A low earth orbit satellite navigation signal system, device and system capable of fast acquisition
Patent Information
- Application Number
- CN202411387026.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2026-09-25
- Estimated Expiration
- 2044-09-30
AI Technical Summary
由于低轨卫星星座的规模远高于中高轨卫星系统，因此所需要搜索的卫星的数量也远高于中高轨卫星，这就造成了捕获计算量被成倍的放大
[0030]上述可快速捕获的低轨卫星导航信号体制、装置和系统，通过所有卫星播发完全相同的扩频码生成的导航信号，并且同一轨道面相邻卫星的载波频率有一定差异，通过频率隔离的方式减小同一轨道面相邻卫星导航信号的互相关干扰，用户机在粗捕获阶段只需在多个并行通道中使用一种扩频码信号便可对接收到的所有导航信号进行捕获。由于低轨卫星的运动速度快，不同低轨卫星导航信号到达接收机的多普勒值和码相位值差异较大，可以通过捕获到的多个不同多普勒值和码相位值的组合将多个卫星信号区分开来。不用对所有卫星依次进行捕获，提高了用户机捕获效率，节省了捕获时间。
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Figure CN119045008B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of satellite navigation technology, and in particular to a low-Earth orbit satellite navigation signal system, apparatus and system that can be rapidly acquired. Background Technology
[0002] In recent years, low-Earth orbit (LEO) satellite systems have flourished. Due to their low orbital altitude, LEO satellites experience less signal attenuation and higher signal power upon landing. Utilizing LEO satellite systems for navigation enhancement can significantly improve the performance of existing satellite navigation systems. However, the large number and high speed of LEO satellites in these systems introduce extremely high computational complexity to acquiring their navigation signals.
[0003] Traditional satellite navigation signals primarily employ Code Division Multiple Access (CDMA). This means different satellites use different pseudo-random sequences (PRN codes) as spreading codes for Direct Sequence Spread Spectrum (DSSS) modulation. Ground receivers utilize the strong cross-correlation properties between different PRN codes to separate signals from different satellites. Therefore, during acquisition, the ground receiver sequentially acquires the PRN codes of each satellite. Since the scale of low-Earth orbit (LEO) satellite constellations is much larger than that of medium- and high-Earth orbit (MEO) satellite systems, the number of satellites requiring searching is also significantly higher, resulting in a multiplied computational burden during acquisition. Furthermore, carrier frequency offset in this signal acquisition system leads to correlation loss, necessitating intensive frequency searches for carrier Doppler to eliminate carrier ambiguity. LEO satellites move at speeds approximately six times faster than MEO satellites, resulting in a Doppler search space that is also approximately six times larger. These two factors contribute to the low efficiency and long acquisition time of LEO satellite navigation signals by user terminals. Summary of the Invention
[0004] Therefore, it is necessary to provide a system, apparatus, and mechanism for rapidly acquiring low-Earth orbit satellite navigation signals to address the aforementioned technical problems.
[0005] A low-Earth orbit (LEO) satellite navigation signal system capable of rapid acquisition, the LEO satellite navigation signal system comprising:
[0006] Satellite payload phase:
[0007] A spreading code is generated, and all satellite payloads use the same spreading code to generate navigation signals. The navigation signals are modulated onto a radio frequency carrier and broadcast. The radio frequency carrier includes multiple differential carrier frequencies.
[0008] User machine stage:
[0009] The system receives navigation signals arriving simultaneously from different satellite payloads, performs frequency conversion compensation on the navigation signals based on the different carrier frequencies, obtains multiple digital intermediate frequency (IF) signals with different center frequencies, generates spreading codes, and performs parallel acquisition of multiple IF signals with different center frequencies in each channel based on the spreading codes. Based on the combination of multiple different Doppler values and code phase values obtained from the acquisition, it generates multiple local carriers with different frequencies modulated by different phase spreading codes, and performs tracking and demodulation based on the local carriers.
[0010] In one embodiment, the spreading code is a Gold code, an m-sequence, or a Weil code.
[0011] In one embodiment, the method further includes: generating N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values obtained from the capture; wherein the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
[0012] In one embodiment, the difference between the differential carrier frequencies is greater than 60 kHz.
