A dual-antenna carrier phase difference measurement method, device, equipment and medium
Patent Information
- Application Number
- CN202611378142.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-07
- Publication Date
- 2026-11-03
AI Technical Summary
Existing dual-antenna direction-finding receivers are prone to loss of lock in weak signal environments, resulting in a sharp increase in carrier phase difference observation noise, which cannot meet the reliable direction-finding requirements in complex obstructed environments.
A dual-antenna signal joint processing mechanism is adopted. By rotating the signal, the polarity reversal of the navigation message, the fluctuation of the crystal oscillator frequency and the tracking error of the frequency-locked loop are eliminated. Combined with ultra-narrow bandwidth phase-locked tracking and ultra-long coherent integration, the relative carrier phase difference between the antennas is measured.
It can stably lock onto and accurately measure the relative carrier phase difference under extremely weak signal conditions, improving the direction finding accuracy and reliability, and is suitable for complex obstructed environments such as urban canyons and tree-lined roads.
Smart Images
Figure CN123029570A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of satellite navigation and positioning technology, and in particular to a method, apparatus, device, and medium for measuring the phase difference of dual-antenna carriers. Background Technology
[0002] Global Navigation Satellite Systems (GNSS) are widely used in vehicle navigation, drones, precision agriculture, and other fields. Dual-antenna direction-finding receivers calculate baseline pointing by measuring the difference in satellite signals received by the two antennas, making them crucial for obtaining the heading and attitude of a vehicle.
[0003] Existing dual-antenna direction-finding receivers typically employ two completely independent signal processing architectures. Each antenna independently tracks and measures the carrier phase value of each satellite using a phase-locked loop through its own RF front-end and baseband processing channel. The carrier phase difference between the two antennas is then calculated, and the baseline vector is calculated by combining data from multiple satellites to ultimately obtain the heading angle and attitude information of the carrier.
[0004] With the increasing demand for dual-antenna direction-finding receivers in complex, obstructed environments (such as urban canyons and tree-lined roads), these receivers often face weak signal scenarios with severely attenuated satellite signals. In existing independent processing architectures, each phase-locked loop (PLL) must simultaneously withstand multiple error sources, including satellite motion, carrier dynamics, crystal oscillator fluctuations, and message flipping. To maintain lock-on, a wide loop bandwidth and a short coherent integration time (typically not exceeding one message bit duration) must be used. When the signal-to-noise ratio (SNR) drops to approximately 28 dB-Hz, the PLL is highly susceptible to lock-on failure, leading to jumps or loss of the measured carrier phase values. This results in a sharp increase in noise in the inter-antenna carrier phase difference observation, potentially rendering it unusable. Ultimately, this leads to severe degradation of direction-finding accuracy or complete functional interruption, failing to meet the application requirements for continuous and reliable direction finding in weak signal environments. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a method, apparatus, device and medium for measuring the phase difference of dual-antenna carriers, in order to solve at least one of the above-mentioned technical problems.
[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, this application provides a method for measuring the phase difference of a dual-antenna carrier, employing the following technical solution: A method for measuring the phase difference of a dual-antenna carrier includes: The satellite radio frequency signals received by the first and second antennas of the dual-antenna direction-finding receiver are processed by radio frequency to obtain the first zero-IF complex baseband signal and the second zero-IF complex baseband signal. The first zero-IF complex baseband signal and the second zero-IF complex baseband signal are processed by the baseband channel to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero-IF complex baseband signal is not subjected to independent carrier frequency or phase tracking. The first baseband signal and the second baseband signal are coherently integrated and rotated to obtain the rotated signal; wherein, the rotation process is to multiply the digital signal of the second antenna of the same satellite by the complex conjugate of the digital signal of the first antenna. The rotated signal is subjected to extremely narrow bandwidth phase-locked tracking, and the relative carrier phase difference between the first antenna and the second antenna is measured; wherein, the coherent integration duration used in the extremely narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
[0007] Based on the above technical solution, the present invention can be further improved as follows.
[0008] Furthermore, the step of performing baseband channel processing on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal respectively includes: The first zero-IF complex baseband signal is subjected to frequency-locked loop tracking to obtain the estimated carrier frequency. Based on the carrier frequency estimate, carrier stripping processing is performed on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal respectively to obtain the first carrier stripped signal and the second carrier stripped signal. Delay-locked loop processing and pseudocode stripping processing are performed on the first carrier stripping signal and the second carrier stripping signal, respectively, to obtain the first baseband signal and the second baseband signal.
