Integrated Roland C and GNSS combined receiving system

Abstract

The invention belongs to the technical field of radio navigation and time service, and discloses an integrated Roland C and GNSS combined receiving system, which comprises an antenna unit, a Roland C receiving module unit, a GNSS receiving module unit and a combined processor unit, the antenna unit is used for receiving a Roland C signal and a satellite signal in a space and transmitting the received signals to the Roland C receiving module unit and the GNSS receiving module unit through the coupler, the Roland C and GNSS combined all-in-one machine adopts an integrated and combined coupling circuit design, and through the design of a miniaturized circuit board and the antenna, the Roland C and GNSS combined all-in-one machine can be used for receiving the satellite signal and the satellite signal in the space. Compared with the prior art, the signal-to-noise ratio and sensitivity of signals are greatly improved, the problem that a traditional antenna is inconvenient to transport and assemble is solved, miniaturization design is achieved, and by means of the combined integrated design, under the condition of some weak signals, through complementation of two signal systems of Roland C and GNSS, the performance of time service positioning navigation is improved.

Description

Technical Field

[0001] This invention belongs to the field of radio navigation and timing technology, specifically an integrated Loran C and GNSS combined receiving system. Background Technology

[0002] Navigation and timing technologies are core supports for the stable operation of key fields such as aviation, aerospace, navigation, and power. Currently, the industry mainly relies on two types of technology systems: the Loland C navigation system and the Global Navigation Satellite System (GNSS). Although each has its advantages, significant technical defects still exist when used alone or in simple combinations, making it difficult to meet the application requirements of high precision, high reliability, and wide application scenarios. As a previous generation of land-based radio navigation system, the Loland C system has distinctive technical architecture and functions: a transmitter chain of the system contains at least three navigation stations (usually four to five), one of which is the master station (M), and the rest are secondary stations (W, X, Y, Z). Each navigation station achieves strict time synchronization by being equipped with a cesium atomic clock. It has the core advantages of high transmission power and strong anti-interference capability, and can maintain signal stability in complex electromagnetic environments, providing reliable timing and positioning references for equipment. GNSS systems are a new generation of satellite-based radio navigation systems. After years of development, they have matured and become the mainstream technology in the field of navigation and timing due to their ease of use, wide coverage, and high positioning and timing accuracy. They are widely used in personal terminals, transportation, power dispatching and other scenarios.

[0003] However, the limitations of the Loland C system are also prominent: on the one hand, its signal coverage area is limited by the layout of land-based stations, making it impossible to achieve seamless global coverage, and the signal strength attenuates significantly in areas far from the stations; on the other hand, its navigation accuracy lags behind that of new-generation navigation systems, making it difficult to meet the needs of high-precision application scenarios (such as precision surveying and aviation navigation). Therefore, relying solely on the Loland C system cannot meet the diversified needs of modern navigation and timing. The signal characteristics of GNSS systems make them face significant shortcomings in anti-interference: since the transmission power of GNSS satellites is only tens of watts, the signal strength is weak during space transmission, and it is susceptible to deceptive interference (forged satellite signals) and suppression interference (strong electromagnetic signal shielding) in the space segment (satellite signal transmission path), the operation and control segment (satellite operation and maintenance), and the user segment (terminal receiving segment). Globally, numerous incidents of GNSS signal interference leading to equipment positioning failures and timing deviations have exposed the security risks of relying solely on GNSS systems. These incidents fail to meet the critical requirements of uninterrupted and highly reliable navigation and timing in sectors such as power and navigation. Given the complementarity between Loland C and GNSS systems, attempts have emerged in the industry to combine them: for example, Europe uses the Loland C system to broadcast GNSS differential and integrity information to enhance GNSS navigation capabilities, while China uses the Loland C system as a backup for the GNSS system, attempting to combine their advantages to improve overall reliability and anti-interference capabilities. However, current equipment with combined Loland C and GNSS receiving capabilities has not yet overcome the technical bottleneck of "discrete and large-volume" architecture: existing equipment's GNSS receiver and Loland C receiver are mostly independent components. A GNSS receiver consists of an antenna, a main unit, and external cable connectors. The Roland C receiver uses a standard 1-2U chassis structure (main unit dimensions are 483mm×44mm×320mm, width×height×depth), paired with an external mushroom-shaped antenna with a height of 100mm and an outer diameter of 200mm. Both types of equipment need to be installed separately and connected by cables, resulting in a large overall size and a complex installation process. This not only makes it difficult to adapt to scenarios with limited space (such as vehicle-mounted terminals and portable devices), but also causes the time and spatial position signals received by the two types of equipment to be unable to be synchronized for comparison due to separate installation, further affecting the accuracy and reliability of combined applications. At the same time, the separate structure also increases the difficulty of equipment maintenance and carrying costs, and cannot meet the working requirements of high-intensity and complex outdoor environments, thus restricting the application expansion of Roland C and GNSS combined technology. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated Roland C and GNSS combined receiving system to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an integrated Roland C and GNSS combined receiving system, comprising an antenna unit, a Roland C receiving module unit, a GNSS receiving module unit, and a combined processor unit; the antenna unit is used to receive Roland C signals and satellite signals in space, and transmits the received signals to the Roland C receiving module unit and the GNSS receiving module unit respectively via couplers; the Roland C receiving module unit is used to measure the arrival time of the Roland C signal broadcast by the locked transmitter, demodulate and decode the Roland C signal broadcast message information; the GNSS receiving module unit is used to measure the arrival time of the signal broadcast by the locked satellite, demodulate and decode the message broadcast by the satellite signal; the combined processor unit is used to verify the consistency and quality of satellite and Roland C measurement, select the best measurement combination calculation time and integrity information through RAIM, and output timing pulse 1PPS and TOD information through RS422 serial port; the combined receiving system is a cylindrical structure, [1] with a height not greater than 300mm and a diameter not greater than 200mm.

