High-precision navigation anti-interference module based on optical switch control

Abstract

The invention belongs to the technical field of satellite navigation, and particularly relates to a high-precision navigation anti-interference module based on optical switch control, which comprises an antenna array unit used for receiving BDS B3 and BDS S frequency point navigation signals; the central independent oscillator is used for completing a function of transmitting BDS L frequency point signals; the optical switch chip control module is used for controlling signal receiving and transmitting; the low noise amplifier unit is used for amplifying and filtering the navigation signal; the anti-interference processing unit is used for completing anti-interference processing services of BDS B3 and RDSS S frequency points; the power supply and navigation unit is used for completing internal and external interface service processing, completing the functions of capturing, tracking, telegraph text decoding, PVT resolving and time service of satellite navigation signals of BDS B3 and BDS S frequency points, and completing the functions of modulation, up-conversion emission and emission enabling control of BDS L frequency points; and a communication port for communicating with an external device. According to the invention, three frequency point signals of BDS L, BDS B3 and BDS S can be supported at the same time, and the anti-interference performance is good.

Description

Technical Field

[0001] The invention belongs to the technical field of satellite navigation, and in particular relates to a high-precision navigation anti-interference module based on optical switch control. Background Art

[0002] With the popularization of navigation technology, GNSS signals are susceptible to multipath interference in complex environments such as cities, canyons, and indoors. In the military, security and other fields, GNSS signals are more likely to suffer from intentional human interference, such as deception interference, blocking interference, etc. These interferences seriously affect the accuracy and reliability of the navigation system.

[0003] To this end, the present application provides a navigation anti-interference module. The navigation anti-interference module is an important technical means, which is mainly used in global navigation satellite system (GNSS, such as GPS, GLONASS, Beidou, etc.) receiving equipment to ensure stable reception of navigation signals and accurate navigation in complex electromagnetic environments.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a high-precision navigation anti-interference module based on optical switch control to solve the problem that GNSS signals are susceptible to multipath interference.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A high-precision navigation anti-interference module based on optical switch control, comprising:

[0008] The antenna array unit adopts a circular array layout and is used to complete the reception function of BDS B3 and BDS S frequency navigation signals; the central independent array of the antenna array unit is used to complete the transmission function of BDS L frequency signals;

[0009] An optical switch control module controls signal reception and transmission by controlling the optical switch;

[0010] The low noise amplifier unit includes a group of low noise amplifier modules with independent structures, which are used to amplify and filter the navigation signal; the front stage of the low noise amplifier unit is designed with a high power protection circuit;

[0011] The anti-interference processing unit includes an anti-interference module for completing the anti-interference processing services of the BDS B3 frequency point and the RDSS S frequency point;

[0012] The power amplifier filter unit adopts an integrated design, including a power amplifier module and a cavity filter, which is used to complete the power amplification and out-of-band noise suppression functions of the BDS L frequency point;

[0013] The power supply and navigation unit is used to provide power to the internal systems, complete the internal and external interface business processing, complete the satellite navigation signal capture, tracking, message decoding, PVT solution and timing functions of BDSB3 frequency and BDS S frequency, complete the ephemeris injection function, complete the modulation, up-conversion transmission and transmission enable control functions of BDS L frequency;

[0014] The communication port is used to communicate with external devices, send RTK navigation module information, and receive navigation ephemeris information provided by external devices.

[0015] Preferably, the anti-interference processing unit comprises two parts: a radio frequency board and a digital board; the radio frequency board comprises two four-channel radio frequency chips, multiple intermediate frequency filters and two up-conversion channels, which are used to complete the down-conversion, intermediate frequency filtering and up-conversion of the intermediate frequency signal after anti-interference processing of the antenna received signal; the digital board is used to complete the anti-interference processing of multiple received signals.

