Satellite Ka-band variable coding modulation data transmission system and method

Abstract

The present invention proposes a satellite Ka-band variable coding modulation data transmission system and method, which can be applied to the Ka-band satellite-to-ground data transmission system of non-geostationary circular orbit remote sensing satellites such as low orbit or medium orbit. It includes: a navigation receiver, a data transmission integrated controller, a data processor, a Ka variable coding modulator, a filter, a line amplifier input switch matrix, a traveling wave tube amplifier, a line amplifier output switch matrix, and a ground data transmission antenna; the navigation receiver calculates the position / speed / time (PVT) information of the satellite and transmits it to the data transmission integrated controller; the data transmission integrated controller completes the modulation parameter selection of the modulation coding mode (MODCOD) and the line amplifier input power back-off (IBO) according to the information and the stored parameters, and sends the MODCOD / IBO setting instruction to the Ka variable coding modulator when the modulation parameters change; after the data processor completes the payload data processing, it sends the baseband data to the Ka variable coding modulator.

Description

Technical Field

[0001] The present invention relates to a satellite Ka-band variable coding modulation data transmission system and method, which is applicable to high-resolution remote sensing satellites using non-geostationary circular orbits such as low orbits or medium orbits. Background Art

[0002] With the continuous development of my country's remote sensing technology, the spatial resolution, spectral resolution and other indicators are rapidly improving, and the remote sensing satellite payload will generate more and more observation data. Within the limited data transmission arc to the ground, these data need to be transmitted back in a timely manner, which puts higher and higher requirements on the effective information rate of the downlink data transmission link.

[0003] In the prior art, "System demonstrations of Ka-band 5-Gbit / s datatransmission for satellite applications" (Int J Satell Commun Network, November 2021) proposed a Ka-band ground data transmission system suitable for high-resolution remote sensing satellites. It adopts a fixed coding modulation (CCM) method of 7 / 8LDPC channel coding and 8PSK modulation that complies with the CCSDS131.OB-2 standard, with a symbol rate of 500Mbaud, a single-channel channel transmission rate of 1.5Gbps, and an effective information rate of up to 1.25Gbps. Through dual circular polarization frequency reuse, a maximum four-channel 5Gbps effective information rate transmission is achieved within a 1.5GHz bandwidth (frequency range 25.5~27GHz).

[0004] However, the system does not take advantage of the favorable conditions for increasing link margin brought about by factors such as the reduction of free space loss as the elevation angle increases, resulting in a certain waste of resources. Summary of the invention

[0005] To solve the above problems, the present invention proposes a satellite Ka-band variable coding modulation data transmission system and method, which can be applied to the Ka-band satellite-to-ground data transmission system of non-geostationary circular orbit remote sensing satellites such as low orbit or medium orbit.

[0006] The present invention is achieved through the following technical solutions.

[0007] Satellite Ka-band variable coding modulation data transmission system, including: navigation receiver, data transmission integrated controller, data processor, Ka variable coding modulator, filter, line amplifier input switch matrix, traveling wave tube amplifier, line amplifier output switch matrix, and ground data transmission antenna;

[0008] The navigation receiver calculates the position / velocity / time (PVT) information of the satellite and transmits it to the data transmission integrated controller;

[0009] The data transmission integrated controller completes the modulation parameter selection of the modulation coding mode (MODCOD) and the input power back-off (IBO) of the line amplifier according to the information and the stored parameters, and sends the MODCOD / IBO setting instruction to the Ka variable coding modulator when the modulation parameters change;

[0010] After the data processor completes the payload data processing, the baseband data is sent to the Ka variable coding modulator;

[0011] The Ka variable coding modulator completes the channel coding, shaping filtering, constellation mapping, and radio frequency modulation of the baseband data signal according to the MODCOD / IBO setting instruction, and forms a radio frequency signal to send to the filter;

[0012] The filter performs band-limited filtering on the radio frequency signal;

[0013] The line amplifier input switch completes the cross switching of the Ka variable coding modulator and the traveling wave tube amplifier;

[0014] The traveling wave tube amplifier performs power amplification on the radio frequency signal;

[0015] The row amplifier output switch matrix synthesizes the high-power signal and selects the ground-to-ground data transmission antenna used by the digital transmission signal, and radiates the high-power signal after the polarization mode is set by the ground-to-ground data transmission antenna.

