of-sight data link signal by information. The airborne data link receives the uplink remote control signal sent by the ground data link, and after amplification, de-spread, demodulation and decryption, the remote control command is taken out and sent to the flight control computer. Meanwhile, the airborne data chain digitally compresses the reconnaissance information, then multiplexes the reconnaissance information with the telemetering data, and sends the reconnaissance information to the ground after coding, encrypting, modulating, up-converting and power amplifying; the ground data chain receives, demodulates and decodes the image telemetering signals, and transmits the image telemetering signals to the command control port through an optical cable or an electric cable. The ground and airborne data chain of the invention also realizes the tracking and positioning of the unmanned aerial vehicle by tracking and angle measurement and distance measurement of the downlink signal. The invention also has the characteristics of interference resistance, interception resistance, good multi-channel resistance, high integration level, simple and reliable equipment and the like.
The technical problem to be solved by the invention is realized by the following technical scheme, comprising the following steps:
ground signal transmission of line-of-sight data link
Firstly, receiving unmanned aerial vehicle image/telemetering radio-frequency signals input by a C-band transceiving antenna 1 by a full duplexer 3, transmitting the image/telemetering radio-frequency signals to a frequency converter 5 for frequency conversion and amplification, and inputting the image/telemetering radio-frequency signals after frequency conversion and amplification to an intermediate frequency amplifier 8 for down-conversion into image/telemetering intermediate-frequency signals;
secondly, inputting the image/telemetering intermediate-frequency signal into an image telemetering receiver 11 by an intermediate-frequency amplifier 8 for demodulation and then outputting the demodulated signal in two paths, wherein one path is sent to a tracking receiver 10, an error voltage is demodulated from the demodulated image/telemetering intermediate-frequency signal and sent to an antenna controller 7, and the antenna controller 7 sends the error voltage to a main remote control receiving and sending antenna 1 for tracking and positioning the unmanned aerial vehicle; the other path of the filtered baseband signals selects corresponding baseband signals with two code rates of 2048kbps and 256kbps, and the baseband signals with the two code rates are sent to the coding and coding ranging unit 14;
the coding and decoding ranging unit 14 performs synchronous extraction, viterbi decoding, decryption and ranging on the baseband signals of the two code rates, and sends the decrypted image/telemetering data stream to a command control port to complete the receiving and processing of the image/telemetering data; sending the decrypted image/telemetering data stream to the local control unit 15 for resolving and displaying the state of the airborne equipment;
fourthly, the coding and decoding ranging unit 14 receives the remote control data stream from the command control port, and divides the remote control data stream into two paths for output after synchronization, encryption, difference and spread spectrum of the remote control data stream are carried out; one path of the remote control signal is sent to a main remote control transmitter 12 to be subjected to intermediate frequency modulation to be a remote control intermediate frequency signal, the remote control intermediate frequency signal is sent to a frequency converter 5 to be subjected to frequency mixing to be a remote control radio frequency signal, the remote control radio frequency signal is sent to a C power amplifier 6 to be amplified, the amplified remote control radio frequency signal is input to a duplexer 3 to be isolated and output to a C-band receiving and transmitting antenna 1, the C-band receiving and transmitting antenna 1 transmits the remote control radio frequency signal to an unmanned aerial vehicle, and the unmanned; the other path is sent to a UFH band transmitter 13 to be subjected to FSK modulation to be modulated into a remote control radio frequency signal, the UFH band transmitter 13 sends the remote control radio frequency signal to a UHF power amplifier 9 to be amplified, the amplified remote control radio frequency signal is sent to a UHF band transmitting antenna 2, the UHF band transmitting antenna 2 transmits the remote control radio frequency signal to an unmanned aerial vehicle, and the unmanned aerial vehicle is remotely controlled;
the local oscillation signals of the uplink remote control signal and the downlink image remote measuring signal generated by the frequency synthesizer 4 are sent to the frequency converter 5, and the uplink remote control signal of the frequency converter 5 and the uplink remote control signal local oscillation signal generated by the frequency synthesizer 4 are mixed to form a remote control radio frequency signal; the downlink image telemetering signal of the frequency converter 5 and the local oscillator signal of the downlink image telemetering signal generated by the frequency synthesizer 4 are mixed into a down-conversion image telemetering signal;
sixthly, the control unit 15 adjusts and sets the state of the airborne equipment and observes the content of the sent remote control data; setting the ground equipment state for adjustment setting; receiving the telemetering data stream input by the coding and decoding ranging unit 14 for resolving, and displaying the state of the airborne equipment; receiving monitoring data sent by a command control port, resolving the data and displaying the state of the ground equipment;
airborne signal transmission of line-of-sight data link
The onboard duplexer 21 receives the main remote control radio frequency signal input by the C-band omnidirectional antenna 18, and sends the remote control radio frequency signal to the main remote control receiver 25 for frequency conversion, amplification, filtering and automatic gain control, and then outputs an intermediate frequency signal to the terminal processor 28; the terminal processor 28 performs despreading demodulation processing on the remote control intermediate frequency signal, demodulated remote control data is decrypted by the airborne encryption unit, framed and encoded again and then sent to the port of the flight control computer to control the unmanned aerial vehicle, and the terminal processor 28 also receives the remote control data of the satellite communication link port and sends the remote control data to the flight control computer to control the unmanned aerial vehicle;
the assistant remote control receiver 26 receives UHF remote control radio frequency signals sent by the UHF waveband omnidirectional antenna 19 from ground equipment, carries out filtering, low noise amplifier and mixing output difference frequency of 70MHz, and inputs the difference frequency to the intermediate frequency amplifier for amplification after being selected by the 70MHz intermediate frequency filter; after the 70MHz intermediate frequency signal is sent to a frequency modulation demodulator, the frequency is shifted to 10.7MHz by a mixer in the frequency modulation demodulator, the intermediate frequency signal is amplified by a multi-stage limiting amplifier and then subjected to frequency detection, and a remote control information code is demodulated and sent to a terminal processor 28 for decoding;
ninthly, the image/telemetering transmitter 23 receives the image/telemetering data stream and the code rate control signal of the terminal processor 28, performs amplitude modulation control on the image/telemetering data stream, sends the image/telemetering data stream to a tuning end of a voltage-controlled oscillator to generate 790MHz intermediate frequency modulation image/telemetering signal, and the modulated intermediate frequency image/telemetering signal and a local oscillator signal sent by the C-band frequency synthesizer 24 output image/telemetering radio-frequency signals of 4910MHz to 5000MHz through up-conversion of a mixer and send the image/telemetering radio-frequency signals to the C-band omnidirectional antenna 17 to be transmitted to a ground line-of-sight data chain;
and completing the observation and control of the unmanned reconnaissance aircraft and the information transmission line-of-sight data link signal.
The coding and decoding ranging unit 14 in the second step of the invention is composed of a synchronous decoding unit, a remote control coding unit and a tapping ranging unit; the synchronous decoding unit carries out synchronous extraction, Viterbi decoding and decryption on the image/telemetering data stream; the remote control coding unit codes a remote control instruction for the remote control data stream; the tapping and ranging unit taps and ranges the image/telemetering data stream, switches the code rate, acquires AGC voltage, processes GPS data, forwards the image data and outputs telemetering, image, distance and state data according to a specified format.
The terminal processor 28 in the seventh step of the present invention is composed of a synchronous control unit, a main despreading unit and a remote control demodulation unit; the synchronous control unit receives the image data of the image encoder 27 and the telemetering data of the flight control machine port, and performs remote control data processing, telemetering data encoding, image telemetering data multiplexing and data receiving, selecting and distributing to enable the uplink and downlink frames to synchronously complete ranging; the main despreading unit receives the intermediate frequency remote control signal sent by the main remote control receiver 25 in two stages of capturing and tracking for despreading, and the despread remote control signal is subjected to BPSK demodulation and decryption by the remote control demodulation unit to output main remote control data; the remote control demodulation unit receives the remote control information code sent by the auxiliary remote control receiver 26 for de-spreading and decryption, and the output auxiliary remote control data is sent to the port of the flight control machine by the synchronous control unit to control the flight of the unmanned aerial vehicle.