[0006] Preferably, the antenna unit integrates a GNSS antenna and a Loran C magnetic antenna, and the antenna unit is disposed within the main body of the cylindrical combined receiving system; the GNSS antenna is a three-in-one active ceramic microstrip antenna, and the GNSS antenna is fixed to the top of the combined receiving system, and the GNSS antenna has circularly polarized radiation characteristics; the Loran C magnetic antenna includes a magnet, an impedance matching circuit, and a back-end operational amplifier differential circuit. The magnet is composed of ferrite and a coil. The ferrite senses the magnetic field strength in space, and excites a changing current in the wound coil to receive electromagnetic waves in space. The signal is then amplified by the active matching circuit, and finally converted into a differential output signal by the operational amplifier differential circuit.

[0007] Preferably, the system structure of the GNSS antenna includes an antenna, a low-noise amplifier, and a bandpass filter connected in sequence, and also includes a power divider, a power combiner, an RF front-end, a feeding structure, and a transmission line; the signal received by the antenna is amplified by the low-noise amplifier, filtered by the bandpass filter, distributed by the power divider, processed by the RF front-end, synthesized by the power combiner, and finally transmitted through the feeding structure and the transmission line.

[0008] Preferably, the Loran-C receiving module unit comprises an RF signal processing unit and a digital signal processing unit; the RF signal processing unit includes a bandpass filter, an RF amplifier, an automatic gain control circuit, a notch filter, and a limiting amplifier, used to further process the Loran-C signal processed by the antenna coupler; the digital signal processing unit includes an A / D converter, a microprocessor, a memory, and various interfaces, used to complete the search, acquisition, and tracking of the Loran-C signal, the identification and period identification of sky and ground waves, time delay correction and time difference extraction, the generation of timing signals, and navigation and positioning calculations.

[0009] Preferably, the GNSS receiving module unit adopts a miniaturized integrated module that can simultaneously receive multiple satellite signals such as BeiDou and GPS. The GNSS receiving module unit internally includes a low-noise amplifier, a surface acoustic wave (SAW) filter, a GNSSIC chip, a reset circuit, a battery, a real-time clock, a temperature-compensated crystal oscillator, and a crystal. After receiving the satellite signal, the GNSS receiving module unit amplifies the satellite signal through the internal low-noise amplifier, then filters out out-of-band noise signals through the SAW filter, and then sends the satellite signal to the GNSSIC chip to complete signal search, acquisition, tracking, bit synchronization, frame synchronization, error correction decoding, extraction and splicing of navigation messages, pseudorange measurement, and integral Doppler measurement. Finally, according to the navigation mode requirements, it completes the user's PVT calculation, i.e., position, velocity, and time calculation, and outputs navigation information as well as satellite position and time information.

