Clock phase synchronization method for satellite navigation processing load equipment

Abstract

The invention discloses a clock phase synchronization method for satellite navigation processing load equipment, which is based on a reference time frequency unit and navigation processing load equipment, and specifically comprises the following steps: step 1, the reference time frequency unit generates a system clock and a 1PPS second pulse time mark signal, the system clock generates a local 1PPS second pulse time mark signal, and the local 1PPS second pulse time mark signal is transmitted to the navigation processing load equipment; the time reference is used as a local time reference; step 2, the navigation processing load equipment uses the system clock obtained in the step 1 to sample the rising edge of the 1PPS time mark signal obtained in the step 1, and performs N frequency division by taking the rising edge of the 1PPS time mark signal as a starting point to obtain a measurement reference signal f0; by performing signal type time-sharing control on 1PPS second pulse time mark signals, measuring high-precision phase measurement values and performing self-adaptive phase dynamic adjustment design, time synchronization of navigation processing loads can be stably and reliably realized, and the technical problem that the high-precision clock synchronization requirement of satellite navigation load equipment cannot be ensured in the prior art is solved.

Description

Technical Field

[0001] The invention belongs to the field of satellite navigation processing payload, relates to a clock synchronization system, and specifically is a clock phase synchronization method for satellite navigation processing payload equipment. Background Art

[0002] In the design of satellite navigation processing payload equipment, a variety of high-precision time and frequency measurement and processing services are usually implemented. High-precision clock phase synchronization between multiple services within the processing payload is an important feature of navigation payload processing services, such as the transmission channel delay uncertainty of satellite signal generation, multi-channel signal consistency, and satellite receiver pseudo code measurement uncertainty.

[0003] For navigation processing payload equipment, the traditional method is to design a 1PPS second pulse time signal that is homologous to the reference clock and has a fixed phase. This time signal is used for system time synchronization. It is distributed to the navigation processing payload equipment together with the reference clock signal as an external input. In the navigation processing payload equipment, the phase relationship of the reference clock is determined by sampling and latching the time signal using the reference frequency, thereby achieving local time maintenance and delay uncertainty in receiving and transmitting navigation satellite signals. Since the reference clock signal is usually transmitted in a sinusoidal form, it is easy for the reference clock and the 1PPS signal to cause the sampling and latching phase to be non-fixed in the navigation processing payload equipment due to factors such as amplitude, temperature, and component level judgment threshold deviation. In particular, as the frequency of the reference clock increases, it is more likely to cause the navigation processing payload equipment to be out of synchronization. For example, in the design of navigation signal generation services, a fixed phase relationship is established between the reference clock and the system synchronization identification 1PPS signal inside the FPGA. It is necessary to ensure that the reference clock and the 1PPS signal can meet the timing constraints of establishment and maintenance, and no metastable situation occurs, that is, the clock inside the FPGA can stably and accurately sample the 1PPS signal, and determine the rising edge as the phase fixed moment, so as to achieve the consistency of the phase of the multi-channel navigation signal, and the consistency state of each signal under conditions such as multiple power on and off, reset, etc. However, as the reference clock frequency increases, the timing margin for establishing and maintaining between such signals becomes smaller and smaller, and it is very difficult to ensure the delay uncertainty requirements of the navigation signal, especially when accompanied by changes in external temperature, devices, and even FPGA design versions, it is even more impossible to ensure accurate phase judgment between the reference clock and the 1PPS time mark signal.

[0004] Therefore, in the face of the high-precision synchronization requirements of future satellite navigation payload equipment, a clock phase synchronization method for satellite navigation processing payload equipment is urgently needed. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a clock phase synchronization method for satellite navigation processing payload equipment, so as to solve the technical problem that the prior art cannot guarantee the high-precision clock synchronization requirements of satellite navigation payload equipment.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0007] A clock phase synchronization method for satellite navigation processing payload equipment, based on a reference time-frequency unit and a navigation processing payload equipment, specifically comprises the following steps:

[0008] Step 1: The reference time-frequency unit generates a system clock and a 1PPS pulse-per-second time-scale signal. The system clock generates a local 1PPS pulse-per-second time-scale signal and uses it as a local time reference.