Compared with the background technology, the invention has the following advantages:
the invention uses the sharing of image transmission and distance measuring channel and remote control and remote measuring channel, so that the uplink and downlink only use one link, the equipment is simple and the reliability is high.
The uplink of the invention adopts the spread spectrum technology, and has good anti-interference, anti-interception and anti-multipath performances. The image transmission adopts a digital image compression technology, the image transmission quality is high, the uplink and downlink signals are comprehensively utilized for ranging, an additional channel is not needed, the integration level is high, and the equipment is simple and reliable.
Drawings
Fig. 1 is an electrical schematic block diagram of a terrestrial signaling embodiment of the line-of-sight data link of the present invention. In fig. 1: the system comprises a C-band transmitting and receiving antenna 1, a UHF-band transmitting antenna 2, a full duplexer 3, a frequency synthesizer 4, a frequency converter 5, a C power amplifier 6, an antenna controller 7, an intermediate frequency amplifier 8, a UHF power amplifier 9, a tracking receiver 10, an image/remote measuring receiver 11, a main remote control transmitter 12, a UHF-band transmitter 13, a coding and decoding ranging unit 14 and a local control unit 15.
Fig. 2 is an electrical schematic block diagram of an embodiment of the on-board signaling of the line-of-sight data link of the present invention. In fig. 2: 17 is a C-band omnidirectional antenna, 18 is a C-band omnidirectional antenna, 19 is a UHF-band omnidirectional antenna, 20 is a C-band filter, 21 is an airborne duplexer, 22 is a C-band power amplifier, 23 is an image telemetering transmitter, 24 is a C-band frequency synthesizer, 25 is a main remote control receiver, 26 is a secondary remote control receiver, 27 is an image encoder, and 28 is a terminal processor.
Fig. 3 is an electrical schematic operational flow diagram of an embodiment of the inventive diplexer 3.
Fig. 4 is a pattern diagram of a pattern of the C-band transmitting/receiving antenna 1 according to the embodiment of the present invention.
Fig. 5 is an electrical schematic operational flow diagram of an embodiment of the frequency converter 5 of the present invention.
Fig. 6 is an electrical schematic operational flow diagram of an embodiment of the intermediate frequency amplifier 8 of the present invention.
Fig. 7 is an electrical schematic operational flow diagram of an embodiment of the image/telemetry receiver 11 of the present invention.
Fig. 8 is an electrical schematic operational flow diagram of an embodiment of the tracking receiver 10 of the present invention.
FIG. 9 is an electrical schematic operational flow diagram of a remote control coding unit embodiment of the codec ranging unit 14 of the present invention.
FIG. 10 is an electrical schematic flowchart of an embodiment of a synchronous decoding unit of the codec ranging unit 14 of the present invention.
Fig. 11 is an electrical schematic operational flow diagram of an embodiment of the master remote control transmitter 12 of the present invention.
Figure 12 is an electrical schematic operational flow diagram of an embodiment of a UFH band transmitter 13 of the present invention.
Fig. 13 is an electrical schematic operational flow diagram of an embodiment of the frequency synthesizer 4 of the present invention.
Fig. 14 is an electrical schematic work flow diagram of an embodiment of the control unit 15 of the present invention.
Figure 15 is an electrical schematic operational flow diagram of an embodiment of the airborne duplexer 21 of the present invention.
Fig. 16 is an electrical schematic operational flow diagram illustrating the implementation of the master remote control receiver 25 of the present invention.
Fig. 17 is an electrical schematic operational flow diagram of a synchronization control unit cell embodiment of the terminal processor 28 of the present invention.
Fig. 18 is an electrical schematic operational flow diagram of an embodiment of the inventive image encoder 27.
Fig. 19 is an electrical schematic flow diagram of a main despreading unit embodiment of the terminal processor 28 of the present invention.
Fig. 20 is an electrical schematic flow diagram of a remote demodulation unit embodiment of terminal processor 28 of the present invention.
Fig. 21 is an electrical schematic operational flow diagram of an embodiment of the secondary remote control receiver 26 of the present invention.
Fig. 22 is a schematic structural diagram of an embodiment of the airborne UHF-band omnidirectional antenna 19 of the present invention.
Figure 23 is an electrical schematic operational flow diagram of an embodiment of the image/telemetry transmitter 23 of the present invention.
Fig. 24 is an electrical schematic workflow diagram of an embodiment of the C-band frequency synthesizer 24 of the present invention.
Figure 25 is a schematic diagram of the structure of an embodiment of the airborne C-band omni-directional antenna 17, 18 of the present invention.
Detailed Description
Referring to fig. 1-25, fig. 1 is an electrical schematic block diagram of a terrestrial signaling embodiment of the line-of-sight data link of the present invention, comprising: the system comprises a C-band transceiving antenna 1, a UHF-band transmitting antenna 2, a full duplexer 3, a frequency synthesizer 4, a frequency converter 5, a C power amplifier 6, an antenna controller 7, an intermediate frequency amplifier 8, a UHF power amplifier 9, a tracking receiver 10, an image/remote measuring receiver 11, a main remote control transmitter 12, a UHF-band transmitter 13, a coding and decoding ranging unit 14 and a local control unit 15. Embodiments connect the lines as in fig. 1.
FIG. 2 is an electrical schematic block diagram of an embodiment of the present invention for on-board signaling of a line-of-sight data link, comprising: the system comprises a C-band omnidirectional antenna 17, a C-band omnidirectional antenna 18, a UHF-band omnidirectional antenna 19, a C-band filter 20, an onboard duplexer 21, a C-band amplifier 22, an image telemetering transmitter 23, a C-band frequency synthesizer 24, a main remote control receiver 25, an auxiliary remote control receiver 26, an image encoder 27 and a terminal processor 28. Embodiments connect the lines as in fig. 2.
The invention comprises the following steps:
firstly, the full duplexer 3 receives the unmanned aerial vehicle image/telemetering radio-frequency signals input by the C-band transceiving antenna 1, the image/telemetering radio-frequency signals are sent to the frequency converter 5 for frequency conversion and amplification, and the image/telemetering radio-frequency signals after frequency conversion and amplification are input to the intermediate frequency amplifier 8 for frequency down-conversion into image/telemetering intermediate-frequency signals.
Embodiment the working flow of the inventive full duplexer 3 is as follows.
The full duplexer 3 is composed of a 0/pi modulator, an electronic switch, a duplex filter and a low-noise amplifier, and mainly completes the receiving and transmitting isolation of a duplex system; the sum-difference network consists of a sum-difference device, a single pulse modulator and the like and mainly completes tracking, sum-difference signal generation and modulation. The operation principle block diagram is shown in fig. 3, and fig. 3 is an electrical principle operation flow diagram of the duplexer 3 embodiment of the present invention. The uplink main remote control signal is firstly input into a transmitting filter of the duplexer, the middle common end of the full duplexer 3 is connected to the common end of the electronic switch, and the other port of the electronic switch is connected to the C-band transmitting-receiving antenna 1 and is transmitted out from the C-band transmitting-receiving antenna 1.
The receiving process of the downlink signal is as follows, the difference branch signal channel of the C-band receiving and transmitting antenna 1 firstly enters a 0/pi modulator to be modulated with a 1kHz signal, the modulated signal is coupled to a sum branch signal to be synthesized into a path of directional signal, the C-band receiving and transmitting antenna 1 is selected through an electronic switch, filtered through a receiving filter of a full duplexer 3 and then sent to a low noise amplifier for amplification, and finally the downlink signal is output.
