Roland C propagation time delay measurement system

Abstract

The invention belongs to the technical field of time service navigation, and discloses a Roland C propagation time delay measurement system, which comprises an industrial personal computer, and integrates a satellite receiving module, a Roland C receiving module, a time interval counting module and a data acquisition unit by taking the industrial personal computer as a carrier, thereby thoroughly solving the problem of pain points caused by dispersed connection of multiple devices in the prior art, and improving the measurement accuracy. Compared with a traditional measurement system which needs to be independently provided with a Roland C receiver, a GNSS receiver, a counter and a PC, the size of the system is reduced by more than 70%, the weight is reduced to 1 / 3 of that of the traditional system, complex cable connection debugging is not needed, rapid deployment of field mountain and offshore measurement points can be completed by a single person, the deployment time is shortened from traditional 2-3 hours to 30 minutes or less, and meanwhile, the deployment efficiency is greatly improved. Each module transmits data through an internal synchronization link, so that synchronization errors and transmission delay caused by an external cable are avoided, the real-time performance and reliability of measured data are remarkably improved, and the risk of measurement errors caused by the collaboration problem between devices is effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of timing and navigation technology, specifically a Loran C propagation delay measurement system. Background Technology

[0002] In the field of timing and navigation, high-precision time synchronization is a core support for the stable operation of military communications, weaponry, aerospace, and civilian infrastructure such as power dispatching and financial transactions. With the full completion and promotion of my country's BeiDou Navigation Satellite System (BDS), it has become the mainstream timing method due to its advantages of wide-area coverage and real-time positioning and timing. However, the BeiDou system relies on space-based satellite signals and is greatly affected by complex electromagnetic environments, extreme weather, and human interference. In battlefield confrontations, areas with strong electromagnetic interference, or scenarios where satellite signals are obscured, such as deep mountains, canyons, and underground engineering projects, signal loss, decreased timing accuracy, or even failure are prone to occur, making it difficult to meet the high requirements of key fields for the continuity and reliability of timing.

[0003] However, the existing Loland C propagation delay measurement system has obvious defects. On the one hand, the system is scattered and complex. It requires separate configuration of Loland C receiver, GNSS receiver to provide position and clock reference, time interval counter to measure the time difference of two 1PPS signals, and PC to install data acquisition software. Each device needs to be connected and debugged by cable. Not only is it bulky and poorly portable, it is difficult to adapt to the rapid deployment needs of multiple measurement points in the field such as mountains and seas. Furthermore, due to synchronization errors between devices and data transmission delays, the risk of measurement errors increases. On the other hand, the existing system generally uses a single antenna, electric antenna or magnetic antenna to receive Loland C signals, lacking the ability to measure two types of antennas at the same time [1][2]. Electric antennas are sensitive to vertically polarized signals, and magnetic antennas are sensitive to horizontally polarized signals. Single-type antennas are prone to incomplete data reception due to differences in signal polarization characteristics. It is impossible to ensure the accuracy and difference of measurement results through data cross-verification. Especially in the land-sea interface area, the signal polarization mode is complex. Single antenna measurement is prone to ASF correction deviation exceeding 500ns, which is difficult to meet the correction requirements of 100 nanosecond-level timing accuracy. Summary of the Invention

[0004] The purpose of this invention is to provide a Roland C propagation delay measurement system to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A Loran-C propagation delay measurement system includes an industrial control computer, and a satellite receiving module, a Loran-C receiving module, a time interval counting module, and a data acquisition unit integrated within the industrial control computer; The satellite receiving module is used to provide current time, location information and UTC-1PPS second pulse signal, and outputs navigation and positioning data through serial port; The Roland C receiving module is used to receive Roland C signals and output a 1PPS second pulse signal, and communicates with the industrial control computer through a serial port. The time interval counting module is connected to the satellite receiving module and the Roland C receiving module respectively. The UTC-1PPS second pulse signal output by the satellite receiving module is used as the opening signal of the time interval counting module, and the 1PPS second pulse signal output by the Roland C receiving module is used as the closing signal of the time interval counting module. The time interval counting module is used to measure the time difference between the two 1PPS second pulse signals. The data acquisition unit is data acquisition software installed in the industrial control computer, used to store and count the time difference data measured by the time interval counting module.