[0016] Preferably, the anti-interference processing unit provides an anti-interference module algorithm, specifically:

[0017] The satellite navigation signal is down-converted through the RF channel module. The analog intermediate frequency signal is first sampled and quantized by the A / D converter, and the S frequency and BDS B3 frequency digital signals are sent to the chip, converted to zero intermediate frequency by the digital down-converter to form a baseband digital signal; after low-pass filtering, it is sent to the interference suppression module; after completing the interference suppression, it is sent to the AGC module, so that the interference suppressed signal is converted to the corresponding digital intermediate frequency through the digital up-converter, and then converted to an analog signal by D / A output.

[0018] Preferably, the power amplifier filter unit controls the output power according to the transmission frequency band at the receiver end to ensure that the performance indicators of the whole machine meet the requirements; and the power amplifier output power is stabilized by adding an ALC automatic level control loop to avoid over-drive saturation of the power amplifier at low temperature.

[0019] Preferably, the power supply and navigation unit includes a power supply module, an interface information processing module and an RTK navigation module; the power supply module includes a filter, a protection module and a voltage conversion module, which are used to complete circuit protection and power supply to each internal module; the RTK navigation module includes a core processor peripheral circuit design, a power management circuit design, an SDRAM memory expansion circuit, a satellite signal receiving circuit design and a level conversion circuit design.

[0020] Preferably, the RTK navigation module provides an RTK navigation algorithm, specifically comprising the following steps:

[0021] Step 1: Establish RTK double-difference observation model;

[0022] If the base station receiver b and the mobile station receiver r observe satellite s and satellite j at the same time, then for satellite s and satellite j, inter-station difference is performed between the two receivers to obtain the single difference observation equations of their pseudorange and carrier phase respectively;

[0023] Then, inter-satellite difference is performed between satellite s and satellite j to obtain the double difference observation equation of pseudorange and carrier phase.

[0024] Finally, after the secondary difference between stations and satellites, the satellite clock error and receiver clock error are completely eliminated, and the distance-related errors such as ionospheric delay and tropospheric delay are weakened, and the following double-difference observation equation of pseudorange and carrier phase is obtained:

[0025]

[0026]

[0027] Step 2: Create BDS RTK positioning equation group;

[0028] Assume that the mobile station and the base station simultaneously observe BDS satellites, and the Satellites are reference satellites; The frequency points can obtain a set of equations;

[0029] Similarly, if there is The common-view satellite of the BDS system, satellites are reference satellites, then for Frequency points, another set of equations can also be obtained;

[0030] By combining the above two sets of equations, we can get the BDS single-frequency RTK positioning equations:

[0031]

[0032] in ;

[0033] Step 3: The whole cycle ambiguity is fixed;

[0034] The LAMBDA method is used for ambiguity fixation;

[0035] Firstly, the floating point solutions of ambiguity parameters and unambiguity parameters and their covariance matrices are calculated;

[0036] Then take an integer vector The floating point solution calculated in the first step The square of the distance between is the objective function, and the fuzziness parameter Search to obtain the integer solution of the fuzziness parameter to minimize the objective function;

[0037] Finally, the optimal ambiguity integer solution is obtained After that, the fixed solution of the non-ambiguity parameters and its covariance matrix are obtained by the following two formulas:

[0038]

[0039] .

[0040] As a preferred method, step 3 proposes an integer ambiguity fixing method. In the ambiguity fixing process, the quadratic form of the floating point solution residual is obtained respectively. The quadratic form of each group of candidate ambiguity residuals And the corresponding quadratic form of the fixed solution residual , specifically:

[0041]

[0042]

[0043]

[0044] in, is the variance-covariance matrix of the observations, For the Group candidate fuzziness;

[0045] After searching for integer solutions to the ambiguity, the R-ratio test method is used as a statistical difference test method to confirm it, which can be expressed as:

[0046] .

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The high-precision navigation anti-interference module based on optical switch control of the present invention can simultaneously support three frequency signals of BDS L, BDSB3, and BDS S. At the same time, it can control the module to receive a certain frequency signal through the optical switch chip. It has good anti-interference performance and supports RTK positioning function and ephemeris injection.