[0010] Preferably, the combined processor unit adopts a pseudorange rate combination mode; the system operating mode of the combined processor unit is as follows: when GNSS is available, the GNSS timing result is selected for output first, and the timing error of Loran C is calculated in real time using the GNSS result; when GNSS is unavailable, the timing result is output using Loran C plus error estimation.

[0011] Preferably, the overall structure of the combined receiving system, from top to bottom, consists of a GNSS antenna array, a Roland C magnetic antenna coupling plate, a GNSS signal receiving plate, a Roland C signal receiving plate, a vent valve, and an eight-core aviation connector; the GNSS signal receiving plate and the Roland C signal receiving plate are used to amplify, filter, and perform impedance matching processing on the corresponding signals received by the antenna.

[0012] Preferably, to address potential interference from the power supply of the GNSS antenna array and the Roland C magnetic antenna coupling plate, the following anti-interference measures are adopted: First, the power supply circuits of the GNSS antenna array and the Roland C magnetic antenna coupling plate are strictly isolated from the power supply circuits of the GNSS signal receiving board, the Roland C signal receiving board, and the integrated processor unit within the combined receiving system; second, the power supply grounding terminal of the GNSS antenna array and the power supply grounding terminal of the Roland C magnetic antenna coupling plate are connected to the same grounding node to achieve a common ground design.

[0013] Preferably, the Loland C receiving module unit calculates the distance difference between the user and the station by measuring the phase difference of the transmitted signals from two Loland C stations, obtaining a hyperbolic position line. Two intersecting hyperbolic position lines are obtained from the phase difference measurement of the signals from the two pairs of stations, and the intersection point is the user's position. The hyperbolic positioning equation is: r1=((x-xs1)2+(y-ys1)2+(z-zs1)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 r2=((x-xs3)2+(y-ys3)2+(z-zs3)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 In the formula, r1 is the distance difference between the user and stations s1 and s2, and r2 is the distance difference between the user and stations s3 and s2; x, y, and z are the user's positions, and xs1, ys1, zs1, xs2, ys2, zs2 and xs3, ys3, zs3 are the positions of the three stations s1, s2 and s3, respectively.

[0014] Preferably, the Roland C receiving module unit obtains a hyperbolic position line by measuring the time difference between the arrival of signals from two navigation stations, and its time difference equation is: TD ij =(r ij -r i -r j ) / c)+CD TD in the formula ij Here are the observed time differences between stations i and j, where c is the radio wave propagation speed, and r is the time difference between stations i and j. ij It is the distance between two stations, CD is the encoding delay, and r i r j The distance from the user to the station can be obtained using the hyperbolic positioning equation. The time difference data output by the Loland C receiving module unit and the pseudorange data output by the GNSS receiving module unit support fusion to improve the stability, reliability and anti-interference capability of the signal transmission and time system of the GNSS and Loland C systems, and overcome the risk of dependence on GNSS within the effective coverage area of ​​the combined system.