[0006] Preferably, the Roland C receiving module consists of an analog signal processing unit and a digital signal processing unit; The analog signal processing unit consists of a bandpass filter, an automatic gain control circuit, a notch filter, and a limiting amplifier, while the digital signal processing unit consists of an A / D converter, a microprocessor, a memory, and an interface.

[0007] Preferably, the digital signal processing unit integrates an FPGA, which is used to control the Roland C receiving module to output a 1PPS pulse signal per second.

[0008] Preferably, the satellite receiving module adopts a GNSS time and frequency reference module design, which integrates a high-precision GNSS satellite measurement receiver and a rubidium clock.

[0009] Preferably, the time interval counting module is configured with an external 1PPS input interface, and the Roland C receiving module receives a real-time comparison of the 1PPS pulse signal output by the module with an external reference 1PPS pulse signal. The Roland C outputs the comparison result in the form of serial port data.

[0010] Preferably, the processing procedure of the Roland C receiving module for the Roland C signal is as follows: Digital filtering, notch filtering, amplification, digitization, start chain detection, signal search, signal acquisition, carrier tracking, ground wave / south wave identification, period identification and decision, tracking lock, frame header detection, data demodulation, and start TOC synchronization.

[0011] A Loland C propagation delay measurement antenna includes an antenna element, which is composed of a GNSS antenna and a Loland C antenna, wherein the Loland C antenna is composed of a Loland C electric antenna and a Loland C magnetic antenna.

[0012] Preferably, the GNSS antenna is a measurement-type microstrip antenna, which is a four-system full-frequency external measurement antenna covering BDS, GPS, GLONASS and GALILEO.

[0013] Preferably, the Roland C antenna adopts a columnar structure design, the length of the Roland C antenna is about 30 cm, and the Roland C is installed and fixed by a threaded rod.

[0014] Preferably, the Roland C magnetic antenna adopts a mushroom-shaped structure design, the Roland C magnetic antenna can be installed and fixed with a threaded rod, and the internal structure of the Roland C magnetic antenna adopts an orthogonal magnetic rod design.

