CN114095070A - Rocket body information returning device based on Beidou satellite navigation - Google Patents
Rocket body information returning 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, quantizing the navigation signals into 4-bit digital intermediate-frequency signals by using a radio frequency receiving module, then combining, capturing and tracking 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 error and clock drift calculation in an information processing module, returning arrow body position and speed information serving as short message information, carrying out Doppler frequency shift compensation according to carrier speed, then carrying out digital-to-analog conversion, intermediate-frequency filtering and orthogonal 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 method can realize the resolving of the motion information of the rocket body under high dynamic state and finish 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 60 th generation of the 20 th century in the United states is widely applied to the field of military and civilian, and provides position, speed and time service for the world and the near-earth space. China also develops the Beidou satellite navigation system (BDS for short) vigorously in the 21 st century, and through the third-stage construction, satellite navigation service can be provided for global users at present, and compared with a GPS, the short message communication service can be provided in addition to position, speed and time information.
One characteristic of the rocket-borne equipment in the recovery section is that the attitude is not controllable, so that for a single-frequency single-antenna rocket-borne navigation receiver, effective positioning cannot be realized due to insufficient satellite number, and the other characteristic is that the dynamic is large, and the short message service in a conventional application mode has a risk of failure.
Disclosure of Invention
In view of the above problems, the invention provides an rocket body information returning device based on Beidou satellite navigation, which is based on an FPGA + DSP architecture and can return rocket body information by using a BDS short message communication function.
In order to achieve the purpose, the invention adopts the technical scheme that:
an rocket body information returning device based on Beidou satellite navigation comprises a high-temperature-resistant antenna, a receiving radio frequency module, a transmitting radio frequency module, an FPGA (field programmable gate array) and a DSP (digital signal processor); 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 combination, high dynamic signal capture, signal channel tracking and short message intermediate frequency signal modulation;
the information processing module is used for completing bit synchronization, frame synchronization, observation quantity extraction, telegraph text analysis, positioning calculation, speed calculation, frequency offset compensation and quick out-of-lock relocation;
the high-temperature-resistant antenna comprises two navigation signal receiving active antennas and two short message signal sending passive antennas, and the four antennas are arranged on the outer diameter of the arrow body at intervals in a crossed mode according to phases with 90-degree phase difference; the receiving active antenna converts the space navigation signal into an electric signal, and the navigation signal with the gain of 40dB is output 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 amplification function of navigation signals and counteracts signal energy loss caused by transmission distance, the radio frequency filter circuit is realized by a band-pass filter and finishes the suppression function of image signals and interference signals, and the RNSS radio frequency circuit realizes the functions of frequency mixing, intermediate frequency filtering, automatic gain control and analog-to-digital conversion of the navigation signals and outputs 4-bit digital intermediate frequency signals;
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 FPGA short message intermediate frequency signal spread spectrum modulation, realizes digital-to-analog conversion, filtering and orthogonal up-conversion functions and outputs a short message radio frequency signal, the power amplifier circuit realizes the power amplification function of the short message radio frequency signal to meet the communication power requirement, the power switch circuit realizes the switching function of the short message radio frequency signal and outputs the short message communication signal to two high-temperature-resistant passive transmitting antennas in a time-sharing manner;
when the return device works, the receiving active antenna converts the received navigation signal into an electric signal, and then outputs the navigation signal to the receiving radio frequency module after filtering, amplifying and filtering; the receiving radio frequency module receives BDS/GPS satellite navigation signals and outputs 4-bit digital intermediate frequency signals to the signal processing module; the signal processing module firstly realizes the combination of two-way navigation digital intermediate frequency signals, then captures and tracks the combined navigation signals, outputs related 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 and stable tracking of the navigation signals, the position and speed information is motion information of an arrow body and is sent to the transmitting radio frequency module as short message communication content through BPSK spread spectrum modulation, and the short message frequency offset information is the compensation of modulation frequency, so that the finally generated short message communication frequency can be accurately received; the information processing module receives a correlation value and channel parameter information output by the signal processing module, wherein the correlation 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, the observed quantity extraction and the channel parameter information are matched to finally complete position calculation and speed calculation, and the speed information obtained through 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 a BDS short message radio frequency communication signal after frequency conversion and filtering, and sends the rocket body information out through the power amplifier module.
