An atmospheric waveguide detection payload clock system based on occultation observation technology

Abstract

The present application provides an atmospheric waveguide detection payload clock system based on occultation observation technology, including a front-end radio frequency module, a clock module and a back-end data processing module connected to each other, the clock module including a temperature compensation crystal oscillator and a clock configuration unit, the data processing module including an FPGA unit and an ARM unit; the clock configuration unit is configured to provide a sampling clock to the front-end radio frequency module and a global working clock to the FPGA unit; the temperature compensation crystal oscillator is configured to provide a working clock to the front-end radio frequency module, and to provide a reference clock to the main and backup clock configuration units; the ARM unit is configured to perform clock configuration on the main and backup clock configuration units to configure the outputs thereof respectively, and the ARM unit also performs power supply enable control on the main and backup clock configuration units respectively, and switches and selects them. The present application effectively improves the reliability and flexibility of the clock system, and further improves the working stability of the occultation detection system.

Description

Technical Field

[0001] The present application belongs to the field of occultation detection technology, and in particular, relates to an atmospheric waveguide detection payload clock system based on occultation observation technology. Background Art

[0002] Occultation detection technology is a high-precision meteorological detection method. It can obtain important meteorological parameters such as temperature, humidity and air pressure along the path of the navigation star signal in a timely manner by actively receiving the navigation star signal transmitted by the global navigation system (GNSS) through the occultation detection payload distributed in low orbit. The basis of occultation detection technology is the occultation detection payload. The stable operation of the detection payload requires a highly reliable clock system to ensure it.

[0003] The design of the existing internal clock system of the occultation payload is rather complicated. Each working module is configured with a separate working clock, and the clock frequency cannot be adjusted. It is impossible to meet the different clock working requirements of each internal module through a single clock module. In particular, the clock module inside the payload only has a separate clock module and there is no backup design. In this way, when an abnormality occurs in the clock module, the entire detection payload will not be able to work normally, ultimately resulting in poor reliability and stability of the occultation payload. Summary of the invention

[0004] In view of this, the present application aims to propose an atmospheric waveguide detection payload clock system based on occultation observation technology to solve at least one of the above problems.

[0005] To achieve the above purpose, the technical solution of this application is implemented as follows:

[0006] The present application provides an atmospheric waveguide detection payload clock system based on occultation observation technology, comprising a front-end radio frequency module, a clock module and a back-end data processing module connected to each other, wherein the clock module comprises a temperature compensation crystal oscillator and a clock configuration unit, and the data processing module comprises an FPGA unit and an ARM unit;

[0007] The clock configuration unit is configured to provide a sampling clock to the front-end RF module and a global working clock to the FPGA unit;

[0008] The clock configuration unit is configured as a master and backup unit, and the temperature compensation crystal oscillator is configured to provide a working clock for the front-end radio frequency module and a reference clock for the master and backup clock configuration units;

[0009] The ARM unit is configured to perform clock configuration on the main and backup clock configuration units to configure their outputs respectively. The ARM unit also performs power supply enable control on the main and backup clock configuration units respectively, and switches and selects them so that the main and backup clock configuration units work independently.

[0010] Furthermore, the temperature compensated crystal oscillator sends the reference clock to the main and backup clock configuration units respectively through the first clock distributor, wherein a π-type attenuation circuit is also provided between the first clock distributor and the main and backup clock configuration units respectively to adjust the input signal power;

[0011] The temperature compensated crystal oscillator sends the working clock to the front-end RF module through the second clock distributor.

[0012] Furthermore, the main and backup clock configuration units are respectively connected to the matching resistor through the driving resistor set in the branch, and the other end of the matching resistor is connected to the third clock distributor through a π-type attenuation circuit, and the third clock distributor outputs the sampling clock and the global working clock to the outside.

[0013] Furthermore, the first clock distributor is a one-to-two clock distributor, the second clock distributor is a one-to-three clock distributor, and the third clock distributor is a one-to-four clock distributor.

[0014] Furthermore, the resistance of the matching resistor matches the output impedance of the signal line and is 50Ω.

