An inter-satellite link equipment delay real-time calibration method based on full duplex system

Abstract

The application provides an inter-satellite link equipment time delay real-time calibration method based on a simultaneous same-frequency full duplex system, which realizes real-time continuous equipment time delay calibration on a satellite, does not need to additionally introduce a special self-calibration channel, overcomes the problem of high hardware complexity of the existing method, saves satellite resources without introducing the self-calibration channel, avoids time delay uncertainty caused by switch switching, and supports continuous real-time calibration and has good real-time performance.

Description

Technical Field

[0001] This invention belongs to the field of navigation inter-satellite link measurement and communication technology, specifically relating to a real-time time delay calibration method for inter-satellite link equipment based on full-duplex system. Background Technology

[0002] The BeiDou-3 Global Navigation Satellite System (BDS-3) was completed on July 31, 2020, and officially began providing positioning, navigation, and timing services globally. All BDS-3 satellites are equipped with Ka-band inter-satellite link payloads, enabling precise orbit determination and time synchronization through precise inter-satellite measurements and data transmission. By establishing measurement and communication links between navigation satellites, these links can continuously correct long-term predicted ephemeris and clock parameters, autonomously generate navigation messages, and achieve autonomous navigation without the support of a ground-based telemetry, tracking, and command (TT&C) system. This improves orbit determination accuracy and enhances the constellation's autonomous configuration maintenance capabilities.

[0003] Based on current research on inter-satellite autonomous orbit determination and time synchronization, achieving meter-level accuracy in orbit determination and time synchronization requires inter-satellite ranging accuracy down to the decimeter or even centimeter level. Therefore, the accuracy and precision of inter-satellite link ranging play a crucial role in comprehensively improving the performance of the inter-satellite link system. Currently, the BeiDou inter-satellite link employs a dual-one-way pseudocode ranging mode based on a time-division half-duplex system. During bidirectional measurement in the inter-satellite link, the nonlinearity of onboard equipment such as mixers, power amplifiers, and low-noise amplifiers leads to group delay fluctuations and phase distortion in the received signal. Furthermore, the equipment delay changes due to factors such as device aging, multiple access interference, and temperature drift. This equipment delay error is included in the pseudorange measurement value, affecting the overall ranging, orbit determination, and time synchronization performance of the system. This error is a significant source of error in the inter-satellite measurement system, reaching the order of milliseconds, and must be controlled and eliminated through appropriate measures. Therefore, the time delay measurement and calibration technology of inter-satellite link equipment is a key link to improve the accuracy of inter-satellite measurement and realize precise orbit determination and time synchronization of inter-satellite links. It has important engineering value and practical significance for promoting the construction and development of my country's satellite navigation inter-satellite link system.

[0004] The current main method for calibrating the latency of inter-satellite link equipment is to introduce a frequency converter with integrated up-conversion and down-conversion functions into the ranging equipment as a self-calibration channel, forming a closed-loop transmission and reception circuit between the transmitting and receiving channels. Figure 1 The diagram shown illustrates the principle of this method. The specific steps of the method are described below:

[0005] The first step is to configure a closed-loop circuit with integrated up / down conversion function in the inter-satellite link equipment, allowing the signal to be coupled directly back to the receiver without passing through the antenna radiation;

[0006] The second step is to disable the self-calibration channel and measure the delay T1 of loop 1, i.e., the device transmission delay H. TX With reception delay H RX sum;

[0007] The third step is to close the receiving channel, open the self-calibration channel, and measure the delay T2 of loop 2, which is the delay H of the device's transmitting channel. TX and self-calibration channel delay H CX sum;

[0008] Fourth step: Close the transmit channel, open the self-calibration channel, and measure the delay T3 of loop 3, which is the delay H of the device's receive channel. RX and self-calibration channel delay H CX sum;

[0009] Fifth, based on the measurement results from steps two through four, the simultaneous equations can be obtained.

[0010]

[0011] Solving the system of equations yields the transmit / receive channel delay as follows:

[0012]

[0013] The accuracy of the delay detection method is related to the accuracy of the baseband signal processing. During closed-loop self-calibration, since the signal transmission path is shorter and the quality of the received signal is better, high-precision delay correction can be achieved.