The working principle of the C-band transceiving antenna 1 of the embodiment is as follows: in ground-to-air communications, antennas on the ground are required to produce beams that are sharp in the azimuth plane, but "cosecant-squared" in the elevation plane. The coverage of the azimuth plane is obtained by scanning and the beam shape in the elevation plane must provide coverage of the hollow target over a range of altitudes and elevation angles. As shown in fig. 4, fig. 4 is a pattern diagram of a pattern of the C-band transmitting/receiving antenna 1 according to the embodiment of the present invention, and shows a general shape of a desired coverage in a pitch plane. The C-band receiving and transmitting antenna 1 adopts a 1.8 m-caliber azimuth self-tracking and pitching surface residual-cutting shaped beam antenna, and comprises an antenna reflecting surface, a bracket, a feed source horn, a magic T, waveguide coaxial conversion, a feed source pull rod and the like.
The working process of the frequency converter 5 of the embodiment of the invention is as follows:
the up-converter of the frequency converter 5 works on the principle that the remote control signal of the L waveband enters the filter for filtering, then is mixed with the local oscillator, and then enters the filter for filtering, and then the remote control radio frequency signal is output. The down converter of the frequency converter 5 works in the principle that a downlink signal of a C wave band enters a frequency mixer after passing through an isolator, and is output after being filtered and amplified after down-converted and enters an intermediate frequency amplification unit. The operation schematic block diagram is shown in fig. 5, and fig. 5 is an electrical schematic operation flowchart of an embodiment of the frequency converter 5 of the present invention.
The working flow of the intermediate frequency amplifier 8 of the embodiment of the invention is as follows:
the intermediate frequency amplifier 8 filters the downlink image/telemetry radio frequency signal sent by the frequency converter 5 by a filter and sends the filtered downlink image/telemetry radio frequency signal to an intermediate frequency amplifier. The signal of 960MHz is AGC amplified by an AGC amplifying circuit consisting of an amplifier and an attenuator, wherein the gain of the AGC amplifying circuit is determined by the attenuation of the attenuator. And the first intermediate signal amplified by the AGC is sent to a mixer for frequency mixing, wherein a local oscillator signal of 1030MHz is generated by a phase-locked loop, a reference source of 10MHz is input from the outside, and a second intermediate signal of 70MHz is output after the frequency mixing and filtering by a filter. And the second intermediate signal is subjected to AGC amplification by an AGC amplification circuit consisting of an electronic switch, a filter and an AGC amplifier. The second-center signal amplified by the AGC is output to the image/telemetry receiver 11. The operation principle block diagram is shown in fig. 6, and fig. 6 is an electrical principle operation flow diagram of the embodiment of the intermediate frequency amplifier 8 of the present invention.
Secondly, inputting the image/telemetering intermediate-frequency signal into an image telemetering receiver 11 by an intermediate-frequency amplifier 8 for demodulation and then outputting the demodulated signal in two paths, wherein one path is sent to a tracking receiver 10, an error voltage is demodulated from the demodulated image/telemetering intermediate-frequency signal and sent to an antenna controller 7, and the antenna controller 7 sends the error voltage to a main remote control receiving and sending antenna 1 for tracking and positioning the unmanned aerial vehicle; the other path of the filtered baseband signal selects corresponding baseband signals with two code rates of 2048kbps and 256kbps, and the baseband signals with the two code rates are sent to the codec ranging unit 14. The coding and decoding ranging unit 14 of the invention is composed of a synchronous decoding unit, a remote control coding unit and a tapping ranging unit; the synchronous decoding unit carries out synchronous extraction, Viterbi decoding and decryption on the image/telemetering data stream; the remote control coding unit codes a remote control instruction for the remote control data stream; the tapping and ranging unit taps and ranges the image/telemetering data stream, switches the code rate, acquires AGC voltage, processes GPS data, forwards the image data and outputs telemetering, image, distance and state data according to a specified format.
The working flow of the image/telemetry receiver 11 of the present invention is as follows:
the image/telemetry receiver 11 receives the image/telemetry intermediate frequency signal from the intermediate frequency amplifier 8, and the image/telemetry intermediate frequency signal is sent to a one-to-two power divider through a filter. One path of the power divider is output to the image/telemetering demodulation branch, and the other path is output to the tracking receiver 10. The demodulator uses a modulation tracking loop, i.e. a phase locked loop to complete the demodulation. The demodulated signal is divided into two parts, baseband signals corresponding to two code rates of 2048kbps and 256kbps are selected by different video filters, and one part of the baseband signals is selected by an electronic switch and output to a coding and decoding ranging unit 14 for processing. A block diagram of the operational principle of the image/telemetry receiver 11 is shown in fig. 7. fig. 7 is an electrical schematic operational flow diagram of an embodiment of the image/telemetry receiver 11 of the present invention.
Embodiment the working flow of the tracking receiver 10 of the present invention is as follows:
the tracking receiver 10 receives the intermediate frequency signal sent by the image/telemetry receiver 11, demodulates an error voltage from the carrier signal carrying the target azimuth information and sends the error voltage to the antenna controller 7, so that the antenna is always automatically aligned to the target unmanned aerial vehicle, and the automatic tracking of the unmanned aerial vehicle is realized.
The azimuth self-tracking adopts a amplitude comparison pseudo single pulse tracking system. The pseudo monopulse is to modulate the difference signal in the sum-difference device at low frequency, so that the monopulse system is converted into a cone scanning system, i.e. the simultaneous lobe method is converted into a sequential lobe method. This system is called a hidden cone scanning system, also called pseudo-monopulse system.
The tracking receiver 10 is composed of six circuits, i.e., a local reference oscillation circuit, a pre-detection circuit, a reference demodulation filter circuit, a local reference filter circuit, an error voltage demodulation circuit, and an error voltage filtering amplification circuit, and its operation schematic block diagram is shown in fig. 8, and fig. 8 is an electrical schematic operation flowchart of the embodiment of the tracking receiver 10 according to the present invention.
The working flow of the antenna controller 7 of the embodiment of the present invention is as follows:
the antenna controller 7 is an important component of the self-tracking system, and functions to control the rotation of the antenna so that the antenna is automatically and accurately aimed at a target. The antenna control combination adopts a second-order non-static error loop and a coarse-fine combined multi-stage rotation transformation angle measurement and coding so as to ensure high-precision angle measurement. The antenna control combination is controlled by a command control station (GCS), and drives a ground directional antenna to track a target in the modes of automatic tracking, manual tracking, search scanning and the like, and simultaneously acquires an axial angle in real time and reports the axial angle information and a servo state to the GCS. The system mainly comprises a power drive unit, a shaft angle coding unit, a motor, a speed measuring element, an angle measuring element, an embedded industrial personal computer and the like.
The coding and decoding ranging unit 14 performs synchronous extraction, viterbi decoding, decryption and ranging on the baseband signals of the two code rates, and sends the decrypted image/telemetering data stream to a command control port to complete the receiving and processing of the image/telemetering data; and sending the decrypted image/telemetry data stream to the local control unit 15 for resolving and displaying the state of the airborne equipment.
The working flow of the codec ranging unit 14 according to the embodiment of the present invention is as follows:
the remote control encoding unit 14 mainly completes the functions of synchronization, encryption, differentiation, spread spectrum, and the like of the remote control command stream, and a working principle block diagram of the remote control encoding unit is shown in fig. 9, and fig. 9 is an electrical principle working flow diagram of an embodiment of the remote control encoding unit of the coding and decoding ranging unit 14 of the present invention.