[0009] Furthermore, the carrier stripping process performed on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal based on the carrier frequency estimate includes: The estimated carrier frequency output from the frequency-locked loop of the first antenna is used as the reference frequency for carrier stripping of both the first zero-IF complex baseband signal and the second zero-IF complex baseband signal, so that the baseband channel corresponding to the second antenna shares the estimated carrier frequency of the first antenna for carrier stripping.
[0010] Furthermore, the step of performing coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal includes: Perform coherent integration of the first baseband signal and the second baseband signal for a navigation message bit duration respectively to obtain the first coherent integration result and the second coherent integration result; The rotated signal is obtained by multiplying the second coherent integral result of the same satellite by the complex conjugate of the first coherent integral result; The rotation process eliminates navigation message polarity, crystal frequency fluctuations, and frequency-locked loop tracking errors in the first and second baseband signals.
[0011] Furthermore, the rotated signal only contains the phase difference information and noise corresponding to the projection delay of the relative position vector between the first antenna and the second antenna in the satellite line-of-sight direction.
[0012] Furthermore, the step of performing extremely narrow bandwidth phase-locked tracking on the rotated signal includes: The rotated signal is multiplied by a complex number with the local carrier. Perform a coherent integral of 1 second on the result of complex multiplication; The phase error is obtained by performing four-quadrant carrier phase discrimination on the result of coherent integration over a 1-second duration. The phase error is input into a second-order loop filter for processing, and the initial phase and frequency of the local carrier are updated based on the output of the second-order loop filter; wherein, the bandwidth of the phase-locked loop is 0.25Hz.
[0013] Furthermore, it also includes: Using the relative carrier phase difference as an observation, and combining it with observation data from multiple satellites, the orientation of the baseline vector between the first antenna and the second antenna in the navigation coordinate system is calculated. The heading angle of the vehicle is calculated based on the direction of the baseline vector.
[0014] Secondly, this application provides a dual-antenna carrier phase difference measurement device, which adopts the following technical solution: A dual-antenna carrier phase difference measurement device, comprising: The radio frequency processing module is used to process the satellite radio frequency signals received by the first and second antennas of the dual-antenna direction-finding receiver to obtain the first zero-IF complex baseband signal and the second zero-IF complex baseband signal. The baseband channel processing module is used to perform baseband channel processing on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal respectively to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero-IF complex baseband signal does not undergo independent carrier frequency or phase tracking. The coherent integration and rotation module is used to perform coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal; wherein, the rotation processing is to multiply the digital signal of the second antenna of the same satellite with the complex conjugate of the digital signal of the first antenna; An ultra-narrow bandwidth phase-locked tracking module is used to perform ultra-narrow bandwidth phase-locked tracking on the rotated signal and measure the relative carrier phase difference between the first antenna and the second antenna; wherein, the coherent integration duration used in the ultra-narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
[0015] Thirdly, this application provides an electronic device that adopts the following technical solution: An electronic device includes a memory and a processor, wherein the memory stores a computer program capable of being loaded by the processor and executing a dual-antenna carrier phase difference measurement method as described in any of the first aspects.
[0016] Fourthly, this application provides a computer-readable storage medium, which adopts the following technical solution: A computer-readable storage medium storing a computer program capable of being loaded by a processor and executing the dual-antenna carrier phase difference measurement method according to any one of the first aspects.
[0017] In summary, the beneficial effects of this invention are: 1. By designing a dual-antenna signal joint processing mechanism, the coherent integration result of the second antenna is multiplied by the complex conjugate of the coherent integration result of the first antenna using rotation processing. This effectively eliminates the common main error sources affecting the phase measurement of dual-antenna signals, such as navigation message polarity reversal, crystal oscillator frequency fluctuation, and frequency-locked loop tracking error. This ensures that the signal in subsequent processing only contains the target phase difference information, namely the projection delay of the antenna baseline vector in the satellite line of sight direction, and noise. This lays a key foundation for solving the problem of phase locking of radio waves in extremely weak signals.
[0018] 2. The signal is tracked using an ultra-long coherent integration time and an extremely narrow bandwidth phase-locked loop. The long coherent integration greatly enhances the signal energy accumulation, while the narrow bandwidth loop effectively suppresses in-band noise, thereby lowering the carrier-to-noise ratio threshold for carrier phase tracking. This enables stable locking and accurate measurement of the relative carrier phase difference in weak signal environments with lower signal-to-noise ratios.