[0015] The beneficial effects of this invention are as follows: 1. This invention integrates a satellite receiving module, a Loran-C receiving module, a time interval counting module, and a data acquisition unit into a single system using an industrial control computer as the carrier. This completely solves the pain point of multiple devices being scattered in existing technologies. Compared with traditional measurement systems that require separate configuration of a Loran-C receiver, a GNSS receiver, a counter, and a PC, this system is more than 70% smaller in size and weighs only 1 / 3 of the traditional system. It eliminates the need for complex cable connections and debugging, allowing a single person to quickly deploy measurement points in mountainous or marine environments. Deployment time is reduced from the traditional 2-3 hours to less than 30 minutes. At the same time, each module transmits data through an internal synchronous link, avoiding synchronization errors and transmission delays caused by external cables. The real-time performance and reliability of the measurement data are significantly improved, effectively reducing the risk of measurement errors caused by inter-device coordination issues. 2. This invention equips the system with a Loland C electric antenna and a magnetic antenna. The columnar structure of the electric antenna is sensitive to vertically polarized signals, while the mushroom-shaped and orthogonal magnetic rod design of the magnetic antenna is sensitive to horizontally polarized signals. The coordinated reception of the two antennas can completely capture the polarization characteristics of the Loland C signal, making it particularly suitable for complex polarization environments in land-sea border areas. Through cross-verification of data from the two antennas, invalid data caused by polarization blind spots of a single type of antenna can be eliminated, ensuring the integrity and consistency of the received data. Combined with the high-precision time difference measurement error of the time interval counting module (≤10ns), the ASF correction deviation can be controlled within 300ns, which is more than 40% more accurate than the traditional single-antenna measurement deviation of more than 500ns. This can meet the core requirement of Loland C time synchronization from microsecond to nanosecond level, providing a high-precision time delay correction basis for BeiDou-Loland C coordinated time synchronization. 3. This invention employs a GNSS time and frequency reference module design in its satellite receiving module, which integrates a high-precision GNSS receiver and a rubidium clock. When the GNSS signal is normal, the rubidium clock is trained using satellite measurement data to output a highly stable 1PPS signal and UTC time. When the GNSS signal is interfered with or obstructed, such as in deep mountains or canyons, the rubidium clock can independently and continuously output high-precision time and frequency signals, with a timekeeping accuracy deviation of ≤50ns within 1 hour. This design solves the problem of traditional measurement systems relying on a single GNSS clock and being unable to perform normal measurements when the satellite is lost. It ensures that Loran C propagation delay measurement can still be carried out continuously in complex scenarios where the BeiDou signal fails, further enhancing the applicability of the system in key fields such as military communications and emergency rescue. 4. This invention achieves automated filtering, acquisition, tracking, and 1PPS signal output of the Loran-C signal through the coordinated action of analog signal processing unit bandpass filtering, automatic gain control, notch filtering, digital signal processing unit A / D conversion, and FPGA control via the Loran-C receiving module. No manual intervention is required in the signal processing process. The data acquisition software automatically stores the measurement data from the time interval counting module and, combined with the position information output from the satellite receiving module, generates a Loran-C propagation delay database. It supports data visualization and comparison, such as the analysis and export of deviations between theoretical and measured values, significantly reducing the data analysis workload for operators. Compared to traditional systems that require manual data recording and organization, this system reduces operational complexity by 60%, effectively minimizing human error and improving the standardization and traceability of measurement data. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the ASF measurement principle of the present invention; Figure 2 This is a diagram showing the internal architecture of the system of the present invention; Figure 3 This is a hardware overall design architecture diagram of the present invention; Figure 4 This is a structural diagram of the GNSS antenna of the present invention; Figure 5 This is a design diagram of the Loran C magnetic antenna structure of the present invention; Figure 6 This is a structural diagram of the Roland C electric antenna of the present invention; Figure 7 This is a block diagram of the signal processing components of the Roland receiver module of the present invention; Figure 8 This is a block diagram illustrating the principle of the time interval counting module of the present invention. Detailed Implementation

[0017] 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.

[0018] like Figures 1 to 8 As shown, this embodiment of the invention provides a Loran-C propagation delay measurement system, including an industrial control computer, and a satellite receiving module, a Loran-C receiving module, a time interval counting module, and a data acquisition unit integrated within the industrial control computer; The satellite receiving module provides current time, location information, and UTC-1PPS second pulse signal, and outputs navigation and positioning data via serial port. The Roland C receiver module is used to receive Roland C signals and output a 1PPS pulse signal per second, and communicates with the industrial control computer via a serial port. The time interval counting module is connected to the satellite receiving module and the Roland C receiving module respectively. The UTC-1PPS second pulse signal output by the satellite receiving module is used as the opening signal of the time interval counting module, and the 1PPS second pulse signal output by the Roland C receiving module is used as the closing signal of the time interval counting module. The time interval counting module is used to measure the time difference between the two 1PPS second pulse signals. The data acquisition unit is data acquisition software installed in the industrial control computer, used to store and count the time difference data measured by the time interval counting module.

[0019] The industrial control computer integrates a satellite receiving module, a Loran-C receiving module, a time interval counting module, and a data acquisition unit. The satellite receiving module provides time, position, and UTC-1PPS signals. The Loran-C receiving module receives the signals and outputs a 1PPS signal. The time interval counting module measures the time difference between the two 1PPS signals. The data acquisition software stores and statistically analyzes the time difference data, thus completing the basic function of Loran-C propagation delay measurement.

