CN102141627A - Burst type navigation signal system and receiving method - Google Patents

Abstract

The invention discloses a burst navigation signal system and receiving method, which relates to space technology. The signal broadcasting carrier can be a navigation satellite, a space balloon or an airship, etc.; the navigation signal comes from: a direct satellite navigation system or a transponder satellite The burst satellite navigation beacons broadcast by the navigation system satellites, or intermittent satellite navigation signals; the user terminal uses a high-gain antenna to cover the sky in time-sharing by two-dimensional scanning in elevation and azimuth. For satellites within the pointing range of the high-gain antenna , has the additional advantage of the signal-to-interference ratio endowed by the antenna gain, so as to achieve the effect of anti-interference. The present invention utilizes the burst signal system and receiving method to effectively avoid the problem of large-area phased array antennas in traditional airspace anti-jamming measures, and is also convenient to implement time-frequency domain anti-jamming measures at the same time, and is easy to set up in small and highly maneuverable areas. On the weapon platform, the cost is low and the reliability is high.

Description

A Burst Navigation Signal System and Receiving Method

technical field

The invention relates to the field of space technology, in particular to a burst navigation signal system and receiving method.

Background technique

The wide application of satellite navigation has given birth to the concept of "navigation confrontation". With the continuous upgrading of navigation countermeasure technology, various jamming methods to deal with satellite navigation receivers emerge in endlessly; from the perspective of jamming signal system, there are pulse jamming, decoy jamming, broadband noise suppressive jamming, broadband FM suppressive jamming, narrowband Jamming, etc.; from the carrier of the jammer, there are ground-mounted jammers, balloon-borne high-altitude jammers, and aircraft-borne jammers. As a means to deal with interference, various anti-jamming measures have also emerged. From the perspective of navigation receivers, there are anti-jamming technologies through various time-domain filters, anti-jamming technologies through frequency-domain filters, and airspace through antenna arrays. Filter anti-interference technology, etc. "Interference" and "anti-interference" are an endless relationship between "spear" and "shield". From the perspective of "shield", it is very meaningful to continuously develop anti-interference means with better performance and lower cost things.

The design of the entire satellite navigation system is based on the starting point of the receiver continuously receiving satellite navigation signals, so most of the existing satellite navigation receivers are designed based on the idea of continuously tracking satellite navigation signals. On the Internet, we have not found any report on the satellite navigation method using burst signals for navigation and positioning.

Contents of the invention

The purpose of the present invention is to disclose a burst-type navigation signal system and an anti-jamming satellite navigation receiving method based on burst signals, use burst satellite navigation signals for navigation and positioning, and establish a low-cost, high-dynamic, anti-jamming system based on burst signals The satellite navigation receiving system enhances the service capability of the satellite navigation system in the navigation confrontation environment.

For achieving the above object, technical solution of the present invention is:

A "burst" navigation signal system, which includes:

A) The signal dissemination carrier can be a navigation satellite, a space balloon or an airship;

B) The navigation signal comes from:

a) Burst navigation beacons broadcast by the direct navigation satellite itself;

b) The ground station of the transponder satellite navigation system uplinks to the satellite and then transmits the burst satellite navigation beacon through the satellite;

c) When the enemy interferes intermittently with the continuous navigation signals broadcast by our navigation satellites, the "clean fragment" satellite navigation signals received by the receiver during the intermission period;

d) When the enemy continuously interferes with the continuous navigation signals broadcast by our navigation satellites, the receiver rotates the satellite navigation signal antenna, and when the antenna is aligned with the navigation satellites, the burst satellite navigation with a better signal-to-interference ratio is received Signal;

C) User terminal:

Use a high-gain antenna to cover the sky in time-sharing by two-dimensional scanning in elevation and azimuth. For satellites within the pointing range of the high-gain antenna, it has an additional signal-to-interference ratio advantage endowed by the antenna gain, so as to achieve the effect of anti-interference; This anti-jamming method avoids the problem of large-area phased array antennas in traditional airspace anti-jamming measures, and it is also convenient to implement time-frequency domain anti-jamming measures at the same time. It is easy to set up on small and highly maneuverable weapon platforms, and the cost is low. High reliability.

In the burst navigation signal system, the burst navigation signal, or "pulse" type, the duration of the signal pulse is between 10 milliseconds and 1 second; for the direct sending satellite navigation system, This signal system provides another possible way to realize the regional enhancement of navigation signals on navigation satellites: the satellite navigation signal adopts the burst pulse form, and the power amplifier on the satellite only needs to increase the radiation power during the pulse duration. When the duty cycle of the signal is low, it can greatly reduce the implementation difficulty of navigation signal area enhancement.

In the burst navigation signal system, when the duty cycle of the burst signal is relatively low, it means that the duty cycle is about 10%.

The burst navigation signal system adopts a shorter and faster navigation message. Since the satellite navigation signal adopts a burst pulse form, the power amplifier on the satellite increases the radiation power during the pulse duration to improve the satellite signal transmission power. Afterwards, the navigation message is broadcast at a faster transmission rate.