Furthermore, the signal processing module comprises a digital signal combining submodule, a high dynamic signal capturing submodule, a signal channel tracking submodule and a short message intermediate frequency signal spread spectrum modulation submodule;
the digital signal combining submodule is used for directly carrying out synchronous addition operation on the 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 pipeline mode to realize signal searching in a frequency block and rapidly capture a navigation signal; the matched filtering adopts 420 groups of correlators, the input of the correlators is a down-sampled navigation signal and a local pseudo code signal, the local pseudo code input of each correlator has a half chip difference in sequence, 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 signal is obtained, and the acquisition is completed;
the signal channel tracking submodule continuously locks and tracks the captured pseudo code and carrier phase, a DLL code loop is adopted to track code phase information, a PLL carrier loop is adopted to track carrier phase information, and a second-order frequency locking auxiliary third-order phase locking mode is adopted to track a carrier loop;
and the short message intermediate frequency signal spread spectrum modulation submodule carries out BPSK modulation on the short message information, the RDSS pseudo code and the intermediate frequency carrier, wherein the frequency of the intermediate frequency carrier is dynamically adjusted in real time according to the carrier.
Furthermore, the information processing module comprises a bit synchronization sub-module, a frame synchronization sub-module, an observed quantity extraction sub-module, a telegraph text analysis sub-module, a positioning calculation sub-module, a speed calculation sub-module, a frequency offset compensation sub-module and a quick lock losing relocation sub-module;
the bit synchronization submodule realizes bit synchronization by adopting a histogram method or an NH coding mode, and continuous bit data are obtained after the synchronization is successful;
the frame synchronization submodule judges whether the continuous 11-bit data is '0 x 712' or '0 x0 ED', if the continuous 11-bit data passes the judgment, 180-degree phase ambiguity is eliminated, BCH decoding is carried out on the following 16-bit telegraph text, and if the decoding passes the judgment, the frame synchronization is successful;
the observation quantity extraction submodule is used for extracting pseudo-range observation quantity information and carrier observation quantity information, and the return device extracts pseudo code phase and carrier phase counts in a code ring and a 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 an ICD file by using navigation message information collected after frame synchronization to obtain orbit information and time information of the satellite;
the positioning resolving sub-module uses the pseudo-range observed quantity and satellite orbit information obtained by telegraph text resolving to realize positioning resolving by utilizing least square operation;
the speed calculation submodule realizes speed calculation by utilizing least square operation through position information and carrier observed quantity information obtained by positioning calculation;
the frequency deviation compensation submodule carries out frequency deviation compensation on the short message signal in a high dynamic scene according to
Calculating to obtain Doppler compensation frequency, wherein fsdIn order for the frequency to be compensated for,
the speed of the arrow body is shown as the speed,
is the cosine of the direction, flThe communication uplink frequency is short message communication, and c is the speed of light;
the quick lock losing relocation submodule is triggered after a navigation signal is unlocked, firstly, unbiased estimation of an arrow body information returning device on a signal state before lock losing is obtained, calculation of each parameter of the lock losing signal is maintained by utilizing channel information before lock losing, each parameter of the lock losing signal comprises pseudo code period counting, code chip counting, code NCO counting, carrier cycle counting and carrier NCO counting, and normal tracking is switched after a recapture signal meets a tracking threshold; secondly, relevant information of relevant time and carrier phase before lock losing is reserved, local time counting and Doppler information are used for calculating the transmitting time after lock losing and re-repairing, then pseudo range is obtained and compared with the pseudo range after re-repairing, and the pseudo range and stored ephemeris information participate in positioning resolving 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 the BDS to return the arrow body information.
(2) The invention adopts a two-way navigation signal synthesis mode to improve the continuity and the usability of signals.
(3) The invention adopts PMF (matched filtering) + FFT to realize the fast capture of the high dynamic navigation signal.
(4) The invention adopts a high dynamic unlocking and re-complementing mode to realize the quick recovery capability of positioning of short-time signal unlocking.
(5) The invention adopts a frequency compensation mode to ensure the correct return of the short message information.
Drawings
FIG. 1 is a flow chart of signal processing of an apparatus according to an embodiment of the present invention.
Fig. 2 is a flow chart of the operation of an apparatus according to an 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 capture schematic of an apparatus according to an embodiment of the invention.