The single chip processor in the control logic decodes the received monitoring information and outputs a control command to the coding encryption differential circuit, the circuit selects one path of remote control data flow and synchronizes the remote control data flow with a local clock, and the remote control data flow is encrypted by an M sequence and M sequence composite encryption network and is subjected to differential conversion to output two paths of signals which are respectively subjected to spread spectrum processing with bit code modulo two generated by the pseudo code generator 1 and the pseudo code generator 2. The pseudo code generator 1 generates an M sequence of code length 2048 bits at a rate of 13.1072Mcps, and the spread signal therefrom is sent to the master remote control transmitter 12. The pseudo code generator 2 generates an m-sequence of 127 bits in code length at a rate of 102.4kcps, and the spread signal is sent to the slave remote control transmitter 13.
In addition, a singlechip processor in the control logic outputs a control command to a relevant unit to complete a monitoring task according to the received monitoring information; the state acquisition circuit acquires various state information to the control logic to form monitoring information and outputs the monitoring information to the optical transceiver through the asynchronous serial port; the timing generator starts with a remote frame sync word and outputs a ranging pulse (positive pulse) every four words, the duration of the high level being one information bit width. Due to the influence of circuit processing time delay, when a system is tested in a joint way, the phase relation between the output ranging pulse and the remote control information frame is adjusted by matching with other circuits so as to adjust the ranging zero value, the ranging zero value is smaller than the width of one remote control information bit, and the formed ranging pulse is output to the tapping ranging unit.
The synchronous decoding unit of the codec ranging unit 14 mainly performs bit synchronization extraction, viterbi decoding, decryption, and the like, and performs an equipment monitoring function together with other extension units. Operational block diagram fig. 10 is a schematic diagram of an electrical schematic operation of an embodiment of a synchronous decoding unit of the codec ranging unit 14 of the present invention shown in fig. 10.
The image/telemetering data sent by the receiver firstly passes through a shaping circuit, and the shaped image/telemetering data is sent to a bit synchronization extraction loop. The frequency dividing ratio in the synchronous loop is controlled by the code rate control signal sent by the monitoring station. The image/telemetering data sent by the receiver is simultaneously sent to an A/D converter to obtain a 3-bit signal, the 3-bit signal is sent to a Viterbi decoder to be decoded to obtain an image/telemetering serial encrypted data stream, and clear data and a clock are output after decryption.
The codec ranging unit 14 is composed of an FPGA logic, a single chip microcomputer and an interface circuit, and mainly completes functions of tapping and ranging. In addition, the functions of switching code rate, collecting AGC voltage, processing GPS data, forwarding image data, outputting telemetering, image, distance and state data according to a specified format and the like are also completed.
The tapping unit comprises a frame synchronization extraction loop and a tapping circuit, wherein the frame synchronization extraction loop is used for extracting frame synchronization pulses in the serial data stream, and the tapping circuit separates image data and telemetering data from the image/telemetering data stream according to a time reference provided by the frame synchronization pulses.
The distance measuring unit comprises a switch pulse forming circuit, a distance measuring counter, a counting clock, a latch and a microprocessor, wherein a distance measuring pulse is output by the remote control encoder every 4 bytes and is used as a counter door opening counting signal, the remote measuring data provides related distance measuring pulses as door closing signals according to different code rates, and the number of the counting pulses after the door is closed is latched and sent to the microprocessor. The microprocessor finishes the zero calibration of the distance and the smooth filtering of the distance data, measures the distance for 16 times by one frame of remote control data, carries out the smooth filtering of the 16 times of data and outputs 12.5 times of distance data per second.
Fourthly, the coding and decoding ranging unit 14 receives the remote control data stream from the command control port, and divides the remote control data stream into two paths for output after synchronization, encryption, difference and spread spectrum of the remote control data stream are carried out; one path of the remote control signal is sent to a main remote control transmitter 12 to be subjected to intermediate frequency modulation to be a remote control intermediate frequency signal, the remote control intermediate frequency signal is sent to a frequency converter 5 to be subjected to frequency mixing to be a remote control radio frequency signal, the remote control radio frequency signal is sent to a C power amplifier 6 to be amplified, the amplified remote control radio frequency signal is input to a duplexer 3 to be isolated and output to a C-band receiving and transmitting antenna 1, the C-band receiving and transmitting antenna 1 transmits the remote control radio frequency signal to an unmanned aerial vehicle, and the unmanned; the other path is sent to a UFH band transmitter 13 to be subjected to FSK modulation to be modulated into remote control radio frequency signals, the UFH band transmitter 13 sends the remote control radio frequency signals to a UHF power amplifier 9 to be amplified, the amplified remote control radio frequency signals are sent to a UHF band transmitting antenna 2, the UHF band transmitting antenna 2 transmits the remote control radio frequency signals to the unmanned aerial vehicle, and the unmanned aerial vehicle is remotely controlled.
The working flow of the master remote control transmitter 12 of the present invention is as follows:
the master remote control transmitter 12 is used for L-band intermediate frequency modulation of line-of-sight data chain C-band link remote control signals. The main remote control transmitter 12 is composed of unit circuits such as a phase-locked unit, an oscillator (including a modulator), an attenuator, and a reference source. The main functions are as follows: the remote control spread spectrum code is utilized to carry out BPSK modulation on the L-band intermediate frequency carrier, and the output level can be controlled in large and small power, and the modulated intermediate frequency signal is output. The functional block diagram is shown in fig. 11, and fig. 11 is an electrical functional flowchart of an embodiment of the master remote control transmitter 12 of the present invention.
The main remote control transmitter 12 is designed in a modular manner, and the inside of the transmitter is divided into four modules, such as a reference source (corresponding to a reference source shunt in fig. 11), a phase locking unit (corresponding to a frequency divider, a phase discriminator and a low pass in fig. 11), an oscillator (corresponding to a voltage controlled oscillator, a BPSK modulator and an isolation amplifier in fig. 11), an attenuator and the like according to a printed board.
The reference source shunt circuit, the phase-locking unit and the oscillator form a phase-locked frequency source, and the function of the phase-locked frequency source is to generate a 1110MHz intermediate-frequency local oscillator signal to be provided to the BPSK modulator. The BPSK modulator completes the BPSK modulation function, namely, the shaped terminal remote control spread spectrum code is used for carrying out BPSK spread spectrum modulation on the local oscillation signal, and the local oscillation signal is sent to the attenuator after being isolated and amplified. The attenuator in the master remote control transmitter 12 performs the power control function of the master remote control transmitter 12.
The working flow of the UFH band transmitter 13 of the embodiment of the present invention is as follows:
the UFH band transmitter 13 uses a phase-locked loop direct FSK modulation scheme. The device comprises a carrier generating circuit consisting of a phase-locked loop unit and an oscillator, wherein the two parts also shape a modulation signal sent by the remote control coding unit, then modulate the modulation signal to a carrier to generate a radio frequency signal, and carry out filtering and amplification to generate enough level to drive a power amplifier. Fig. 12 is a block diagram of the operation principle of the UFH band transmitter 13 according to the present invention, and fig. 12 is a flowchart of the electrical principle operation of the UFH band transmitter 13 according to the present invention.
The local oscillation signals of the uplink remote control signal and the downlink image remote measuring signal generated by the frequency synthesizer 4 are sent to the frequency converter 5, and the uplink remote control signal of the frequency converter 5 and the uplink remote control signal local oscillation signal generated by the frequency synthesizer 4 are mixed to form a remote control radio frequency signal; the downlink image telemetering signal of the frequency converter 5 is mixed with the local oscillating signal of the downlink image telemetering signal generated by the frequency synthesizer 4 to form a down-conversion image telemetering signal.
