A Spaceborne GNSS Occultation Receiver System

Abstract

The present application provides a satellite-borne GNSS occultation receiver system, comprising: a pre-branch unit including a plurality of microwave switches and a cavity filter, wherein every two microwave switches are connected to a cavity filter to form a switch branch, the switch branch is divided into a main switch branch and a backup switch branch, one of the microwave switches of the main switch branch and the backup switch branch is connected to two occultation antennas, and the microwave switch is connected to a digital processing unit, and the digital processing unit is used to control the switching of the occultation antenna signal; the other microwave switch of the main switch branch and the backup switch branch is connected to a main backup switching circuit, the main backup switching circuit is connected to a radio frequency unit, and the main backup switching circuit is used to autonomously switch the occultation antenna signal. The present application can realize that the satellite can still normally receive the occultation signal when rotating, and adopts a main backup design to improve the reliability of the system.

Description

Technical Field

[0001] The present application belongs to the technical field of occultation detection, and in particular, relates to a satellite-borne GNSS occultation receiver system. Background Art

[0002] GNSS occultation receiver is a meteorological remote sensing technology that uses occultation to measure the atmosphere. This technology has been applied to earthquake prediction, weather detection, etc. Currently, commercial remote sensing detection is developing rapidly, with advantages such as low cost, short cycle, small size and light weight. How to further improve the reliability of occultation receivers is of great significance to commercial meteorological remote sensing.

[0003] At present, the main problems of occultation receivers are as follows:

[0004] (1) Existing occultation receivers can only receive occultation signals in a single direction and cannot receive signals normally when the satellite is adjusting its attitude or rotating.

[0005] (2) In the prior art, microwave switches are switched mainly through external instructions, and the control signal needs to be connected separately in the hardware design, resulting in a complex circuit structure and a high failure rate;

[0006] (3) The existing main and standby kneading technology requires a separately designed kneading plate, which is large in size and weight and has a high cost. Summary of the invention

[0007] In view of this, the present application aims to propose a satellite-borne GNSS occultation receiver system to solve at least one of the above problems.

[0008] To achieve the above purpose, the technical solution of this application is implemented as follows:

[0009] The present application provides a satellite-borne GNSS occultation receiver system, comprising a cascaded front-end branch unit, a receiving module and a whole-star service unit, wherein the input end of the front-end branch unit is connected to the occultation antenna, the receiving module comprises a connected radio frequency unit, a digital processing unit and a kneading unit, and the kneading unit is connected to the whole-star service unit;

[0010] The pre-branch unit includes a plurality of microwave switches and cavity filters, wherein every two microwave switches are connected to a cavity filter to form a switch branch, the switch branch is divided into a main switch branch and a backup switch branch, one of the microwave switches of the main switch branch and the backup switch branch is connected to two occultation antennas, and the microwave switch is connected to the digital processing unit, and the digital processing unit is used to control the switching of occultation antenna signals;

[0011] The main switch branch and the other microwave switch of the backup switch branch are connected with a main backup switching circuit, the main backup switching circuit is connected to the radio frequency unit, and the main backup switching circuit is used to autonomously switch the occultation antenna signal.

[0012] Further, the RF1 pin of the microwave switch is configured to receive the occultation antenna signal, and the RF2 pin and the RF3 pin of the microwave switch are configured to connect to the radio frequency unit;

[0013] The VCTL pin of the microwave switch is connected to the RF3 pin through a voltage divider circuit;

[0014] The RF2 pin is further connected to the VDD pin through a first diode, and the RF3 pin is further connected to the VDD pin through a second diode.

[0015] Further, the voltage divider circuit includes a first resistor and a second resistor, one end of the second resistor is connected to the VCTL pin, and the other end is connected to the RF3 pin;

[0016] One end of the first resistor is connected to the VCTL pin, and the other end is grounded.

[0017] Furthermore, the radio frequency unit, the digital processing unit and the kneading unit are in a primary-backup configuration;

[0018] The main digital processing unit is respectively connected to the two microwave switches connected to the occultation antenna, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the occultation antenna;

[0019] The main radio frequency unit is respectively connected to the two microwave switches connected to the main and backup switching circuits, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the main and backup switching circuits.

[0020] Furthermore, the main kneading unit and the backup kneading unit are connected, and both the main kneading unit and the backup kneading unit are configured with multiple interface modules and connectors, wherein one end of the interface module is connected to the digital processing unit, and the other end is connected to each connector through a third resistor, and the connector is connected to the entire star service unit.

