CN114095070B - Arrow body information feedback device based on Beidou satellite navigation - Google Patents
Arrow body information feedback device based on Beidou satellite navigation Download PDFInfo
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Abstract
The invention discloses an arrow information returning device based on Beidou satellite navigation, and belongs to the field of satellite navigation equipment. The method comprises the steps of receiving navigation signals through an active antenna, quantifying the navigation signals into 4bit digital intermediate frequency signals by using a radio frequency receiving module, then carrying out combining, capturing and channel tracking on the digital intermediate frequency signals in a signal processing module, simultaneously carrying out BPSK modulation on the short message intermediate frequency signals, carrying out message analysis, arrow body position, speed, clock difference and Zhong Piao calculation in an information processing module, carrying out back transmission on the arrow body position and speed information serving as short message information, carrying out Doppler frequency shift compensation according to carrier speed, carrying out digital-to-analog conversion, intermediate frequency filtering and quadrature up-conversion on the short message intermediate frequency modulation signals in a transmitting radio frequency module to generate BDS short message radio frequency communication signals, and finally transmitting the arrow body information to a passive transmitting antenna. The invention can realize the calculation of the arrow motion information under high dynamic state, and complete the return of the short message information in a frequency compensation mode.
Description
Technical Field
The invention belongs to the technical field of satellite navigation equipment, and particularly relates to an arrow body information returning device based on Beidou satellite navigation.
Background
The global positioning system (GPS for short) built in the 20 th century of the united states is widely used in the military and civilian field to provide location, speed and time services for the global and near-earth space. China also develops Beidou satellite navigation system (BDS) in 21 st century, and through three-period construction, satellite navigation service can be provided for global users at present.
One characteristic of the arrow-mounted equipment in the recovery section is that the posture is uncontrollable, so that for the arrow-mounted navigation receiver with a single frequency and a single antenna, the satellite number is insufficient and the effective positioning cannot be realized, and the other characteristic is that the dynamic is large, and the risk of failure exists for short message service in a conventional application mode.
Disclosure of Invention
In view of the above problems, the invention provides an arrow information returning device based on Beidou satellite navigation, which is based on an FPGA+DSP architecture and can return arrow information by utilizing a BDS short message communication function.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
an arrow information feedback device based on Beidou satellite navigation comprises a high-temperature resistant antenna, a receiving radio frequency module, a transmitting radio frequency module, an FPGA and a DSP; the FPGA is used for realizing a signal processing module; the DSP is used for realizing an information processing module;
the signal processing module is used for completing digital signal combining, high dynamic signal capturing, signal channel tracking and short message intermediate frequency signal modulation;
the information processing module is used for completing bit synchronization, frame synchronization, observed quantity extraction, text analysis, positioning and resolving, speed resolving, frequency offset compensation and quick lock-out repositioning;
the high-temperature-resistant antenna comprises two paths of navigation signal receiving active antennas and two paths of short message signal transmitting passive antennas, and the four antennas are arranged on the outer diameter of the arrow body according to phase crossing intervals which differ by 90 degrees; the receiving active antenna converts the space navigation signal into an electric signal, and outputs a navigation signal with 40dB gain after passing through a preselection filter, a low noise amplifier and a band-pass filter;
the receiving radio frequency module comprises a low noise amplifier circuit, a radio frequency filter circuit and an RNSS radio frequency circuit; the low-noise discharge circuit realizes the amplifying function of the navigation signal, counteracts the signal energy loss caused by the transmission distance, the radio frequency filter circuit is realized by the band-pass filter, the inhibiting function of the image signal and the interference signal is completed, and the RNSS radio frequency circuit realizes the mixing, intermediate frequency filtering, automatic gain control and analog-to-digital conversion functions of the navigation signal and outputs a 4-bit digital intermediate frequency signal;