In the burst navigation signal system, the satellite navigation signal antenna is a high-gain antenna with a gain ≥ 5dBic, which covers the sky in time-sharing by two-dimensional scanning in elevation and azimuth.

A navigation and positioning receiving method based on a burst signal satellite for a user terminal in the navigation signal system, no matter what kind of signal source, from the perspective of the user terminal, the satellite navigation signal received by the burst satellite navigation terminal is "burst" The burst signal navigation receiver can only measure the pseudo-range and Doppler frequency according to the non-continuous intermittent signal, and perform navigation and positioning calculation; including steps:

1) Pseudorange extraction method, first, extract the spreading code from the received burst satellite navigation signal, and then adopt the traditional serial or parallel search algorithm to obtain the rough estimation of code phase and Doppler frequency; On the basis of the estimation, the code phase is refined and refined to obtain a fine code phase;

2) The Doppler frequency extraction method, starting from the code phase of the coarse capture or the refined code phase, strips the spreading code from the burst satellite navigation signal, and then uses the classical spectrum estimation or modern spectrum estimation method to calculate the frequency of the navigation signal. Doppler frequency;

3) The navigation parameter calculation method, using the inertial navigation component IMU observations combined with the satellite navigation pseudo-range and Doppler observations to jointly solve the receiver navigation parameters: use the auxiliary information of the inertial navigation IMU component to determine the position of the receiver , and speed are constrained to a certain extent. At the same time, a high-stability frequency source is used to maintain the time between the burst satellite navigation signal pulses received at different times. The Kalman filter method is used to obtain the pseudorange and multiple The position, velocity and time information are calculated from the Puller information.

In the navigation and positioning receiving method, the code phase refinement process is based on a rough estimate of the code phase and Doppler frequency, and uses a finer search step size and a method of correlation peak shape curve fitting to accurately obtain the decoding The phase and refinement search adopts the Zoom FFT algorithm. At the same time, the position integral and instantaneous velocity information given by the inertial navigation aid are used to further reduce the calculation amount of the refinement code phase search

In the navigation and positioning receiving method, the code phase, in the case of a short code period, there is an integer corresponding to the code period between the obtained refined code phase and the actual pseudorange Fuzzy distance, for GPS and GLONASS civilian codes, the fuzzy distance is an integer multiple of 300 kilometers, and this integer multiple must be solved correctly. The solution of this integer multiple is to reconstruct the transmission time of the signal in units of code periods.

Said navigation and positioning receiving method, the measurement of speed in said navigation parameters, uses the direct periodogram method to estimate the Doppler frequency shift of the burst GPS signal, calculates the line-of-sight change rate, establishes the line-of-sight change rate equation, and then obtains receiver speed.

Said navigation and positioning receiving method, said navigation parameter solution method, drifts in time due to the clock error of the satellite navigation receiver, so a relatively precise time measurement is carried out between each burst satellite navigation signal pulse Maintain, calibrate the frequency accuracy of the crystal oscillator, within a few seconds, keep the arrival time of each burst satellite navigation signal pulse within 10 nanoseconds; In order to overcome the influence of insufficient pseudo-range and Doppler frequency observations in a single burst satellite navigation signal, the navigation parameters can be solved reliably by using multi-burst satellite navigation signals.

Said navigation and positioning receiving method, said Doppler frequency estimation and velocity calculation flow, include:

S1. Perform frequency-domain FFT capture on the original intermediate frequency sampling signal, and roughly capture the code phase and Doppler frequency shift of the signal by means of parallel code phase search and capture;

S2. After capturing the initial code phase and Doppler frequency shift, further refine the Doppler frequency shift;

S3. Perform refinement processing on the initially captured code phase to obtain an ideal refined code phase;

S4. Using the code phase refined in step S3 to readjust the local code, perform modulo two addition operation with the original signal, and peel off the C/A code. For high dynamic situations, the frequency generated by the local code generator should be readjusted according to the Doppler frequency shift added to the C/A code;

S5. Perform periodogram estimation on the intermediate frequency carrier plus noise signal obtained after stripping the C/A code, and the frequency corresponding to the obtained spectral peak maximum value is the estimated carrier Doppler frequency shift;

S6, according to the line-of-sight change rate equation between the Doppler frequency shift and the receiver and the GPS satellite, use the least square method to solve the line-of-sight change rate equation of n (n≥4) satellites, that is, the user speed and the user receiver Clock rate of change.

The burst type satellite navigation signal system of the present invention provides another possible way for realizing the area enhancement of navigation signals on navigation satellites. The satellite navigation signal adopts a burst pulse form, and the power amplifier on the satellite only needs to increase the radiation power during the pulse duration. When the duty cycle of the burst signal is relatively low (such as about 10%), the area enhancement of the navigation signal can be greatly reduced. Difficulty of implementation. There are two types of means to realize the regional enhancement of navigation signals on navigation satellites. One is to increase the power of the navigation signal transmitted by the navigation satellite, and the other is to concentrate the limited navigation signal power in a smaller local area by increasing the radiating antenna diameter of the navigation signal on the satellite. The first method is used to realize the regional enhancement of the navigation signal. If the satellite navigation signal is a continuous wave signal, it means that the power consumption of the power amplification payload on the satellite increases sharply, and it brings the difficulty of thermal control on the satellite; through the second There are two ways to realize the enhancement of the navigation signal area, which means that a large-caliber antenna must be configured on the satellite, which brings difficulties to satellite manufacturing.