[0016] Satellite Ka-band variable coding modulation data transmission method, comprising the following steps:

[0017] Step 1: The navigation receiver 1 receives, captures and tracks the GNSS navigation signal, obtains the original observation data and completes the positioning solution, obtains the satellite PVT data with a period of Δt1, and outputs it to the data transmission integrated controller 2 with the same period;

[0018] Step 2, the data transmission integrated controller 2 receives the PVT data information and performs orbit extrapolation calculation, and combines it with the ground station position information, calculates the ground station's receiving elevation angle to the satellite with a period Δt2, and compares it with the switching elevation angle threshold combination to select the corresponding MODCOD; if the MODCOD changes, a MODCOD / IBO setting instruction is generated and sent to the Ka variable coding modulator 7;

[0019] Step 3, the Ka variable coding modulator 7 performs corresponding BCH-LDPC cascade channel coding and constellation mapping on the input data sent by the front-end data processor 6 to form a VCM physical layer frame that meets the DVB-S2 protocol, and then after baseband shaping filtering and RF modulation processing, it sets parameters according to the received MODCOD / IBO setting instruction and outputs a RF modulated signal;

[0020] Step 4, the filter 8 filters the RF modulated signal, and enters the traveling wave tube amplifier 10 after passing through the row amplifier input switch matrix 9, and the traveling wave tube amplifier 10 completes the power amplification matched with the IBO, and then the row amplifier output switch matrix 11 completes the power synthesis and signal flow selection, and then the ground data transmission antenna 12 radiates and transmits it to the ground station.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention upgrades the Ka-band ground-to-earth data transmission system from a fixed coding modulation (CCM) system to a variable coding modulation (VCM) system, making full use of the system link margin and improving the satellite-to-ground data transmission efficiency;

[0023] 2. Based on the free space loss, the present invention further considers the statistical characteristics that the atmospheric attenuation in the lower elevation angle region decreases rapidly with the increase of the elevation angle. In this region, as the elevation angle increases, the modulation and coding mode with higher spectrum efficiency can be selected to fully utilize the margin of the satellite-to-ground data transmission link;

[0024] 3. Simulation analysis proves that the present invention can further enhance the transmission capacity of the satellite-to-ground data transmission system of my country's remote sensing satellite. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The satellite Ka-band variable coding modulation data transmission system of the present invention is a block diagram;

[0026] Figure 2 This is a flow chart of the satellite Ka-band variable coding modulation data transmission method of the present invention. DETAILED DESCRIPTION

[0027] The exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are only exemplary and are intended to illustrate the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0028] like Figure 1As shown, a satellite Ka-band variable coding modulation data transmission system of the present invention comprises: a navigation receiver 1, a data transmission integrated controller 2, a data processor 6, a Ka variable coding modulator 7, a filter 8, a line amplifier input switch matrix 9, a traveling wave tube amplifier 10, a line amplifier output switch matrix 11, and a ground-to-ground data transmission antenna 12.

[0029] The navigation receiver 1 calculates the position / velocity / time (PVT) information of the satellite and transmits it to the data transmission integrated controller 2;

[0030] The data transmission integrated controller 2 completes the modulation parameter selection of the modulation coding mode (MODCOD) and the input power back-off (IBO) of the line amplifier according to the information and the pre-stored parameters, and sends the MODCOD / IBO setting instruction to the Ka variable coding modulator 7 when the modulation parameters change;

[0031] After completing the payload data processing, the data processor 6 sends the baseband data to the Ka variable coding modulator 7;

[0032] The Ka variable coding modulator 7 completes the channel coding, shaping filtering, constellation mapping, and radio frequency modulation of the baseband data signal according to the MODCOD / IBO setting instruction, and forms a radio frequency signal to be sent to the filter 8;

[0033] The filter 8 performs band-limiting filtering on the radio frequency signal;

[0034] The line amplifier input switch 9 completes the cross switching of the Ka variable coding modulator and the traveling wave tube amplifier; this method can improve the reliability of system use.