[0049] (2) The high-precision navigation anti-interference module based on optical switch control of the present invention, the anti-interference processing unit receives the 4-channel RDSS S and 4-channel BDS B3 intermediate frequency signals output by the down-conversion module, converts them into digital signals through AD, and sends them to the anti-interference chip, completes the anti-interference signal processing in the anti-interference chip, and finally converts them into analog intermediate frequencies through DA and outputs them to the up-conversion, which can effectively filter out malicious interference in the RDSS S receiving band and the BDS B3 band, including broadband suppressive interference, narrowband interference, single-tone interference, swept frequency interference, etc.

[0050] (3) The high-precision navigation anti-interference module based on optical switch control of the present invention controls the output power according to the transmission frequency band at the receiver end to ensure that the performance indicators of the whole machine meet the requirements, and adds an ALC automatic level control loop to stabilize the output power of the power amplifier, avoid over-drive saturation of the power amplifier at low temperature, and help improve the phenomenon that high and low temperatures affect gain changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a block diagram of the hardware composition principle of the present invention;

[0052] Figure 2 is a logic diagram of the optical switch control module of the present invention;

[0053] Figure 3 It is a principle block diagram of the low noise amplifier unit of the present invention;

[0054] Figure 4 is a principle block diagram of the anti-interference processing unit of the present invention;

[0055] Figure 5 It is a principle block diagram of the digital down-conversion of the present invention;

[0056] Figure 6 It is a principle block diagram of space-time signal processing of the present invention;

[0057] Figure 7 It is a principle block diagram of the digital up-conversion of the present invention;

[0058] Figure 8 It is a principle block diagram of power supply of each module of the present invention;

[0059] Fig. 9 It is a circuit schematic diagram of the RTK navigation module of the present invention. DETAILED DESCRIPTION

[0060] The following is a clear and complete description of the technical solution of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by technicians in this field without creative work are within the scope of protection of the present invention.

[0061] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0062] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0063] Example 1

[0064] See attached Figure 1 The present invention provides a high-precision navigation anti-interference module based on optical switch control, comprising the following modules:

[0065] (1) Antenna array unit

[0066] The antenna array unit consists of a central array at L frequency, four S-band circular arrays in the inner ring, and four B3-band circular arrays in the outer ring, which are used to complete BDS B3 and BDS S signal reception and BDS L signal transmission.

[0067] The RDSS L antenna requires that the gain at high elevation angles be less than 5.7dB and the gain at low elevation angles be higher than -4.3dB, so that the output EIRP can meet the requirements. The design selects -3dB above 10 degrees elevation and 5dB at 75 degrees elevation.

[0068] The RDSS S antenna requires that the minimum gain at a 30-degree elevation angle be -2dB, the calculated margin is 1.2dB, the minimum antenna gain can be -3dB, and the antenna gain selected in the design is -2dB. The minimum gain at a high elevation angle is 5dB, the calculated margin is 5.2dB, the minimum antenna gain can be 0dB, and the antenna gain selected in the design is 1dB.

[0069] The BDS B3 antenna requires a minimum gain of -3dB at an elevation angle of 30 degrees, with a calculated margin of 0.4dB. The minimum gain of the antenna can be -2.6dB, and the antenna gain selected in the design is -1dB. The minimum gain at a high elevation angle is 1dB, with a calculated margin of 1.4dB. The minimum gain of the antenna can be -0.4dB, and the antenna gain selected in the design is 3dB.

[0070] (2) Optical switch control module

[0071] The optical switch control module controls the reception and transmission of signals. The control logic diagram is shown in the attached figure. Figure 2 As shown, through the optical switch, the module can be controlled to have 8 different receiving signals.

[0072] (3) Low noise amplifier unit

[0073] The low noise amplifier unit contains a group of independently structured low noise amplifier modules. Its front-end is designed with a protection circuit and has the ability to resist high power burnout. The circuit filter selects devices with good out-of-band suppression, and the amplifier tube selects devices with good linearity. The principle block diagram of the low noise amplifier unit is as follows: Figure 3 shown.