[0009] Step 2: The navigation processing payload device uses the system clock obtained in step 1 to sample the rising edge of the 1PPS pulse per second time scale signal obtained in step 1, and performs N-frequency division with the rising edge of the 1PPS pulse per second time scale signal as the starting point to obtain a measurement reference signal f0;

[0010] Step 3: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale signal switching instruction, the reference time-frequency unit performs baseband modulation on the 1PPS second pulse time-scale signal obtained in step 1 to obtain a baseband modulation signal f c ;

[0011] Step 4: The navigation processing payload uses its internal local independent clock to measure the reference signal f0 and the baseband modulation signal f c Perform capture and tracking to obtain the phase measurement value NCO after tracking stabilization Fp and NCO Cp , the mutual difference measurement value φ is calculated according to the following formula;

[0012] φ=NCO Fp -NCO Cp ;

[0013] Step 5, determine whether the phase difference measurement value φ obtained in step 4 is greater than 1 system clock cycle. If so, adjust the local 1PPS second pulse time mark signal forward by 1 system clock cycle in the next second counting cycle, and enter step 6; if not, keep the local 1PPS second pulse time mark signal and enter step 6;

[0014] Step 6: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale switching instruction, the reference time-frequency unit converts the baseband modulation signal f c Switch to 1PPS second pulse form, i.e. 1PPS second pulse time scale signal;

[0015] Step 7: The navigation processing payload equipment monitors whether the mutual difference measurement value φ between the local 1PPS second pulse time signal and the 1PPS second pulse time signal obtained in step 6 is a fixed value. If so, continue to use the local 1PPS second pulse time signal as the local time reference to maintain synchronization; otherwise, return to step 3 and resynchronize.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] (I) The present invention can stably and reliably achieve time synchronization of navigation processing payloads by performing time-sharing control on the signal type of the 1PPS second pulse time scale signal, measuring high-precision phase measurement values ​​and designing adaptive phase dynamic adjustment, thereby solving the technical problem that the prior art cannot guarantee the high-precision clock synchronization requirements of satellite navigation payload equipment.

[0018] (II) The present invention has strong adaptability to the time synchronization problem of navigation processing payload. Without increasing the hardware overhead of the traditional system, it can effectively solve the control of navigation processing payload time uncertainty caused by multiple power on / off and reset of a certain unit or multiple units of the navigation processing payload. It avoids the implementation risk of initial phase determination of high-speed sinusoidal high-speed clock signal through synchronization time scale under high-speed reference clock conditions, and effectively reduces the complexity of the payload equipment that implements this feature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The principle block diagram of the high-precision clock phase synchronization method for navigation processing payload equipment;

[0020] Figure 2 Principle block diagram of the high-precision clock phase synchronization method for navigation processing payload equipment.

[0021] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0022] It should be noted that, unless otherwise specified, all components in the present invention are components known in the art.

[0023] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0024] The present invention provides a clock phase synchronization method for satellite navigation processing payload equipment, based on a reference time-frequency unit and a navigation processing payload equipment, specifically comprising the following steps:

[0025] Step 1: The reference time-frequency unit generates a system clock and a 1PPS pulse-per-second time-scale signal. The system clock generates a local 1PPS pulse-per-second time-scale signal and uses it as a local time reference.

[0026] Step 2: The navigation processing payload device uses the system clock obtained in step 1 to sample the rising edge of the 1PPS pulse per second time scale signal obtained in step 1, and performs N-frequency division with the rising edge of the 1PPS pulse per second time scale signal as the starting point to obtain a measurement reference signal f0;

[0027] Step 3: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale signal switching instruction, the reference time-frequency unit performs baseband modulation on the 1PPS second pulse time-scale signal obtained in step 1 to obtain a baseband modulation signal f c ;

[0028] Step 4: The navigation processing payload uses its internal local independent clock to measure the reference signal f0 and the baseband modulation signal f c Perform capture and tracking to obtain the phase measurement value NCO after tracking stabilization Fp and NCO Cp , the mutual difference measurement value φ is calculated according to the following formula;

[0029] φ=NCO Fp -NCO Cp ;

[0030] Step 5, determine whether the phase difference measurement value φ obtained in step 4 is greater than 1 system clock cycle. If so, adjust the local 1PPS second pulse time mark signal forward by 1 system clock cycle in the next second counting cycle, and enter step 6; if not, keep the local 1PPS second pulse time mark signal and enter step 6;

[0031] Step 6: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale switching instruction, the reference time-frequency unit converts the baseband modulation signal f c Switch to 1PPS second pulse form, i.e. 1PPS second pulse time scale signal;

[0032] Step 7: The navigation processing payload equipment monitors whether the mutual difference measurement value φ between the local 1PPS second pulse time signal and the 1PPS second pulse time signal obtained in step 6 is a fixed value. If so, continue to use the local 1PPS second pulse time signal as the local time reference to maintain synchronization; otherwise, return to step 3 and resynchronize.