[0015] Furthermore, the main and backup clock configuration units are independently powered, respectively by the main power supply unit and the backup power supply unit, and the ARM unit controls the enable control signal of each power supply unit, and enables the main and backup clock configuration units to work independently by switching the enable.

[0016] Furthermore, the main clock configuration unit, the main power supply unit and one of the driving resistors are arranged on one side of the printed circuit board, and the backup clock configuration unit, the backup power supply unit and another driving resistor are symmetrically arranged on the other side of the printed circuit board.

[0017] Compared with the prior art, the atmospheric waveguide detection payload clock system based on occultation observation technology described in this application has the following beneficial effects:

[0018] The atmospheric waveguide detection payload clock system based on occultation observation technology described in the present application uses an independent temperature compensated crystal oscillator as the working clock of the radio frequency unit, and also as the reference clock source of the sampling clock and the global clock, and sends them to two independent clock configuration units respectively, which are configured and outputted separately by the back-end data processing module; in addition, by independently supplying power to the clock configuration unit, controlling the power supply enablement through the data processing module, and switching and selecting the clock configuration units, the main and standby clock units can work independently without affecting each other, which greatly improves the reliability and flexibility of the clock system, and further improves the reliability and stability of the occultation detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0020] Figure 1 This is an overall block diagram of an atmospheric waveguide detection payload clock system based on occultation observation technology described in an embodiment of the present application;

[0021] Figure 2 A detailed block diagram of an atmospheric waveguide detection payload clock system based on occultation observation technology described in an embodiment of the present application;

[0022] Figure 3 This is a schematic diagram of the position relationship between the main and backup clock configuration units described in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0024] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] The normal operation of the occultation detection payload is inseparable from a highly reliable clock system, which provides the basic working clock, sampling clock and global working clock for the radio frequency unit and data processing unit inside the detection payload. It can be said that a highly reliable clock system is the heart of the occultation detection payload. The more reliable the clock system is, the higher the reliability and robustness of the occultation detection payload will be.

[0026] See also Figure 1 As shown, the present application provides a design scheme for an atmospheric waveguide detection payload clock system based on occultation observation technology, including a front-end radio frequency module, a clock module and a back-end data processing module connected to each other, wherein the clock module includes a temperature compensation crystal oscillator and a clock configuration unit, and the data processing module includes an FPGA unit and an ARM unit;

[0027] The clock configuration unit is configured to provide a sampling clock to the front-end radio frequency module and a global working clock to the FPGA unit;

[0028] The clock configuration unit is set as a master and backup, and the temperature compensation crystal oscillator is configured to provide a working clock for the front-end RF module and a reference clock for the master and backup clock configuration units;

[0029] The ARM unit is configured to perform clock configuration on the main and backup clock configuration units to configure their outputs respectively. The ARM unit also performs power supply enable control on the main and backup clock configuration units respectively, and switches them so that the main and backup clock configuration units work independently.

[0030] Specifically, in this embodiment, the main function of the front-end RF module is to receive and process the occultation antenna signal, and after processing, send the low-frequency digital signal after down-conversion to the back-end data processing module for deep analysis. In general, the front-end RF module of the occultation detection payload can be subdivided into three units, each of which is responsible for processing one channel of RF data; among them, the normal operation of each RF processing unit requires a basic working clock and a RF data sampling clock. The working clock is used to realize the basic functions inside the RF unit, and the RF data sampling clock is used to sample the received RF data and complete the analog-to-digital conversion and down-conversion processing of the RF data.

[0031] The main function of the clock module is to provide the basic working clock and RF data sampling clock for the front-end RF module, and provide the global working clock for the FPGA unit of the back-end data processing module. It uses a temperature compensated crystal oscillator (TCXO) as the basic clock source. The temperature compensated crystal oscillator has a special temperature compensation circuit inside. When the external environment changes, the clock output frequency can still be kept stable through the adjustment of the temperature compensation circuit. It is suitable for use in satellite payloads with drastic changes in ambient temperature. On the one hand, the temperature compensated crystal oscillator directly outputs to the three RF processing units as the basic working clock, as shown in the working clock 1, working clock 2 and working clock 3 in the front-end RF module block diagram in Figure 1; on the other hand, the temperature compensated crystal oscillator outputs the clock as a reference clock, which is output to the clock configuration unit for corresponding configuration processing. After meeting the frequency and amplitude requirements of the sampling clock of the RF processing unit and the back-end FPGA unit, it is output to the outside and given to the three RF processing units and the back-end FPGA unit respectively.