the transmitting radio frequency module comprises an RDSS radio frequency circuit, a power amplifier circuit and a power switch circuit; the RDSS radio frequency circuit receives a modulation signal output by spread spectrum modulation of a frequency signal in an FPGA short message, realizes digital-to-analog conversion, filtering and orthogonal frequency conversion functions and outputs the short message radio frequency signal, the power amplifier circuit realizes a power amplification function of the short message radio frequency signal so as to meet the communication power requirement, the power switch circuit realizes a switching function of the short message radio frequency signal, and the short message communication signal is output to two paths of high-temperature-resistant passive transmitting antennas in a time-sharing manner;
when the back transmission device works, the received navigation signal is converted into an electric signal by the receiving active antenna, and then the electric signal is filtered, amplified and filtered to output the navigation signal to the receiving radio frequency module; the receiving radio frequency module receives BDS/GPS satellite navigation signals and outputs 4bit digital intermediate frequency signals to the signal processing module; the signal processing module firstly realizes the combination of the two-way navigation digital intermediate frequency signals, then captures and tracks the combined navigation signals, outputs relevant values and channel parameters to the information processing module, and simultaneously receives channel loop control parameters, position and speed information and short message frequency offset information provided by the information processing module, wherein the loop control parameters realize the continuous stable tracking of the navigation signals, the position and speed information is the movement information of an arrow body, the movement information is used as short message communication content and is sent to the transmitting radio frequency module through BPSK spread spectrum modulation, and the short message frequency offset information is compensation of modulation frequency, so that the finally generated short message communication frequency can be accurately received; the information processing module receives the related value and channel parameter information output by the signal processing module, wherein the related value information is used for completing bit synchronization, frame synchronization, loop parameter calculation and navigation message analysis, the channel parameter information is used for realizing observed quantity extraction, and the two are matched with the final completion of position calculation and speed calculation, and the speed information obtained by calculation is used for calculating Doppler frequency shift; the transmitting radio frequency module receives the short message intermediate frequency signal output by the signal processing module, generates BDS short message radio frequency communication signal after frequency conversion and filtering, and transmits the arrow body information through the power amplification module.
Further, the signal processing module comprises a digital signal synthesis sub-module, a high dynamic signal capturing sub-module, a signal channel tracking sub-module and a short message medium frequency signal spread spectrum modulation sub-module;
the digital signal synthesis submodule is used for directly carrying out synchronous addition operation on two paths of input signals;
the high dynamic signal capturing submodule traverses a high dynamic Doppler range by using a frequency block searching method, adopts a mode of combining matched filtering with fast Fourier transform, and utilizes a parallel correlator group and a multipoint parallel FFT pipelining mode to realize signal searching in a frequency block and rapidly captures navigation signals; the matched filtering adopts 420 groups of correlators, the inputs of the correlators are down-sampled navigation signals and local pseudo code signals, the local pseudo code inputs of the correlators are sequentially different by half a chip, and the correlation result of each group of correlators is input into a 128-point parallel FFT module for calculation, so that the time domain and frequency domain information of the navigation signals are obtained, and capturing is completed;
the signal channel tracking sub-module continuously locks and tracks the captured pseudo code and carrier phase, tracks the code phase information by adopting a DLL code loop, tracks the carrier phase information by adopting a PLL carrier loop, and tracks the carrier loop by adopting a mode of second-order frequency locking and auxiliary third-order phase locking;
and the short message medium-frequency signal spread spectrum modulation sub-module carries out BPSK modulation on the short message information, the RDSS pseudo code and the medium-frequency carrier, wherein the frequency of the medium-frequency carrier is dynamically and in real time adjusted according to the carrier.