[0019] 3. By performing independent frequency-locked loop tracking on the first antenna signal and using its tracking result as a common carrier stripping reference frequency for carrier stripping of the second antenna signal, the baseband processing structure of the second antenna channel is simplified, avoiding the drawbacks of both paths being affected by dynamic stress, noise, etc. in the traditional dual independent tracking loop. Attached Figure Description
[0020] Figure 1 This is a flowchart illustrating a dual-antenna carrier phase difference measurement method according to an embodiment of the present invention. Figure 2This is a schematic flowchart of a dual-antenna direction-finding receiver processing according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a narrow-bandwidth phase-locked tracking loop provided in one embodiment of the present invention; Figure 4 This is a structural diagram of a dual-antenna carrier phase difference measurement device provided in one embodiment of the present invention.
[0021] Figure 5 This is a schematic diagram of the structure of an electronic device provided in one embodiment of the present invention. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0023] Furthermore, the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article, unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship.
[0024] This application provides a method for measuring the phase difference of a dual-antenna carrier. This method can be executed by an electronic device, which can be a server or a mobile terminal device. The server can be an independent physical server, a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides cloud computing services. The mobile terminal device can be a laptop computer, a desktop computer, etc., but is not limited to these.
[0025] like Figure 1 and Figure 2 As shown, a dual-antenna carrier phase difference measurement method mainly includes: S101, the satellite radio frequency signals received by the first antenna and the second antenna of the dual-antenna direction-finding receiver are processed by radio frequency to obtain the first zero intermediate frequency complex baseband signal and the second zero intermediate frequency complex baseband signal; In this embodiment of the application, a dual-antenna direction-finding receiver refers to a device that provides high-precision heading and attitude information to a mobile vehicle by measuring the difference between GNSS satellite signals received by two antennas.
[0026] The first and second antennas are two GNSS antennas mounted on a carrier. The line connecting them forms a baseline, the length of which is known. The physical distance between the two antennas is usually within a few meters. Satellite radio frequency (RF) signals refer to the radio signals transmitted from GNSS satellites to the ground, including a carrier wave, pseudo-random code, and navigation message. Zero-IF complex baseband signals refer to discrete-time digital complex baseband signals with a center frequency of zero, obtained after the satellite RF signal has undergone RF filtering, quadrature down-conversion, and analog-to-digital conversion. These signals include in-phase (I) and quadrature (Q) components.
[0027] In this embodiment of the application, the airborne radio signals received by the receiver's two antennas are... and Each signal is processed through its respective RF channel, performing RF filtering, quadrature down-conversion, and analog-to-digital conversion, transforming it into a zero-IF discrete-time digital complex baseband signal. and .
[0028] ; .
[0029] The above-mentioned antennas 1 and 2 in time Sensed radio signals and The expression. In the expression Representing time, index Indicates the satellite serial number. This indicates the total number of satellites received. This indicates that antennas 1 and 2 are in time... Received satellite signal strength, Indicates satellite In time Transmitted message bits, Indicates satellite In time The transmitted pseudo-random code, Indicates the radio frequency carrier frequency transmitted by the satellite. Indicates at time satellite The total signal propagation delay to antennas 1 and 2 respectively. Indicates satellite Carrier initial phase.
[0030] In dual-antenna direction finding applications, the physical distance between the two antennas is usually close, within a few meters. and The phases are approximately equal, typically differing by no more than 50 nanoseconds. Therefore, the power and pseudorange differences between the two antennas can be ignored, and only the carrier phase difference needs to be considered. Furthermore, the time-dependent variable... Simplify to constants, thus and The expression simplifies to: ; .
[0031] satellite Total signal propagation delay to antennas 1 and 2 respectively and Signal propagation delay from satellite to the physical center of the two antennas Projection delay of the relative position vectors of the two antennas along the satellite's line-of-sight direction express: ; ; in, Indicates satellite The total signal propagation delay to the physical center of the two antennas, Indicates the physical center of the two antennas to the satellite The relative position vector, This represents the relative position vector between the two antennas. This indicates the wavelength corresponding to the satellite signal carrier frequency.
[0032] After orthogonal downconversion and digitization processing via the radio frequency channel, the zero-IF orthogonal complex baseband signal is obtained: ; .
[0033] Digital intermediate frequency complex baseband signal Channelization is performed in the baseband.