[0021] Furthermore, the whole star service unit is provided with a main and backup, and the main and backup whole star service units are correspondingly connected to the connectors of the main and backup kneading units.

[0022] Furthermore, the interface module at least includes a satellite service 422 communication interface, a CAN communication interface and a LVDS data transmission interface.

[0023] Compared with the prior art, the satellite-borne GNSS occultation receiver system described in this application has the following beneficial effects:

[0024] The satellite-borne GNSS occultation receiver system described in the present application has the advantages of conventional commercial remote sensing, such as low cost, short cycle, small size and light weight. Its main features are that forward and backward occultation antennas are installed on the two sides of the satellite perpendicular to the flight direction, and another forward and backward occultation antennas are installed on the two sides parallel to the flight direction, so that the satellite can still receive occultation signals normally when rotating; the system is designed with a main and standby function, and corresponding designs are made for the front-end RF branching and the back-end digital signal kneading, thereby improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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:

[0026] Figure 1 A schematic diagram of the structure of a satellite-borne GNSS occultation receiver system according to an embodiment of the present application;

[0027] Figure 2 A schematic diagram of a microwave switch and a primary / backup switching circuit according to an embodiment of the present application;

[0028] Figure 3 This is a schematic diagram of the connection between the kneading unit and the main backup whole star service unit described in the embodiment of the present application;

[0029] Figure 4 This is a schematic diagram of a short circuit failure of a kneading unit described in an embodiment of the present application. DETAILED DESCRIPTION

[0030] 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.

[0031] 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.

[0032] See also Figure 1 As shown, this embodiment provides a satellite-borne GNSS occultation receiver system, including a cascaded front-end branch unit, a receiving module and a whole-star service unit, the input end of the front-end branch unit is connected to the occultation antenna, the receiving module includes a radio frequency unit, a digital processing unit and a kneading unit connected to each other, and the kneading unit is connected to the whole-star service unit;

[0033] The pre-branch unit includes a plurality of microwave switches and cavity filters, wherein every two microwave switches are connected to a cavity filter to form a switch branch, the switch branch is divided into a main switch branch and a backup switch branch, one of the microwave switches of the main switch branch and the backup switch branch is connected to two occultation antennas, and the microwave switch is connected to a digital processing unit, and the digital processing unit is used to control the switching of occultation antenna signals;

[0034] Another microwave switch of the main switch branch and the backup switch branch is connected with a main backup switching circuit, the main backup switching circuit is connected with the radio frequency unit, and the main backup switching circuit is used for autonomously switching the occultation antenna signal.

[0035] Specifically, in this embodiment, the system is composed of a forward occultation antenna 1, a backward occultation antenna 1, a forward occultation antenna 2, a backward occultation antenna 2, a front branching unit, a main backup radio frequency unit, a main backup digital processing unit, and a kneading unit.

[0036] Among them, there are 4 sets of passive components, which are installed in the front, back, left and right directions of the satellite. The normal satellite flight direction is forward, and the occultation signal is received in the forward and backward directions. When the satellite attitude changes, its occultation signal can be switched to the left and right occultation antennas to achieve normal signal reception.

[0037] The front branch unit is a single set, which includes microwave switch 1, microwave switch 2, cavity filter 1, cavity filter 2, microwave switch 3, microwave switch 4, and main and backup switching circuits. The microwave switch uses high-reliability devices, and its working power is fed through the RF cable. Microwave switch 3 and microwave switch 4 can be switched through the main and backup switching circuits. Microwave switch 1 and microwave switch 2 are forward and backward by default. When switching is required, the digital processing unit controls the signal to switch; the internal RF and digital processing units are designed with double cold backups, and the failure of one will not affect the normal operation of the other; the kneading unit completes the kneading of the external interface, which can reduce the number of external interfaces while ensuring reliability. The satellite service unit can complete the telemetry and data transmission of the main and backup units through one interface.

[0038] The system design improves the reliability of the entire system through the main-backup design. By using passive devices at the antenna output end, the low noise coefficient and high sensitivity of the occultation receiver system are ensured, while the complexity of the front-end design is simplified. The switching of the antenna between the main and backup machines at the back end is completed through a simple main-backup switching circuit.

[0039] The system described in this application has the advantages of low cost, short cycle, small size and light weight of conventional commercial remote sensing. The main features are that the forward and backward occultation antennas are installed on the two sides of the satellite perpendicular to the flight direction, and another forward and backward occultation antenna is installed on the two sides parallel to the flight direction, so that the satellite can still receive the occultation signal normally when rotating; and the system is designed with main and standby, and the front-end RF splitting and back-end digital signal kneading are designed accordingly, which improves the reliability of the system.