Further, the information processing module comprises a bit synchronization sub-module, a frame synchronization sub-module, an observed quantity extraction sub-module, an electric text analysis sub-module, a positioning and resolving sub-module, a speed resolving sub-module, a frequency offset compensation sub-module and a quick lock-out repositioning sub-module;
the bit synchronization sub-module adopts a histogram method or an NH coding mode to realize bit synchronization, and continuous bit data is obtained after the synchronization is successful;
the frame synchronization submodule judges whether the continuous 11bit data is 0x712 and 0x0ED, if the continuous 11bit data is judged to pass, 180-degree phase ambiguity is eliminated, BCH decoding is carried out on the subsequent 16bit message, and if the decoding passes, the frame synchronization is successful;
the observed quantity extraction submodule is used for extracting pseudo-range observed quantity information and carrier observed quantity information, and the return device extracts pseudo-code phase and carrier phase count in the code ring and the carrier ring at a clock beat of 50ms to obtain pseudo-range and carrier phase information;
the message analysis submodule analyzes ephemeris parameters according to a protocol specified in the ICD file by utilizing navigation message information collected after frame synchronization to obtain orbit information and time information of satellites;
the positioning solution operator module uses the satellite orbit information obtained by pseudo-range observed quantity and text analysis to realize positioning solution by least square operation;
the speed resolving operator module achieves speed resolving through least square operation through position information and carrier observed quantity information obtained through positioning resolving;
the frequency offset compensation sub-module performs frequency offset compensation on the short message signal under the high dynamic scene according to the following parametersCalculating to obtain Doppler compensation frequency, wherein f sd For the frequency to be compensated +.>For arrow speed, < >>Is the cosine of the direction, f l The uplink frequency of short message communication is represented by c, which is the speed of light;
the quick unlocking repositioning sub-module is triggered after the navigation signal is unlocked, firstly, the unbiased estimation of the arrow body information feedback device to the signal state before unlocking is obtained, the calculation of all parameters of the unlocking signal is maintained by utilizing the channel information before unlocking, and all parameters of the unlocking signal comprise pseudo code period count, code chip count, code NCO count, carrier cycle count and carrier NCO count, and normal tracking is switched after the recaptured signal meets the tracking threshold; and secondly, reserving related information of time and carrier phase before unlocking, calculating transmitting time after unlocking and resetting by utilizing local time count and Doppler information, further obtaining a pseudo range, comparing the pseudo range with the pseudo range after resetting, and participating in positioning calculation together with the stored ephemeris information within an error range.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention adopts the short message communication function of BDS to return arrow information.
(2) The invention adopts a double-path navigation signal synthesis mode to improve the continuity and usability of signals.
(3) The invention adopts PMF (matched filtering) +FFT to realize the rapid acquisition of the high dynamic navigation signal.
(4) The invention adopts a high dynamic lock loss weight compensation mode to realize the positioning and quick recovery capability of short-time signal lock loss.
(5) The invention adopts a frequency compensation mode to ensure the correct return of the short message information.
Drawings
Fig. 1 is a signal processing flow chart of an apparatus according to an embodiment of the present invention.
Fig. 2 is a flow chart of the operation of the apparatus of the embodiment of the present invention.
Fig. 3 is a navigation signal combining diagram of the device according to the embodiment of the present invention.
Fig. 4 is a schematic diagram of the capture of an apparatus according to an embodiment of the present invention.
Fig. 5 is a block diagram of a loss-of-lock weight compensation flow of the device according to the embodiment of the invention.
Detailed Description
The invention will be described in further detail with reference to the accompanying drawings and specific examples.
The arrow information feedback device based on Beidou satellite navigation comprises four paths of high-temperature resistant antennas, a radio frequency receiving front end module, an intermediate frequency digital signal processing module, an information processing module and a radio frequency transmitting module based on an FPGA+DSP architecture.
The four high temperature resistant antennas are divided into two paths of navigation signal receiving active antennas, the two paths of short message sending passive antennas are arranged at intervals with a phase difference of 90 degrees with the receiving antennas on the outer circle axis of the arrow body, and the receiving antennas comprise preselect filtering, low noise amplifying and band-pass filtering processing functions.
The intermediate frequency digital signal processing module comprises a navigation signal combining module, a high-dynamic capturing module, a loop tracking module and a quick lock-loss weight compensation module.
The navigation signal combining module adopts a mode of synthesizing after digital intermediate frequency sampling.
The high dynamic capture module traverses the high dynamic Doppler range by adopting a frequency block search method, adopts a PMF+FFT mode to use a large number of parallel correlator sets and a frequency parallel FFT pipeline mode, and can rapidly capture navigation signals under the condition of lower working clock.
The carrier loop tracking mode in the loop tracking module is a second-order frequency locking auxiliary third-order phase locking, and the code loop tracking mode is a broadband second-order code loop.
The quick out-of-lock weight compensation module firstly obtains unbiased estimation of an arrow-borne receiver on the state of a signal before the out-of-lock after the signal is out-of-lock, and utilizes the information of a channel before the out-of-lock to maintain calculation of all parameters of the out-of-lock signal, mainly comprising pseudo code period counting, chip counting, code NCO counting and carrier NCO counting of a carrier cycle counter, and switches normal tracking after a tracking threshold is met. And secondly, reserving related information of time and carrier phase before unlocking, calculating transmitting time after unlocking and resetting by utilizing local time count and Doppler information, further obtaining a pseudo range, comparing the pseudo range with the pseudo range after resetting, and referencing the pseudo range with the already stored ephemeris information in an error range for positioning and resolving.