[0034] S102, the first zero intermediate frequency complex baseband signal and the second zero intermediate frequency complex baseband signal are processed by the baseband channel respectively to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero intermediate frequency complex baseband signal is not subjected to independent carrier frequency or phase tracking. In this embodiment of the application, the second zero intermediate frequency complex baseband signal does not perform independent carrier frequency or phase tracking, which means that the baseband channel corresponding to the second antenna does not set an independent frequency-locked loop or phase-locked loop to track the carrier frequency and phase, but instead uses the carrier frequency estimate of the first antenna for carrier stripping.
[0035] Specifically, the baseband channel processing of the first zero-IF complex baseband signal and the second zero-IF complex baseband signal includes: First, the first zero-IF complex baseband signal is tracked by a frequency-locked loop to obtain a carrier frequency estimate. The frequency-locked loop tracks the signal frequency change through a frequency discriminator and a loop filter, and its output reflects the combined effect of satellite Doppler shift and local oscillator frequency deviation.
[0036] Then, the carrier frequency estimate output from the frequency-locked loop of the first antenna is used as the carrier stripping reference frequency for both the first and second zero-IF complex baseband signals. In other words, the baseband channel corresponding to the second antenna shares the carrier frequency estimate from the first antenna for carrier stripping. This design eliminates the need for independent carrier frequency search and tracking for the channel corresponding to the second antenna, reducing computational complexity and providing a foundation for eliminating common factors in subsequent rotation operations.
[0037] Based on the carrier frequency estimate, carrier stripping processing is performed on the first zero intermediate frequency complex baseband signal and the second zero intermediate frequency complex baseband signal respectively. That is, the complex baseband signal is multiplied by the complex conjugate of the locally generated complex exponential carrier signal to remove the carrier frequency component in the signal, thus obtaining the first carrier stripped signal and the second carrier stripped signal. The first carrier stripped signal and the second carrier stripped signal are subjected to delay-locked loop processing and pseudo-code stripping processing, respectively. The code phase of the pseudo-random code is tracked by a code phase discriminator and a loop filter. After code phase alignment, pseudo-code stripping processing (i.e., correlation removal of code modulation with the locally generated pseudo-random code copy) is performed to obtain the first baseband signal and the second baseband signal. At this time, only carrier phase information and navigation message bit information are retained in the first baseband signal and the second baseband signal.
[0038] In the above embodiments, the digital intermediate frequency complex baseband signal The digital signal obtained after carrier stripping, delay-locked loop (LDL) and pseudocode stripping processes is obtained from the interface. .
[0039] in, ; .
[0040] S103, perform coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal; wherein, the rotation processing is to multiply the digital signal of the second antenna of the same satellite with the complex conjugate of the digital signal of the first antenna; In this embodiment, coherent integration refers to the operation of complex summation of baseband signals over a certain time period to improve the signal-to-noise ratio. Rotation processing refers to the complex number operation of multiplying the digital signal from the second antenna of the same satellite by the complex conjugate of the digital signal from the first antenna; essentially, it is a differential operation. Complex conjugation refers to inverting the imaginary part of a complex number; that is, if the complex number is a+jb, then its complex conjugate is a-jb. The navigation message bit duration refers to the duration of a navigation data bit, which is 20 milliseconds for both GPS L1 C / A signals and BeiDou B1I signals.
[0041] Specifically, the step of performing coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal includes: First, coherent integration of the first baseband signal and the second baseband signal is performed on each of the two signals for the duration of a navigation message bit, resulting in a first coherent integration result and a second coherent integration result; the duration of a navigation message bit is 20 milliseconds. Specifically, the complex summation of all sampling points of the first baseband signal within one bit duration is performed to obtain the first coherent integration result; similarly, the coherent integration of the second baseband signal for the same duration is performed to obtain the second coherent integration result. The coherent integration for one bit duration ensures that the polarity of the navigation message does not reverse within the integration interval, thus avoiding mutual cancellation of integration results.
[0042] Then, for the same satellite, the second coherent integral result of the same satellite is multiplied by the complex conjugate of the first coherent integral result to obtain the rotated signal; ; The rotation process eliminates navigation message polarity, crystal frequency fluctuations, and frequency-locked loop tracking errors in the first and second baseband signals.
[0043] in, ; ; .
[0044] The physical significance of this rotation operation is that, since the two antenna signals contain the same navigation message polarity, the same crystal oscillator frequency fluctuation (due to sharing the same crystal oscillator), and the same frequency-locked loop tracking error (due to the second antenna sharing the frequency-locked result of the first antenna), the complex conjugate multiplication operation cancels out the phase contributions of these common factors, while retaining the phase difference information between the two.