[0020] The Roland C receiver module consists of an analog signal processing unit and a digital signal processing unit. The analog signal processing unit consists of a bandpass filter, an automatic gain control circuit, a notch filter, and a limiting amplifier, while the digital signal processing unit consists of an A / D converter, a microprocessor, a memory, and an interface.

[0021] The Loran C receiver module utilizes an analog signal processing unit with a bandpass filter, automatic gain control circuit, notch filter, and limiting amplifier, as well as a digital signal processing unit with an A / D converter, microprocessor, memory, and interface. The analog unit optimizes the Loran C signal, while the digital unit converts and processes the signal, thus enabling the reception and processing of the Loran C signal.

[0022] The digital signal processing unit integrates an FPGA, which is used to control the Roland C receiver module to output a 1PPS pulse signal.

[0023] The FPGA integrated into the digital signal processing unit controls the Roland C receiving module to output a 1PPS pulse signal per second, ensuring that the 1PPS signal is synchronized with the Roland C signal.

[0024] The satellite receiving module is designed as a GNSS time and frequency reference module, which integrates a high-precision GNSS satellite measurement receiver and a rubidium clock.

[0025] The time interval counting module is equipped with an external 1PPS input interface. The Roland C receives the 1PPS pulse signal output by the module and compares it with the external reference 1PPS pulse signal in real time. The Roland C outputs the comparison result in the form of serial port data.

[0026] The Loran-C receiving module performs digital filtering, notch filtering, amplification, digitization, start chain detection, signal search, signal acquisition, carrier tracking, ground wave / south wave identification, period identification and decision, tracking lock, frame header detection, data demodulation, and start TOC synchronization on the Loran-C signal, completing the full processing of the Loran-C signal and providing an accurate signal source for 1PPS output and time delay measurement.

[0027] The Loran-C receiver module processes the Loran-C signal as follows: Digital filtering, notch filtering, amplification, digitization, start chain detection, signal search, signal acquisition, carrier tracking, ground wave / south wave identification, period identification and decision, tracking lock, frame header detection, data demodulation, and start TOC synchronization.

[0028] A Loland C propagation delay measurement antenna includes an antenna element, which consists of a GNSS antenna and a Loland C antenna. The Loland C antenna consists of a Loland C electric antenna and a Loland C magnetic antenna.

[0029] The antenna elements of the Loland C propagation delay measurement antenna, namely the GNSS antenna and the Loland C antenna (which includes an electric antenna and a magnetic antenna), enable the reception of satellite signals and Loland C signals, providing signal input for the system.

[0030] Among them, the GNSS antenna is a measurement-type microstrip antenna, which is a four-system full-frequency external measurement antenna covering BDS, GPS, GLONASS and GALILEO.

[0031] The GNSS antenna employs a measurement-type microstrip antenna, which is a full-frequency external measurement antenna covering four systems: BDS, GPS, GLONASS, and GALILEO, ensuring the reception of multi-system satellite signals and providing high-precision position and time references.

[0032] The Roland C antenna features a columnar structure design, with a length of approximately 30 cm. It is mounted and fixed using a threaded rod.

[0033] The Loland C antenna, with its cylindrical structure, approximately 30 cm in length, and threaded rod installation, enables the reception of vertically polarized Loland C signals and facilitates installation and deployment.

[0034] The Roland C magnetic antenna features a mushroom-shaped structure and can be installed and fixed using threaded rods. The internal structure of the Roland C magnetic antenna adopts an orthogonal magnetic rod design.

[0035] By employing a mushroom-shaped structure, threaded rod mounting, and internal orthogonal magnetic rod design, the Loland C magnetic antenna achieves the reception of horizontally polarized Loland C signals, while also providing omnidirectional reception capability and facilitating installation and deployment.