[0014] This method has high hardware complexity, requiring the design of a dedicated self-calibration channel, which increases the size and power consumption of the RF link. Frequent switching may introduce transient noise that affects calibration accuracy. At the same time, this method has low real-time performance, requiring switching between three modes and failing to achieve rapid continuous calibration. Summary of the Invention

[0015] In view of this, the purpose of this invention is to provide a real-time latency calibration method for inter-satellite link equipment based on a full-duplex system. This method does not require the introduction of an additional self-calibration channel, making it more suitable for resource-constrained satellite platforms and avoiding latency uncertainties introduced by frequent switching. Furthermore, this method overcomes the low real-time performance problem of the original method, supports continuous closed-loop calibration and simultaneous two-way ranging, and is better adapted to the influence of factors such as temperature drift and high-dynamic inter-satellite scenarios.

[0016] A real-time latency calibration method for inter-satellite link devices based on full-duplex architecture, comprising:

[0017] The first step is for Satellite A and Satellite B to plan and establish an inter-satellite link based on their respective onboard frequency standards, according to the time slot schedule marked on the ground.

[0018] The second step is that satellite A and satellite B agree on the same launch time, using their respective clocks as the reference, and simultaneously send information frames with the same structure to each other.

[0019] The third step is that the baseband signal processing unit of satellite A generates a ranging signal, converts it into an analog signal, and then broadcasts it through the transmitting antenna.

[0020] Fourthly, the ranging signal broadcast by satellite A is transmitted through space and then received by satellite B, completing the reception of the ranging signal. The corresponding transmission delay measurement value T1 is expressed as follows:

[0021] T1 = t A +τ AB +r B (1)

[0022] Among them, t A τ is the launch channel delay for satellite A. AB Let r be the propagation delay of the signal from the transmitter at satellite A to the receiver at satellite B. B For the receiving channel delay of satellite B;

[0023] Fifth, the ranging signal broadcast by satellite A also directly enters its receiver. After self-interference suppression in the spatial and radio frequency domains, it reaches the baseband signal processing unit. While performing self-interference suppression in the digital domain, it also completes the internal self-loopback of satellite A. The corresponding time delay measurement value T2 can be expressed as...

[0024] T2=t A +τ A +r A (2)

[0025] Where, τ A To account for the air interface time delay of the signal from the transmitting antenna of Satellite A to the receiving antenna of Satellite A, calibration can be performed in advance in an anechoic chamber. A For the receiving channel delay of satellite A;

[0026] Step 6: Simultaneously, while satellite A broadcasts the ranging signal to satellite B, satellite B also synchronously broadcasts the ranging signal to satellite A. The signal propagates through space and is received by satellite A; the corresponding time delay measurement value T3 can be expressed as...

[0027] T3 = t B +τ BA +r A (3)

[0028] Among them, t B τ is the launch channel delay for satellite B. BA The propagation delay of the signal from the transmitter on satellite B to the receiver on satellite A;

[0029] In the seventh step, the ranging signal broadcast by satellite B will also directly enter the receiver of satellite B, completing the internal self-loopback of satellite B. The corresponding time delay measurement value T4 can be expressed as:

[0030] T4 = t B +τ B +r B (4)

[0031] Where, τ B The air interface delay is the time it takes for the signal to travel from the transmitting antenna of Satellite B to the receiving antenna of Satellite B.

[0032] Step 8: Due to the high dynamism between satellites and the clock difference between satellite A and satellite B, the two-way propagation delays between satellites are not equal. Therefore, it is necessary to use the broadcast ephemeris stored on the satellite to perform time-stamping, which yields the following relationship:

[0033] τ AB =τ BA +△τ (5)

[0034] Where Δτ is the difference in propagation delay obtained by time-scale reduction;

[0035] Step 9: Solve the system of equations (1) to (5) simultaneously to calculate the equipment delay. The system of equations is as follows:

[0036]

[0037] Solving for

[0038]

[0039] t A +r B and t B +r A The device delay is measured bidirectionally for inter-satellite links, and the device delay error in bidirectional inter-satellite measurements can be eliminated based on this result.