[0045] The converted signal only contains the phase difference information and noise corresponding to the projection delay of the relative position vector between the first and second antennas in the satellite line-of-sight direction, and no longer includes the influence of common factors such as navigation message polarity reversal, crystal oscillator frequency fluctuations, and frequency-locked loop tracking errors. Differential operation eliminates the core factors restricting the tracking sensitivity of conventional phase-locked loops, creating conditions for subsequent ultra-long coherent integration and ultra-narrow bandwidth phase-locked tracking.
[0046] S104, perform extremely narrow bandwidth phase-locked tracking on the rotated signal and measure the relative carrier phase difference between the first antenna and the second antenna; wherein, the coherent integration duration used in the extremely narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
[0047] Among them, extremely narrow bandwidth phase-locked tracking (PLL) refers to a technique that uses a PLL with a bandwidth far narrower than that of a conventional PLL to track the carrier phase of a signal. Conventional PLL bandwidths are typically in the range of 10Hz to 25Hz, while the bandwidth of the extremely narrow bandwidth PLL in this scheme is 0.25Hz, much smaller than the conventional value. Coherence integration time greater than navigation message bit duration means that the coherence integration time used in extremely narrow bandwidth PLL tracking far exceeds the duration of a single navigation message bit; for example, a coherence integration time of 1 second is used, while the bit duration of a GPS L1 C / A signal is only 20 milliseconds. Relative carrier phase difference refers to the difference in carrier phase when the same satellite signal arrives at two antennas; this difference reflects the projected distance of the relative position vectors of the two antennas along the satellite's line-of-sight direction.
[0048] Specifically, such as Figure 3 As shown, after the rotation processing in step S3, the factors that restrict the coherent integration time and bandwidth of conventional phase-locked loops, such as navigation message polarity, crystal oscillator frequency fluctuation and frequency-locked loop tracking error, have been eliminated. Therefore, coherent integration with a duration far exceeding that of a bit and extremely narrow loop bandwidth can be used for tracking.
[0049] The step of performing extremely narrow bandwidth phase-locked tracking on the rotated signal includes: The rotated signal is multiplied by a complex number with the local carrier. The local carrier is a complex exponential signal generated inside the phase-locked loop, and its frequency and phase are controlled by the output of the loop filter. The purpose of the complex multiplication is to align the remaining phase difference component in the rotated signal with the phase of the local carrier, so that the phase discriminator can extract the phase error.
[0050] A coherent integration of 1 second is performed on the result of the complex multiplication. This ultra-long coherent integration time of 1 second is equivalent to accumulating the signal energy over a period of 50 bits (for GPS L1 C / A signals), which can improve the signal-to-noise ratio and enable the extraction of effective phase information even under weak signal conditions. This is because the rotation operation has eliminated the effect of polarity reversal in the navigation message, and the 1-second coherent integration will not result in energy cancellation due to bit reversal.
[0051] The phase error is obtained by performing four-quadrant carrier phase discrimination on the result after coherent integration over a 1-second duration. The discrimination range of the four-quadrant discriminator is ±π, which can detect the phase error across the entire range.
[0052] The phase error is input into a second-order loop filter for processing. The second-order loop filter calculates the frequency correction and phase correction based on the input phase error, and updates the initial phase and frequency of the local carrier based on the output of the second-order loop filter; wherein, the bandwidth of the phase-locked loop is 0.25Hz.
[0053] This extremely narrow bandwidth effectively suppresses thermal noise within the loop, further enhancing tracking sensitivity. In static or low-dynamic application scenarios, since the rotation operation has eliminated the common dynamic stress caused by satellite and carrier motion, the remaining signal dynamics are extremely slow (caused only by changes in the projection of the relative position vector between the two antennas onto the satellite's line-of-sight direction). The extremely narrow bandwidth of 0.25Hz is perfectly sufficient to track this slow change. After the loop is stably locked, the phase of the local carrier is the precise measurement of the relative carrier phase difference between the first and second antennas, which is directly used as an observation for subsequent direction-finding calculations.