The broadcasting of the burst type satellite navigation signal of the present invention is also very convenient in the forwarding type satellite navigation system, as long as the uplink navigation signal of the ground control station to the satellite is changed into a burst type, the burst type signal broadcasting of the satellite to the user can be realized. In the case of using burst signals, it is more convenient to hide the navigation signals in the normal broadcast signals of communication satellites, especially by deliberately reducing the frequency of burst signals (reducing the duty cycle), which is very conducive to the implementation of navigation warfare .

For weapon platforms with low cost, small size, and high maneuverability (such as medium and long-range weapon strike systems, etc.), in order to combat the enemy's electromagnetic interference, we can set a high-gain satellite navigation antenna on the weapon platform to use pitch and azimuth. Time-sharing coverage of the sky in a three-dimensional scanning manner. At this time, each satellite navigation beacon signal always arrives in time-sharing, which has the feature of bursting. Likewise, enemy jamming signals are time-division and fragmented, and are likely not to overlap in time with navigation beacon signals (unless the jamming source is in the same direction as the satellite navigation satellite). In this case, for the satellites within the pointing range of the high-gain antenna, there is an additional signal-to-interference ratio advantage endowed by the antenna gain, so as to achieve the effect of anti-interference.

The present invention can also be applied in application occasions such as sea surface sonar buoy positioning, forest area, because the reasons such as sea wave slapping receiver antenna and branches and leaves blocking, the signal that receives also will be burst; Spinning shells, spinning missiles, fighters and other applications) in harsh dynamic environments, because the receiver antenna is often not omnidirectional, the received navigation signals are often fragmented and also have burst characteristics.

Description of drawings

Fig. 1 is a kind of burst type navigation signal system structure schematic diagram of the present invention;

Fig. 2 is the refined code phase flowchart of the navigation positioning receiving method of the present invention;

Fig. 3 is a schematic diagram of the signal length and the estimated code phase accuracy curve of the navigation and positioning receiving method of the present invention;

Fig. 4 is the constraint boundary schematic diagram of initial position and time error of the inventive method under GPS CA code condition;

Fig. 5 is the flow chart of seeking Doppler and speed for the navigation and positioning receiving method of the present invention;

Figure 6 Contour diagram of the mean square error of Doppler frequency shift estimation under different carrier-to-noise ratios and different signal lengths, where the unit of the contour is Hz;

Fig. 7 is the receiver speed setting curve diagram when the present invention utilizes the GPS high dynamic simulator to simulate;

Fig. 8 utilizes the signal acquisition flowchart of GSS7700 emulator analog signal and acquisition process for the present invention;

Fig. 9 is a schematic diagram of velocity measurement errors when C/N ₀ =43dBHz burst signal lengths are 10ms and 15ms respectively.

Detailed ways

A kind of burst type navigation signal system and receiving method of the present invention, the concept of its burst signal navigation is:

The main sign of burst satellite navigation is that, from the perspective of the user terminal, the satellite navigation signal received by the burst satellite navigation terminal is "burst", or "pulse", which is the difference between burst satellite navigation and The hallmark difference of traditional continuous signal satellite navigation.

In the burst satellite navigation system, the burst satellite navigation signal seen from the receiving terminal can come from the following situations:

●Burst navigation beacons broadcast by the direct navigation satellite itself;

●The ground station of the forwarding satellite navigation system uplinks to the satellite and then forwards the burst satellite navigation beacon through the satellite;

●When the enemy interferes intermittently with the continuous navigation signals broadcast by our navigation satellites, the “segmented clean” satellite navigation signals received by the receiver during the intermission period;

When the enemy continuously interferes with the continuous navigation signals broadcast by our navigation satellites, the receiver rotates the high-gain satellite navigation signal antenna, and when the antenna is aligned with the navigation satellites, the received burst satellites with better signal-to-interference ratio navigation signal.

A burst navigation signal system and receiving method of the present invention:

1. System composition and principle

The satellite navigation system based on burst signals has no essential difference from the traditional satellite navigation system in terms of system-level structure, and is also composed of navigation satellite constellations, ground measurement and control, and user receiving terminals.