[0036] Working principle and usage process: After the system starts up, the external antenna unit first performs signal reception. The GNSS antenna receives satellite signals from four systems: BDS, GPS, GLONASS, and GALILEO, and transmits them to the satellite receiving module and GNSS time and frequency reference module in the industrial control computer. At the same time, the Loland C electric antenna and the magnetic antenna respectively receive 100kHz Loland C ground wave signals. The electric antenna captures vertically polarized signals, and the magnetic antenna is designed with orthogonal magnetic rods to capture horizontally polarized signals. The two Loland C signals are transmitted synchronously to the Loland C receiving module, realizing the complete acquisition of signals with different polarization characteristics, laying the foundation for subsequent data cross-validation. After receiving satellite signals transmitted from the GNSS antenna, the satellite receiving module uses an internal high-precision GNSS satellite measurement receiver to analyze the signals and generate TOD (Time and Date) information, latitude and longitude location information of the receiving point, and a UTC-1PPS second pulse signal. On one hand, the location information and TOD information are transmitted to the industrial control computer's data analysis software via serial port as a location reference and time reference for delay calculation. On the other hand, the TOD information and UTC-1PPS signal are used to discipline the integrated rubidium clock, enabling it to output a highly stable time and frequency signal synchronized with the GNSS reference. If the GNSS signal is interfered with or blocked, the rubidium clock automatically switches to independent working mode, continuously outputting a high-precision 1PPS pulse and time signal to ensure uninterrupted time and frequency reference. The Loran-C receiving module processes the Loran-C signal transmitted from the dual antennas in stages. First, the analog signal processing unit filters 10... Outside the 0kHz band, noise is detected. The automatic gain control circuit adjusts the signal amplitude to the appropriate range, the notch filter suppresses specific frequency interference such as power line harmonics, and the limiting amplifier avoids signal overload, thus completing the analog signal optimization. Subsequently, the A / D converter converts the optimized analog signal into a digital signal and transmits it to the digital signal processing unit. The microprocessor of the digital signal processing unit performs start-up chain detection, signal search, acquisition, and carrier tracking on the digital signal. At the same time, it completes the identification of ground wave and sky wave signals, period identification and judgment, and eliminates invalid sky wave signals. Then, the propagation time delay deviation of the Loran C signal is calculated through the time delay correction algorithm to extract the time difference information. Finally, the FPGA generates a 1PPS second pulse signal synchronized with the Loran C signal based on the time difference information, transmits it to the time interval counting module through the internal link, and feeds back the signal processing data, such as the acquisition status and tracking accuracy, to the industrial control computer through the serial port. The time interval counting module receives two key signals: the UTC-1PPS second pulse signal output by the satellite receiver module is used as the door opening signal, and the 1PPS second pulse signal output by the Roland C receiver module is used as the door closing signal. The module adopts high-precision time difference measurement technology with an error of ≤10ns to measure the time difference between the two 1PPS signals in real time. This time difference is the propagation delay deviation of the Roland C signal relative to the GNSS reference. At the same time, if it is necessary to compare with an external reference signal, an external signal can be connected through the module's external 1PPS input interface to realize parallel measurement of the time difference of multiple signals. The measurement results are transmitted to the data analysis software of the industrial control computer in real time in the form of serial port data. The data acquisition software within the industrial control computer receives multi-source data: location information and TOD information from the satellite receiving module, time delay measurement data from the time interval counting module, and signal processing status data from the Loran-C receiving module. The software first cross-validates the Loran-C signal data received by both antennas, eliminating invalid data from a single-polarized antenna to ensure the validity of the measurement data. Then, combining the latitude and longitude information of the receiving point, it calls a preset empirical formula for atmospheric refractive index, such as Ns = 1.000325 - 0.028h × 10⁻¹⁰ in spring and autumn. -8 h is a lookup table of average altitude and geoelectric conductivity. The theoretical values ​​of the primary phase factor PF and the secondary phase factor SF are calculated. Then, combined with the measured time delay deviation, the correction value of the additional secondary phase factor ASF is derived. Finally, all data is automatically stored to generate a Loland C propagation time delay database. It supports data visualization and comparison, such as charts of the deviation between theoretical and measured values, export, and historical data backtracking, thus completing the entire Loland C propagation time delay measurement process.