[0013] A low-Earth orbit satellite navigation device capable of rapid acquisition, the device comprising:
[0014] Satellite payload:
[0015] The first spreading code generation module is used to generate spreading codes;
[0016] A navigation signal transmission module is used to generate a navigation signal using the same spreading code, modulate the navigation signal onto a radio frequency carrier, and broadcast it; the radio frequency carrier includes multiple different carrier frequencies.
[0017] User terminal:
[0018] The navigation signal receiving module is used to receive navigation signals arriving simultaneously from different satellites;
[0019] The second spreading code generation module is used to generate the same spreading code as the first spreading code generation module.
[0020] The navigation signal acquisition module is used to perform frequency conversion compensation on the navigation signal according to the differential carrier frequency to obtain multiple digital intermediate frequency signals with different center frequencies, generate a spreading code, and perform parallel acquisition of multiple digital intermediate frequency signals with different center frequencies in each channel according to the spreading code, and acquire multiple different Doppler values and code phase values obtained from the acquisition.
[0021] The navigation signal tracking and demodulation module is used to generate multiple local carriers of different frequencies modulated with different phase spreading codes based on the combination of multiple different Doppler values and code phase values obtained by capture, and to perform tracking and demodulation based on the local carriers.
[0022] In one embodiment, to prevent the navigation signals of adjacent satellites from overlapping in the spectrum after being superimposed with Doppler frequencies, the carrier frequency difference f is... T The value usually needs to be greater than 60kHz.
[0023] In one embodiment, the spreading code is a Gold code, an m-sequence, or a Weil code.
[0024] In one embodiment, the navigation signal acquisition module is further configured to generate N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values acquired; wherein the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
[0025] A low-Earth orbit satellite navigation system capable of rapid acquisition, comprising: multiple satellite payloads and a user terminal;
[0026] The satellite payload generates a spreading code, and all satellite payloads use the same spreading code to generate navigation signals. The navigation signals are modulated onto a radio frequency carrier and broadcast. The radio frequency carrier includes multiple differential carrier frequencies.
[0027] The user terminal receives navigation signals arriving simultaneously from different satellite payloads. Based on the difference in carrier frequency, it performs frequency conversion compensation on the navigation signals to obtain multiple digital intermediate frequency (IF) signals with different center frequencies. It generates a spreading code and performs parallel acquisition of multiple IF signals with different center frequencies in each channel according to the spreading code. Based on the combination of multiple different Doppler values and code phase values obtained from the acquisition, it generates multiple local carriers with different frequencies modulated by different phase spreading codes. It then performs tracking and demodulation based on the local carriers.
[0028] In one embodiment, the spreading code is a Gold code, an m-sequence, or a Weil code.
[0029] In one embodiment, the user terminal generates N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values captured; wherein the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
[0030] The aforementioned low-Earth orbit (LEO) satellite navigation signal system, apparatus, and mechanism utilize navigation signals generated by all satellites broadcasting identical spreading codes. Furthermore, the carrier frequencies of adjacent satellites within the same orbital plane differ to some extent; frequency isolation reduces cross-correlation interference between navigation signals from adjacent satellites within the same orbital plane. During the coarse acquisition phase, the user terminal only needs to use one spreading code signal in multiple parallel channels to acquire all received navigation signals. Due to the high speed of LEO satellites, the Doppler values and code phase values of different LEO satellite navigation signals arriving at the receiver vary significantly. Multiple satellite signals can be distinguished by combining several different Doppler values and code phase values. This eliminates the need to acquire all satellites sequentially, improving user terminal acquisition efficiency and saving acquisition time. Attached Figure Description
[0031] Figure 1 This is an application scenario diagram of a low-Earth orbit satellite navigation signal system that can be quickly acquired in one embodiment;
[0032] Figure 2 This is a flowchart illustrating a low-Earth orbit satellite navigation signal system that can be rapidly acquired in one embodiment.
[0033] Figure 3 This is a schematic diagram of different combinations of Doppler and code phases in one embodiment;
[0034] Figure 4 This is a schematic diagram of a low-Earth orbit satellite navigation device that can be quickly acquired in one embodiment;
[0035] Figure 5 This is a schematic diagram of a low-Earth orbit satellite navigation system that can be rapidly acquired in one embodiment. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0037] like Figure 1 The diagram illustrates an application scenario for a low-Earth orbit satellite navigation signal system that can be rapidly acquired. Figure 1 The system includes satellite payload and user equipment. The satellite payload is a low-Earth orbit satellite, and the user equipment can be a vehicle-mounted receiver, a ship-mounted receiver, or a flight receiver, etc., which will not be elaborated here.