The working flow of the frequency synthesizer 4 of the embodiment of the invention is as follows:
the frequency synthesizer 4 outputs local oscillation signals for transmitting uplink remote control signals and receiving downlink image remote measurement signals to finish signal frequency mixing. In addition, the frequency synthesizer 4 can complete the switching of the output frequency according to the received control command, thereby completing the function of switching the channel. The operation schematic block diagram is shown in fig. 13, and fig. 13 is an electrical schematic operation flowchart of the embodiment of the frequency synthesizer 4 of the present invention.
The synthesizer is a single loop digital phase locked loop. The output of the voltage-controlled oscillator in the loop is divided, one path is amplified and output, the other path enters a single-chip phase-locked loop through a divide-by-four frequency divider, a 2.5MHz signal is obtained in the single-chip phase-locked loop through a divide-by-N program frequency divider, phase comparison is carried out in a phase discriminator with the divide-by-four frequency of a standard reference signal of 10MHz, error voltage is generated according to the phase difference of the two signals, the frequency and the phase of the voltage-controlled oscillator are controlled, and when the loop is locked, the output frequency of the voltage-controlled oscillator is the required frequency. An uplink local oscillator is 3400 MHz-3490 MHz, and is stepped by 10 MHz; and the downlink local oscillator is 3950 MHz-4040 MHz, and the step is 10 MHz.
The single chip microcomputer receives frequency synthesis control data sent by the RS422 asynchronous serial port, decodes the received data to obtain frequency point control information, and outputs the frequency synthesis control data corresponding to the frequency point to complete frequency switching; and decoding to obtain power amplifier and antenna control signals to control the states of the power amplifier and the antenna. And meanwhile, the locking state, the antenna state and the power amplifier state of the frequency synthesizer are collected, and the state information is output through an RS422 asynchronous serial port. The initial state of the link controller is 1 frequency point.
Sixthly, the control unit 15 adjusts and sets the state of the airborne equipment and observes the content of the sent remote control data; setting the ground equipment state for adjustment setting; receiving the telemetering data stream input by the coding and decoding ranging unit 14 for resolving, and displaying the state of the airborne equipment; and receiving monitoring data sent by the command control port, resolving the data and displaying the state of the ground equipment.
The working flow of the control unit 15 of the embodiment of the invention is as follows:
the local control unit 15 performs control and monitoring on the ground equipment and the airborne equipment according to the method of the distance data link signal, and the working principle block diagram is shown in fig. 14, and fig. 14 is an electrical principle working flow chart of the embodiment of the local control unit 15 of the present invention.
The local control unit 15 turns to the onboard equipment state setting screen in the local control state, can adjust and set the onboard equipment state (such as switching channels) by using a keyboard, and can observe the transmitted remote control data content by synchronously turning to an asynchronous analog source; switching to a ground equipment monitoring setting screen, and adjusting and setting the ground equipment state (such as switching channels) by using a keyboard; completing the receiving of the telemetering data, resolving the telemetering data according to a corresponding telemetering data frame structure, and displaying the state of the airborne equipment; receiving monitoring data, resolving the data and displaying the state of the ground equipment; the internal control/external control state is set by operating the small key, the equipment state is controlled by the local control unit in the internal control mode, and the equipment state is controlled by a control command from the command control port in the external control mode.
Airborne signal transmission of line-of-sight data link
The onboard duplexer 21 receives the main remote control radio frequency signal input by the C-band omnidirectional antenna 18, and sends the remote control radio frequency signal to the main remote control receiver 25 for frequency conversion, amplification, filtering and automatic gain control, and then outputs an intermediate frequency signal to the terminal processor 28; the terminal processor 28 de-spreads and demodulates the remote control intermediate frequency signal, the demodulated remote control data is decrypted by the airborne encryption unit, re-framed and encoded and then sent to the port of the flight control computer to control the unmanned aerial vehicle, and the terminal processor 28 also receives the remote control data of the satellite communication link port and sends the remote control data to the flight control computer to control the unmanned aerial vehicle. The terminal processor 28 of the invention is composed of a synchronous control unit, a main despreading unit and a remote control demodulation unit; the synchronous control unit receives the image data of the image encoder 27 and the telemetering data of the flight control machine port, and performs remote control data processing, telemetering data encoding, image telemetering data multiplexing and data receiving, selecting and distributing to enable the uplink and downlink frames to synchronously complete ranging; the main despreading unit receives the intermediate frequency remote control signal sent by the main remote control receiver 25 in two stages of capturing and tracking for despreading, and the despread remote control signal is subjected to BPSK demodulation and decryption by the remote control demodulation unit to output main remote control data; the remote control demodulation unit receives the remote control information code sent by the auxiliary remote control receiver 26 for de-spreading and decryption, and the output auxiliary remote control data is sent to the port of the flight control machine by the synchronous control unit to control the flight of the unmanned aerial vehicle.
The working flow of the airborne duplexer 21 of the embodiment of the invention is as follows:
the airborne duplexer 21 is used for receiving and amplifying uplink remote control radio frequency signals with low noise, filtering downlink image/remote measurement radio frequency small signals and isolating and transmitting large signals. The operation schematic block diagram is shown in fig. 15, and fig. 15 is an electrical schematic operation flowchart of the embodiment of the airborne duplexer 21 of the present invention.
Embodiment the working flow of the master remote control receiver 25 of the present invention is as follows:
the main remote control receiver 25 completes the functions of frequency conversion, amplification, filtering, automatic gain control and the like of the uplink remote control signals, and ensures that the intermediate frequency signals with stable power and enough carrier-to-noise ratio are sent to the main remote control despreading unit. The functional block diagram is shown in fig. 16, and fig. 16 is an electrical functional flow diagram illustrating the implementation of the master remote control receiver 25 of the present invention.
The main remote control receiver 25 is implemented using a double conversion scheme. The local oscillator I frequency is provided by the C-band frequency synthesizer and is stepped by 10 MHz. And the local oscillator II adopts a phase-locked loop, and the frequency is 1224 MHz. The front middle frequency is 1320MHz, the second middle frequency is 96MHz, and the middle frequency bandwidth is 26 MHz.
The amplified signal after the first frequency mixing is then subjected to a second frequency mixing selection, wherein the amplifying part consists of two amplifiers and an electric adjustable attenuator, and the amplifying part and the later main amplifying part complete the automatic gain control function together. The 96MHz intermediate frequency signal obtained by mixing is sent to a main intermediate amplifier after passing through a band pass filter and an amplifier, and is subjected to intermediate frequency amplification, so that an intermediate frequency signal with the power of-10 ± 2dBm is obtained, and finally, the intermediate frequency signal is sent to a terminal processor 28 for processing.
The working flow of the terminal processor 28 of the embodiment of the present invention is as follows:
the terminal processor 28 receives the image data of the image encoder 27 and the telemetering data of the flight control machine port, and the synchronous control unit thereof completes the remote control data processing, telemetering data encoding, image telemetering data multiplexing and data receiving selection distribution, and simultaneously, the uplink and downlink frames are synchronously used for completing the ranging. The main despreading unit receives the intermediate frequency of the remote control signal sent by the main remote control receiver 25 in two stages of capturing and tracking for despreading, and the despread remote control signal is subjected to BPSK demodulation and decryption by the remote control demodulation unit to output main remote control data; and receiving the remote control information code sent by the auxiliary remote control receiver 26, despreading and decrypting, outputting auxiliary remote control data, and controlling the unmanned aerial vehicle to fly by using the synchronous control unit to remotely control the main and auxiliary remote control to the port of the flight control machine.
In the embodiment of the invention, the synchronization and control unit of the terminal processor 28 is the center of data processing of the line-of-sight data chain airborne equipment, completes the functions of remote control processing, telemetering coding, image telemetering data multiplexing, data receiving, selecting and distributing and the like, and simultaneously synchronizes the uplink and downlink frames for completing ranging. The operation block diagram is shown in fig. 17, and fig. 17 is an electrical operation flow diagram of an embodiment of the synchronization control unit of the terminal processor 28 of the present invention.