[0037] 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.

[0038] 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. A Loran C propagation delay measurement system, characterized in that: It includes an industrial control computer, as well as a satellite receiving module, a Loran-C receiving module, a time interval counting module, and a data acquisition unit integrated within the industrial control computer; The satellite receiving module is used to provide current time, location information and UTC-1PPS second pulse signal, and outputs navigation and positioning data through serial port; The Roland C receiving module is used to receive Roland C signals and output a 1PPS second pulse signal, and communicates with the industrial control computer through a serial port. The time interval counting module is connected to the satellite receiving module and the Roland C receiving module respectively. The UTC-1PPS second pulse signal output by the satellite receiving module is used as the opening signal of the time interval counting module, and the 1PPS second pulse signal output by the Roland C receiving module is used as the closing signal of the time interval counting module. The time interval counting module is used to measure the time difference between the two 1PPS second pulse signals. The data acquisition unit is data acquisition software installed in the industrial control computer, used to store and count the time difference data measured by the time interval counting module.

2. The Loran C propagation delay measurement system according to claim 1, characterized in that: The Roland C receiver module consists of an analog signal processing unit and a digital signal processing unit. The analog signal processing unit consists of a bandpass filter, an automatic gain control circuit, a notch filter, and a limiting amplifier, while the digital signal processing unit consists of an A / D converter, a microprocessor, a memory, and an interface.

3. The Loran C propagation delay measurement system according to claim 2, characterized in that: The digital signal processing unit integrates an FPGA, which is used to control the Roland C receiving module to output a 1PPS pulse signal per second.

4. The Loran C propagation delay measurement system according to claim 1, characterized in that: The satellite receiving module is designed as a GNSS time and frequency reference module, and integrates a high-precision GNSS satellite measurement receiver and a rubidium clock.

5. The Loran C propagation delay measurement system according to claim 1, characterized in that: The time interval counting module is equipped with an external 1PPS input interface. The 1PPS pulse signal output by the Roland C receiving module is compared in real time with the external reference 1PPS pulse signal. The Roland C outputs the comparison result in the form of serial port data.

6. The Loran C propagation delay measurement system according to claim 1, characterized in that: The Loran-C receiving module processes the Loran-C signal as follows: Digital filtering, notch filtering, amplification, digitization, start chain detection, signal search, signal acquisition, carrier tracking, ground wave / south wave identification, period identification and decision, tracking lock, frame header detection, data demodulation, and start TOC synchronization.

7. A Loland C propagation delay measurement antenna, characterized in that: It includes an antenna unit, which consists of a GNSS antenna and a Loran-C antenna, wherein the Loran-C antenna consists of a Loran-C electric antenna and a Loran-C magnetic antenna.

8. The Loland C propagation delay measurement antenna according to claim 7, characterized in that: The GNSS antenna is a measurement-type microstrip antenna, which is a four-system full-frequency external measurement antenna covering BDS, GPS, GLONASS and GALILEO.

9. A Loland C propagation delay measurement antenna according to claim 7, characterized in that: The Roland C antenna adopts a columnar structure design, with a length of approximately 30 cm. The Roland C antenna is installed and fixed using a threaded rod.

10. A Loland C propagation delay measurement antenna according to claim 7, characterized in that: The Roland C magnetic antenna adopts a mushroom-shaped structure design and can be installed and fixed with a threaded rod. The internal structure of the Roland C magnetic antenna adopts an orthogonal magnetic rod design.

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