[0038] In one embodiment, such as Figure 2 As shown, a low-Earth orbit satellite navigation signal system capable of rapid acquisition is provided, including:
[0039] Satellite payload phase:
[0040] Step 202: Generate spreading code. All satellite payloads use the same spreading code to generate navigation signals, which are then modulated onto a radio frequency carrier and broadcast.
[0041] In this step, the carrier frequencies of adjacent satellites on the same orbital plane have a certain difference, the difference being f. T There are three types of radio frequency carrier frequencies used in all satellite payloads: f R ,f R +f T and f R -f T .
[0042] In addition, unlike existing technologies that use different spreading codes, this technology uses the same spreading code, so that only one spreading code is needed for signal acquisition during the signal acquisition stage, which greatly reduces the acquisition time.
[0043] In this step, unlike the existing technology that uses the same carrier frequency, different carrier frequencies are used on adjacent satellites in the same orbital plane. This ensures that the carrier frequencies of adjacent satellites do not overlap during the signal acquisition phase, reducing the impact of cross-correlation interference.
[0044] User machine stage:
[0045] Step 204: Receive navigation signals arriving simultaneously from different satellite payloads, and perform frequency conversion compensation on the navigation signals according to the different carrier frequencies to obtain multiple digital intermediate frequency signals with different center frequencies.
[0046] The center frequency is f0.
[0047] Step 206: Generate spreading code, and in each channel, acquire multiple digital intermediate frequency signals with different center frequencies in parallel according to the spreading code.
[0048] Step 208: Based on the combination of multiple different Doppler values and code phase values obtained from the capture, generate multiple local carriers of different frequencies modulated with different phase spreading codes, and perform tracking and demodulation based on the local carriers.
[0049] In this step, relying on the characteristics of low-Earth orbit satellites, a combination of Doppler values and code phase values is used to distinguish different satellite navigation signals. This scheme has low technical complexity and can greatly reduce the signal acquisition time.
[0050] In the aforementioned low-Earth orbit (LEO) satellite navigation signal system capable of rapid acquisition, navigation signals are generated by all satellites broadcasting the exact same spreading code. Furthermore, the carrier frequencies of adjacent satellites in the same orbital plane differ to some extent. Frequency isolation reduces cross-correlation interference between navigation signals from adjacent satellites in the same orbital plane. During the coarse acquisition phase, the user terminal only needs to use one spreading code signal in three parallel channels to acquire all received navigation signals. Due to the high speed of LEO satellites, the Doppler values and code phase values of different LEO satellite navigation signals arriving at the receiver vary significantly. Multiple satellite signals can be distinguished by combining several different Doppler values and code phase values. This eliminates the need to acquire all satellites sequentially, improving the user terminal's acquisition efficiency and saving acquisition time.
[0051] In one embodiment, to prevent the navigation signals of adjacent satellites from overlapping in the spectrum after being superimposed with Doppler frequencies, the carrier frequency difference f is... T The value usually needs to be greater than 60kHz.
[0052] In one embodiment, the frequency code is a Gold code, an m-sequence, or a Weil code. It is worth noting that other pseudo-random sequences can also be used, as long as the spreading code used by different satellites is exactly the same.
[0053] In one embodiment, based on the N different combinations of captured Doppler values and code phase values, N corresponding local carriers at different frequencies, each modulated with a different phase spreading code, are generated; wherein the N different combinations of Doppler values and code phase values are used to distinguish different satellite navigation signals. Examples of combinations of Doppler values and code phase values are (1 kHz, 15 chips), (2.2 kHz, 700 chips), (3.1 kHz, 110 chips), and (4.4 kHz, 350 chips), such as... Figure 3 As shown.
[0054] In one embodiment, in order to prevent adjacent satellite navigation signals from overlapping in the spectrum after being superimposed with Doppler frequencies, the difference between the different carrier frequencies is greater than 60 kHz.