1) In the space segment, the navigation signal transmitted by the satellite navigation constellation has the characteristics of "burst", and the duration of the burst signal pulse is about 10 milliseconds to 1 second. The modulation of the burst navigation signal is similar to that of the traditional satellite navigation system signal. First, the The navigation message is spread by pseudo code, and then the combined code after the spread is modulated on the carrier. However, the burst navigation signal system can use shorter and faster navigation messages. Since the satellite navigation signal adopts the burst pulse form, the power amplifier on the satellite can increase the radiation power during the pulse duration and increase the satellite signal transmission power. Navigation messages can be broadcast at a faster transmission rate. The basic format with a length of 300bit and a sending time of 12s can be used for broadcasting. The navigation message is composed of different types of data blocks according to the content, and the time interval for broadcasting different data content is different.

2) User segment

The working principle of the receiving system based on the burst navigation signal:

From the perspective of the functions that the receiver itself must have to complete the navigation task, the main difference between the burst signal satellite navigation receiver and the traditional continuous signal receiver is that the burst signal satellite navigation receiver is based on the fragmentary pulse signal extraction pseudo range, Doppler frequency and other basic observations, so its pseudorange and Doppler extraction algorithms are fundamentally different from those of traditional receivers; due to the burst signal satellite navigation receiver may not be able to receive more than 4 signals at the same time The satellite navigation signal and the navigation message cannot be obtained by continuous tracking of the signal. Therefore, the algorithm for calculating the navigation parameters from the pseudorange and Doppler is also very different from the traditional receiver.

Below in conjunction with a typical battlefield environment, the situation of using a burst signal-based anti-jamming satellite navigation receiving technology of the present invention for a low-cost anti-jamming receiver on a micro-miniature, high-mobility platform is introduced.

In general, for cost-sensitive, small-sized, and highly maneuverable weapon platforms, high-gain antennas are used to cover the sky in time-sharing by two-dimensional scanning in elevation and azimuth. At this time, each satellite navigation beacon signal always arrives in time-sharing, which is bursty. Similarly, the interference signal is also time-sharing and intermittent, and does not overlap in time with the navigation beacon signal (unless the interference source is in the same spatial direction as the navigation satellite). In this case, for the satellites within the pointing range of the high-gain antenna, there is an additional signal-to-interference ratio advantage endowed by the antenna gain, so as to achieve the effect of anti-interference. To put it another way, in this way, the traditional anti-jamming problem in the air domain is transformed into a time-domain anti-jamming problem, and then the time-frequency domain signal processing method is used to further suppress the interference, and the pseudo-range is calculated using the burst signal. , Doppler frequency and other basic observations, and then complete the navigation and positioning calculation.

The anti-jamming method of the present invention avoids the problem of large-area phased array antennas in traditional airspace anti-jamming measures, and is also convenient for implementing time-frequency domain anti-jamming measures at the same time. , high reliability.

From the perspective of the receiver structure, the structure of the burst signal satellite navigation receiver can be similar to the traditional receiver. As shown in Fig. 1, it is a demonstration system structure diagram of a burst signal-based anti-jamming satellite navigation receiving method of the present invention, and it is a low-cost time-space-frequency anti-jamming receiver of a microminiature, highly maneuverable platform. In the figure, antenna 1 has a high gain and has the ability to scan the two-dimensional airspace in pitch and azimuth; the radio frequency front end 2 and A/D converter 3 follow the popular design of traditional continuous signal receiver; the inertial navigation aid 4 adopts micro-inertia Guide MIMU components; the digital signal processing platform 5 is composed of large-scale FPGA and high-performance DSP to meet the needs of extracting pseudorange and Doppler frequency from burst signals and calculating navigation parameters.

The difference between the anti-jamming satellite navigation receiver based on the burst signal and the traditional continuous signal receiver is mainly the following three points:

●In the selection of antenna 1, since the anti-jamming satellite navigation receiver based on the burst signal of the present invention does not require at least receiving the navigation signals of more than 4 navigation satellites at the same time, therefore, according to different application requirements, the antenna 1 can The choice is high gain or normal. This is different from traditional continuous signal receivers;

The anti-jamming satellite navigation receiver based on the burst signal of the present invention needs the assistance of the inertial navigation component IMU or the navigation message and the crystal oscillator with certain stability and accuracy requirements; when applied to the harsh battlefield environment, it cannot Obtaining continuous satellite navigation signals may also require external input of navigation satellite ephemeris and other navigation messages. It is worth pointing out that for traditional receivers, it is very likely that they will not receive complete navigation messages in harsh battlefield environments;

The anti-jamming satellite navigation receiver based on the burst signal of the present invention is based on the basic observations such as extracting pseudo-range and Doppler frequency from the fragmented pulse-type signal, so its pseudo-range and Doppler extraction algorithms have similarities with traditional receivers Essentially different; in addition, because the anti-jamming satellite navigation receiver based on the burst signal of the present invention is likely not simultaneously to the pseudo-range of different navigation satellites, Doppler frequency observation, therefore, from pseudo-range and Doppler solution navigation The algorithm of the parameters is also very different from the traditional receiver.

In the following, the principle of pseudorange and Doppler frequency extraction and the navigation parameter (position, velocity, time) calculation principle of the burst signal-based anti-jamming satellite navigation receiving method of the present invention will be explained emphatically.