[0015] The beneficial effects of this invention are as follows: 1. In this invention, addressing the shortcomings of existing GNSS receivers and Roland C receivers being installed separately, resulting in large size (e.g., the Roland C receiver main unit is a standard 19-inch chassis of 483mm×44mm×320mm, and the antenna is a mushroom-shaped structure with a height of 100mm and an outer diameter of 200mm) and significant space occupation, this system integrates the antenna unit, Roland C receiver module unit, GNSS receiver module unit, and combined processor unit into a single cylindrical body through an integrated structural design (the overall structure is a cylinder with a height of no more than 300mm and a diameter of no more than 200mm). Simultaneously, it uses a magnetic antenna to replace the traditional Roland C external antenna and a miniaturized integrated substrate to reduce circuit volume, significantly reducing the overall size of the equipment. This solves the problems of "large space occupation, difficulty in installation, maintenance, and portability" in dedicated equipment and complex field environments, expanding the application range of the equipment in space-constrained scenarios (such as vehicle-mounted and portable terminals). 2. In this invention, the system uses an integrated circuit design to enable the GNSS receiver module and the Loland C receiver module to synchronously acquire signals. The combined processor unit can directly verify the consistency of the two types of measurements and select the optimal combination through RAIM, realizing "real-time and convenient" signal comparison. At the same time, it utilizes the advantages of high Loland C signal strength (on average more than 1 million times that of conventional GPS signals) and strong anti-interference capability to complement the high precision characteristics of GNSS. When the GNSS signal is interfered with and unavailable, the system can output the timing result by adding error estimation through Loland C, avoiding service interruption caused by the failure of a single navigation system, and significantly improving the reliability and continuity of timing, positioning, and navigation. 3. In this invention, the antenna unit design integrates a GNSS three-in-one active ceramic microstrip antenna (with circularly polarized radiation characteristics) with a Loland C magnetic antenna. To address the power supply interference issue, a "power supply isolation + common ground design" is adopted (the antenna power supply is strictly isolated from other circuits, and the two types of antennas share a common ground), effectively avoiding signal interference from the power supply circuit. At the same time, the RF processing unit of the Loland C receiver module (including bandpass filtering, automatic gain control, notch filtering, etc.) and the surface acoustic wave (SAW) filter and low-noise amplification circuit of the GNSS receiver module can respectively perform targeted noise reduction and amplification processing on the two types of signals, significantly improving the signal-to-noise ratio and receiving sensitivity. Even in weak signal environments (such as urban areas with obstruction or electromagnetic interference), the complementary reception of the two types of signals can ensure normal function and improve the performance in extreme scenarios. 4. In this invention, the system is integrated into a single unit, requiring only a single installation of the cylindrical main body to deploy two types of receivers without the need for additional external antennas or cables. At the same time, the internal structure adopts a "vertical stacking + modular design" (e.g., antenna unit on top, receiver board group in the middle, processor unit at the bottom), and the interfaces of each module are standardized. During subsequent maintenance, individual modules can be repaired specifically without disassembling the entire device, which significantly reduces installation complexity and maintenance costs, and improves the practicality and economy of the equipment in mass application scenarios (such as power base stations and marine equipment). Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the invention; Figure 2 This is a schematic diagram of the GNSS antenna system of the present invention; Figure 3 This is the overall design drawing of the Loran C magnetic antenna of the present invention; Figure 4 This is a basic structural diagram of the Roland C receiving module unit of the present invention; Figure 5 This is a block diagram of the internal structure of the GNSS receiving module unit of the present invention; Figure 6 This is a block diagram of the combined processor unit of the present invention; Figure 7 This is a schematic diagram illustrating the positioning principle of the present invention; Figure 8 This is a front view of the Roland C and GNSS integrated unit of the present invention; Figure 9 This is a schematic diagram of the internal structure of the Roland C and GNSS integrated unit of the present invention; Figure 10 This is a top view of the Roland C and GNSS integrated unit of the present invention; Figure 11 This is a structural diagram of the Roland C and GNSS integrated unit of the present invention.

[0017] In the diagram: 1. Roland C signal receiver board; 2. GNSS signal receiver board; 3. Roland C magnetic antenna; 4. GNSS antenna; 5. Vent valve; 6. Eight-core aviation connector. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figures 1 to 11As shown, this embodiment of the invention provides an integrated Loran-C and GNSS combined receiving system. The integrated Loran-C and GNSS combined receiving system includes an antenna unit, a Loran-C receiving module unit, a GNSS receiving module unit, and a combined processor unit. The antenna unit receives Loran-C signals and satellite signals in space and transmits the received signals to the Loran-C receiving module unit and the GNSS receiving module unit respectively via couplers. The Loran-C receiving module unit measures the Time of Arrival (TOA) of the Loran-C signal broadcast by the locked transmitter, demodulates and decodes the Loran-C signal broadcast message information. The GNSS receiving module unit measures the Time of Arrival (TOA) of the signal broadcast by the locked satellite, demodulates and decodes the satellite signal broadcast message. The combined processor unit verifies the consistency and quality of satellite and Loran-C measurements, selects the optimal measurement combination calculation time and integrity information through RAIM (Receiver Autonomous Integrity Monitoring), and outputs timing pulse 1PPS and TOD information through an RS422 serial port. The combined receiving system has an overall cylindrical structure with a height not exceeding 300mm and a diameter not exceeding 200mm. The antenna unit integrates a GNSS antenna 4 and a Loland C magnetic antenna 3, and is housed within the main body of the cylindrical combined receiving system. The GNSS antenna 4 is a three-in-one active ceramic microstrip antenna, and is fixed to the top of the combined receiving system. The GNSS antenna 4 has circularly polarized radiation characteristics. The Loland C magnetic antenna 3 includes a magnet, an impedance matching circuit, and a back-end operational amplifier differential circuit. The magnet consists of ferrite and a coil. The ferrite senses the magnetic field strength in space, which excites a changing current in the wound coil to receive electromagnetic waves in space. The signal is then amplified by the active matching circuit, and finally converted into a differential output signal by the operational amplifier differential circuit.