[0040] The present invention has the following beneficial effects:

[0041] This invention proposes a real-time time delay calibration method for inter-satellite link equipment based on a simultaneous, same-frequency, full-duplex system. This method achieves real-time continuous time delay calibration of equipment on the satellite without the need for an additional dedicated self-calibration channel. It overcomes the problem of high hardware complexity in existing methods, saves satellite resources by eliminating the need for a self-calibration channel, avoids the time delay uncertainty caused by switching, and performs time delay calibration and bidirectional ranging synchronously, supporting continuous real-time calibration with good real-time performance. Attached Figure Description

[0042] Figure 1 A schematic diagram illustrating the principle of existing equipment delay calibration methods;

[0043] Figure 2 This is a schematic diagram showing the location for suppressing self-interference in simultaneous, same-frequency, full-duplex communication.

[0044] Figure 3 A schematic diagram illustrating the principle of a real-time latency calibration method for inter-satellite link devices based on full-duplex architecture;

[0045] Figure 4 This is a flowchart of a real-time latency calibration method for inter-satellite link devices based on a full-duplex system. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] This invention provides a real-time time delay calibration method for inter-satellite link devices based on a simultaneous, same-frequency, full-duplex system. This method can save on-board resource consumption, avoid the time delay uncertainty introduced by frequent switching, and achieve continuous closed-loop calibration.

[0048] First, the feasibility of applying full-duplex technology is analyzed. If simultaneous, same-frequency full-duplex technology is introduced into the BeiDou inter-satellite link communication and measurement system, it is necessary to meet the requirement that the satellite receiver receives a self-interference signal P. SI This means that the transmitted signal directly entering the receiving antenna can be suppressed below the receiver's noise floor, thus not affecting normal inter-satellite communication measurements. Since the self-interference signal is directly received by the receiving antenna after being transmitted, considering the effects of transmission circuit losses, polarization losses, and other loss factors, the required self-interference suppression C for the system can be calculated as follows:

[0049] [C] = [EIRP] - [L] P ]-[N](dB)

[0050] Where EIRP is the equivalent isotropic radiated power, L P Let N be the antenna polarization loss and N be the receiver thermal noise power. The budget table for the BeiDou inter-satellite link is given below, as shown in Table 1.

[0051] Table 1. Budget Parameters for BeiDou Navigation Inter-Satellite Links

[0052]

[0053] The equivalent isotropic radiated power (EIRP) is defined as follows:

[0054] [EIRP] = [P t ]+[G t ]-[L s (dB)

[0055] Substituting the corresponding parameter values ​​into the budget parameter table, we can calculate EIRP≈49.53dBW. Using the Frye formula, the total noise temperature T of the receiving system can be calculated. s for

[0056] T s =T a +(L N -1)T0+(F-1)LT0

[0057] By substituting the corresponding parameter values ​​into the link budget parameter table, T can be calculated. s If the receiver thermal noise power is approximately 964.51K, then the receiver thermal noise power N is...

[0058] [N] = [k] + [T] s ]+[B n ]≈-125.65dBW

[0059] Substituting the results calculated earlier, we can obtain the system's self-interference suppression requirement C as follows:

[0060] [C]=49.53dBW-2dB-(-125.65dBW)≈173.18dB

[0061] To achieve normal measurement and communication, the isolation level of the system's receiving end must be greater than or close to this value, which makes the system design difficult and complex. However, in recent years, the academic community has conducted extensive and in-depth research on the theoretical basis and technical implementation of simultaneous full-duplex technology, gradually improving the level of self-interference suppression and accumulating certain achievements in the aerospace field. Simultaneous full-duplex inter-satellite link communication and measurement system is no longer impossible.

[0062] Currently, the industry is conducting extensive research on full-duplex self-interference suppression technology. Based on the location of the full-duplex self-interference suppression, it can be roughly divided into spatial domain (antenna domain) self-interference suppression, analog domain self-interference suppression, and digital domain self-interference suppression. Among them, analog domain self-interference suppression can be further subdivided into radio frequency (RF) and intermediate frequency (IF) self-interference suppression, with RF domain self-interference suppression being the main focus.