FIG. 5 is a block diagram of an apparatus for lost-lock resupply process according to an embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
The utility model provides an arrow body information passback device based on big dipper satellite navigation, its is based on FPGA + DSP framework, contains four ways high temperature resistant antenna, receives radio frequency front end module, intermediate frequency digital signal processing module, information processing module, transmission radio frequency module.
The four high-temperature resistant antennas are divided into two navigation signal receiving active antennas, two short message sending passive antennas and receiving antennas arranged on the outer circle axis of the arrow body at a phase interval of 90 degrees, and the receiving antennas have the functions of pre-selection filtering, low-noise amplification and band-pass filtering.
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 losing and re-supplementing module.
The navigation signal combining module adopts a mode of synthesizing after digital intermediate frequency sampling.
The high dynamic capturing module traverses a high dynamic Doppler range by adopting a frequency block search method, uses a large number of parallel correlator groups and a frequency parallel FFT pipeline mode by adopting a PMF + FFT mode, and can rapidly capture navigation signals under the condition of a lower working clock.
The carrier loop tracking mode in the loop tracking module is a second-order frequency locking auxiliary third-order phase locking mode, and the code loop tracking mode is a broadband second-order code loop.
The quick lock losing and re-supplementing module firstly obtains unbiased estimation of the rocket-borne receiver on the signal state before lock losing after the signal is unlocked, utilizes channel information before lock losing to maintain calculation of all parameters of the lock losing signal, mainly comprises pseudo code period counting, chip counting, code NCO counting and carrier NCO counting of a carrier cycle counter, and switches to normal tracking after a tracking threshold is met. Secondly, relevant information of relevant time and carrier phase before lock losing is reserved, the transmitting time after lock losing and re-repairing is calculated by using local time counting and Doppler information, then pseudo range is obtained and compared with the pseudo range after re-repairing, and the pseudo range and stored ephemeris information participate in positioning calculation within an error range.
The frequency compensation module is used for acquiring the rocket body speed information through the rocket body receiver according to
And calculating to obtain the Doppler compensation frequency.
The following is a more specific example:
an rocket body information returning device based on Beidou satellite navigation is based on a DSP + FPGA framework and comprises a double-path active antenna, a parallel receiving radio frequency front end processing part, a baseband signal digital processing part, a positioning information resolving part, a transmitting radio frequency processing part and the like, wherein the double-path active antenna, the parallel receiving radio frequency front end processing part, the baseband signal digital processing part, the positioning information resolving part, the transmitting radio frequency processing part and the like are shown in figure 1.
The active antenna converts the received navigation signal into an electric signal, then filters out potential interference and image signals through a band-pass filter, then amplifies the signal through a low-noise amplifier, and outputs the navigation signal through the band-pass filter to enter 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 signals to obtain digital intermediate frequency signals, and then enters a baseband signal digital processing module,
the baseband signal digital processing module completes logic management of the whole system, including 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 completes the functions of bit synchronization, frame synchronization processing, loop parameter calculation, observed quantity extraction, navigation message analysis, positioning calculation, Doppler frequency shift calculation, external data interaction and the like.
The transmitting radio frequency module completes analog-to-digital conversion and orthogonal up-conversion processing of the intermediate frequency signal, finally generates a short message communication signal of the BDS and sends the rocket body information to the transmitting passive antenna through the power amplifier module.
The working flow of the whole dual-mode dual-antenna navigation rocket body information returning device is shown in fig. 2, and is specifically described as follows:
the method comprises the steps of starting self-checking, wherein an rocket-borne navigation positioning control module detects whether information such as a stored ephemeris, time, a user position and the like exists or not at present so as to determine a satellite searching mode and improve capturing efficiency;
there are many combining ways for rocket-borne navigation signals, and fig. 3 lists three common combining ways, each combining way has advantages and disadvantages, and can be flexibly selected according to different application scenarios, and in this example, a way of combining after digital intermediate frequency sampling is adopted, as shown in fig. 3(2), after the navigation signals are converted into digital intermediate frequency signals through a radio frequency front end, high dynamic capture is required after synchronization because of the difference of sampling clock phases of an RNSS radio frequency circuit.