[0054] Through the processing flow from S101 to S104 described above, this method introduces the differential concept into the measurement of the carrier phase difference between two antennas. After eliminating common factors through rotation, it uses a 1-second ultra-long coherent integration and a 0.25Hz ultra-narrow bandwidth phase-locked loop for tracking. Compared with the conventional approach where each antenna independently uses a 10Hz~25Hz bandwidth phase-locked loop and a 20ms coherent integration time, this method can still accurately measure the relative carrier phase difference between the two antennas under weak signal conditions with a carrier-to-noise ratio far below 28dB-Hz, thereby maintaining the direction finding function and significantly improving the availability of dual-antenna direction finding receivers in complex obstructed environments such as urban canyons, tree-lined roads, and indoor spaces.
[0055] Furthermore, this formula also includes: Using the relative carrier phase difference as an observation, and combining it with observation data from multiple satellites, the orientation of the baseline vector between the first antenna and the second antenna in the navigation coordinate system is calculated. The heading angle of the vehicle is calculated based on the direction of the baseline vector.
[0056] Since carrier phase measurements can only measure a fractional portion of the phase less than one wavelength, it's impossible to determine the number of integer cycles (i.e., integer ambiguity). Therefore, it's necessary to first determine the integer ambiguity for each satellite using integer ambiguity resolution methods such as the LAMBDA (Least-squares AMBiguity Decorrelation Adjustment) algorithm. After successfully fixing the integer ambiguity, observation equations are established using carrier phase difference observations from multiple satellites. The three-dimensional components of the baseline vector between the first and second antennas in the local navigation coordinate system (northeast-east coordinate system) are then calculated using methods such as least squares or Kalman filtering. Based on the projection direction of the calculated baseline vector onto the horizontal plane, the heading angle of the carrier is calculated. Specifically, the heading angle is equal to the arctangent of the eastward and northward components of the baseline vector, i.e., heading angle = atan2(eastward component, northward component). If the vertical component information of the baseline vector can be further processed, attitude information such as the carrier's pitch angle can also be output.
[0057] Furthermore, in carrier phase difference observations from multiple satellites, a carrier phase double-difference model can be used. The double-difference model selects a reference satellite and performs a second difference analysis between the carrier phase difference observations from other satellites and the reference satellite, thereby eliminating common errors such as receiver clock bias that may remain, further improving the solution accuracy and the success rate of integer ambiguity fixation.
[0058] Furthermore, in dynamic application scenarios, GNSS direction finding results can be fused with angular rate measurements from an inertial measurement unit (IMU). When a momentary interruption of the satellite signal causes the carrier phase difference observation to be temporarily unavailable, the IMU can provide a short-term heading change for bridging. Once the signal is restored, the GNSS observation can be used to correct the IMU's drift error, thereby achieving continuous high-precision direction finding in dynamic environments.
[0059] Furthermore, in practical engineering implementation, the 1-second coherent integration duration is not the only option and can be adjusted according to the dynamic characteristics and signal environment of the application scenario. In completely static application scenarios, the coherent integration duration can be further extended to 2 seconds or even 5 seconds, and the corresponding loop bandwidth can be further reduced to 0.1Hz or even narrower to obtain higher tracking sensitivity. In low-dynamic application scenarios, the coherent integration duration can be shortened to 0.5 seconds, and the loop bandwidth can be correspondingly increased to 0.5Hz to balance sensitivity and dynamic tracking capability. The selection of loop bandwidth and coherent integration duration requires comprehensive consideration of the balance between signal dynamic characteristics, noise level, and tracking stability.
[0060] Furthermore, in the rotation process of step S103, since the two antenna signals come from the same satellite, the sky background radiation noise in the two signals is also correlated. For the sky background noise entering within the same RF front-end bandwidth, its correlated part will also be suppressed after the rotation operation, thereby further reducing the equivalent noise floor in the rotated signal, which is beneficial to improving the measurement accuracy of ultra-narrow bandwidth phase-locked tracking.
[0061] Furthermore, although the baseband channel corresponding to the second antenna in step S102 does not perform independent carrier frequency or phase tracking, its delay-locked loop (DLL) still operates independently. This is because although the physical distance between the two antennas is relatively short (within a few meters), the chip width of the pseudo-random code (approximately 300 meters corresponds to a 1-microsecond chip of GPS L1 C / A code) is much larger than the antenna spacing. The code phase difference between the signals received by the two antennas is extremely small, and the tracking accuracy of the DLL can completely cover this small difference. In actual implementation, the DLL of the second antenna can also directly share the code phase estimation value of the first antenna without affecting performance, thereby further simplifying the hardware design.
[0062] Figure 4 A schematic diagram of a dual-antenna carrier phase difference measurement device 200 is shown.