The frequency compensation module obtains arrow speed information through an arrow receiver according toAnd calculating to obtain Doppler compensation frequency.
The following is a more specific example:
the arrow information feedback device based on Beidou satellite navigation is based on a DSP+FPGA architecture and comprises a double-path active antenna, parallel receiving radio frequency front end processing, baseband signal digital processing, positioning information resolving, transmitting radio frequency processing and the like, as shown in figure 1.
The active antenna firstly converts the received navigation signal into an electric signal, then filters potential interference and image signals through a band-pass filter, amplifies the signal through a low-noise amplifier, outputs the navigation signal through the band-pass filter, and enters a receiving radio frequency front end processing module through a cable;
the receiving radio frequency front end processing module performs signal amplification, radio frequency filtering and RNSS radio frequency circuit (down mixing, intermediate frequency filtering, automatic gain control and analog-to-digital conversion) on the satellite signal to obtain a digital intermediate frequency signal, then enters the baseband signal digital processing module,
the baseband signal digital processing module completes logic management of the whole system, and comprises configuration of an RNSS radio frequency circuit, combination of two-way navigation digital intermediate frequency signals, acquisition of navigation signals, tracking of navigation signals, output of time service signals, spread spectrum modulation of transmitting intermediate frequency signals and protocol management of external communication.
The information processing part is used for completing the functions of bit synchronization, frame synchronization processing, loop parameter calculation, observational quantity extraction, navigation text analysis, positioning calculation, doppler frequency shift calculation, external data interaction and the like.
The transmitting radio frequency module completes analog-to-digital conversion and quadrature up-conversion processing on the intermediate frequency signals, short message communication signals of the BDS are finally generated, and arrow information is sent to the transmitting passive antenna through the power amplification module.
The work flow of the whole dual-mode dual-antenna navigation arrow information feedback device is shown in fig. 2, and is specifically described as follows:
starting up self-checking, and detecting whether ephemeris, time, user position and other information are stored currently or not by an arrow-mounted navigation positioning control module so as to determine a star searching mode and improve capturing efficiency;
the arrow-carried navigation signal has various combining modes, three common combining modes are listed in fig. 3, each combining mode has advantages and disadvantages, the combining modes can be flexibly selected according to different application scenes, the mode of combining after digital intermediate frequency sampling is adopted in the embodiment, as shown in fig. 3 (2), after the navigation signal is converted into the digital intermediate frequency signal through the radio frequency front end, the sampling clock phase of the RNSS radio frequency circuit is different, and therefore, high dynamic capturing is needed after synchronization.
The high dynamic capturing module traverses the high dynamic Doppler range by using a frequency block searching method for visible satellites in the list, adopts a PMF+FFT mode to use a large number of parallel correlator sets and a frequency parallel FFT pipelining mode, and can rapidly capture navigation signals under the condition of lower working clock, as shown in figure 4;
the input to the capture module is downsampled digital intermediate frequency data, which is done so that the code matched filter hardware adder can be multiplexed. The code matching filter group comprises 420 groups of correlators, each correlator group is different by half a chip in sequence, input sampling data received in the correlator group is correlated with a locally generated signal, and then the I/Q correlation result is sent to the FFT module after the amplitude value is obtained. The FFT module performs 128-point transformation on the correlation value, the frequency resolution is calculated using the following formula,
Δf＝f s /N＝1/Nt s
wherein Δf is the frequency resolution, N is the FFT point number, t s Is the sampling interval. In the embodiment, a 25 mu s short integral correlation value is adopted, so that the frequency resolution is 312.5Hz, and then the frequency obtained by further estimation through the fine acquisition module can meet the requirement of transfer tracking. Zero values are padded prior to FFT to reduce processing loss. And comparing the result obtained by FFT conversion with a capture threshold value, and storing the amplitude value exceeding the threshold value and the corresponding time domain and frequency domain values into a register for subsequent processing, wherein the frequency domain values can be converted into code Doppler and control a local code NCO to generate a local code.
And then traction is carried out to lock the frequency part of the intermediate frequency signal, so that the carrier ring locking success rate is improved.
The motion trail of the arrow body is complex, has larger acceleration and jerk, and the common carrier tracking loop can not meet the large dynamic range, so that the carrier loop tracking is performed by adopting a mode of second-order frequency locking to assist third-order phase locking, as shown in fig. 5, and simultaneously, the broadband second-order code loop tracking is performed to ensure the stable locking of the code phase.