[0055] In one embodiment, such as Figure 4 As shown, a low-Earth orbit satellite navigation device capable of rapid acquisition is provided, wherein the satellite payload includes a first spreading code generation module 402 and a navigation signal transmission module 404, and the user terminal includes a navigation signal receiving module 406, a second spreading code generation module 408, a navigation signal acquisition module 410, and a navigation signal tracking and demodulation module 412.
[0056] The first spreading code generation module 402 is used to generate spreading codes.
[0057] The navigation signal modulation module 404 is used to generate navigation signals using the same spreading code, modulate the navigation signals onto the radio frequency carrier, and broadcast them.
[0058] The carrier frequencies of adjacent satellites on the same orbital plane have a certain difference, the difference being f. T There are three types of radio frequency carrier frequencies used in all satellite payloads: f R ,f R +f T and f R -f T .
[0059] The navigation signal transmitting module 406 is used to broadcast navigation signals.
[0060] The navigation signal receiving module 408 is used to receive navigation signals arriving simultaneously from different satellites.
[0061] The radio frequency front-end processing module 410 is used to downconvert the received navigation signal to a digital intermediate frequency signal with a center frequency of f0.
[0062] The frequency conversion compensation module 412 is used to perform frequency conversion compensation processing on the signal, obtaining center frequencies of f0, f0+f in the three channels respectively. T ,f0-f T Digital intermediate frequency signal;
[0063] The second spreading code generation module 414 is used to generate the same spreading code as the first spreading code generation module.
[0064] The navigation signal acquisition module 416 is used to acquire the digital intermediate frequency signal in each channel according to the spreading code, and obtain a combination of multiple different Doppler values and code phase values.
[0065] The navigation signal tracking and demodulation module 418 is used to generate multiple local carriers of different frequencies modulated with different phase spreading codes based on the combination of multiple different Doppler values and code phase values obtained by capture, and to perform tracking and demodulation based on the local carriers.
[0066] In one embodiment, to prevent the navigation signals of adjacent satellites from overlapping in the spectrum after being superimposed with Doppler frequencies, the carrier frequency difference f is... T The value usually needs to be greater than 60kHz.
[0067] In one embodiment, the frequency code is a Gold code, an m-sequence, or a Weil code.
[0068] In one embodiment, the navigation signal acquisition module 416 is further configured to generate N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values acquired; wherein the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
[0069] Specific limitations regarding the rapid acquisition of low-Earth orbit (LEO) satellite navigation devices can be found in the limitations of the rapid acquisition LEO satellite navigation method described above, and will not be repeated here. The various modules in the aforementioned rapid acquisition LEO satellite navigation device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware or independently of the processor in a computer device, or stored in software in the memory of a computer device, so that the processor can call and execute the operations corresponding to each module.
[0070] In one embodiment, such as Figure 5 As shown, a low-Earth orbit (LEO) satellite navigation system capable of rapid acquisition is provided, comprising: multiple satellite payloads 100 and a user terminal 200; the satellite payloads generate spreading codes, and all satellite payloads use the same spreading code to generate navigation signals, which are modulated onto radio frequency carriers and broadcast. The carrier frequencies of adjacent satellites in the same orbital plane have a certain difference, the difference being f. T There are three types of radio frequency carrier frequencies used in all satellite payloads: f R ,f R +f T and f R -f T The user terminal receives navigation signals arriving simultaneously from different satellite payloads, processes them through the radio frequency front-end, and converts them into digital intermediate frequency signals with a center frequency of f0. Then, frequency conversion compensation processing is performed on the signals in different channels to obtain center frequencies of f0 and f0+f, respectively. T ,f0-f T The digital intermediate frequency (IF) signal is sent to a parallel acquisition channel; then a spreading code is generated, and the IF signal is acquired in each channel according to the spreading code. Based on the combination of multiple different Doppler values and code phase values obtained from the acquisition, multiple local carriers of different frequencies modulated with different phase spreading codes are generated, and tracking and demodulation are performed based on the local carriers.
[0071] In one embodiment, to prevent the navigation signals of adjacent satellites from overlapping in the spectrum after being superimposed with Doppler frequencies, the carrier frequency difference f is... T The value usually needs to be greater than 60kHz.
[0072] In one embodiment, the spreading code is a Gold code, an m-sequence, or a Weil code.