[0020] The system structure of GNSS antenna 4 includes an antenna, low-noise amplifiers (LNA1, LNA2, LNA3), bandpass filters (bandpass filter 1, bandpass filter 2, bandpass filter 3) connected in sequence, as well as a power divider, a power combiner, an RF front-end, a feeding structure, and a transmission line. The signal received by the antenna is amplified by the low-noise amplifier, filtered by the bandpass filter, distributed by the power divider, processed by the RF front-end, synthesized by the power combiner, and finally transmitted through the feeding structure and transmission line.

[0021] The Loran-C receiver module consists of an RF signal processing unit and a digital signal processing unit. The RF signal processing unit includes a bandpass filter, an RF amplifier, an automatic gain control circuit, a notch filter, and a limiting amplifier, which are used to further process the Loran-C signal processed by the antenna coupler. The digital signal processing unit includes an A / D converter, a microprocessor, a memory, and various interfaces. The digital signal processing unit is used to complete the search, acquisition, and tracking of the Loran-C signal, the identification and period identification of sky and ground waves, the time delay correction and time difference extraction, the generation of timing signals, and the navigation and positioning calculation.

[0022] The GNSS receiver module unit adopts a miniaturized integrated module that can simultaneously receive multiple satellite signals such as BeiDou and GPS. Internally, the GNSS receiver module unit includes a low-noise amplifier (LNA), a surface acoustic wave (SAW) filter, a GNSSIC chip (model UM220-IV), a reset circuit (RESETN), a battery, a real-time clock (RTC), a temperature-compensated crystal oscillator (TCXO), and a crystal. After receiving satellite signals, the GNSS receiver module unit amplifies the satellite signals through its internal LNA, then filters out out-of-band noise signals through the SAW filter. The satellite signals are then sent to the GNSSIC chip to complete signal search, acquisition, tracking, bit synchronization, frame synchronization, error correction decoding, navigation message extraction and splicing, pseudorange measurement, and integrating Doppler measurement. Finally, according to the navigation mode requirements, it completes the user's PVT (Position, Velocity, and Time) calculation and outputs navigation information as well as satellite position and time information.

[0023] The combined processor unit adopts a pseudorange rate combination mode. The system working mode of the combined processor unit is as follows: when GNSS is available, the GNSS timing result is selected first for output, and the timing error of Loran C is calculated in real time using the GNSS result; when GNSS is unavailable, the timing result is output using Loran C plus error estimation.

[0024] The overall structure of the combined receiving system, from top to bottom, consists of a GNSS antenna array, a Roland C magnetic antenna coupling plate, a GNSS signal receiving plate 2, a Roland C signal receiving plate 1, a vent valve 5, and an eight-core aviation connector 6. The GNSS signal receiving plate 2 and the Roland C signal receiving plate 1 are used to amplify, filter, and impedance match the corresponding signals received by the antenna.

[0025] To address potential interference from the power supply of the GNSS antenna array and the Roland C magnetic antenna coupling plate, the following anti-interference measures are adopted: First, the power supply circuits of the GNSS antenna array and the Roland C magnetic antenna coupling plate are strictly isolated from the power supply circuits of the GNSS signal receiving board 2, the Roland C signal receiving board 1, and the combined processor unit within the integrated receiving system; Second, the power supply grounding terminal of the GNSS antenna array and the power supply grounding terminal of the Roland C magnetic antenna coupling plate are connected to the same grounding node to achieve a common ground design.