[0074] The operating frequency of the BDS S frequency point is 2491.75±8.16MHz, the gain is 18±1dB, the noise figure is ≤1.6dB, the 3dB bandwidth is ≥19Mhz, OP1dB is ≥10dBm, OIP3 is ≥28dBm, and the input anti-burnout power is 10 (CW).

[0075] The operating frequency of BDS B3 frequency point is 1268.52±10.23MHz, the gain is 18±1dB, the noise figure is ≤1.5dB, the 3dB bandwidth is ≥19Mhz, OP1dB is ≥10dBm, OIP3 is ≥28dBm, and the input anti-burnout power is 10 (CW).

[0076] (4) Anti-interference processing unit

[0077] The anti-interference processing unit mainly completes the anti-interference processing of the four-element RDSS S signal and the four-element BDS B3 signal, and can effectively filter out malicious interference within the RDSS S receiving band and the BDS B3 band, including broadband suppression interference, narrowband interference, single-tone interference, sweep frequency interference, etc. The anti-interference processing unit receives the 4-channel RDSS S and 4-channel BDS B3 intermediate frequency signals output by the down-conversion module, converts them into digital signals through AD, and sends them to the anti-interference chip. The anti-interference signal processing is completed in the anti-interference chip, and finally converted into an analog intermediate frequency through DA and output to the up-conversion. The principle block diagram of the anti-interference processing unit is shown in the attached figure. Figure 4 shown.

[0078] The anti-suppression interference capability of BDS B3 is that the number of interferences is not more than 3, the interference-signal ratio of a single interference is not less than 100dB, and the interference-signal ratio of 3 interferences is not less than 90dB.

[0079] The anti-suppression interference capability of RDSS S is that the number of interferences is not more than 3, the interference-signal ratio of a single interference is not less than 90dB, and the interference-signal ratio of three interferences is not less than 80dB.

[0080] Specifically, the anti-interference processing unit consists of two parts: the radio frequency board and the digital board. The radio frequency board is mainly composed of two four-channel radio frequency chips, multiple intermediate frequency filters and two up-conversion channels, and mainly completes the down-conversion, intermediate frequency filtering and up-conversion of the intermediate frequency signal after anti-interference processing of the antenna received signal; the digital board mainly completes the anti-interference processing of multiple received signals.

[0081] The anti-interference processing unit provides an anti-interference module algorithm, as follows:

[0082] The satellite navigation signal is down-converted through the RF channel module. First, the analog intermediate frequency signal is sampled and quantized by the A / D converter, and the 14.25MHz±4.08MHz digital signal of the RDSS S frequency point and the 15.48MHz±10.23MHz digital signal of the BDS B3 frequency point are sent to the chip, converted to zero intermediate frequency by the digital down-converter to form a baseband digital signal; after low-pass filtering, it is sent to the interference suppression module; after completing the interference suppression, it is sent to the AGC module, so that the interference suppressed signal is converted to a digital intermediate frequency of 46.52MHz±10.23MHz through a digital up-converter, and then converted into an analog signal by D / A output.

[0083] Since the digital signal rate sent into the chip by the A / D is 62M, it far exceeds the bandwidth required for signal processing, and the correlation in the NLMS algorithm is the main factor affecting its performance. In order to improve the performance of the NLMS algorithm, the input signal needs to be extracted. Among them, the S frequency point is extracted 8 times, and the B3 frequency point is extracted 4 times to reduce the correlation of the signal, and the input S frequency point 14.25MHz±4.08MHz digital signal and the B3 frequency point 15.48MHz±10.23MHz digital signal are digitally down-converted and converted to zero intermediate frequency. The principle block diagram of digital down-conversion is shown in the attached figure. Figure 5 shown.