It is conceivable that if the navigation satellite broadcasts a navigation signal specially designed for the burst satellite navigation system, the launch time of the navigation signal on the satellite may be relatively easy to extract from the signal. For the case of a burst segment in the continuous navigation signal received by the receiver, it is much more difficult to recover the code phase. Therefore, the following description will focus on the case of receiving burst segment content in continuous satellite navigation signals.

(1) Pseudorange extraction principle

Pseudorange is the basis for the navigation receiver to calculate position and time information. To obtain the pseudorange corresponding to a certain navigation satellite from the burst navigation signal, the most important thing is to obtain the following two quantities: one is the code phase of the navigation satellite spreading code corresponding to the measurement time of the receiver, and the other is the code phase received by the receiver. The code phase of is at the launch time on the satellite.

For a burst signal output by the A/D converter received by the digital signal processing unit of the receiver, it may contain a navigation signal corresponding to a certain satellite. The spreading code sequences of different satellite navigation signals correspond to different spreading code periods. For example, the spreading code period of the L1 CA code of GPS is 1ms, the spreading code period of the GPS L2C code is divided into two types, and the spreading code period of the L2CM code is The code period is 20ms, the code period of L2CL code is 1.5s; the code period of GLONASS civil code is 1ms; the code period of Beidou-2 system civilian code is 2ms; the code period of GPS, GLONASS and Beidou system is very long.

The first step in extracting the pseudorange is to extract the fine code phase of the spread spectrum code from the received signal. To achieve this goal, the traditional serial or parallel search algorithm can be used first to obtain the code phase and Doppler frequency rough estimate. On this basis, the code phase is finely refined, as shown in Figure 2, to obtain a fine code phase.

The core idea of the code phase refinement process is to use a more refined search step size and correlation peak shape curve fitting method to accurately obtain the decoding phase on the basis of rough estimation of the code phase and Doppler frequency. The refinement search can use Zoom FFT Algorithm to speed up the search speed. At the same time, the position integral and instantaneous velocity information given by the inertial navigation aid can be used to further reduce and refine the calculation amount of the code phase search. The detailed calculation is a well-known technology, and will not be repeated here. As shown in Figure 3, the relationship between the code phase refinement accuracy obtained by Monte Carlo simulation and the effective length of the burst signal and the signal-to-noise ratio is given. The preset real code phase in the figure is 0.982 chips of the CA code. From the figure It can be seen from Fig. 3 that by using the method of refining the code phase, better code phase estimation accuracy can be achieved.

In the case of a short code period (such as GPS, GLONASS, Beidou No. 2 system civilian code, etc.), due to the short code period, there is still a code period correspondence between the refined code phase obtained above and the actual pseudorange Integer blur distance. For GPS and GLONASS civil codes, the fuzzy distance is an integer multiple of 300 kilometers, and this integer multiple must be solved correctly. To put it another way, the solution of this integer multiple is to reconstruct the transmission time of the signal in units of code periods.

For the ambiguous distance that is an integer multiple of 300 kilometers, if the location of the receiver and the local time of the receiver are roughly known, since 300 kilometers is already a large number, it is relatively easy to reconstruct the signal transmission time. As shown in Figure 4, the error boundary constraints of the receiver's initial rough position and time required for correct reconstruction of the signal transmission time for the GPS civil code signal obtained by our analysis are given. It can be seen from Fig. 4 that even for GPS and GLONASS civil codes with short code periods, the requirements for prior knowledge of receiver position and time are very loose.

For various military code signals and GPS L2 civilian code signals, since the spreading code period is very long, the reconstruction of the signal transmission time on the navigation satellite is much easier than that of GPS civilian code and GLONASS civilian code.

(2) Doppler frequency extraction principle

In the case of continuous signals, usually, the measurement of the Doppler frequency shift of the carrier frequency is to continuously track the received GPS signal, adjust the frequency of the local carrier and code generator through the carrier tracking loop and the code tracking loop, so that the local Carrier, code and input signal are synchronized to obtain Doppler frequency shift. This method is essentially based on approximately infinitely long continuous signals, and is obviously not suitable for burst signal applications. After analysis and comparison, the periodogram method of classic spectrum estimation is used to estimate the frequency of finite length signals, which is characterized by simple implementation and strong real-time performance, especially when the signal-to-noise ratio is low, higher resolution can be obtained.

The Doppler frequency is the basis for the digital signal processing unit to calculate the motion speed of the receiver. The core of solving the Doppler frequency is to start from the coarsely captured code phase or refined code phase, and strip the spread spectrum code from the burst navigation signal , and then calculate the Doppler frequency of the navigation signal by using classical spectrum estimation or modern spectrum estimation method.

In the simulation experiment, using the classic spectrum estimation method can obtain better Doppler frequency estimation accuracy, and the calculation time is relatively short. As shown in Figure 5, the flow of Doppler frequency estimation and velocity calculation is given.