[0026] The Loland C receiver module unit calculates the distance difference between the user and the station by measuring the phase difference of the transmitted signals from two Loland C stations, thus obtaining a hyperbolic position line. Two intersecting hyperbolic position lines are obtained from the phase difference measurements of the signals from the two pairs of stations; the intersection point is the user's position. The hyperbolic positioning equation is: r1=((x-xs1)2+(y-ys1)2+(z-zs1)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 r2=((x-xs3)2+(y-ys3)2+(z-zs3)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 In the formula, r1 is the distance difference between the user and stations s1 and s2, and r2 is the distance difference between the user and stations s3 and s2; x, y, and z are the user's positions, and xs1, ys1, zs1, xs2, ys2, zs2 and xs3, ys3, zs3 are the positions of the three stations s1, s2 and s3, respectively.

[0027] The Roland C receiver module unit obtains a hyperbolic position line by measuring the time difference between the arrival of signals from two navigation stations. Its time difference equation is: TD ij =(r ij -r i -r j ) / c)+CD TD in the formula ij Here are the observed time differences between stations i and j, where c is the radio wave propagation speed, and r is the time difference between stations i and j. ij It is the distance between two stations, CD is the encoding delay, and r i r j The distance from the user to the station can be obtained using the hyperbolic positioning equation. The time difference data output by the Loland C receiver module and the pseudorange data output by the GNSS receiver module support fusion to improve the stability, reliability and anti-interference capability of the signal transmission and time system of both GNSS and Loland C systems. Moreover, within the effective coverage area of ​​the combined system, it overcomes the risk of dependence on GNSS.

[0028] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An integrated Roland C and GNSS combined receiving system, characterized in that: It includes an antenna unit, a Loran-C receiver module unit, a GNSS receiver module unit, and a combined processor unit; the antenna unit is used to receive Loran-C signals and satellite signals in space, and transmits the received signals to the Loran-C receiver module unit and the GNSS receiver module unit respectively via couplers; the Loran-C receiver module unit is used to measure the arrival time of the Loran-C signal broadcast by the locked transmitter, demodulate and decode the Loran-C signal to broadcast message information; The GNSS receiving module unit is used to measure the arrival time of signals broadcast by the locked satellite, demodulate and decode the messages broadcast by the satellite signals; the combined processor unit is used to verify the consistency and quality of satellite and Roland C measurement, select the best measurement combination to calculate time and integrity information through RAIM, and output timing pulse 1PPS and TOD information through RS422 serial port; the combined receiving system is a cylindrical structure with a height not exceeding 300mm and a diameter not exceeding 200mm.

2. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The antenna unit integrates a GNSS antenna (4) and a Loran C magnetic antenna (3), and the antenna unit is located inside the main body of the cylindrical combined receiving system; the GNSS antenna (4) adopts a three-in-one active ceramic microstrip antenna, and the GNSS antenna (4) is fixed on the top of the combined receiving system. The GNSS antenna (4) has circular polarization radiation characteristics; the Loran C magnetic antenna (3) includes a magnet, an impedance matching circuit and a back-end operational amplifier differential circuit. The magnet is composed of ferrite and a coil. The ferrite senses the magnetic field strength in the space and excites a changing current in the wound coil to receive electromagnetic waves in the space. The signal is then amplified by the active matching circuit and finally converted into a differential output signal by the operational amplifier differential circuit.

3. The integrated Roland C and GNSS combined receiving system according to claim 2, characterized in that: The system structure of the GNSS antenna (4) includes an antenna, a low-noise amplifier, and a bandpass filter connected in sequence, as well as a power divider, a power combiner, an RF front end, a feed structure, and a transmission line. The signal received by the antenna is amplified by the low-noise amplifier, filtered by the bandpass filter, distributed by the power divider, processed by the RF front end, synthesized by the power combiner, and finally transmitted through the feed structure and the transmission line.

4. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The Loran-C receiving module unit consists of an RF signal processing unit and a digital signal processing unit. The RF signal processing unit includes a bandpass filter, an RF amplifier, an automatic gain control circuit, a notch filter, and a limiting amplifier, used to further process the Loran-C signal processed by the antenna coupler. The digital signal processing unit includes an A / D converter, a microprocessor, a memory, and various interfaces. The digital signal processing unit is used to perform Loran-C signal search, acquisition, and tracking; identification and period identification of sky and ground waves; time delay correction and time difference extraction; generation of timing signals; and navigation and positioning calculations.

5. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The GNSS receiver module unit adopts a miniaturized integrated module and can simultaneously receive multiple satellite signals such as Beidou and GPS. The GNSS receiver module unit is equipped with a low-noise amplifier, surface acoustic wave filter, GNSSIC chip, reset circuit, battery, real-time clock, temperature-compensated crystal oscillator and crystal. After receiving satellite signals, the GNSS receiving module amplifies the satellite signals through an internal low-noise amplifier, then filters out out-of-band noise signals through a surface acoustic wave (SAW) filter. Subsequently, the satellite signals are sent to the GNSSIC chip to complete signal search, acquisition, tracking, bit synchronization, frame synchronization, error correction decoding, extraction and splicing of navigation messages, pseudorange measurement, and integral Doppler measurement. Finally, according to the navigation mode requirements, the module completes the user's PVT calculation, i.e., position, velocity, and time calculation, and outputs navigation information as well as satellite position and time information.

6. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The combined processor unit adopts a pseudorange rate combination mode; the system working mode of the combined processor unit is as follows: when GNSS is available, GNSS timing results are selected for output first, and the timing error of Loran C is calculated in real time using the GNSS results. When GNSS is unavailable, the timing result is output using Roland C plus error estimation.

7. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The overall structure of the combined receiving system, from top to bottom, consists of a GNSS antenna array, a Roland C magnetic antenna coupling plate, a GNSS signal receiving plate (2), a Roland C signal receiving plate (1), a vent valve (5), and an eight-core aviation connector (6). The GNSS signal receiving plate (2) and the Roland C signal receiving plate (1) are used to amplify, filter, and impedance match the corresponding signals received by the antenna.

8. The integrated Roland C and GNSS combined receiving system according to claim 7, characterized in that: To address potential interference from the power supply of the GNSS antenna array and the Roland C magnetic antenna coupling plate, the following anti-interference measures are adopted: First, the power supply circuits of the GNSS antenna array and the Roland C magnetic antenna coupling plate are strictly isolated from the power supply circuits of the GNSS signal receiving board (2), the Roland C signal receiving board (1), and the combined processor unit in the integrated receiving system; Second, the power supply grounding terminal of the GNSS antenna array and the power supply grounding terminal of the Roland C magnetic antenna coupling plate are connected to the same grounding node to achieve a common ground design.

9. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The Loland C receiving module unit calculates the distance difference between the user and the station by measuring the phase difference of the transmitted signals from two Loland C stations, thus obtaining a hyperbolic position line. Two intersecting hyperbolic position lines are obtained from the phase difference measurements of the signals from the two pairs of stations; the intersection point is the user's position. The hyperbolic positioning equation is: r1=((x-xs1)2+(y-ys1)2+(z-zs1)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 r2=((x-xs3)2+(y-ys3)2+(z-zs3)2)1 / 2-((x-xs2)2+(y-ys2)2+(z-zs2)2)1 / 2 In the formula, r1 is the distance difference between the user and stations s1 and s2, and r2 is the distance difference between the user and stations s3 and s2; x, y, and z are the user's positions, and xs1, ys1, zs1, xs2, ys2, zs2 and xs3, ys3, zs3 are the positions of the three stations s1, s2 and s3, respectively.

10. The integrated Roland C and GNSS combined receiving system according to claim 1, characterized in that: The Roland C receiver module unit obtains a hyperbolic position line by measuring the time difference between the arrival of signals from two navigation stations. The time difference equation is as follows: TD ij =((r ij -r i -r j ) / c)+CD TD in the formula ij Here are the observed time differences between stations i and j, where c is the radio wave propagation speed, and r is the time difference between stations i and j. ij It is the distance between two stations, CD is the encoding delay, and r i r j The distance from the user to the station can be obtained using the hyperbolic positioning equation. The time difference data output by the Loland C receiving module unit and the pseudorange data output by the GNSS receiving module unit support fusion to improve the stability, reliability and anti-interference capability of the signal transmission and time system of the GNSS and Loland C systems, and overcome the risk of dependence on GNSS within the effective coverage area of ​​the combined system.

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