[0084] The adaptive nulling adopts the power inversion criterion and the iteration adopts the NLMS algorithm. The space-time signal processing of this scheme consists of 4 receiving channels, each of which contains 5 taps. The weight coefficient of the first element of the antenna array is always set to 1, and the weights of other branches are adaptively iterated to minimize the output power of the antenna array. The synthesized antenna array radiation pattern will form a null in the interference direction. The greater the interference, the deeper the null formed. The space-time signal processing is implemented on the digital board of the anti-interference processing unit. Its principle block diagram is shown in the attached figure. Figure 6 shown.

[0085] The anti-interference module outputs a zero intermediate frequency complex digital signal. To convert it into the S frequency point 47.75MHz±4.08MHz and the B3 frequency point 46.52MHz±10.23MHz signal output from the D / A, it is necessary to first interpolate to 124M, and then up-convert and convert the complex signal into a real signal and send it to the D / A output. The principle block diagram of digital up-conversion is shown in the attached figure. Figure 7 shown.

[0086] (5) Power amplifier filter unit

[0087] The RDSS L amplifier is used to ensure that the transmission power meets the transmission EIRP index requirements. By controlling the output power according to the transmission frequency band at the receiver end, the performance indicators of the whole machine meet the requirements. The ALC automatic level control loop is added to stabilize the output power of the amplifier, avoid over-drive saturation of the amplifier at low temperature, and improve the phenomenon that high and low temperatures affect gain changes.

[0088] The operating frequency of the RDSS L amplifier is 1610MHz~1676MHz, the gain is 44±1dB, the maximum output power is 43dBm±1 dBm, the continuous working time is 10 minutes (transmitting power reduction ≤0.5dB), the operating voltage is DC+28V±1V, and the operating current is ≤3A.

[0089] The passband frequency of the filter is 1610MHz~1676MHz; under normal temperature conditions, the insertion loss is ≤1.5dB; within the full temperature range, the insertion loss is ≤1.8dB; the out-of-band suppression performance is ≥40dBc (≤1GHz), ≥70dBc (1166MHz~1278MHz), ≥35dBc (1559MHz~1592MHz), ≥70dBc (2480MHz~2502MHz), and the power capacity is ≥30W.

[0090] (6) Power supply and navigation unit

[0091] In order to enhance electromagnetic compatibility, the power module, interface information processing module and RTK navigation module are concentrated in an independent structural cavity to form a power supply and navigation unit.

[0092] The power module includes a filter, a protection module and a voltage conversion module, which are used to complete circuit protection and supply power to each module. The power supply and supply voltage of each module are as shown in the attached Figure 8 shown.

[0093] The RTK navigation module circuit mainly includes the core processor peripheral circuit design, power management circuit design, SDRAM memory expansion circuit, satellite signal receiving circuit design and level conversion circuit design. VDD 5V and VBAT are provided externally. VDD 5V is reduced to VCC 3.3V through a step-down chip to power the chip. The RF input is connected to the navigation anti-interference component to assist the GNSS function. The circuit schematic diagram of the RTK navigation module is as follows: Fig. 9 shown.

[0094] To improve the positioning accuracy of the product, add the RTK navigation algorithm to the RTK navigation module, which includes the following steps:

[0095] Step 1: Establish RTK double difference observation model;

[0096] One of the important measures to improve positioning accuracy is to reduce the impact of observation errors on positioning. The differential method is a method that can effectively reduce various measurement errors. For the same area, the satellite clock error, satellite ephemeris error, ionospheric delay and tropospheric delay of different receivers in this area have a strong correlation. Based on this characteristic, the differential method constructs a double difference observation model through inter-satellite and inter-station differences to improve positioning accuracy. RTK is a typical application of the differential method.

[0097] If the base station receiver b and the mobile station receiver r observe satellite s and satellite j at the same time, for satellite s, inter-station difference is performed between the two receivers to obtain the single difference observation equation of pseudorange and carrier phase:

[0098]

[0099]

[0100] In the formula, ” represents the inter-station difference operator.