The high dynamic acquisition module traverses a high dynamic Doppler range by using a frequency block search method for visible satellites in the list, adopts a PMF + FFT mode to use a large number of parallel correlator groups and a frequency parallel FFT pipeline mode, and can quickly acquire navigation signals under the condition of a lower working clock, as shown in FIG. 4;
the input to the capture module is the down-sampled digital intermediate frequency data, which is done so that the code matched filter hardware adder can be multiplexed. The code matching filter bank comprises 420 correlators, each correlator bank has a half chip difference in sequence, the received input sampling data and the locally generated signal in the correlator banks are correlated, and then the amplitude value of the I/Q correlation result is obtained and sent to the FFT module. The FFT module performs a 128-point transform on the correlation value, the frequency resolution is calculated using the following formula,
Δf＝fs/N＝1/Nts
where Δ f is the frequency resolution, N is the number of FFT points, tsIs the sampling interval. In the embodiment, a short integration correlation value of 25 mus is adopted, so that the frequency resolution is 312.5Hz, and the frequency obtained by further estimation of the fine capture module can meet the requirement of switching to tracking. Zero values are padded prior to the FFT to reduce processing loss. The result obtained by FFT conversion is compared with the capture threshold value, and the amplitude value exceeding the threshold value and the corresponding time domain and frequency domain values are stored in a register for subsequent processing, wherein the frequency domain value can be converted into code Doppler and control the local code NCO to generate the local code.
And then, pulling to lock the frequency part of the intermediate frequency signal, thereby improving the success rate of carrier loop locking.
The motion track of the arrow body is complex, and the arrow body has larger acceleration and jerk, and a common carrier tracking loop cannot meet the large dynamic range, so that a second-order frequency-locking auxiliary third-order phase-locking mode is adopted to track the carrier loop, as shown in fig. 5, and meanwhile, broadband second-order code loop tracking is also carried out to ensure stable locking of a code phase.
If the signal is unlocked, the signal enters an unlocked re-compensation module, and the module accurately reserves relevant information of relevant time and carrier phase before the lock is unlocked, so that the capturing speed is improved, and the tracking state can be quickly recovered. The lost lock refilling flow chart is shown in fig. 5:
after the signal is unlocked, firstly acquiring unbiased estimation of the rocket-borne receiver on the signal state before unlocking, maintaining the calculation of each parameter of the unlocked signal by utilizing channel information before unlocking, mainly carrying out pseudo code period counting, chip counting, code NCO counting and carrier NCO counting by a carrier cycle counter, and switching to normal tracking after a tracking threshold is met. Secondly, relevant information of relevant time and carrier phase before lock losing is reserved, the transmitting time after lock losing and re-repairing is calculated by using local time counting and Doppler information, then pseudo range is obtained and compared with the pseudo range after re-repairing, and the pseudo range and stored ephemeris information participate in positioning resolving within an error range.
Bit synchronization:
the GPS signal bit synchronization adopts a histogram method, namely, the data jumping situation between two adjacent 1 milliseconds is counted one by one, counting processing is carried out at the jumping place, and if the counting value at the jumping place reaches a threshold value first, the bit synchronization is considered to be completed.
Due to different coding modes, the BDS No. 1-5 satellites also adopt a histogram method to realize bit synchronization, the BDS No. 6-14 satellites carry out bit synchronization by using an NH coding (00000100110101001110) mode, and 1 millisecond wide integral value output by 20 groups of carrier rings is sequentially multiplied by an NH code and accumulated, and compared with the previous result until the maximum accumulated value is obtained, namely the bit synchronization is finished.
Frame synchronization:
the last two bits of each subframe of the GPS signal are fixed as '00', so that 180-degree phase ambiguity is eliminated; searching a frame header '0 x 8B' in the TLM, and verifying the TLM; then, checking the HOW after TLM, and analyzing 17-30 bits, 18 bits and 20-22 bits; and completing the frame synchronization if all the verification passes.
The BDS signal judges whether the continuous 11 bits are '0 x 712' and '0 x0 ED', if the judgment is passed, the BCH (15,11,1) decoding is carried out on the following 16bit telegraph text after 180-degree phase ambiguity is eliminated, if the decoding is passed, the frame synchronization is successful, the frame header is judged for each following subframe, and if the frame header errors occur for five times continuously, the frame synchronization is exited.