If the signal is out of lock, the signal enters an out-of-lock weight compensation module, the module accurately reserves the relevant time and carrier phase related information before the out-of-lock, the capturing speed is improved, and the tracking state can be quickly recovered. The loss-of-lock weight compensation flow chart is shown in fig. 5:
after the signal is unlocked, firstly, obtaining unbiased estimation of an arrow-borne receiver on the signal state before the unlocking, and using the channel information before the unlocking to maintain calculation of all parameters of the unlocking signal, wherein the estimation mainly comprises pseudo code period counting, chip counting, code NCO counting and carrier NCO counting of a carrier cycle counter, and switching normal tracking after the tracking threshold is met. And secondly, reserving related information of time and carrier phase before unlocking, calculating transmitting time after unlocking and resetting by utilizing local time count and Doppler information, further obtaining a pseudo range, comparing the pseudo range with the pseudo range after resetting, and participating in positioning calculation together with the stored ephemeris information within an error range.
Bit synchronization:
the GPS signal bit synchronization adopts a histogram method, namely, the data jump condition between two adjacent 1 ms is counted one by one, the counting processing is carried out at the jump position, and if the count value at the jump position reaches the threshold value, the bit synchronization is considered to be completed.
Because of different coding modes, the BDS 1-5 satellites realize bit synchronization by adopting a histogram method, the BDS 6-14 satellites perform bit synchronization by adopting an NH coding (00000100110101001110) mode, and the 1 millisecond wide integral value output by 20 groups of carrier rings is sequentially taken to perform multiplication accumulation operation with an NH code and is compared with the previous result until the maximum accumulated value is obtained, namely the bit synchronization is completed.
Frame synchronization:
the last two bits of each subframe of the GPS signal are fixed to be '00', so that 180-degree phase ambiguity is eliminated; searching for a frame header '0 x 8B' in the TLM, and checking the TLM; then, checking the HOW after TLM, and analyzing 17-30bit, 18bit and 20-22bit; all verification passes then frame synchronization is completed.
The BDS signal judges whether the continuous 11bit is 0x712 and 0x0ED, if yes, the BCH (15,11,1) decoding is carried out on the subsequent 16bit message after 180-degree phase ambiguity is eliminated, if the decoding is passed, the frame synchronization is successful, and the frame header is judged for each subsequent subframe, and if the frame header error occurs for five times continuously, the frame synchronization is exited.
Pseudo-range observed quantity information and carrier observed quantity information are extracted in a loop:
the rocket-borne receiver extracts the code ring, pseudo code phase and carrier phase counting information in the carrier ring at a clock beat of 50ms, and calculates the transmission time T sv And Doppler frequency shift, the emission time calculation formula is:
T sv ＝N sow ×1000+N bit ×20+N epoch +N chip /1023+N nco /1023/65536
wherein is N sow Counting seconds in week, N bit Count for sub-frame bits, N epoch For pseudo-code period, N chip N is the number of chips nco The NCO count is pseudo-code.
The pseudo-range calculation formula is as follows:
ρ＝c(T r -T sv )
wherein ρ is the pseudo-range observed quantity, c is the speed of light, T r Is the local time, maintained by a 50ms time beat.
Satellite position solution:
and analyzing ephemeris parameters according to a protocol specified in the ICD file by utilizing navigation text information collected after frame synchronization to obtain six kepler orbits of the satellite, and further calculating the position coordinates of the satellite under a geocentric earth fixed coordinate system.
Receiver position resolution:
in the embodiment, a GPS/BDS combined positioning mode is adopted for positioning and resolving to obtain arrow body position information x u ，y u ，z u Due to differences in navigation systems, there are also two clock skew unknowns δt uG And δt uB . And (3) performing pseudo-range joint processing on the BDS and the GPS by using a pseudo-range fusion method to form an equation set, wherein a pseudo-range observation equation is as follows:
in order to improve reliability, an autonomous integrity detection algorithm (RAIM) is adopted to perform fault detection on satellites participating in positioning, and the method is used for eliminating satellites in abnormal states, so that ephemeris information of at least 6 satellites is needed, and clock error and position information are solved by a least square method.