[0101] Similarly, for satellite j, inter-station difference can be obtained as follows:

[0102]

[0103]

[0104] Using the obtained single difference observation equation, intersatellite difference is performed between satellite s and satellite j to obtain the double difference observation equation of pseudorange and carrier phase:

[0105]

[0106]

[0107] In the formula, ” represents the intersatellite difference operator.

[0108] After the secondary difference between stations and satellites, the satellite clock error and receiver clock error are completely eliminated, and the errors related to distance such as ionospheric delay and tropospheric delay are weakened. Generally, for a short baseline less than 10km, the error of atmospheric delay after double difference can be ignored, thus obtaining the following double difference observation equation for pseudorange and carrier phase:

[0109]

[0110] .

[0111] Step 2: Create BDS RTK positioning equations;

[0112] Assume that the mobile station and the base station simultaneously observe BDS satellites, and the Satellites are used as reference satellites. The frequency point, pseudo-range and carrier phase double difference observation equation obtained in step 1 can be listed as equation, but it also brings There are unknown double-difference ambiguity parameters. Considering that the receiver position parameters are also unknown, the normal equation is rank-deficient. Therefore, based on the double-difference carrier phase observation equations, this paper adopts the method of simultaneous pseudo-range double-difference observation equations to solve the rank-deficient problem. The combined equations are as follows:

[0113]

[0114] in .

[0115] Similarly, if there is The common-view satellite of the BDS system, satellites are reference satellites, then for The frequency point can also get the following equations:

[0116]

[0117] in .

[0118] Combining the above two equations, we can get the BDS single-frequency RTK positioning equations:

[0119]

[0120] Step 3: Integer ambiguity is fixed;

[0121] One of the core issues of precise positioning using carrier phase is to solve the integer ambiguity, which includes two parts: ambiguity fixation and ambiguity confirmation. The floating point solution of the ambiguity parameter can be obtained through the above-mentioned extended Kalman filter, and the accuracy of the corresponding position parameter solution or baseline vector solution is usually poor. Only by correctly fixing the ambiguity parameter to an integer value can the position parameter solution or baseline vector solution reach the centimeter level or even millimeter level accuracy.

[0122] At present, the most widely used ambiguity fixation method is the Least-squares Ambiguity Decorrelation Adjustment (LAMBDA), which mainly uses the integer least squares estimation principle and is a search method based on the ambiguity domain.

[0123] To facilitate the expression of the integer least squares principle, the BDS single-frequency RTK positioning equations obtained in step 2 are written as follows:

[0124] ;

[0125] in, is the double difference observation vector, is the fuzziness parameter vector ( is an integer), is the other unambiguous parameter vector, and are the coefficient matrices of ambiguity parameters and unambiguity parameters respectively, is the observation noise.

[0126] When using the least squares principle to solve the above equation, since it contains two parameters to be solved, integer and real numbers, its solution process is usually called integer least squares estimation. Generally speaking, its solution has no analytical form. Integer least squares estimation is usually solved according to the following three processes:

[0127] In the first step, ignoring the integer nature of the ambiguity parameters, the floating point solutions of the ambiguity parameters and the unambiguity parameters and their covariance matrix are calculated:

[0128] ,

[0129] The superscript “~” indicates a floating point.

[0130] The second step is to use an integer vector The floating point solution calculated in the first step The square of the distance between is the objective function, and the fuzziness parameter Search to obtain the integer solution of the fuzziness parameter to minimize the objective function, that is:

[0131]

[0132] The third step is to obtain the optimal integer solution of ambiguity from the second step. After that, the fixed solution of the non-ambiguity parameters and its covariance matrix are obtained by the following two formulas:

[0133]

[0134]

[0135] The LAMBDA method specifies the following search space when searching in the second step:

[0136]

[0137] in, The integers in the above search space are all search objects, and a set of integer vectors in it can satisfy the above formula.