The synchronization control unit of the terminal processor 28 completes remote control data processing, telemetry data encoding, image telemetry data multiplexing, data reception selection distribution, and simultaneously synchronizes the uplink and downlink frames for completing ranging. The main despreading unit receives the intermediate frequency of the remote control signal sent by the main remote control receiver 25 in two stages of capturing and tracking for despreading, and the despread remote control signal is subjected to BPSK demodulation and decryption by the remote control demodulation unit to output main remote control data; and receiving the remote control information code sent by the auxiliary remote control receiver 26, despreading and decrypting, outputting auxiliary remote control data, and controlling the unmanned aerial vehicle to fly by using the synchronous control unit to remotely control the main and auxiliary remote control to the port of the flight control machine.
The unit comprises a remote control signal processing module, a telemetering data acquisition module, a clock signal generation module, a line-of-sight data link image telemetering multiplexing module and a satellite relay data link image telemetering multiplexing module according to functions.
The remote control signal processing module receives the remote control data stream and the clock of the main channel and the auxiliary channel from the demodulation unit; and receiving Ku band and UHF band remote control data stream and clock sent by the satellite relay data chain at RS422 level. And extracting remote control frames, characters, bits, numbers and frame locking signals through a frame synchronization locking ring, and sending the remote control frames, the characters, the bits, the numbers and the frame locking signals to a remote control selection module, wherein the frame locking signals are controlled by a frame locking detection module to ensure that the frame locking is correct. The remote control data selection module is used for selecting the following remote control frames according to the locking condition of the remote control frames in a priority order: and the sight distance main channel, the sight distance auxiliary channel, the Ku waveband of the satellite relay link and the UHF waveband of the satellite relay link select and output remote control data to the remote control decoding module, and simultaneously output the state of the remote control link. The remote control decoding module carries out remote control decoding on the remote control data and outputs a bandwidth control signal and a TV control signal; and simultaneously, remote control data is sent to an airborne flight control computer, satellite relay data link Ku waveband equipment and a Ku antenna servo system through an RS422 asynchronous serial port, the remote control data is sent to a link controller through a TTL level, the content is the same as a remote control frame structure, the remote control data is quasi-synchronous with a remote control synchronous bit stream on bytes, and the data sending is stopped when the lock is lost.
The clock signal generating module receives a clock signal of 102.4kHz sent by the despreading unit and a remote control sub-channel baseband spread spectrum signal (modulo-two addition of a sub-channel ranging pseudo code and remote control information) with a code rate of 102.4kcps sent by the receiving demodulation unit, selects one path to send to the digital frequency multiplier according to the frame locking condition sent by the remote control selection processing module, outputs a clock signal (TTL level) with frequency of 4.096MHz through digital phase-locked loop frequency multiplication, and outputs frame, word, bit and digital logic related to an uplink frame signal for downlink telemetering frame coding.
The telemetering data acquisition module receives frequency synthesis return data input by a digital camera through an RS422 asynchronous serial port, a link controller through a TTL level asynchronous serial port, monitoring data input by a satellite relay data link through the RS422 asynchronous serial port, antenna servo monitoring data input by a Ku antenna servo through the RS422 asynchronous serial port and telemetering data input by an airborne flight control computer through the RS422 asynchronous serial port, and the telemetering data are respectively cached in FIFO to facilitate telemetering coding. The telemetering data acquisition module receives the AGC level sent by the auxiliary remote control receiver and sends the AGC level to the telemetering encoder through A/D conversion. And the telemetering image encoder receives the telemetering data and AGC (automatic gain control) acquired data cached by the telemetering data acquisition buffer to complete telemetering frame encoding.
And the line-of-sight data chain image telemetry multiplexing module converts the telemetry data stream into a telemetry data stream in accordance with a time sequence relationship according to the clock signal which is sent by the clock signal generating module and is related to the uplink signal, and multiplexes the telemetry data stream and the image data. The multiplexed composite data stream is scrambled, differentially encoded, and convolutionally encoded before being sent to the image telemetry transmitter 23 for modulation.
In the embodiment of the present invention, the image encoder 27 collects, processes, and compresses the analog video signal sent by the onboard CCD camera, and the compressed code stream is sent in a serial manner, and the working schematic block diagram is shown in fig. 18. Fig. 18 is an electrical schematic operational flow diagram of an embodiment of the inventive image encoder 27.
The analog video signal is converted to a CCIR601 compatible video data stream by a video decoder chip (VideoDecoder) and the data is sent to the FPGA. The FPGA performs YUV component separation on the data stream, performs data extraction, and performs anti-aliasing filtering; the filtered data is written into a FIFO memory with large capacity in a certain sequence. The digital signal processing chip reads the data in the FIFO for compression coding and fault-tolerant coding, and the compressed video bit stream is sent to the terminal processor 28 through a transmission circuit.
Embodiment the main despreading unit of the terminal processor 28 of the present invention performs despreading of the remote control receiver output if signal, as shown in fig. 19, and fig. 19 is an electrical schematic flow diagram of an embodiment of the main despreading unit of the terminal processor 28 of the present invention.
The operation of the despreading circuit is divided into two stages of acquisition and tracking.
In the capturing stage, the main despreading unit of the terminal processor 28 mixes the 96MHz wideband signal sent by the main remote control receiver 25 with the 74.6MHz local oscillator, down-converts to output 21.4MHz spread spectrum signal, correlates with the local M-sequence pseudo code with 2048 bit code rate 13.1072MHz, filters by the narrow band filter, when the local spread spectrum code is not correlated with the received spread spectrum code phase, detects to determine out lock level, and the AGC outputs low level, and simultaneously the clock control circuit searches for the external pseudo code phase, and outputs the narrow band 21.4MHz PSK signal after phase correlation, and detects to determine out lock signal, so that the clock control circuit enters the tracking state, and the AGC outputs the 0-5V dc level varying with the input signal.
In the tracking stage, a delta ring shift register is adopted by a tracking loop to output an advance signal, a delay signal and a same three-way signal, an advance pseudo-random code and a delay pseudo-random code are respectively related to an input signal, the advance pseudo-random code and the delay pseudo-random code are respectively related to the input signal, the correlation levels are respectively output by the detection of a narrow band filter, the two relevant levels are subtracted, and an error voltage is output by a loop filter and is sent to a 13.1072MHz voltage.
In the embodiment of the present invention, the remote control demodulation unit of the terminal processor 28 demodulates the main remote control signal and despreads the sub remote control signal, and extracts the synchronization signal of the remote control main and sub channel information codes. As shown in fig. 20, fig. 20 is an electrical schematic flow diagram of an embodiment of a remote demodulation unit of terminal processor 28 of the present invention.
When the main channel works, the narrow-band high-signal-to-noise-ratio intermediate frequency 21.4M signal sent by the despreading circuit is received, the intermediate frequency signal is restored into a baseband encrypted remote control serial data stream through main demodulation, and then main remote control data and a main remote control clock signal are output through de-differencing and decryption processing. When the auxiliary channel works, the 102.4kbps baseband spread spectrum signal sent by the receiver is shaped and output, and is restored into a baseband encrypted remote control serial data stream through an auxiliary de-spreading circuit, and then the auxiliary remote control data and an auxiliary remote control clock signal are output through de-differentiation and decryption processing.