Extracting pseudo-range observation information and carrier observation information in a loop:
the rocket-borne receiver extracts pseudo code phase and carrier phase counting information in a code ring and a carrier ring at a clock beat of 50ms, and calculates the transmitting time TsvAnd Doppler frequency shift, wherein the emission time calculation formula is as follows:
Tsv＝Nsow×1000+Nbit×20+Nepoch+Nchip/1023+Nnco/1023/65536
in the formula, is NsowSecond in week count, NbitCounting the sub-frame bits, NepochIs a pseudo code period, NchipIs the number of chips, NncoCount for pseudo-code NCO.
The pseudo-range calculation formula is as follows:
ρ＝c(Tr-Tsv)
where ρ is pseudo-range observed quantity, c is light speed, and TrIs the local time, maintained by a 50ms time beat.
Resolving the satellite position:
and analyzing the ephemeris parameters by using the navigation message information collected after frame synchronization according to a protocol specified in the ICD file to obtain six Kepler orbits of the satellite, and further calculating the position coordinates of the satellite in the geocentric and geostationary coordinate system.
And (3) resolving the position of the receiver:
in the embodiment, GPS/BDS combined positioning mode is adopted for positioning calculation to obtain the rocket body position information xu，yu，zuDue to differences in the navigation system, there will also be two clock difference unknowns δ tuGAnd δ tuB. And (3) carrying out combined processing on the pseudoranges of the BDS and the GPS by using a pseudorange fusion method to form an equation set, wherein a pseudorange observation equation is as follows:
in order to improve reliability, an autonomous integrity detection algorithm (RAIM) is adopted to perform fault detection on the satellites participating in positioning, and the RAIM is used for eliminating the 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 velocity and clock drift information can be calculated from the doppler shift after the position information is resolved, and their relationship is as follows:
where the left equations are all known quantities, c is the speed of light, fdExtracted by the receiver carrier ring for Doppler shift, fTThe actual transmitting frequency for the satellite is obtained from the nominal frequency and the frequency correction value in the message,
the velocity of the satellite motion is obtained from the ephemeris data and the orbit model,
the directional cosine is obtained from the satellite satellites and the user position,
the speed of the arrow body is shown as the speed,
is the receiver clock drift information.
The doppler shift compensation calculation formula is as follows:
in the formula (f)lAnd (c) calculating the Doppler frequency to be compensated for the BDS short message communication uplink frequency and the light speed.
In a word, the device can be applied to an rocket-borne environment, returns rocket body information by using the short message communication service of the BDS system, receives satellite navigation signals by using double antennas, fuses the BDS and the GPS system, and improves the continuity and the positioning accuracy of positioning.
Claims (3)
1. An arrow information returning 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 combination, high dynamic signal capture, signal channel tracking and short message intermediate frequency signal modulation;
the information processing module is used for completing bit synchronization, frame synchronization, observation quantity extraction, telegraph text analysis, positioning calculation, speed calculation, frequency offset compensation and quick unlocking relocation;
the high-temperature-resistant antenna comprises two navigation signal receiving active antennas and two short message signal sending passive antennas, and the four antennas are arranged on the outer diameter of the arrow body at crossed intervals according to phases with 90-degree phase difference; the receiving active antenna converts the space navigation signal into an electric signal, and the navigation signal with the gain of 40dB is output 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 amplification function of navigation signals and counteracts signal energy loss caused by transmission distance, the radio frequency filter circuit is realized by a band-pass filter and finishes the suppression function of image signals and interference signals, and the RNSS radio frequency circuit realizes the functions of frequency mixing, intermediate frequency filtering, automatic gain control and analog-to-digital conversion of the navigation signals and outputs 4-bit digital intermediate frequency signals;
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 FPGA short message intermediate frequency signal spread spectrum modulation, realizes digital-to-analog conversion, filtering and orthogonal up-conversion functions and outputs a short message radio frequency signal, the power amplifier circuit realizes the power amplification function of the short message radio frequency signal to meet the communication power requirement, the power switch circuit realizes the switching function of the short message radio frequency signal and outputs the short message communication signal to two high-temperature-resistant passive transmitting antennas in a time-sharing manner;
when the return device works, the receiving active antenna converts the received navigation signal into an electric signal, and then outputs the navigation signal to the receiving radio frequency module after filtering, amplifying and filtering; the receiving radio frequency module receives BDS/GPS satellite navigation signals and outputs 4-bit digital intermediate frequency signals to the signal processing module; the signal processing module firstly realizes the combination of two-way navigation digital intermediate frequency signals, then captures and tracks the combined navigation signals, outputs related 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 and stable tracking of the navigation signals, the position and speed information is the motion information of an arrow body and is sent to the transmitting radio frequency module as the short message communication content through BPSK spread spectrum modulation, and the short message frequency offset information is the compensation of modulation frequency, so that the finally generated short message communication frequency can be accurately received; the information processing module receives a correlation value and channel parameter information output by the signal processing module, wherein the correlation 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, the observation quantity extraction and the channel parameter information are matched to finally complete position calculation and speed calculation, and the calculated speed information 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 a BDS short message radio frequency communication signal after frequency conversion and filtering, and sends the rocket body information out through the power amplifier module.