[0138] Since there is a correlation between the double-difference ambiguities, the search process is time-consuming and inefficient. Therefore, the LAMBDA method first performs a down-correlation process on the ambiguity parameters and their covariance matrix before searching. This operation is usually called The transformation process is as follows:

[0139]

[0140]

[0141] Among them, the descending correlation matrix It should satisfy the following requirements: (1) full rank, which means that it can perform not only forward transformation but also inverse transformation; (2) ; (3) It has an integer property, ensuring that the fixed ambiguity remains an integer after the inverse transformation.

[0142] This time Correspondingly becomes:

[0143]

[0144] Then based on Decomposed sequential least squares method to search, and finally inverse the search results The integer solution of the ambiguity parameters can be obtained by transformation.

[0145] Specifically, a method for fixing integer ambiguity is proposed.

[0146] In the process of ambiguity fixation, the quadratic form of the floating-point solution residual can be obtained respectively The quadratic form of each group of candidate ambiguity residuals And the corresponding quadratic form of the fixed solution residual :

[0147]

[0148]

[0149]

[0150] in, is the variance-covariance matrix of the observations, For the Group candidate fuzziness.

[0151] After searching for integer solutions to the ambiguity, it is usually necessary to confirm it to determine whether it can be considered correct from a probability and statistical perspective. Only ambiguities that pass the test can be used to calculate fixed solutions to non-ambiguous parameters. Ambiguity confirmation methods usually include two types of methods: statistical difference test methods and success rate / failure rate indicator determination methods.

[0152] The statistical difference test method constructs a hypothesis test statistic, analyzes its distribution, and determines the threshold value. If the distribution of the statistic is unknown, a reasonable threshold is set based on the actual situation. When the statistic is greater than the threshold, the ambiguity is considered to be successfully fixed. Common statistical difference test methods mainly include difference test, F-ratio test and R-ratio test. Among the two types of ambiguity confirmation methods, the R-ratio test method is the most widely used. However, since the distribution of its statistic is not clear, the test threshold cannot be strictly calculated and is usually set to a fixed empirical value.

[0153] The R-ratio test uses the quadratic ratio of the suboptimal ambiguity to the optimal ambiguity residual as the test statistic. It can be directly obtained during the ambiguity search. It is convenient and fast and is the most widely used test method. It can be expressed as:

[0154] .

[0155] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A high-precision navigation anti-interference module based on optical switch control, characterized in that: include: The antenna array unit adopts a circular array layout and is used to complete the reception function of BDS B3 and BDS S frequency navigation signals; the central independent array of the antenna array unit is used to complete the transmission function of BDS L frequency signals; An optical switch control module controls signal reception and transmission by controlling the optical switch; The low noise amplifier unit includes a group of low noise amplifier modules with independent structures, which are used to amplify and filter the navigation signal; the front stage of the low noise amplifier unit is designed with a high power protection circuit; The anti-interference processing unit includes an anti-interference module for completing the anti-interference processing services of the BDS B3 frequency point and the RDSS S frequency point; The power amplifier filter unit includes a power amplifier module and a cavity filter, which is used to complete the power amplification and out-of-band noise suppression functions of the BDS L frequency point; The power supply and navigation unit is used to provide power to the internal systems, complete the internal and external interface business processing, complete the capture, tracking, message decoding, PVT solution and timing functions of the satellite navigation signals of the BDS B3 frequency and BDS S frequency, complete the ephemeris injection function, complete the modulation, up-conversion transmission and transmission enable control functions of the BDS L frequency; The communication port is used to communicate with external devices, send RTK navigation module information, and receive navigation ephemeris information provided by external devices.

2. The high-precision navigation anti-interference module based on optical switch control according to claim 1 is characterized in that: The anti-interference processing unit includes two parts: a radio frequency board and a digital board; the radio frequency board includes two four-channel radio frequency chips, multiple intermediate frequency filters and two up-conversion channels, which are used to complete the down-conversion, intermediate frequency filtering and up-conversion of the intermediate frequency signal after anti-interference processing of the antenna received signal; the digital board is used to complete the anti-interference processing of multiple received signals.