[0035] The traveling wave tube amplifier 10 performs power amplification on the radio frequency signal;

[0036] The row amplifier output switch matrix 11 synthesizes the high-power signal and selects the ground-to-ground data transmission antenna used for the digital transmission signal, and radiates the high-power signal after the polarization mode is set through the ground-to-ground data transmission antenna 12.

[0037] In this embodiment, the data transmission integrated controller 2 includes an elevation angle calculation module 3, a modulator parameter selection module 4 and a parameter storage module 5; the elevation angle calculation module 3 performs orbit extrapolation calculation based on the information solved by the navigation receiver 1, and combines it with the ground station position information (longitude / latitude / elevation) stored in the parameter storage module 5, calculates the receiving elevation angle of the ground station (specified number) to the satellite with a period Δt2, and outputs it to the modulator parameter selection module 4 with the same period, and the modulator parameter selection module 4 completes the modulation parameter selection of the modulation coding mode (MODCOD) and the input power back-off (IBO) of the line amplifier.

[0038] During specific implementation, different numbers of product configuration schemes can be selected according to the data transmission channel configuration requirements of different satellites; for example, for a four-channel configuration, 2 data processors, 4 Ka variable coding modulators, 4 filters, 1 row amplifier input switch matrix, 4 traveling wave tube amplifiers, 1 row amplifier output switch matrix, and 2 ground-to-ground data transmission antennas can be configured.

[0039] like Figure 2 As shown, a satellite Ka-band variable coding modulation data transmission method of the present invention specifically includes the following steps:

[0040] Step 1: The navigation receiver 1 receives, captures and tracks the GNSS (Global Navigation Satellite System) navigation signal (China's Beidou Navigation Satellite System or the United States' GPS Navigation Satellite System), obtains the original observation data and completes the positioning solution, obtains the satellite PVT data with a period of Δt1, and outputs it to the data transmission integrated controller 2 with the same period;

[0041] Step 2, the data transmission integrated controller 2 receives the PVT data information and performs orbit extrapolation calculation, and combines it with the ground station location information (longitude / latitude / elevation), calculates the receiving elevation angle of the ground station (specified number) to the satellite with a period Δt2, and compares it with the switching elevation angle threshold combination to select the corresponding MODCOD; if the MODCOD changes, a MODCOD / IBO setting instruction is generated and sent to the Ka variable coding modulator 7; in specific implementation, the period Δt1 and the period Δt2 can be set to a default value of 1s.

[0042] Step 3, the Ka variable coding modulator 7 performs corresponding BCH-LDPC cascade channel coding and constellation mapping on the input data sent by the front-end data processor 6 according to the received MODCOD / IBO setting instruction, forms a VCM physical layer frame that meets the DVB-S2 protocol, and then outputs a radio frequency modulated signal after baseband shaping filtering and radio frequency modulation processing;

[0043] Step 4, the filter 8 filters the RF modulated signal, and enters the traveling wave tube amplifier 10 after passing through the row amplifier input switch matrix 9, and the traveling wave tube amplifier 10 completes the power amplification matched with the IBO, and then the row amplifier output switch matrix 11 completes the power synthesis and signal flow selection, and then the ground data transmission antenna 12 radiates and transmits it to the ground station.

[0044] In specific implementation, when the Ka variable coding modulator 7 does not receive the MODCOD / IBO setting instruction, it uses the previous MODCOD and IBO setting instructions to set parameters for execution.