S1, the original intermediate frequency sampling signal is shown in formula (1):

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; IF</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, y _j is the intermediate frequency signal received by the jth satellite at the sampling time τ _j ; p _r is the power of the received signal; d(τ) is the 50Hz navigation message modulation; t _s (τ) is the signal transmission delay; C (τ) is the 1.023MHz C/A code spreading sequence; ω _IF is the received signal carrier intermediate frequency angular frequency; ω _d is the Doppler frequency shift between the receiver and the satellite; φ ₀ is the initial value of the carrier phase; n _j is zero-mean Gaussian white noise with variance δ _n ² ;

Firstly, the frequency-domain FFT acquisition is carried out, and the code phase and Doppler frequency shift of the signal are roughly captured by the method of parallel code phase search and acquisition.

S2. After capturing the initial code phase and Doppler frequency shift, further refine the Doppler frequency shift according to the carrier phase difference at two moments n and m in a short time (as shown in Equation 2).

$\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

S3. Perform refinement processing on the initially captured code phase to obtain an ideal refined code phase.

S4. Using the refined code phase to readjust the local code, perform modulo two addition operation with the original signal, and strip the C/A code. For high dynamic situations, it is necessary to readjust the frequency generated by the local code generator according to the Doppler frequency shift added to the C/A code. The Doppler frequency shift f _dr added to the L1 carrier is the same as that added to the C The Doppler frequency shift f _dCA ratio relationship on the /A code is shown in Equation 3:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Ca</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 1540</span>}}{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; dr</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

S5, carry out cycle spectrum estimation (such as formula 5) with the intermediate frequency carrier plus noise signal (as formula 4) obtained after the C/A code is stripped off, the frequency corresponding to the peak value of the obtained spectrum is the estimated carrier Doppler Le shift.

${\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; IF</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&phi;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}{<span\; class="notranslate">\; |</span>\underset{\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="HSA00000019099900042.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;nf</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; |</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

S6. The relationship between the Doppler frequency shift and the distance (line of sight LOS) change rate (that is, the radial velocity) between the receiver and the GPS satellite is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}{\mathrm{<span\; class="notranslate">\; c</span>}}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

where f _r is the carrier frequency of the satellite signal. From formula (6), it can be seen that as long as the Doppler frequency shift of the carrier frequency is measured, the line-of-sight change rate can be obtained That is, the observed value of velocity. According to the line-of-sight change rate equation (as shown in Equation 7), using the least squares method to solve the line-of-sight change rate equation of n (n≥4) satellites, the user speed and the user receiver clock error change rate can be solved

${\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&CenterDot;</span>}{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; z</span>}}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; z</span>}}<span\; class="notranslate">\; )</span>}{\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; z</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\stackrel{<span\; class="notranslate">\; \&Center\; Dot;</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

是用户接收机钟差的变化率，

是由第i颗卫星无线电传播延迟误差等引起的延迟变化率，因为测距过程的时间间隔很短，这一项可以忽略不计。in,

is the rate of change of the clock error of the user receiver,

is the delay change rate caused by the i-th satellite radio propagation delay error, etc., because the time interval of the ranging process is very short, this item can be ignored.

Simulation

In order to objectively analyze the speed measurement performance of the above methods, two sets of simulation experiments were designed:

The first group, in order to verify and analyze the accuracy of Doppler frequency shift and speed measurement by using the periodogram method under different signal-to-noise ratios and different instantaneous signal lengths, a static intermediate frequency signal was simulated with Matlab. For this group of signals, we know exactly which True code phase and Doppler shift for comparative analysis with measured estimates.

The sampling rate of the signal is 5×10 ⁶ Hz, and the intermediate frequency is 1.25MHz. The intermediate frequency sampling signals when the C/N ₀ value is from 35dBHz to 49dBHz are respectively simulated. When the refined code phase accuracy reaches 0.01 chips, use The intercepted instantaneous signals of different lengths of 10-30 ms are used to estimate the Doppler frequency shift by the above method. Do 1000 Monte Carlo simulations for signals with different lengths and different signal-to-noise ratios, and the mean square error between the obtained Doppler frequency shift and the true value is shown in Figure 6. The burst satellite navigation signal can estimate the Doppler frequency shift with high precision.

The second group, using the GSS7700GPS simulator of the British company Spirent, conducted a simulation experiment on the speed measurement accuracy of burst satellite navigation signals under high dynamic conditions

A) First set the receiver speed change curve on the emulator, as shown in Figure 7;

B) As shown in Figure 8, the original signal simulated by the emulator is connected to the RF front-end. The RF front-end uses a GPS receiver OEM board. The 1575.42MHz GPS L1 radio frequency signal is down-converted three times to an analog intermediate frequency of 4.3MHz, and then sampled with a sampling frequency of 5.714MHz. At the same time, the symbol amplitude of the sampled signal is quantized with 2-bit precision, and finally Two digital intermediate frequency signals of 1.414MHz including sign and amplitude are obtained. The data acquisition unit uses a DSP processing system, and the specific chip model is TMS320C6713 (floating point, 200Hz main frequency, 1800MIPS) of TI Company. This configuration is to transplant the algorithm to the real-time running hardware platform after the algorithm is successfully simulated in the software simulation environment. . Finally, the emulator is used to store the real-time GPS intermediate frequency signal collected by the DSP to the PC in the form of a data file through the JTAG test port.