[0063] Spatial domain self-interference suppression mainly reduces near-field coupling effects between antennas by improving the isolation between transmitting and receiving antennas in space. It can be divided into two main categories: passive passive suppression techniques and active active suppression techniques. Passive passive suppression includes methods such as antenna separation, orthogonal polarization, near-field cancellation, feedback network isolation, and decoupling structure design. Active active suppression primarily uses transmit and receive beamforming technology. Since the BeiDou inter-satellite link uses a Ka-band narrow-beam phased array system, the research progress on spatial domain self-interference suppression of array antennas with center frequencies in the 20GHz–30GHz range is the focus. Table 2 shows the current research status of spatial domain self-interference suppression for array antennas.

[0064] Table 2. Current Status of Research on Spatial Domain Self-Interference Suppression of Array Antennas

[0065]

[0066] Spatial domain self-interference suppression has limited capability and cannot completely eliminate self-interference signals; the residual self-interference signal is still greater than the useful signal. Therefore, further self-interference suppression is needed in the radio frequency (RF) domain. RF domain self-interference suppression refers to self-interference suppression processing at the RF front-end. The idea is to estimate the residual self-interference signal and remove it from the received RF signal, thereby avoiding blocking and saturation of nonlinear devices in the RF receiving channel. Based on current research, RF domain self-interference suppression techniques can be broadly classified into three types: direct RF coupling interference suppression, digitally assisted RF interference suppression, and device design capable of achieving high isolation. Table 3 shows the current research status of RF domain self-interference suppression in the center frequency range of 20 GHz to 30 GHz.

[0067] Table 3. Current Status of Research on Self-Interference Suppression in the Radio Frequency Domain

[0068]

[0069]

[0070] Digital domain self-interference suppression (SOS) refers to further canceling or suppressing the residual self-interference signal after radio frequency SOS suppression in the digital domain to achieve the identification and demodulation of the useful signal. In full-duplex systems, the near-end transmitted signal is considered known, while the characteristics of the self-interference channel are unknown. Therefore, digital domain SOS requires utilizing the known transmitted self-interference signal to estimate and compensate for the self-interference channel, thus achieving the goal of self-interference suppression. Current research on digital domain SOS techniques mainly includes three types: self-interference channel reconstruction suppression, adaptive filtering self-interference suppression, and nonlinear self-interference suppression. Table 4 shows the current status of digital domain SOS research in recent years.

[0071] Table 4. Current Status of Research on Self-Interference Suppression in the Digital Domain

[0072]

[0073] A comprehensive analysis of Tables 2 to 4 shows that research on full-duplex self-interference suppression technology is quite advanced both domestically and internationally, and the self-interference suppression capabilities in various domains have reached a high level. For Ka-band array antennas, by employing spatial separation, orthogonal polarization, and decoupling structure design, a self-interference suppression effect of approximately 100dB can be achieved. For the Ka-band RF domain, through multi-tap channel reconstruction and the development of high-isolation devices, a self-interference suppression effect greater than 35dB can be achieved. For self-interference suppression in the digital domain, with the introduction of technologies such as artificial intelligence and deep learning, the optimal suppression effect can exceed 45dB.

[0074] Reference

[22] proposed a method for multi-tap RF cancellation and digital nonlinear self-interference suppression for a 20MHz bandwidth spread spectrum measurement and control system. Through simulation and experimental verification, it was found that the self-interference suppression effect reached 41.5dB and 38dB in the RF domain and digital domain, respectively. The dual-domain joint elimination of about 81dB of self-interference signal has strong reference value for the research of Beidou inter-satellite link full-duplex communication measurement system. According to the current research status at home and abroad, a full-duplex spread spectrum measurement and communication system with a bandwidth of 20MHz based on Ka band array antenna can achieve a self-interference suppression level of about 180dB, which is about 7dB higher than the calculated system self-interference suppression requirement C. Therefore, it is feasible to introduce the simultaneous and same frequency full-duplex technology into the Beidou inter-satellite link communication measurement system.

[0075] The following section details a method for real-time latency calibration of inter-satellite link devices based on a simultaneous, same-frequency, full-duplex system. Figure 3 , Figure 4 The diagram and flowchart below illustrate the principle of this method, which can be described as consisting of the following nine steps:

[0076] The first step is for Satellite A and Satellite B to plan and establish an inter-satellite link based on their respective onboard frequency standards, according to the time slot schedule marked on the ground.

[0077] The second step is that satellite A and satellite B agree on the same launch time, using their respective clocks as the reference, and simultaneously send information frames with the same structure to each other.