The assistant remote control receiver 26 receives UHF remote control radio frequency signals sent by the UHF waveband omnidirectional antenna 19 from ground equipment, carries out filtering, low noise amplifier and mixing output difference frequency of 70MHz, and inputs the difference frequency to the intermediate frequency amplifier for amplification after being selected by the 70MHz intermediate frequency filter; after the 70MHz intermediate frequency signal is sent to the fm demodulator, the frequency is shifted to 10.7MHz by the mixer in the fm demodulator, amplified by the multistage limiting amplifier and then frequency detected, and the demodulated remote control information code is sent to the terminal processor 28 for decoding.
The working flow of the secondary remote control receiver 26 of the embodiment of the present invention is as follows:
the sub remote control receiver 26 is composed of a front selector, a high frequency amplifier, a rear selector, a mixer, a local oscillator, a 70MHz intermediate frequency filter, an intermediate frequency amplifier, a frequency modulation demodulator, a low pass filter, a video amplifier, and the like, and a working schematic block diagram is shown in fig. 21, where fig. 21 is an electrical schematic working flowchart of the embodiment of the sub remote control receiver 26 of the present invention.
The secondary remote control receiver 26 receives the remote control radio frequency signal from the ground device of the line-of-sight data link from the UHF-band omnidirectional antenna 19 and sends the signal to the unmanned aerial vehicle, and the signal first enters the pre-selector for filtering. The low noise amplifier amplifies the weak signal entering the receiver, further extracts the required signal through the post-selector and sends the signal into the mixer, the signal is mixed with the signal output by the local oscillator, the difference frequency is 70MHz, the signal enters the intermediate frequency amplifier after being selected by the 70MHz intermediate frequency filter, and the intermediate frequency amplifier amplifies the purified intermediate frequency signal to a certain level, so that the level required by the normal work of the frequency modulation demodulator is achieved. After the 70MHz intermediate frequency signal is sent to the FM demodulator, the frequency is shifted to 10.7MHz by a mixer in the FM demodulator, and then the intermediate frequency signal is amplified by a multistage amplitude limiting amplifier and then subjected to frequency detection, so that a remote control information code is demodulated. The remote control information code is finally amplified to the required level by low pass filter filtering and low frequency amplifier and sent to the terminal processor 28 for decoding.
The embodiment of the invention provides that the UHF-band omnidirectional antenna 19 takes the form of a half-wave dipole. As shown in fig. 22, fig. 22 is a schematic structural diagram of an embodiment of the airborne UHF-band omnidirectional antenna 19 of the present invention. The structure of the dipole antenna is shown. It consists of two quarter-wave oscillators placed symmetrically, with a resonant impedance between 50 Ω and 70 Ω. To facilitate the use of coaxial cable feed, quarter-wave matching stubs are used for balun conversion, so that no current passes through the outer conductor of the cable. In the ideal case the pattern of a half-wave dipole is a circle in the H-plane and a regular "8" in the E-plane.
Ninthly, the image/telemetering transmitter 23 receives the image/telemetering data stream and the code rate control signal of the terminal processor 28, performs amplitude modulation control on the image/telemetering data stream, sends the image/telemetering data stream to a tuning end of the voltage-controlled oscillator to generate 790MHz intermediate frequency modulation image/telemetering signal, and the modulated intermediate frequency image/telemetering signal and a local oscillator signal sent by the C-band frequency synthesizer 24 are subjected to up-conversion output by the mixer to obtain 4910 MHz-5000 MHz image/telemetering radio-frequency signal, and are sent to the C-band omnidirectional antenna 17 to be transmitted to the ground line-of-sight data chain.
Embodiment of the invention the image/telemetry transmitter 23 is shown in fig. 23. fig. 23 is an electrical schematic operational flow diagram of an embodiment of the image/telemetry transmitter 23 of the invention.
The image telemetry signal generated by the synchronization control unit of the terminal processor 28 is first shaped and then amplitude controlled in two paths according to different code rates. The gating of the two paths is controlled by a code rate control signal provided by a synchronization control unit of the terminal processor 28, and the oscillator is modulated after one of the paths is gated.
The transmitter uses a 10MHz constant temperature crystal oscillator as a reference source, and a phase detector, a frequency divider, a voltage-controlled oscillator and a loop filter form a phase-locked loop to generate an intermediate frequency signal. The image/telemetry signal is sent to the tuning end of the voltage controlled oscillator after being subjected to amplitude control, so that a 790MHz intermediate frequency modulation signal is generated. The signal is amplified and then harmonic waves are filtered out by a filter. The intermediate frequency signal and the local oscillation signal sent by the C wave band frequency synthesizer 24 are up-converted to radio frequency signals of 4910 MHz-5000 MHz through the frequency mixer. The change in the radio frequency channel is achieved by changing the frequency of the local oscillator signal. The mixed frequency generates various frequency components, after filtering useless components by a filter, the frequency components are divided into two paths which are respectively amplified, one path is directly output to an antenna for joint test, and the other path is output after passing through an electrically-tuned attenuator. The size power conversion is realized by controlling the attenuation value of the electrically-adjusted attenuator. The working/silencing function is realized by controlling the power supply of the oscillator through a relay.
The machine also comprises a reference source circuit, and a high-stability constant-temperature crystal oscillator is adopted in the circuit. The crystal oscillator outputs 10MHz signals, the signals are divided into three paths by the power divider, then the three paths are respectively amplified, and finally the two paths are output to other branch machines for use.
Embodiment the C-band frequency synthesizer 24 of the present invention is composed of a single-loop digital phase-locked loop, as shown in fig. 24, fig. 24 is an electrical schematic work flow diagram of an embodiment of the C-band frequency synthesizer 24 of the present invention. It is a single loop digital phase locked loop. The output of the voltage-controlled oscillator in the loop is divided, one path is amplified and output, the other path enters a single-chip phase-locked loop through a divide-by-four frequency divider, a 2.5MHz signal is obtained in the single-chip phase-locked loop through a divide-by-N program frequency divider, phase comparison is carried out in a phase discriminator with the divide-by-four frequency of a standard reference signal of 10MHz, error voltage is generated according to the phase difference of the two signals, the frequency and the phase of the voltage-controlled oscillator are controlled, and when the loop is locked, the output frequency of the voltage-controlled oscillator is the required frequency. The downlink local oscillation output is 4120 MHz-4210 MHz stepped by 10MHz, and the uplink local oscillation output is 2650 MHz-2740 MHz stepped by 10 MHz.
And a link control circuit in the C-band frequency synthesizer 24 is a singlechip control circuit. The single chip microcomputer receives the frequency synthesis control data sent by the terminal processor 28 through the RS422 asynchronous serial port, then decodes the received data to obtain frequency point control information, outputs the frequency synthesis control data corresponding to the frequency point, and completes frequency switching; and decoding to obtain power amplifier and antenna control signals to control the states of the power amplifier and the antenna. And meanwhile, the locking state, the antenna state and the power amplifier state of the frequency synthesizer are collected, and the state information is output to the image/remote measuring transmitter 23 through an RS422 asynchronous serial port. The initial state of the link controller is 1 frequency point.
Embodiment of the invention the C-band omni directional antenna 17 is in the form of a half-wave dipole antenna, the internal structure of the antenna is shown in fig. 25, fig. 25 is a structural schematic diagram of an embodiment of the airborne C-band omni directional antenna 17, 18 of the invention.
The center conductor of the antenna coaxial cable is connected to a quarter-wave length element and the outer conductor of the coaxial cable is connected to a quarter-wave cylindrical sleeve. The coaxial cylindrical sleeve acts as a quarter wave choke so that most of the current cannot leak to the outer surface of the coaxial cable. A choke is usually added to the lower portion of the coaxial cable to further choke the current leakage to improve the radiation pattern. Such an antenna does not require a ground plane and therefore the gain degradation due to the mounting location is less than a quarter wave monopole antenna. Is suitable for being used as an airborne antenna of a higher frequency band. The pattern of the half-wave dipoles is a circle on the H-plane and a regular "8" on the E-plane.