[0032] The main function of the back-end data processing module is to perform deep processing and solution on the raw occultation data after preprocessing by the front-end RF module, and output it after the solution is completed. Its main components are FPGA unit and ARM unit. The normal operation of the FPGA unit requires a global working clock, which is provided by the clock configuration unit through configuration; the ARM unit is responsible for the corresponding configuration of the clock configuration unit, and the selection and switching of the power supply enable of the clock configuration unit to ensure the normal operation of the clock configuration unit without affecting each other, thereby improving the reliability of the clock module.

[0033] The power-on process of the entire system is as follows: after the occultation detection system is powered on, the ARM unit can work independently because it has a separate crystal oscillator configuration; after the ARM unit completes the initialization configuration, it starts to power on the clock configuration unit according to the established procedure, and selects the main clock output or the backup clock output. After the selection is completed, the registers inside the clock configuration unit are configured accordingly. After the configuration is completed, the clock configuration unit outputs the sampling clock and the global working clock to the outside respectively. In this way, after receiving the sampling clock, the RF processing unit starts sampling and processing the occultation RF data, and then sends it to the back-end data processing module after the processing is completed; the FPGA unit starts working after receiving the global working clock, and performs the down-conversion data processing and solution process sent by the front-end RF processing unit.

[0034] The atmospheric waveguide detection payload clock system based on occultation observation technology described in this embodiment uses an independent temperature compensated crystal oscillator as the working clock of the radio frequency unit, and also as the reference clock source of the sampling clock and the global clock, and sends them to two independent clock configuration units respectively, which are configured and outputted separately through the back-end data processing module; in addition, by independently powering the clock configuration unit and controlling the power supply enablement through the data processing module, it can be switched and selected to realize the independent operation of the main and standby clock units without affecting each other, which greatly improves the reliability and flexibility of the clock system, and further improves the reliability and stability of the occultation detection system.

[0035] Figure 2 The following is a block diagram of the specific design scheme of the clock system. Specifically, the temperature compensation crystal oscillator is first distributed by a one-to-three clock distributor and then directly sent to the RF unit as the basic working clock of the three-way RF unit. The reason for using the clock distributor is to meet the driving capability of the clock output. If the direct line distribution method is used, the driving capability of the clock will be greatly weakened and the power requirement of the RF working clock cannot be met.

[0036] In addition, the temperature compensation crystal oscillator is supplied to the back-end clock configuration unit through a one-to-two clock distributor. The clock configuration unit is divided into a main clock configuration unit and a backup clock configuration unit. The main clock configuration unit and the backup clock configuration unit adopt an independent power supply design, which are powered by the main power supply unit and the backup power supply unit respectively. The power supply unit has an enable control function. The enable control signal of the power supply unit is controlled by the ARM unit of the back-end data processing module. By switching the enable, the main and backup clock configuration units can work independently without affecting each other, meeting the single-machine hot standby requirements of the occultation detection payload clock system.

[0037] Between the clock distributor and the input of the two clock configuration units, corresponding π-type attenuation circuits are added respectively, which are used to meet the signal balance and signal matching between the clock output and the clock configuration unit input. More importantly, the signal power output of the clock distributor is adjusted to meet the signal power and amplitude requirements of the signal input pin of the clock configuration unit. Especially when the clock chip solutions selected by the main clock configuration unit and the backup clock configuration unit are different, it is more necessary to limit and adjust the amplitude and power of the output clock. The clock configuration unit needs to be configured with a special configuration signal before being output. The clock frequency, amplitude, jitter, slope and other parameters need to meet the requirements of the sampling clock of the RF processing unit and the global working clock of the data processing module.