[0040] In some embodiments, the RF1 pin of the microwave switch is configured to receive the occultation antenna signal, and the RF2 pin and the RF3 pin of the microwave switch are configured to connect to the radio frequency unit;

[0041] The VCTL pin of the microwave switch is connected to the RF3 pin through a voltage divider circuit, wherein the voltage divider circuit includes a first resistor and a second resistor, one end of the second resistor is connected to the VCTL pin, and the other end is connected to the RF3 pin, and one end of the first resistor is connected to the VCTL pin, and the other end is grounded;

[0042] The RF2 pin is also connected to the VDD pin through a first diode, and the RF3 pin is also connected to the VDD pin through a second diode;

[0043] The radio frequency unit, digital processing unit and kneading unit are in a primary-backup configuration;

[0044] The main digital processing unit is respectively connected to two microwave switches connected to the occultation antenna, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the occultation antenna;

[0045] The main radio frequency unit is respectively connected to the two microwave switches connected to the main and backup switching circuits, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the main and backup switching circuits.

[0046] Specifically, in the present embodiment, the main-backup switching circuit includes a feeding network and a voltage divider circuit to realize automatic switching of the occultation signal; specifically, the feeding network is connected between the RF2 pin, the RF3 pin and the VDD pin, and mainly includes a diode D1 and a diode D2, wherein the anode end of the diode D1 is connected to the RF2 pin, the anode end of the diode D2 is connected to the RF3 pin, and the cathode ends of the two diodes are both connected to the VDD pin; the voltage divider circuit includes a resistor R1 and a resistor R2, one end of the resistor R1 is connected to the VCTL pin, and the other end is grounded, and one end of the resistor R2 is connected to the VCTL pin, and the other end is connected to the RF3 pin.

[0047] like Figure 1 and Figure 2 The RF1 pin is configured to receive the occultation antenna signal, the RF2 pin is connected to the main RF unit, the RF3 pin is connected to the backup RF unit, the cathodes of the two diodes are connected and power is supplied to the microwave switch, the resistor R1 is a pull-down resistor and is connected to the control end (VCTL) of the microwave switch, and R2 is a pull-up resistor.

[0048] When the main RF unit is powered on, the backup RF unit is not powered on, 5V is fed on the RF2 pin, and 0V is on the RF3 pin. At this time, the microwave switch control end (VCTL) is at a low level, and the microwave switch is switched to RF1-RF2 by default.

[0049] When the backup RF unit is powered on, the main RF unit is not powered on, the RF2 pin is 0V, and the RF3 pin is fed with 5V. At this time, the feed voltage is 3.3V high level after being divided by resistors R2 and R1, and the microwave switch state is switched to RF1-RF3.

[0050] Based on the above description, the functions of signal branching and autonomous signal switching are realized by using the front branching unit and the receiving module. The insertion loss of the microwave switch is small, which is about 3dB smaller than the power divider used in the conventional way. Therefore, this method can improve the sensitivity of the occultation signal.

[0051] The primary-backup switching circuit described in this embodiment can achieve low noise coefficient, high sensitivity, and can independently determine the faulty unit and perform primary-backup radio frequency signal switching.

[0052] In some embodiments, the main kneading unit and the backup kneading unit are connected, and the main kneading unit and the backup kneading unit are both configured with multiple interface modules and connectors, wherein one end of the interface module is connected to the digital processing unit, and the other end is connected to each connector through a third resistor, and the connector is connected to the entire star service unit;

[0053] The interface module includes at least the Star Service 422 communication interface, the CAN communication interface and the LVDS data transmission interface.

[0054] Specifically, in this embodiment, Figure 3 As shown, the interface module mainly includes the satellite service 422 communication interface (RS422 interface, this embodiment adopts 422 series model chip), CAN communication interface (this embodiment adopts CAN chip), LVDS data transmission interface (this embodiment adopts LVDS chip), the output end of the satellite service 422 communication interface is connected in series with a resistor of a certain resistance and then connected to connector 1 and connector 2 respectively, and connector 1 and connector 2 are as close as possible in spatial layout; the signal connection of CAN chip and LVDS chip is consistent with that of 422 chip, and both are connected to connector 1 and connector 2 respectively through resistors, and the design of the backup occultation receiver is completely consistent with that of the main occultation receiver.