[0033] In the above technical scheme, by performing time-sharing control on the signal type of the 1PPS second pulse time scale signal and measuring the high-precision phase measurement value and designing an adaptive phase dynamic adjustment, the time synchronization of the navigation processing payload can be achieved stably and reliably, thereby solving the technical problem that the existing technology cannot guarantee the high-precision clock synchronization requirements of satellite navigation payload equipment.

[0034] It has strong adaptability to the time synchronization problem of navigation processing payload. Without increasing the hardware overhead of traditional systems, it can effectively solve the control of navigation processing payload time uncertainty caused by multiple power on / off and reset of a unit or multiple units of the navigation processing payload. It avoids the implementation risk of initial phase determination of high-speed sinusoidal high-speed clock signal through synchronization time scale under high-speed reference clock conditions, and effectively reduces the complexity of payload equipment that implements this feature.

[0035] in, Figure 1 Design principle block diagram for high-precision clock phase synchronization of navigation processing payload equipment, f s is the reference frequency, 1PPS is the time-stamp signal, f0 is the reference frequency, s The square wave signal after N frequency division, f c It is the baseband pseudo code signal after modulating the time-marked signal.

[0036] C F , C c They are the pseudo code signals after CLK sampling. Fe , C Fl They are the locally generated C F Leading and following codes; C Ce , C Cl They are the locally generated C C Ahead, after code; M F (n), M C (n) are the frequency control words of the NCO accumulator; NCO Fp 、NCO Cp are the phase measurements measured locally, respectively.

Claims

1. A clock phase synchronization method for satellite navigation processing payload equipment, characterized in that: Based on the reference time-frequency unit and the navigation processing payload equipment, the following steps are specifically included: Step 1: The reference time-frequency unit generates a system clock and a 1PPS pulse-per-second time-scale signal. The system clock generates a local 1PPS pulse-per-second time-scale signal and uses it as a local time reference. Step 2: The navigation processing payload device uses the system clock obtained in step 1 to sample the rising edge of the 1PPS pulse per second time scale signal obtained in step 1, and performs N-frequency division with the rising edge of the 1PPS pulse per second time scale signal as the starting point to obtain a measurement reference signal f0; Step 3: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale signal switching instruction, the reference time-frequency unit performs baseband modulation on the 1PPS second pulse time-scale signal obtained in step 1 to obtain a baseband modulation signal f c ; Step 4: The navigation processing payload uses its internal local independent clock to measure the reference signal f0 and the baseband modulation signal f c Perform capture and tracking to obtain the phase measurement value NCO after tracking stabilization Fp and NCO Cp , the mutual difference measurement value φ is calculated according to the following formula; φ=NCO Fp -REMEMBER Cp ; Step 5, determine whether the phase difference measurement value φ obtained in step 4 is greater than 1 system clock cycle. If so, adjust the local 1PPS second pulse time mark signal forward by 1 system clock cycle in the next second counting cycle, and enter step 6; if not, keep the local 1PPS second pulse time mark signal and enter step 6; Step 6: The navigation processing payload sends a time-scale signal switching instruction to the reference time-frequency unit. After receiving the time-scale switching instruction, the reference time-frequency unit converts the baseband modulation signal f c Switch to 1PPS second pulse form, i.e. 1PPS second pulse time scale signal; Step 7: The navigation processing payload equipment monitors whether the mutual difference measurement value φ between the local 1PPS second pulse time signal and the 1PPS second pulse time signal obtained in step 6 is a fixed value. If so, continue to use the local 1PPS second pulse time signal as the local time reference to maintain synchronization; otherwise, return to step 3 and resynchronize.

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