[0073] In one embodiment, the user terminal 200 generates N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values captured; wherein the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
[0074] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.
[0075] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0076] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A low-Earth orbit satellite navigation signal system capable of rapid acquisition, characterized in that, The low-Earth orbit satellite navigation signal system includes: Satellite payload phase: A spreading code is generated, and all satellite payloads use the same spreading code to generate navigation signals. The navigation signals are modulated onto a radio frequency carrier and broadcast. The radio frequency carrier includes multiple differential carrier frequencies, and the difference between the differential carrier frequencies is greater than 60 kHz. User machine stage: The system receives navigation signals arriving simultaneously from different satellite payloads, performs frequency conversion compensation on the navigation signals according to the different carrier frequencies, obtains multiple digital intermediate frequency signals with different center frequencies, generates spreading codes, and performs parallel acquisition of multiple digital intermediate frequency signals with different center frequencies in each channel according to the spreading codes. Based on the combination of multiple different Doppler values and code phase values obtained from the acquisition, it generates multiple local carriers with different frequencies modulated by different phase spreading codes, and performs tracking and demodulation based on the local carriers. The step of generating multiple local carriers of different frequencies modulated with different phase spreading codes based on combinations of multiple captured different Doppler values and code phase values includes: Based on the N different Doppler values and code phase values obtained from the capture, N local carriers of different frequencies modulated with different phase spreading codes are generated; among them, the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
2. The low-Earth orbit satellite navigation signal system capable of rapid acquisition according to claim 1, characterized in that, The spreading code is a Gold code, an m-sequence, or a Weil code.
3. A low-Earth orbit satellite navigation device capable of rapid acquisition, characterized in that, The device includes: Satellite payload: The first spreading code generation module is used to generate spreading codes; A navigation signal transmission module is used to generate a navigation signal using the same spreading code, modulate the navigation signal onto a radio frequency carrier, and broadcast it; the radio frequency carrier includes multiple differential carrier frequencies; the difference between the differential carrier frequencies is greater than 60kHz. User terminal: The navigation signal receiving module is used to receive navigation signals arriving simultaneously from different satellites; The second spreading code generation module is used to generate the same spreading code as the first spreading code generation module. The navigation signal acquisition module is used to perform frequency conversion compensation on the navigation signal according to the differential carrier frequency to obtain multiple digital intermediate frequency signals with different center frequencies, generate a spreading code, and perform parallel acquisition of multiple digital intermediate frequency signals with different center frequencies in each channel according to the spreading code, and acquire multiple different Doppler values and code phase values obtained from the acquisition. The navigation signal tracking and demodulation module is used to generate multiple local carriers of different frequencies modulated with different phase spreading codes based on the combination of multiple different Doppler values and code phase values obtained by capture, and to perform tracking and demodulation based on the local carriers; The navigation signal acquisition module is also used to generate N local carriers of different frequencies modulated with different phase spreading codes based on the N different Doppler values and code phase values obtained from the acquisition; wherein, the N different Doppler values and code phase values are used to distinguish different satellite navigation signals.
4. The apparatus according to claim 3, characterized in that, The spreading code is a Gold code, an m-sequence, or a Weil code.
5. A low-Earth orbit satellite navigation system capable of rapid acquisition, characterized in that, include: Multiple satellite payloads and user terminals; The satellite payload generates a spreading code, and all satellite payloads use the same spreading code to generate navigation signals. The navigation signals are modulated onto a radio frequency carrier and broadcast. The radio frequency carrier includes multiple differential carrier frequencies. The difference between the differential carrier frequencies is greater than 60 kHz. The user terminal receives navigation signals arriving simultaneously from different satellite payloads. Based on the difference in carrier frequency, it performs frequency conversion compensation on the navigation signals to obtain multiple digital intermediate frequency (IF) signals with different center frequencies. It generates a spreading code and performs parallel acquisition of multiple IF signals with different center frequencies in each channel according to the spreading code. Based on the combination of multiple different Doppler values and code phase values obtained from the acquisition, it generates multiple local carriers with different frequencies modulated by different phase spreading codes. It then performs tracking and demodulation based on the local carriers.
6. The system according to claim 5, characterized in that, The spreading code is a Gold code, an m-sequence, or a Weil code.