[0055] The connector 1 of the main kneading unit is connected to the connector 3 configured on the whole star service unit, and the connectors 2 of the main and backup kneading units are connected together, and the backup connector 1 is suspended. In this case, the whole star service unit can communicate and transmit data with the main kneading unit and the backup kneading unit respectively. When the backup kneading unit is not powered on, its internal chip output terminals are all in high impedance state, which will not affect the main kneading unit.

[0056] Each interface chip output terminal in the main backup kneading unit is connected in series with a resistor, which provides source impedance matching and improves signal integrity on the one hand, and plays a role in fault isolation on the other hand. Figure 4 As shown, when a fault occurs inside the backup kneading unit, such as the output terminal of the 422 chip is short-circuited to the ground, the output signal of the 422 chip inside the main receiver will not be directly short-circuited to the ground due to the existence of resistors R3 and R4, and the voltage on the signal line will drop to half of the original value. The RS422 bus requires that the differential voltage amplitude at the receiving end must be greater than 200mV, so even if the voltage drops to half of the original value, it will not affect the normal signal communication.

[0057] The interface design of this part adopts an external kneading method, which can realize the satellite service's telemetry, control and communication of the main and backup occultation receiver systems under a single interface. At the same time, the kneading part simplifies the system hardware design and does not require a separate kneading board.

[0058] In some embodiments, the whole star service unit is provided with a primary and a backup, and the primary and the backup whole star service units are correspondingly connected to the connectors of the primary and the backup kneading units.

[0059] Specifically, in this embodiment, another usage scenario is that the star service unit is designed as a cold standby, and the backup whole star service unit connector 4 is connected to the backup kneading unit connector 2. In this case, the main whole star service unit or the backup whole star service unit can communicate with the main backup kneading unit.

[0060] The system implements dual-machine cold standby. The common parts of the system are all passive devices, which ensures the reliability of the system. The external interface part realizes the reliability design of active-standby integration.

[0061] 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.

[0062] 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. A satellite-borne GNSS occultation receiver system, comprising a cascaded front-end branch unit, a receiving module and a whole-star service unit, wherein the input end of the front-end branch unit is connected to the occultation antenna, the receiving module comprises a radio frequency unit, a digital processing unit and a kneading unit connected to each other, and the kneading unit is connected to the whole-star service unit, characterized in that: The pre-branch unit includes a plurality of microwave switches and cavity filters, wherein every two microwave switches are connected to a cavity filter to form a switch branch, the switch branch is divided into a main switch branch and a backup switch branch, one of the microwave switches of the main switch branch and the backup switch branch is connected to two occultation antennas, and the microwave switch is connected to the digital processing unit, and the digital processing unit is used to control the switching of occultation antenna signals; The other microwave switch of the main switch branch and the backup switch branch is connected with a main backup switching circuit, the main backup switching circuit is connected to the radio frequency unit, and the main backup switching circuit is used to autonomously switch the occultation antenna signal; The RF1 pin of the microwave switch is configured to receive the occultation antenna signal, and the RF2 pin and the RF3 pin of the microwave switch are configured to connect to the radio frequency unit; The VCTL pin of the microwave switch is connected to the RF3 pin through a voltage divider circuit; The RF2 pin is further connected to the VDD pin via a first diode, and the RF3 pin is further connected to the VDD pin via a second diode; The voltage divider circuit includes a first resistor and a second resistor, one end of the second resistor is connected to the VCTL pin, and the other end is connected to the RF3 pin; One end of the first resistor is connected to the VCTL pin, and the other end is grounded; The main kneading unit and the backup kneading unit are connected, and both the main kneading unit and the backup kneading unit are configured with multiple interface modules and connectors, wherein one end of the interface module is connected to the digital processing unit, and the other end is connected to each connector through a third resistor, and the connector is connected to the entire star service unit.

2. A spaceborne GNSS occultation receiver system according to claim 1, characterized in that: The radio frequency unit, the digital processing unit and the kneading unit are arranged in a primary and backup configuration; The main digital processing unit is respectively connected to the two microwave switches connected to the occultation antenna, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the occultation antenna; The main radio frequency unit is respectively connected to the two microwave switches connected to the main and backup switching circuits, and the backup digital processing unit is also respectively connected to the two microwave switches connected to the main and backup switching circuits.

3. The satellite-borne GNSS occultation receiver system according to claim 1, characterized in that: The whole star service unit is provided with a main and backup, and the main and backup whole star service units are correspondingly connected with the connectors of the main and backup kneading units.

4. A spaceborne GNSS occultation receiver system according to claim 3, characterized in that: The interface module at least includes a satellite service 422 communication interface, a CAN communication interface and a LVDS data transmission interface.

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