[0038] After the clock configuration unit is configured, it needs to pass through the driving resistor before it can be output. The function of this resistor is to improve the signal driving capability and reduce signal reflection. After the driving resistor, a matching resistor is added. The resistance of this resistor matches the output impedance of the signal line. The matching resistor used in this embodiment is a 50Ω resistor. While performing impedance matching, it will also be convenient for debugging. After the clock passes through the matching resistor, it passes through the π-type attenuation circuit, which also has the function of adjusting the signal output power and amplitude, and then it is output to the outside through a one-to-four clock distributor. Three of them are given to the RF processing unit as sampling clocks, and the other one is given to the back-end data processing module as a global working clock. The frequencies of the sampling clock and all working clocks need to be consistent.

[0039] like Figure 3 The figure shows the positional relationship between the main and backup clock configuration units in the clock module. In the actual clock system design, the main and backup clock configuration units require single-machine hot backup, that is, two clock configuration units need to be provided simultaneously inside a single printed circuit board, and can be flexibly switched through the control of the ARM processor (ie, ARM unit). In the specific implementation, the specific position placement and arrangement requirements of the main and backup units need to be considered.

[0040] Furthermore, if they are placed in parallel on the front of the printed circuit board, it will first bring about the problem of tight circuit board layout and tight routing, and the difference in the distance between the two clock configuration units and the load will cause signal integrity problems when the clock is output. Therefore, the present application places the main and backup clock configuration units on both sides of the printed circuit board when laying out the printed circuit board, with the main clock configuration unit placed on the front of the printed circuit board and the backup clock configuration unit placed on the back of the printed circuit board.

[0041] The power supply unit, clock configuration unit and driving resistor all need to be placed on the front and back sides of the printed circuit board respectively, and need to be placed symmetrically. After the clock output passes through the corresponding driving resistor, it is connected to the matching resistor at the front end of the clock distributor. This design greatly simplifies the difficulty of printed circuit board layout and wiring, and avoids the related signal integrity problems caused by different distance loads when two units are placed on the front side at the same time.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

[0043] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. An atmospheric waveguide detection payload clock system based on occultation observation technology, characterized in that: It includes a front-end radio frequency module, a clock module and a back-end data processing module connected to each other, wherein the clock module includes a temperature compensation crystal oscillator and a clock configuration unit, and the data processing module includes an FPGA unit and an ARM unit; The clock configuration unit is configured to provide a sampling clock to the front-end RF module and a global working clock to the FPGA unit; The clock configuration unit is configured as a master and backup unit, and the temperature compensation crystal oscillator is configured to provide a working clock for the front-end radio frequency module and a reference clock for the master and backup clock configuration units; The ARM unit is configured to perform clock configuration on the main and backup clock configuration units to configure their outputs respectively. The ARM unit also performs power supply enable control on the main and backup clock configuration units respectively, and switches and selects them so that the main and backup clock configuration units work independently.

2. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 1 is characterized in that: The temperature compensated crystal oscillator sends the reference clock to the main and backup clock configuration units respectively through the first clock distributor, wherein a π-type attenuation circuit is also provided between the first clock distributor and the main and backup clock configuration units respectively to adjust the input signal power; The temperature compensated crystal oscillator sends the working clock to the front-end RF module through the second clock distributor.

3. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 2 is characterized in that: The main and backup clock configuration units are respectively connected to the matching resistor through the driving resistor set in the branch, and the other end of the matching resistor is connected to the third clock distributor through the π-type attenuation circuit, and the third clock distributor outputs the sampling clock and the global working clock.

4. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 3 is characterized in that: The first clock distributor is a one-to-two clock distributor, the second clock distributor is a one-to-three clock distributor, and the third clock distributor is a one-to-four clock distributor.

5. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 3 is characterized by: The resistance value of the matching resistor matches the output impedance of the signal line and is 50Ω.

6. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 3 is characterized by: The main and backup clock configuration units are powered independently, respectively by the main power supply unit and the backup power supply unit, and the ARM unit controls the enable control signal of each power supply unit, and enables the main and backup clock configuration units to work independently by switching.

7. The atmospheric waveguide detection payload clock system based on occultation observation technology according to claim 6 is characterized by: The main clock configuration unit, the main power supply unit and one of the driving resistors are arranged on one side of the printed board, and the backup clock configuration unit, the backup power supply unit and another driving resistor are symmetrically arranged on the other side of the printed board.

Images