[0078] The third step involves the baseband signal processing unit of satellite A generating a ranging signal, which is then converted into an analog signal by a digital-to-analog converter (DAC), and finally transmitted via a transmitting antenna after passing through radio frequency devices such as an up-converter and a power amplifier (PA).

[0079] The fourth step involves the ranging signal broadcast by satellite A propagating through space and being received by satellite B. After passing through devices such as a low-noise amplifier (LNA), down-converter, and analog-to-digital converter (ADC), the signal reaches the baseband signal processing unit, completing the reception of the ranging signal (corresponding to...). Figure 3Path 1 in the diagram). The corresponding transmission delay measurement value T1 can be expressed as:

[0080] T1 = t A +τ AB +r B (1)

[0081] Among them, t A τ is the launch channel delay for satellite A. AB Let r be the propagation delay of the signal from the transmitter at satellite A to the receiver at satellite B. B This is the reception channel delay for satellite B.

[0082] Fifth, because the system adopts a simultaneous, same-frequency, full-duplex mode, the ranging signal broadcast by satellite A will also directly enter its receiver. After self-interference suppression in the spatial and radio frequency domains, it reaches the baseband signal processing unit, where it performs digital domain self-interference suppression while simultaneously completing satellite A's internal self-loopback (corresponding to...). Figure 3 Path 2 in the diagram). The corresponding time delay measurement value T2 can be expressed as:

[0083] T2=t A +τ A +r A (2)

[0084] Where, τ A To account for the air interface time delay of the signal from the transmitting antenna of Satellite A to the receiving antenna of Satellite A, calibration can be performed in advance in an anechoic chamber. A This is the reception channel delay for satellite A.

[0085] Step 6: Simultaneously, while satellite A broadcasts its ranging signal to satellite B, satellite B also synchronously broadcasts its ranging signal to satellite A. This signal propagates through space and is received by satellite A (corresponding to...). Figure 3 The path 3), the corresponding time delay measurement value T3 can be expressed as:

[0086] T3 = t B +τ BA +r A (3)

[0087] Among them, t B τ is the launch channel delay for satellite B. BA This represents the propagation delay of the signal from the transmitter at satellite B to the receiver at satellite A.

[0088] In the seventh step, the ranging signal broadcast by satellite B will also directly enter the receiver of satellite B, completing the internal self-loopback of satellite B (corresponding to...). Figure 3 The path 4), the corresponding time delay measurement value T4 can be expressed as:

[0089] T4 = t B+τ B +r B (4)

[0090] Where, τ B The air interface time delay of the signal from the transmitting antenna of Satellite B to the receiving antenna of Satellite B can be calibrated in advance in an anechoic chamber.

[0091] Step 8: Due to the high dynamism between satellites and the clock difference between satellite A and satellite B, the two-way propagation delays between satellites are not equal. Therefore, it is necessary to use the broadcast ephemeris stored on the satellite to perform time-stamping, which yields the following relationship:

[0092] τ AB =τ BA +△τ (5)

[0093] Where Δτ is the difference in propagation delay obtained by time-scale reduction;

[0094] Step 9: Solve the system of equations (1) to (5) simultaneously to calculate the equipment delay. The system of equations is as follows:

[0095]

[0096] The solution can be obtained

[0097]

[0098] t A +r B and t B +r A The method measures the equipment delay for bidirectional inter-satellite links, and the result can be used to eliminate equipment delay errors in bidirectional inter-satellite measurements. Since the link-establishing satellite pairs can continuously broadcast signals to each other within a specified time slot, this method can achieve real-time continuous calibration of onboard equipment delays.

[0099] References:

[0100] [1] Chen Jianyun, Zhou Yongbin, Yang Jun. Measurement and Communication Principles of Inter-Satellite Links in Satellite Navigation Systems [M]. Beijing: National Defense Industry Press, 2021: 48-50.

[0101] [2] Chen Yuan. Precision Measurement of Inter-Satellite Links [D]. Beijing University of Aeronautics and Astronautics, 2011.

[0102] [3] Liu Xi. Research on high-precision ranging method between navigation satellites [D]. Beijing University of Aeronautics and Astronautics, 2013.