The receiver speed and Zhong Piao information can be calculated from the doppler shift after the position information is solved, their relationships are as follows:
wherein the left equations are all known quantities, c is the speed of light, f d Extracted from the receiver carrier loop for Doppler shift, f T The actual transmit frequency for the satellite is obtained from the nominal frequency and the frequency correction values in the message,obtaining from ephemeris data and orbit model for the satellite movement velocity,/->Obtained for the direction cosine from satellite satellites and the user position,/->For arrow speed, < >>For the receiver Zhong Piao information.
The doppler shift compensation calculation formula is as follows:
wherein f l And c is the light speed, so that the Doppler frequency to be compensated can be obtained.
In a word, the device can be applied to an arrow-borne environment, utilizes the short message communication service of the BDS system to return arrow information, uses double antennas to receive satellite navigation signals, fuses the BDS and the GPS system, and improves the continuity and the positioning precision of positioning.
Claims (3)
1. The arrow information feedback device based on Beidou satellite navigation is characterized by comprising a high-temperature resistant antenna, a receiving radio frequency module, a transmitting radio frequency module, an FPGA and a DSP; the FPGA is used for realizing a signal processing module; the DSP is used for realizing an information processing module;
the signal processing module is used for completing digital signal combining, high dynamic signal capturing, signal channel tracking and short message medium frequency signal modulation;
the information processing module is used for completing bit synchronization, frame synchronization, observed quantity extraction, text analysis, positioning and resolving, speed resolving, frequency offset compensation and quick lock-losing repositioning;
the high-temperature-resistant antenna comprises two paths of navigation signal receiving active antennas and two paths of short message signal transmitting passive antennas, and the four antennas are arranged on the outer diameter of the arrow body according to phase crossing intervals which differ by 90 degrees; the receiving active antenna converts the space navigation signal into an electric signal, and outputs a navigation signal with 40dB gain after passing through a preselection filter, a low noise amplifier and a band-pass filter;
the receiving radio frequency module comprises a low noise amplifier circuit, a radio frequency filter circuit and an RNSS radio frequency circuit; the low-noise discharge circuit realizes the amplifying function of the navigation signal, counteracts the signal energy loss caused by the transmission distance, the radio frequency filter circuit is realized by the band-pass filter, the inhibiting function of the image signal and the interference signal is completed, and the RNSS radio frequency circuit realizes the mixing, intermediate frequency filtering, automatic gain control and analog-to-digital conversion functions of the navigation signal and outputs a 4-bit digital intermediate frequency signal;
the transmitting radio frequency module comprises an RDSS radio frequency circuit, a power amplifier circuit and a power switch circuit; the RDSS radio frequency circuit receives a modulation signal output by spread spectrum modulation of a frequency signal in an FPGA short message, realizes digital-to-analog conversion, filtering and quadrature up-conversion functions and outputs the short message radio frequency signal, the power amplifier circuit realizes a power amplification function of the short message radio frequency signal so as to meet the communication power requirement, and the power switch circuit realizes a switching function of the short message radio frequency signal and outputs the short message communication signal to two paths of high-temperature-resistant passive transmitting antennas in a time-sharing manner;
when the back transmission device works, the received navigation signal is converted into an electric signal by the receiving active antenna, and then the electric signal is filtered, amplified and filtered to output the navigation signal to the receiving radio frequency module; the receiving radio frequency module receives BDS/GPS satellite navigation signals and outputs 4bit digital intermediate frequency signals to the signal processing module; the signal processing module firstly realizes the combination of the two-way navigation digital intermediate frequency signals, then captures and tracks the combined navigation signals, outputs relevant values and channel parameters to the information processing module, and simultaneously receives channel loop control parameters, position and speed information and short message frequency offset information provided by the information processing module, wherein the loop control parameters realize the continuous stable tracking of the navigation signals, the position and speed information is the motion information of an arrow body, the motion information is used as short message communication content and is sent to the transmitting radio frequency module through BPSK spread spectrum modulation, and the short message frequency offset information is compensation of modulation frequency, so that the finally generated short message communication frequency can be accurately received; the information processing module receives the related value and channel parameter information output by the signal processing module, wherein the related value information is used for completing bit synchronization, frame synchronization, loop parameter calculation and navigation message analysis, the channel parameter information is used for realizing observed quantity extraction, and the two are matched with the final completion of position calculation and speed calculation, and the speed information obtained by calculation is used for calculating Doppler frequency shift; the transmitting radio frequency module receives the short message intermediate frequency signal output by the signal processing module, generates BDS short message radio frequency communication signal after frequency conversion and filtering, and transmits arrow body information through the power amplification module.