Claims (3)

1. A method suitable for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signals is characterized by comprising the following steps:
ground signal transmission of line-of-sight data link
Firstly, a full duplexer (3) receives an image and a telemetering radio frequency signal of the unmanned scout plane input by a C-band transceiving antenna (1), the image and the telemetering radio frequency signal are sent to a frequency converter (5) for frequency conversion and amplification, the image and the telemetering radio frequency signal after frequency conversion and amplification are input to an intermediate frequency amplifier (8) for down-conversion, and the image and the telemetering intermediate frequency signal are output;
inputting the image and the telemetering intermediate frequency signal into an image telemetering receiver (11) by an intermediate frequency amplifier (8), demodulating the image and the telemetering intermediate frequency signal, dividing the demodulated image and the telemetering intermediate frequency signal into two paths of signals, outputting the two paths of signals, sending one path of signals to a tracking receiver (10), demodulating error voltage from the demodulated image and the telemetering intermediate frequency signal, sending the error voltage to an antenna controller (7), sending the error signal to a C-band receiving and transmitting antenna (1) by the antenna controller (7), and tracking and positioning the unmanned reconnaissance aircraft; the other path of the baseband signals is filtered to select corresponding baseband signals with two code rates of 2048kbps and 256kbps, and the baseband signals with the two code rates are sent to a coding and coding ranging unit (14);
the coding and decoding ranging unit (14) carries out synchronous extraction, Viterbi decoding, decryption and ranging on baseband signals with two code rates, and sends decrypted images and telemetered data streams to a command control port to complete the receiving and processing of the images and telemetered data; the decrypted image and the telemetering data stream are sent to a local control unit (15) to be resolved and displayed on-board equipment;
receiving the remote control data stream from the command control port by the coding and decoding ranging unit (14), and dividing the remote control data stream into two paths for output after synchronization, encryption, difference and spread spectrum of the remote control data stream; one path of signal is sent to a main remote control transmitter (12) for intermediate frequency modulation, a remote control intermediate frequency signal is output, the remote control intermediate frequency signal is sent to a frequency converter (5) for frequency mixing, a remote control radio frequency signal is output, the remote control radio frequency signal is sent to a C power amplifier (6) for amplification, the amplified remote control radio frequency signal is input to a full duplexer (3) for isolation and output to a C-band transceiver antenna (1), the C-band transceiver antenna (1) transmits the remote control radio frequency signal to an unmanned reconnaissance aircraft, and the unmanned reconnaissance aircraft is remotely controlled; the other path of the remote control signal is sent to a UHF waveband transmitter (13) to be PSK modulated into a remote control radio frequency signal, the UHF waveband transmitter (13) sends the remote control radio frequency signal to a UHF power amplifier (9) to be amplified, the amplified remote control radio frequency signal is sent to a UHF waveband transmitting antenna (2), the UHF waveband transmitting antenna (2) transmits the remote control radio frequency signal to the unmanned reconnaissance machine, and the unmanned reconnaissance machine is remotely controlled;
the local oscillator signal of the uplink remote control signal generated by the frequency synthesizer (4) and the local oscillator signal of the downlink image remote measurement signal are sent to the frequency converter (5), and the uplink remote control signal of the frequency converter (5) and the local oscillator signal of the uplink remote control signal generated by the frequency synthesizer (4) are mixed to form a remote control radio frequency signal; the downlink image telemetering signal of the frequency converter (5) and the local oscillator signal of the downlink image telemetering signal generated by the frequency synthesizer (4) are mixed into a down-conversion image telemetering signal;
adjusting and setting the state of the airborne equipment by the control unit (15), observing the content of the sent remote control data, and adjusting and setting the state of the ground equipment; receiving telemetering data input by a coding and decoding ranging unit (14) for resolving, and displaying the state of the airborne equipment; receiving monitoring data sent by a command control port, resolving the data and displaying the state of the ground equipment;
airborne signal transmission of line-of-sight data link
Seventhly, an onboard duplexer (21) receives a main remote control radio frequency signal input by a C-band omnidirectional antenna (18), sends the main remote control radio frequency signal to a main remote control receiver (25) for frequency conversion, amplification, filtering and automatic gain control, and then outputs a remote control intermediate frequency signal to a terminal processor (28); the terminal processor (28) performs despreading demodulation processing on the remote control intermediate frequency signal, demodulated remote control data is decrypted by the airborne encryption unit, is sent to the port of the flight control computer to control the unmanned reconnaissance plane after being coded by framing again, and the terminal processor (28) also receives the remote control data of the gateway link port and sends the remote control data to the flight control computer to control the unmanned reconnaissance plane;
the auxiliary remote control receiver (26) receives UHF remote control radio frequency signals sent by the UHF waveband omnidirectional antenna (19) from ground equipment, carries out filtering, low-noise amplification and frequency mixing processing, outputs difference frequency 70MHz, and inputs the difference frequency into an intermediate frequency amplifier for amplification after being selected by a 70MHz intermediate frequency filter; after the 70MHz intermediate frequency signal is sent to a frequency modulation demodulator, the frequency is shifted to 10.7MHz by a mixer in the frequency modulation demodulator, the intermediate frequency signal is amplified by a multi-stage limiting amplifier and then subjected to frequency detection, and a remote control information code is demodulated and sent to a terminal processor (28) for decoding;
ninthly, an image and telemetering transmitter (23) receives an image and telemetering data stream of a terminal processor (28) and code rate control signals to perform amplitude modulation control on the image and telemetering data stream, the image and telemetering data stream is sent to a tuning end of a voltage-controlled oscillator to generate 790MHz intermediate frequency modulation image and telemetering signal output, a mixer mixes the 790MHz intermediate frequency modulation image and telemetering signal with a local oscillator signal sent by a C-band frequency synthesizer (24), the image and telemetering radio-frequency signal of 4910MHz to 5000MHz are output to a C-band omnidirectional antenna (17), and the C-band omnidirectional antenna (17) transmits the image and telemetering radio-frequency signal to a ground line-of-sight data chain;
and completing the observation and control of the unmanned reconnaissance aircraft and the information transmission line-of-sight data link signal.
2. The method for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signals according to claim 1, wherein the method comprises the following steps: the coding and decoding unit (14) in the second step is composed of a synchronous decoding unit, a remote control coding unit and a tapping ranging unit; the synchronous decoding unit carries out synchronous extraction, Viterbi decoding and decryption on the image and the telemetering data stream; the remote control coding unit codes a remote control instruction for the remote control data stream; the tapping and ranging unit taps and ranges the image and the telemetering data stream, switches the code rate, acquires AGC voltage, processes GPS data, forwards the image data and outputs telemetering, image, distance and state data according to a specified format.
3. The method for unmanned reconnaissance aircraft measurement and control and information transmission line-of-sight data link signals according to claim 1, wherein the method comprises the following steps: the terminal processor (28) in the step (seventhly) is composed of a synchronous control unit, a main despreading unit and a remote control demodulation unit; the synchronous control unit receives image data of an image encoder (27) and telemetering data of a flight control machine port, and performs remote control data processing, telemetering data encoding, multiplexing of the image and the telemetering data and receiving, selecting and distributing of the data, so that uplink and downlink frames are synchronized to finish ranging; the main despreading unit receives the intermediate frequency telemetering signal sent by the main remote control receiver (25) in two stages of capturing and tracking for despreading, and the despread remote control signal is subjected to BPSK demodulation and decryption by the remote control demodulation unit to output main remote control data; the remote control demodulation unit receives the remote control information code sent by the auxiliary remote control receiver (26) for de-spreading and decryption, and the output auxiliary remote control data is sent to the port of the flight control machine by the synchronous control unit to control the unmanned reconnaissance aircraft to fly.
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