3. The high-precision navigation anti-interference module based on optical switch control according to claim 1 is characterized in that: The anti-interference processing unit provides an anti-interference module algorithm, specifically: The satellite navigation signal is down-converted by the RF channel module. First, the analog intermediate frequency signal is sampled and quantized by the A / D converter, and the digital signals of the RDSS S frequency point and the BDS B3 frequency point are sent to the chip, and then converted to zero intermediate frequency by the digital down-converter to form a baseband digital signal; after low-pass filtering, it is sent to the interference suppression module; After the interference suppression is completed, it is sent to the AGC module, so that the interference suppressed signal is converted to the corresponding digital intermediate frequency through the digital up-converter, and then converted into an analog signal output by D / A.

4. The high-precision navigation anti-interference module based on optical switch control according to claim 1, characterized in that: The power amplifier filter unit controls the output power according to the transmission frequency band at the receiver end to ensure that the performance indicators of the whole machine meet the requirements; by adding an ALC automatic level control loop, the output power of the power amplifier is stabilized to avoid over-driving and saturation of the power amplifier at low temperature.

5. The high-precision navigation anti-interference module based on optical switch control according to claim 1 is characterized in that: The power supply and navigation unit includes a power supply module, an interface information processing module and an RTK navigation module; the power supply module includes a filter, a protection module and a voltage conversion module, which are used to complete circuit protection and power supply to each internal module; the RTK navigation module includes a core processor peripheral circuit design, a power management circuit design, an SDRAM memory expansion circuit, a satellite signal receiving circuit design and a level conversion circuit design.

6. The high-precision navigation anti-interference module based on optical switch control according to claim 5 is characterized in that: The RTK navigation module provides an RTK navigation algorithm, which specifically includes the following steps: Step 1: Establish RTK double-difference observation model; If the base station receiver b and the mobile station receiver r observe satellite s and satellite j at the same time, then for satellite s and satellite j, inter-station difference is performed between the two receivers to obtain the single difference observation equations of their pseudorange and carrier phase respectively; Then, inter-satellite difference is performed between satellite s and satellite j to obtain the double difference observation equation of pseudorange and carrier phase. Finally, after the secondary difference between stations and satellites, the satellite clock error and receiver clock error are completely eliminated, the error related to the distance is weakened, and the following double difference observation equation of pseudorange and carrier phase is obtained: Step 2: Create BDS RTK positioning equation group; Assume that the mobile station and the base station simultaneously observe BDS satellites, and the Satellites are reference satellites; The frequency points can obtain a set of equations; Similarly, if there is The common-view satellite of the BDS system, satellites are reference satellites, then for Frequency points, another set of equations can also be obtained; By combining the above two sets of equations, we can get the BDS single-frequency RTK positioning equations: in ; Step 3: The integer ambiguity is fixed; The LAMBDA method is used for ambiguity fixation; Firstly, the floating point solutions of ambiguity parameters and unambiguity parameters and their covariance matrices are calculated; Then take an integer vector The floating point solution calculated in the first step The square of the distance between is the objective function, and the fuzziness parameter Search to obtain the integer solution of the fuzziness parameter to minimize the objective function; Finally, the optimal ambiguity integer solution is obtained After that, the fixed solution of the non-ambiguity parameters and its covariance matrix are obtained by the following two formulas: 。 7. The high-precision navigation anti-interference module based on optical switch control according to claim 6, characterized in that: Step 3 proposes an integer ambiguity fixation method. In the ambiguity fixation process, the quadratic form of the floating point solution residual is obtained respectively. The quadratic form of each group of candidate ambiguity residuals And the corresponding quadratic form of the fixed solution residual , specifically: in, is the variance-covariance matrix of the observations, For the Group candidate fuzziness; After searching for integer solutions to the ambiguity, the R-ratio test method is used as a statistical difference test method to confirm it, which can be expressed as: 。

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