[0063] like Figure 4 As shown, a dual-antenna carrier phase difference measurement device 200 mainly includes: RF processing module 201 is used to process the satellite RF signals received by the first antenna and the second antenna of the dual-antenna direction-finding receiver respectively to obtain a first zero-IF complex baseband signal and a second zero-IF complex baseband signal. The baseband channel processing module 202 is used to perform baseband channel processing on the first zero intermediate frequency complex baseband signal and the second zero intermediate frequency complex baseband signal respectively to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero intermediate frequency complex baseband signal does not undergo independent carrier frequency or phase tracking. The coherent integration and rotation module 203 is used to perform coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal; wherein, the rotation processing is to multiply the digital signal of the second antenna of the same satellite with the complex conjugate of the digital signal of the first antenna; The ultra-narrow bandwidth phase-locked tracking module 204 is used to perform ultra-narrow bandwidth phase-locked tracking on the rotated signal and measure the relative carrier phase difference between the first antenna and the second antenna; wherein, the coherent integration duration used in the ultra-narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
[0064] In one example, the module in any of the above devices may be one or more integrated circuits configured to implement the above methods, such as one or more application-specific integrated circuits (ASICs), or one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs), or a combination of at least two of these integrated circuit forms.
[0065] For example, when modules in a device can be implemented via a processing element scheduler, the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processor capable of calling programs. Alternatively, these modules can be integrated together as a system-on-a-chip (SOC).
[0066] In this application, various objects such as messages / information / devices / network elements / systems / apparatus / actions / operations / processes / concepts may be named. It is understood that these specific names do not constitute a limitation on the relevant objects. The names may be changed depending on the scenario, context, or usage habits. The understanding of the technical meaning of the technical terms in this application should be mainly determined from their functions and technical effects embodied / performed in the technical solution.
[0067] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0068] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0069] Figure 5 This application provides a structural block diagram of an electronic device 300.
[0070] like Figure 5As shown, the electronic device 300 includes a processor 301 and a memory 302, and may further include one or more of an information input / output (I / O) interface 303, a communication component 304, and a communication bus 305.
[0071] The processor 301 controls the overall operation of the electronic device 300 to complete all or part of the steps in the aforementioned dual-antenna carrier phase difference measurement method. The memory 302 stores various types of data to support the operation of the electronic device 300. This data may include, for example, instructions for any application or method operating on the electronic device 300, as well as application-related data. The memory 302 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as one or more of Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.
[0072] I / O interface 303 provides an interface between processor 301 and other interface modules, such as keyboards, mice, and buttons. These buttons can be virtual or physical. Communication component 304 is used to test wired or wireless communication between electronic device 300 and other devices. Wireless communication includes Wi-Fi, Bluetooth, Near Field Communication (NFC), 2G, 3G, or 4G, or a combination thereof. Therefore, the corresponding communication component 304 may include a Wi-Fi component, a Bluetooth component, and an NFC component.
[0073] The communication bus 305 may include a path for transmitting information between the aforementioned components. The communication bus 305 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The communication bus 305 can be divided into an address bus, a data bus, a control bus, etc.
[0074] The electronic device 300 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform a dual-antenna carrier phase difference measurement method given in the above embodiments.
[0075] The following describes the computer-readable storage medium provided in the embodiments of this application. The computer-readable storage medium described below can be referred to in correspondence with the dual-antenna carrier phase difference measurement method described above.
[0076] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described dual-antenna carrier phase difference measurement method.
[0077] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0078] 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.
[0079] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the foregoing application concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions claimed in this application.
Claims
1. A method for measuring the phase difference of a dual-antenna carrier, characterized in that, include: The satellite radio frequency signals received by the first and second antennas of the dual-antenna direction-finding receiver are processed by radio frequency to obtain the first zero-IF complex baseband signal and the second zero-IF complex baseband signal. The first zero-IF complex baseband signal and the second zero-IF complex baseband signal are processed by the baseband channel to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero-IF complex baseband signal is not subjected to independent carrier frequency or phase tracking. The first baseband signal and the second baseband signal are coherently integrated and rotated to obtain the rotated signal; wherein, the rotation process is to multiply the digital signal of the second antenna of the same satellite by the complex conjugate of the digital signal of the first antenna. The rotated signal is subjected to extremely narrow bandwidth phase-locked tracking, and the relative carrier phase difference between the first antenna and the second antenna is measured; wherein, the coherent integration duration used in the extremely narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
2. The dual-antenna carrier phase difference measurement method according to claim 1, characterized in that, The baseband channel processing of the first zero-IF complex baseband signal and the second zero-IF complex baseband signal includes: The first zero-IF complex baseband signal is subjected to frequency-locked loop tracking to obtain the carrier frequency estimate. Based on the carrier frequency estimate, carrier stripping processing is performed on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal respectively to obtain the first carrier stripped signal and the second carrier stripped signal. Delay-locked loop processing and pseudocode stripping processing are performed on the first carrier stripping signal and the second carrier stripping signal, respectively, to obtain the first baseband signal and the second baseband signal.