C) About 40 seconds of data were collected continuously for 5 satellites. And pre-stored ephemeris for a period of time.

D) Then use the Doppler frequency solution method to measure the speed of the receiver.

It can be seen from Figure 9 that even in the case of high dynamics, the use of burst satellite navigation signals can achieve a certain accuracy. If the signal-to-noise ratio of the signal is stronger (this is entirely possible), or the effective signal The longer the length, the speed measurement accuracy can be significantly improved.

(3) Principle of navigation parameter calculation

The so-called navigation parameters refer to receiver position, speed, time and other information.

Since a single burst signal may not contain enough signals of navigation satellites (4), in some cases, using a single burst signal may not be sufficient to independently resolve receiver position, velocity and time information. Therefore, the basic idea and principle of navigation parameter calculation is: use the auxiliary information of the inertial navigation IMU component to constrain the position and velocity of the receiver to a certain extent, and at the same time use the high stability frequency The time is maintained during the interval, and the position, velocity and time information are calculated from the pseudorange and Doppler information obtained from different burst signals by using the Kalman filter method.

In the existing research at home and abroad, the IMU observations of the inertial navigation component are combined with the satellite navigation pseudorange and Doppler observations to jointly solve the receiver navigation parameters. There have been many mature results, which can be targeted to borrow.

Since the clock error (clock error for short) of the satellite navigation receiver drifts in time, it is very important to maintain a relatively precise time between each burst signal pulse. Considering that the time interval between different burst signal pulses arriving at the receiver is generally not too large, the maximum is generally on the order of seconds. Therefore, a better crystal oscillator is used, and the frequency accuracy of the crystal oscillator is calibrated, within a few seconds , it is entirely possible to keep the arrival time of each burst signal within 10 nanoseconds (the clock error within 10 nanoseconds will not have a significant impact on the navigation and positioning results required by general precision). In Kalman filtering, the local clock offset drift of the receiver can also be solved as a parameter to be estimated, which can completely overcome the influence of insufficient pseudorange and Doppler frequency observations in a single burst signal, and use multi-burst signals to reliably Solve the navigation parameters accurately.

The anti-jamming satellite navigation receiver based on the burst signal of the present invention can meet high dynamic application occasions, and process segment signals of GPS L1 frequency band CA code, GLONASS L1 frequency band civil code, and Beidou No. 2 system L1 frequency band civil code to meet The real-time positioning frequency requirement of 1Hz, the positioning accuracy is 30 meters (1σ), and the speed measurement accuracy is better than 1-2 meters/second (1σ).

In terms of anti-interference, it can basically overcome the influence of pulse interference; for continuous wave interference, in the case of multiple interference sources, the ability to suppress each broadband noise interference source is better than 20dB.

Claims (11)