2. The rocket body information returning device based on Beidou satellite navigation according to claim 1, wherein the signal processing module comprises a digital signal combining sub-module, a high dynamic signal capturing sub-module, a signal channel tracking sub-module and a short message intermediate frequency signal spread spectrum modulation sub-module;
the digital signal combining submodule is used for directly carrying out synchronous addition operation on the 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 pipeline mode to realize signal searching in a frequency block and rapidly capture a navigation signal; the matched filtering adopts 420 groups of correlators, the input of the correlators is a down-sampled navigation signal and a local pseudo code signal, the local pseudo code input of each correlator has a half chip difference in sequence, 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 signal is obtained, and the capturing is completed;
the signal channel tracking submodule continuously locks and tracks the captured pseudo code and carrier phase, a DLL code loop is adopted to track code phase information, a PLL carrier loop is adopted to track carrier phase information, and a second-order frequency locking auxiliary third-order phase locking mode is adopted to track a carrier loop;
and the short message intermediate frequency signal spread spectrum modulation submodule carries out BPSK modulation on the short message information, the RDSS pseudo code and the intermediate frequency carrier, wherein the frequency of the intermediate frequency carrier is dynamically adjusted in real time according to the carrier.
3. The rocket body information returning device based on Beidou satellite navigation is characterized in that the information processing module comprises a bit synchronization sub-module, a frame synchronization sub-module, an observation quantity extraction sub-module, a text analysis sub-module, a positioning calculation sub-module, a speed calculation sub-module, a frequency deviation compensation sub-module and a quick unlocking relocation sub-module;
the bit synchronization submodule realizes bit synchronization by adopting a histogram method or an NH coding mode, and continuous bit data are obtained after the synchronization is successful;
the frame synchronization submodule judges whether the continuous 11-bit data is '0 x 712' or '0 x0 ED', if the continuous 11-bit data passes the judgment, 180-degree phase ambiguity is eliminated, BCH decoding is carried out on the following 16-bit telegraph text, and if the decoding passes the judgment, the frame synchronization is successful;
the observation quantity extraction submodule is used for extracting pseudo-range observation quantity information and carrier observation quantity information, and the return device extracts pseudo code phase and carrier phase counts in a code ring and a 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 an ICD file by using navigation message information collected after frame synchronization to obtain orbit information and time information of the satellite;
the positioning resolving submodule uses the pseudo-range observed quantity and satellite orbit information obtained by telegraph text resolving to realize positioning resolving by utilizing least square operation;
the speed resolving submodule realizes speed resolving by utilizing least square operation through position information and carrier observed quantity information obtained by positioning resolving;
the frequency deviation compensation submodule carries out frequency deviation compensation on the short message signal in a high dynamic scene according to
Calculating to obtain Doppler compensation frequency, wherein fsdIn order for the frequency to be compensated for,
the speed of the arrow body is shown as the speed,
is the cosine of the direction, flThe communication uplink frequency is short message communication, and c is the speed of light;
the quick lock losing relocation submodule is triggered after a navigation signal is unlocked, firstly, unbiased estimation of an arrow body information returning device on a signal state before lock losing is obtained, calculation of each parameter of the lock losing signal is maintained by utilizing channel information before lock losing, each parameter of the lock losing signal comprises pseudo code period counting, code chip counting, code NCO counting, carrier cycle counting and carrier NCO counting, and normal tracking is switched after a recapture signal meets a tracking threshold; secondly, relevant information of relevant time and carrier phase before lock losing is reserved, the transmitting time after lock losing and re-repairing is calculated by using local time counting and Doppler information, and then pseudo range is obtained and compared with the pseudo range after re-repairing, and the pseudo range and stored ephemeris information participate in positioning resolving within an error range.
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