3. The dual-antenna carrier phase difference measurement method according to claim 2, characterized in that, The carrier stripping process, based on the carrier frequency estimate, is performed on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal, respectively, including: The estimated carrier frequency output from the frequency-locked loop of the first antenna is used as the reference frequency for carrier stripping of both the first zero-IF complex baseband signal and the second zero-IF complex baseband signal, so that the baseband channel corresponding to the second antenna shares the estimated carrier frequency of the first antenna for carrier stripping.
4. The dual-antenna carrier phase difference measurement method according to claim 1, characterized in that, The process of performing coherent integration and rotation on the first baseband signal and the second baseband signal to obtain the rotated signal includes: Perform coherent integration of the first baseband signal and the second baseband signal for a navigation message bit duration respectively to obtain the first coherent integration result and the second coherent integration result; The rotated signal is obtained by multiplying the second coherent integral result of the same satellite by the complex conjugate of the first coherent integral result; The rotation process eliminates navigation message polarity, crystal frequency fluctuations, and frequency-locked loop tracking errors in the first and second baseband signals.
5. The dual-antenna carrier phase difference measurement method according to claim 4, characterized in that, The rotated signal contains only the phase difference information and noise corresponding to the projection delay of the relative position vector between the first antenna and the second antenna in the satellite line-of-sight direction.
6. The dual-antenna carrier phase difference measurement method according to claim 1, characterized in that, The step of performing extremely narrow bandwidth phase-locked tracking on the rotated signal includes: The rotated signal is multiplied by a complex number with the local carrier. Perform a coherent integral of 1 second on the result of complex multiplication; The phase error is obtained by performing four-quadrant carrier phase discrimination on the result of coherent integration over a 1-second duration. The phase error is input into a second-order loop filter for processing, and the initial phase and frequency of the local carrier are updated based on the output of the second-order loop filter; wherein, the bandwidth of the phase-locked loop is 0.25Hz.
7. The dual-antenna carrier phase difference measurement method according to claim 1, characterized in that, Also includes: Using the relative carrier phase difference as an observation, and combining it with observation data from multiple satellites, the orientation of the baseline vector between the first antenna and the second antenna in the navigation coordinate system is calculated. The heading angle of the vehicle is calculated based on the direction of the baseline vector.
8. A dual-antenna carrier phase difference measurement device, characterized in that, include: The radio frequency processing module is used to process the satellite radio frequency signals received by the first and second antennas of the dual-antenna direction-finding receiver to obtain the first zero-IF complex baseband signal and the second zero-IF complex baseband signal. The baseband channel processing module is used to perform baseband channel processing on the first zero-IF complex baseband signal and the second zero-IF complex baseband signal respectively to obtain the first baseband signal and the second baseband signal. The baseband signal is a digital signal after carrier stripping and pseudocode stripping. The second zero-IF complex baseband signal does not undergo independent carrier frequency or phase tracking. The coherent integration and rotation module is used to perform coherent integration and rotation processing on the first baseband signal and the second baseband signal to obtain the rotated signal; wherein, the rotation processing is to multiply the digital signal of the second antenna of the same satellite with the complex conjugate of the digital signal of the first antenna; An ultra-narrow bandwidth phase-locked tracking module is used to perform ultra-narrow bandwidth phase-locked tracking on the rotated signal and measure the relative carrier phase difference between the first antenna and the second antenna; wherein, the coherent integration duration used in the ultra-narrow bandwidth phase-locked tracking is greater than the duration of the navigation message bits, and the phase-locked loop bandwidth is less than the conventional phase-locked loop bandwidth.
9. An electronic device, characterized in that, Includes a processor, which is coupled to a memory; The processor is configured to execute a computer program stored in the memory to cause the electronic device to perform the method as described in any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, It includes a computer program or instructions that, when run on a computer, cause the computer to perform the method as described in any one of claims 1 to 7.