2. The arrow body information feedback device based on Beidou satellite navigation according to claim 1, wherein the signal processing module comprises a digital signal synthesis sub-module, a high dynamic signal capturing sub-module, a signal channel tracking sub-module and a short message medium frequency signal spread spectrum modulation sub-module;
the digital signal synthesis submodule is used for directly carrying out synchronous addition operation on two paths of input signals;
the high dynamic signal capturing submodule traverses a high dynamic Doppler range by using a frequency block searching method, adopts a mode of combining matched filtering with fast Fourier transform, and utilizes a parallel correlator group and a multipoint parallel FFT pipelining mode to realize signal searching in a frequency block and rapidly captures navigation signals; the matched filtering adopts 420 groups of correlators, the inputs of the correlators are down-sampled navigation signals and local pseudo code signals, the local pseudo code inputs of the correlators are sequentially different by half a chip, and the correlation result of each group of correlators is input into a 128-point parallel FFT module for calculation, so that the time domain and frequency domain information of the navigation signals are obtained, and the capturing is completed;
the signal channel tracking sub-module continuously locks and tracks the captured pseudo code and carrier phase, tracks code phase information by adopting a DLL code loop, tracks carrier phase information by adopting a PLL carrier loop, and tracks the carrier loop by adopting a mode of second-order frequency locking assisted third-order phase locking;
and the short message medium-frequency signal spread spectrum modulation sub-module carries out BPSK modulation on the short message information, the RDSS pseudo code and the medium-frequency carrier, wherein the frequency of the medium-frequency carrier is dynamically and in real time adjusted according to the carrier.
3. The arrow body information feedback device based on Beidou satellite navigation according to claim 1, wherein the information processing module comprises a bit synchronization sub-module, a frame synchronization sub-module, an observed quantity extraction sub-module, an electric text analysis sub-module, a positioning and resolving sub-module, a speed resolving sub-module, a frequency offset compensation sub-module and a quick out-of-lock weight positioning sub-module;
the bit synchronization sub-module adopts a histogram method or an NH coding mode to realize bit synchronization, and continuous bit data is obtained after the synchronization is successful;
the frame synchronization submodule judges whether the continuous 11bit data is 0x712 and 0x0ED, if the continuous 11bit data is judged to pass, 180-degree phase ambiguity is eliminated, BCH decoding is carried out on the subsequent 16bit message, and if the decoding passes, the frame synchronization is successful;
the observed quantity extraction submodule is used for extracting pseudo-range observed quantity information and carrier observed quantity information, and the return device extracts pseudo code phase and carrier phase count in the code ring and the carrier ring at a clock beat of 50ms to obtain pseudo-range and carrier phase information;
the message analysis submodule analyzes ephemeris parameters according to a protocol specified in the ICD file by utilizing navigation message information collected after frame synchronization to obtain orbit information and time information of satellites;
the positioning solution operator module uses satellite orbit information obtained by pseudo-range observed quantity and text analysis, and realizes positioning solution by least square operation;
the speed resolving operator module achieves speed resolving through least square operation through position information and carrier observed quantity information obtained through positioning resolving;
the frequency offset compensation sub-module performs frequency offset compensation on the short message signal under the high dynamic scene according to the following parametersCalculating to obtain Doppler compensation frequency, wherein f sd For the frequency to be compensated +.>For arrow speed, < >>Is the cosine of the direction, f l The uplink frequency of short message communication is represented by c, which is the speed of light;
the quick unlocking repositioning sub-module is triggered after the navigation signal is unlocked, firstly, the unbiased estimation of the arrow body information feedback device to the signal state before unlocking is obtained, the calculation of all parameters of the unlocking signal is maintained by utilizing the channel information before unlocking, all parameters of the unlocking signal comprise pseudo code period count, chip count, code NCO count, carrier cycle count and carrier NCO count, and normal tracking is switched after the recaptured signal meets the tracking threshold; and secondly, reserving related information of time and carrier phase before unlocking, calculating the transmitting time after unlocking and resetting by utilizing local time count and Doppler information, further obtaining a pseudo range, comparing the pseudo range with the pseudo range after resetting, and participating in positioning calculation together with the stored ephemeris information within an error range.
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