[0103] [4]Nan Feng Liu;Yu Jian Cheng;Ya Fei Wu.K / Ka Dual-Band Dual-Circular-PolarizedCoplanar Phased Array Antenna with High Isolation for SatelliteCommunication[A].2020International Conference on Microwave and MillimeterWaveTechnology(ICMMT)[C],2020.

[0104] [5]D.-C.Son;A.Samaiyar;M.Elmansouri;D.Filipovic;P.ValalePrasannakumar.Phased Array Antenna for Bi-Static Simultaneous Transmit andReceive(STAR)system[A].2020IEEE International Symposium on Antennas andPropagation and NorthAmerican Radio Science Meeting[C],2020.

[0105] [6]Park K,et al.A 28-GHz full duplex front-end and canceller usingtwo cross-polarized 64element phased arrays[J].IEEE Transactions on MicrowaveTheory and Techniques,2021,69(1):1127-1135.

[0106] [7]Mikko Heino;Carlos Baquero Barneto;Taneli Riihonen;MikkoValkama.Design ofPhased Array Architectures for Full-Duplex JointCommunications and Sensing[A].2021 15th European Conference on Antennas andPropagation(EuCAP)[C],2021.

[0107] [8]] Li-Chi Chang; Yi-Hsien Lin; Shih-Yuan Chen; Hsi-Tseng Chou; HueiWang.A Duplexing Hybrid Slot Antenna Design With High Isolation for Short-Range RadarDetection and Identification Applications at 24GHz Band[J]. IEEETransactionson Antennas and Propagation, 2022, Vol.70(4):2468-2479.

[0108] [9] Sun, Haolin. Design and verification of 5G millimeter wave full-duplex radio frequency self-interference suppression circuit [D]. University of Electronic Science and Technology of China, 2022.

[0109]

[10] Li Yang. Research on key technologies of millimeter wave simultaneous and same frequency full-duplex array antenna [D]. University of Electronic Science and Technology of China, 2023.

[0110]

[11] Xie, Zhuoheng; Jin, Shi ChaoCAa; Sun, Jia XingCAb; Liu, Dunge; Huang, Bo; Yang, Yuqian; Mei, Chenyu; Su, Jinhuai; Huang, Jun; Wu, Xiulong; Zhang, Lei. A K-band eight-element reconfigurable phased-array receiver with high Tx-band rejection[J]. IET Microwaves, Antennas and Propagation, 2024, Vol.18(12):1.

[0111]

[12] Zhang, YH; Xiao, SL; Feng, HL; Zhang, L; Zhou, Z; Hu, WS. Self-interferencecancellation using dual-drive Mach-Zehnder modulator for in-bandfull-duplexradio-over-fiber system (Article) [J]. Optics Express, 2015, Vol. 23(26): 33205-33213.

[0112]

[13] Talat Cetin; Can Onol; Gokhun Selcuk. A Ka-Band Front-End in 100nmGaAs Process for In-Band Full Duplex Communications [A]. IEEE EUROCON 2019-18thInternationalConference on Smart Technologies [C], 2019.

[0113]

[14] Yoonsoo Jin; Songcheol Hong.28-GHz In-Band Full-Duplex PowerAmplifier Integrated With an Impedance Matched Hybrid Transformer[J]. IEEEMicrowave andWireless Components Letters, 2020, Vol.30(4):410-413.

[0114]

[15] Haifeng Luo;Abhijeet Bishnu;Tharmalingam Ratnarajah.Design andAnalysis of In-Band Full-Duplex Private 5G Networks Using FR2 Band[J].IEEEAccess,2021,Vol.9:1.

[0115]

[16] Sun, Haolin. Design and verification of 5G millimeter wave full-duplex radio frequency self-interference suppression circuit [D]. University of Electronic Science and Technology of China, 2022.

[0116]

[17] Yu Hao. Research on self-interference cancellation in digital domain with simultaneous frequency and full duplex [D]. Hangzhou Dianzi University, 2021.

[0117]

[18] Mao Bei. Research on digital domain interference cancellation technology in simultaneous transmission and reception systems [D]. Harbin Engineering University, 2022.

[0118]

[19] Yu, Bin; Qian, Chen; Lee, Juho; Shao, Shihai; Shen, Ying; Pan, Wensheng; Lin, Peng; Zhang, Zhiya; Kim, Sundo; Hu, Su; Lee, Kwonjong; Jung, Jungsoo; Choi, Sunghyun; Sun, Chengjun. Realizing High Power Full Duplex in Millimeter WaveSystem: Design, Prototype and Results[J].IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS,2023,Vol.41(9):2893-2906.