1. A burst-type navigation signal system, characterized in that it comprises: A) The signal dissemination carrier is a navigation satellite, a space balloon or an airship; B) The navigation signal comes from: a) Burst navigation beacons broadcast by the direct navigation satellite itself; b) The ground station of the transponder satellite navigation system uplinks to the satellite and then transmits the burst satellite navigation beacon through the satellite; c) When the enemy interferes intermittently with the continuous navigation signals broadcast by our navigation satellites, the "clean fragment" satellite navigation signals received by the receiver during the intermission period; d) When the enemy continuously interferes with the continuous navigation signals broadcast by our navigation satellites, the receiver rotates the satellite navigation signal antenna, and when the antenna is aligned with the navigation satellites, the burst satellite navigation with a better signal-to-interference ratio is received Signal; C) User terminal: Use a high-gain antenna to cover the sky in time-sharing by two-dimensional scanning in elevation and azimuth. For satellites within the pointing range of the high-gain antenna, it has an additional signal-to-interference ratio advantage endowed by the antenna gain, so as to achieve the effect of anti-interference; This anti-jamming method avoids the problem of large-area phased array antennas in traditional airspace anti-jamming measures, and is also convenient for implementing time-frequency domain anti-jamming measures at the same time. It is easy to set up on small and highly maneuverable weapon platforms, with low cost and High reliability. 2. The burst navigation signal system according to claim 1, characterized in that, the burst navigation signal, or "pulse" type, has a signal pulse duration of about 10 milliseconds to about 1 second ; For the direct satellite navigation system, this signal system provides another possible way to realize the area enhancement of the navigation signal on the navigation satellite: the satellite navigation signal adopts the burst pulse form, and the power amplifier on the satellite only needs to The radiated power is increased during the duration, when the duty cycle of the burst signal is low. 3. The burst navigation signal system according to claim 1, wherein when the duty ratio of the burst signal is low, it means that the duty ratio is about 10%. 4. burst navigation signal system as claimed in claim 1, is characterized in that, adopts the navigation message that length is shorter, speed is faster, because satellite navigation signal adopts the pulse form of burst, the power amplifier on the satellite increases during the pulse duration. Large radiation power, after increasing the satellite signal transmission power, broadcast navigation messages at a faster transmission rate. 5. The burst navigation signal system according to claim 1, wherein the satellite navigation signal antenna is a high-gain antenna with a gain ≥ 5dBic, and covers the sky in time-sharing in the manner of two-dimensional scanning in elevation and azimuth. 6. a user terminal in the navigation signal system as claimed in claim 1 is based on the navigation and positioning receiving method of the burst signal satellite, it is characterized in that, no matter what kind of signal source, from the perspective of the user terminal, the burst type satellite navigation terminal receives The received satellite navigation signal is "burst"; the burst signal navigation receiver can only measure the pseudorange and Doppler frequency according to the discontinuous intermittent signal, and perform navigation and positioning calculation; including steps: 1) Pseudorange extraction method, first, extract the spreading code from the received burst satellite navigation signal, and then adopt the traditional serial or parallel search algorithm to obtain the rough estimation of code phase and Doppler frequency; On the basis of the estimation, the code phase is refined and refined to obtain a fine code phase; 2) The Doppler frequency extraction method, starting from the code phase of the coarse capture or the refined code phase, strips the spreading code from the burst satellite navigation signal, and then uses the classical spectrum estimation or modern spectrum estimation method to calculate the frequency of the navigation signal. Doppler frequency; 3) The navigation parameter calculation method, using the inertial navigation component IMU observations combined with the satellite navigation pseudo-range and Doppler observations to jointly solve the receiver navigation parameters: use the auxiliary information of the inertial navigation IMU component to determine the position of the receiver , and speed are constrained to a certain extent. At the same time, a high-stability frequency source is used to maintain the time between the burst satellite navigation signal pulses received at different times. The Kalman filter method is used to obtain the pseudorange and multiple The position, velocity and time information are calculated from the Puller information. 7. The navigation and positioning receiving method as claimed in claim 6, wherein the code phase refinement process is to use a finer search step size and a correlation peak on the basis of roughly estimating the code phase and Doppler frequency The shape curve fitting method accurately calculates the decoding phase, and the ZoomFFT algorithm is used for the refinement search. At the same time, the position integral and instantaneous velocity information given by the inertial navigation aid are used to further reduce the calculation amount of the refinement code phase search 8. The navigation and positioning receiving method as claimed in claim 6, wherein the code phase, in the case of a short code period, the difference between the refined code phase obtained and the actual pseudorange is due to the short code period. There is also an integer fuzzy distance corresponding to the code period. For GPS and GLONASS civil codes, the fuzzy distance is an integer multiple of 300 kilometers, and this integer multiple must be solved correctly. The solution of this integer multiple is based on the code period. , to reconstruct the emission time of the signal. 9. navigation and positioning receiving method as claimed in claim 6, it is characterized in that, the mensuration of speed in the described navigation parameter, application direct periodogram method estimates the Doppler frequency shift of burst GPS signal, calculates line-of-sight change rate, establishes Line-of-sight change rate equation, and then obtain the speed of the receiver. 10. The navigation and positioning receiving method as claimed in claim 6, characterized in that, the navigation parameter solution method drifts in time due to the clock error of the satellite navigation receiver, so each burst satellite navigation signal Relatively accurate time keeping between pulses is carried out to calibrate the accuracy of the crystal oscillator frequency. Within a few seconds, the arrival time of each burst satellite navigation signal pulse is kept within 10 nanoseconds; in Kalman filtering, the The receiver local clock drift is calculated as a parameter to be estimated to overcome the influence of insufficient pseudorange and Doppler frequency observations in a single burst satellite navigation signal, so as to reliably solve the navigation parameters by using multi-burst satellite navigation signals. 11. The navigation and positioning receiving method according to claim 6, wherein the Doppler frequency estimation and velocity calculation process includes: S1. Perform frequency-domain FFT capture on the original intermediate frequency sampling signal, and roughly capture the code phase and Doppler frequency shift of the signal by means of parallel code phase search and capture; S2. After capturing the initial code phase and Doppler frequency shift, further refine the Doppler frequency shift; S3. Perform refinement processing on the initially captured code phase to obtain an ideal refined code phase; S4. Use the code phase refined in step S3 to readjust the local code, perform modulo two addition operation with the original signal, and peel off the C/A code. For high dynamic situations, according to the Doppler added to the C/A code Frequency shift readjusts the frequency generated by the local code generator; S5. Perform periodogram estimation on the intermediate frequency carrier plus noise signal obtained after stripping the C/A code, and the frequency corresponding to the obtained spectral peak maximum value is the estimated carrier Doppler frequency shift; S6, according to the line-of-sight change rate equation between the Doppler frequency shift and the receiver and the GPS satellite, use the least square method to solve the line-of-sight change rate equation of n (n≥4) satellites, that is, the user speed and the user receiver Clock rate of change.

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