[0045] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A satellite Ka-band variable coding modulation data transmission system, characterized in that: include: Navigation receiver, data transmission integrated controller, data processor, Ka variable coding modulator, filter, traveling wave tube amplifier input switch matrix, traveling wave tube amplifier, traveling wave tube amplifier output switch matrix, ground-to-ground data transmission antenna; The navigation receiver calculates the position, speed and time information of the satellite and transmits the information to the data transmission integrated controller; The data transmission integrated controller completes the modulation parameter selection of the modulation coding mode MODCOD and the traveling wave tube amplifier input power back-off IBO according to the information and the stored parameters, and sends the MODCOD and IBO setting instructions to the Ka variable coding modulator when the modulation parameters change; After the data processor completes the payload data processing, the baseband data is sent to the Ka variable coding modulator; The Ka variable coding modulator completes the channel coding, shaping filtering, constellation mapping, and radio frequency modulation of the baseband data signal according to the MODCOD and IBO setting instructions, and forms a radio frequency signal to send to the filter; The filter performs band-limited filtering on the radio frequency signal; The traveling wave tube amplifier input switch matrix completes the cross switching of the Ka variable coding modulator and the traveling wave tube amplifier; The traveling wave tube amplifier output switch matrix synthesizes the high-power signal and selects the ground-to-ground data transmission antenna used for the data transmission signal, and radiates the high-power signal after the polarization mode of the high-power signal is set by the ground-to-ground data transmission antenna.

2. The satellite Ka-band variable coding modulation data transmission system according to claim 1, characterized in that: The data transmission integrated controller comprises an elevation angle calculation module, a modulator parameter selection module and a parameter storage module; the elevation angle calculation module performs orbit extrapolation calculation according to the information solved by the navigation receiver, and combines it with the ground station position information stored in the parameter storage module, calculates the receiving elevation angle of the ground station to the satellite with a period Δt2, and outputs it to the modulator parameter selection module with the same period, and the modulator parameter selection module completes the modulation parameter selection of the modulation coding mode MODCOD and the traveling wave tube amplifier input power reduction amount IBO.

3. A satellite Ka-band variable coding modulation data transmission method, characterized in that: The following steps are involved: Step 1: The navigation receiver completes the reception, capture and tracking of the GNSS navigation signal, obtains the original observation data and completes the positioning solution, obtains the satellite PVT data with a period of Δt1, and outputs it to the data transmission integrated controller with the same period; Step 2, the data transmission integrated controller receives the PVT data information and performs orbit extrapolation calculation, and combines it with the ground station position information, calculates the ground station's receiving elevation angle to the satellite with a period Δt2, and compares it with the switching elevation angle threshold combination to select the corresponding modulation coding mode MODCOD; if MODCOD changes, a setting instruction for MODCOD and a traveling wave tube amplifier input power reduction amount IBO is generated and sent to the Ka variable coding modulator; Step 3, the Ka variable coding modulator performs corresponding BCH-LDPC cascade channel coding and constellation mapping on the input data sent by the front-end data processor according to the received MODCOD and IBO setting instructions, to form a VCM physical layer frame that meets the DVB-S2 protocol, and then outputs a radio frequency modulated signal after baseband shaping filtering and radio frequency modulation processing; Step 4: The filter filters the RF modulated signal, and then enters the traveling wave tube amplifier after being input into the switch matrix by the traveling wave tube amplifier, and the traveling wave tube amplifier completes the power amplification matched with the IBO. After that, the traveling wave tube amplifier output switch matrix completes the power synthesis and signal flow selection, and then is radiated and transmitted to the ground station by the ground data transmission antenna.

4. The satellite Ka-band variable coding modulation data transmission method as claimed in claim 3, characterized in that: The default values ​​of the period Δt1 and the period Δt2 are set to 1s.

5. The satellite Ka-band variable coding modulation data transmission method according to claim 3 or 4, characterized in that: When the Ka variable coding modulator does not receive the MODCOD and IBO setting instructions, it uses the previous MODCOD and IBO setting instructions to set parameters for execution.

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