[0119]

[20] Lu Fan, Fan Zhanchun, Ma Chao, Chen Yuanxiang, Wang Yuhan, Cheng Jingshuang, Du Hailong, Hu Cong. Simultaneous and same frequency full-duplex digital domain self-interference suppression method based on Bi-LSTM [J]. Science in China (Information Science), 2023, 53(10): 1982-1993.

[0120]

[21] Wang Yuhan. Research on nonlinear self-interference suppression technology in simultaneous full-duplex systems with the same frequency [D]. Beijing University of Posts and Telecommunications, 2024.

[0121]

[22] Yu Wei, Zhang Yi, Zhang Zhiya, Shen Ying, Pan Wensheng, Shao Shihai. Design and experimental verification of self-interference suppression in full-duplex telemetry and control links [J]. Journal of Xi'an University of Electronic Science and Technology, 2023, 50(3): 182-191.

[0122] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A real-time latency calibration method for inter-satellite link equipment based on full-duplex system, characterized in that, Without the need for an additional dedicated self-calibration channel, real-time equipment latency calibration is achieved by utilizing the self-loopback characteristic of simultaneous full-duplex transmission and reception, including: The first step is for Satellite A and Satellite B to plan and establish an inter-satellite link based on their respective onboard frequency standards, according to the time slot schedule marked on the ground. The second step is that satellite A and satellite B agree on the same launch time, using their respective clocks as the reference, and simultaneously send information frames with the same structure to each other. The third step is that the baseband signal processing unit of satellite A generates a ranging signal, converts it into an analog signal, and then broadcasts it through the transmitting antenna. The fourth step involves the ranging signal broadcast by satellite A being received by satellite B after propagation through space, thus completing the reception of the ranging signal and measuring the corresponding transmission delay. Represented as: （1） in, For the launch channel delay of satellite A, The propagation delay of the signal from the transmitter on satellite A to the receiver on satellite B. For the receiving channel delay of satellite B; Fifth, the ranging signal broadcast by satellite A directly enters its receiver. After self-interference suppression in the spatial and radio frequency domains, it reaches the baseband signal processing unit. While performing self-interference suppression in the digital domain, the internal self-loopback of satellite A is completed, and the corresponding time delay measurement value is obtained. Represented as: （2） in, The air interface delay of the signal from the transmitting antenna of satellite A to the receiving antenna of satellite A. For the receiving channel delay of satellite A; Step 6: Simultaneously, while satellite A broadcasts the ranging signal to satellite B, satellite B also synchronously broadcasts the ranging signal to satellite A. The signals propagate through space and are received by satellite A, with the corresponding time delay measurement value... Represented as: （3） in, For the launch channel delay of satellite B, The propagation delay of the signal from the transmitter on satellite B to the receiver on satellite A; In the seventh step, the ranging signal broadcast by satellite B directly enters the receiver of satellite B, completing the internal self-loopback of satellite B, and the corresponding time delay measurement value... Represented as: （4） in, The air interface delay is the time it takes for the signal to travel from the transmitting antenna of Satellite B to the receiving antenna of Satellite B. Step 8: Due to the high dynamism between satellites and the clock difference between satellite A and satellite B, the inter-satellite two-way propagation delays are not equal. It is necessary to use the broadcast ephemeris stored on the satellites to perform time-scaled calculations on the inter-satellite two-way propagation delays, resulting in the following relationship: （5） in, This represents the difference in propagation delay obtained from time-scaled reduction; Step 9: Solve the system of equations (1) to (5) simultaneously to calculate the equipment delay. The system of equations is as follows: （6） The solution yields: （7） and The device delay is measured bidirectionally for the inter-satellite link, and the device delay error of the bidirectional inter-satellite measurement is eliminated based on the result.

2. The real-time latency calibration method for inter-satellite link equipment based on full-duplex system as described in claim 1, characterized in that, To calibrate the air interface time delay of the signal from the transmitting antenna of Satellite A to the receiving antenna of Satellite A in advance, calibration was performed in an anechoic chamber.

Images