Satellite-borne X-band miniaturized digital transmitter

Abstract

The present application relates to a satellite-borne X-band miniaturized digital transmission transmitter, comprising: an FPGA module, a high-speed DAC module, an X-band bandpass filter and an X-band amplifier; an X-band modulation signal is generated by using the image frequency output by the high-speed DAC. When generating the X-band modulation signal, a microwave modulation up-conversion module and a local oscillator signal required for the modulation up-conversion are no longer required. The X-band modulation signal is directly generated by using the image frequency in the DAC output signal, which greatly improves the system integration and reduces the hardware cost. Compared with traditional solutions, it has obvious advantages in terms of single-machine weight and overall machine integration.

Description

Technical Field

[0001] The present application relates to the field of microwave high-speed and large-capacity communication technology, and in particular to a satellite-borne X-band miniaturized data transmission transmitter. Background Art

[0002] At present, the X-band is the main frequency band used by low-orbit remote sensing satellites, especially commercial remote sensing satellites, for data transmission to the earth. As the resolution of remote sensing satellites becomes higher and higher, the data rate required for transmission is also getting higher and higher, which will lead to more and more complex hardware design related to on-board data transmission. At the same time, in order to reduce the cost of satellite launch and hardware implementation, the demand for integrated design of the entire satellite and single machine (module) is becoming more and more urgent. In the design process of on-board data transmitters, it is necessary to solve the contradiction between the higher and higher rates and the higher and higher integration requirements.

[0003] The traditional satellite-borne X-band data transmitter consists of FPGA (Field Programmable Gate Array), high-speed DAC (digital-to-analog converter), baseband clock, RF local oscillator, and microwave modulation (up-conversion) module. FPGA receives data and processes baseband data. The baseband clock module generates the sampling clock required for the high-speed DAC. The high-speed DAC converts the digital signal output by the FPGA into a baseband analog signal. The RF local oscillator generates the local oscillator signal required for modulation up-conversion. The microwave modulation up-conversion module modulates (up-converts) the baseband signal to the X-band. According to the traditional design concept, if the integration of the hardware circuit needs to be improved, it mainly depends on the improvement of the integration of the components used in each module and its peripheral circuits. The integrated design is difficult. Summary of the invention

[0004] In order to overcome at least one deficiency in the prior art, an embodiment of the present application provides a satellite-borne X-band miniaturized data transmission transmitter.

[0005] In a first aspect, a satellite-borne X-band miniaturized digital transmitter is provided, comprising: an FPGA module, a high-speed DAC module, an X-band bandpass filter, and an X-band amplifier;

[0006] The FPGA module is used to modulate and digitally up-convert the baseband signal to obtain the processed digital signal;

[0007] The high-speed DAC module is used to up-convert the processed digital signal to an intermediate frequency and output an intermediate frequency signal and multiple image frequency components;

[0008] The X-frequency bandpass filter is used to perform frequency selective filtering on the intermediate frequency signal and multiple image frequency components to obtain a signal after frequency selective filtering;

[0009] The X-band amplifier is used to perform power amplification processing on the signal after the frequency selection filtering processing, and output an X-band modulated signal.

[0010] In one embodiment, the frequency of the signal after the frequency-selective filtering process is Fs+Fc, where Fc is the intermediate frequency carrier frequency and Fs is the sampling rate.

[0011] In one embodiment, the sampling rate of the high-speed DAC module is 6Gsps, and the intermediate frequency carrier frequency is 1.5 GHz to 2.5 GHz.

[0012] In one embodiment, the baseband signal is modulated, including: AOS framing, signal coding, constellation mapping and shaping filtering.

[0013] In one embodiment, it also includes: a DAC sampling clock, where the DAC sampling clock is used to generate a sampling clock required for the high-speed DAC module to work.

[0014] In a second aspect, a method for generating an X-band modulation signal is provided, comprising:

[0015] Modulate and digitally up-convert the baseband signal to obtain a processed digital signal;

[0016] Up-converting the processed digital signal to an intermediate frequency, and outputting an intermediate frequency signal and a plurality of image frequency components;

[0017] Performing frequency selective filtering on the intermediate frequency signal and multiple image frequency components to obtain a signal after frequency selective filtering;

[0018] The signal after frequency selection filtering is power amplified to output an X-band modulated signal.

[0019] In one embodiment, the frequency of the signal after the frequency-selective filtering process is Fs+Fc, where Fc is the intermediate frequency carrier frequency and Fs is the sampling rate.

[0020] In one embodiment, the sampling rate of the high-speed DAC module is 6Gsps, and the intermediate frequency carrier frequency is 1.5 GHz to 2.5 GHz.

[0021] In one embodiment, the baseband signal is modulated, including: AOS framing, signal coding, constellation mapping and shaping filtering.

[0022] In one embodiment, the method further includes generating a sampling clock required for the high-speed DAC module to operate.

[0023] Compared with the prior art, the present application has the following beneficial effects: the present application proposes a novel satellite-borne X-band miniaturized digital transmission transmitter, which generates an X-band modulation signal by utilizing the image frequency output by a high-speed DAC. When generating the X-band modulation signal, a microwave modulation up-conversion module and a local oscillator signal required for the modulation up-conversion are no longer required. The X-band modulation signal is directly generated by utilizing the image frequency in the high-speed DAC output signal, which greatly improves the system integration and reduces the hardware cost. Compared with the traditional solutions, the application has obvious advantages in terms of single-machine weight and overall machine integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present application may be better understood by referring to the following description given in conjunction with the accompanying drawings, which together with the following detailed description are included in this specification and form a part of this specification. In the drawings:

[0025] Figure 1 A schematic diagram of the original signal time domain waveform is shown;

[0026] Figure 2 shows a schematic diagram of the output signal of the DAC module;

[0027] Figure 3 shows a schematic diagram of the reconstructed signal in the frequency domain;

[0028] Figure 4 The hardware block diagram of the satellite-borne X-band miniaturized data transmission transmitter provided according to an embodiment of the present application is shown;

[0029] Figure 5 A schematic diagram of generating an X frequency modulation signal is shown;

[0030] Figure 6 A flow chart showing the modulation and digital up-conversion of a baseband signal by an FPGA module according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0031] The exemplary embodiments of the present application will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that many implementation-specific decisions can be made in the process of developing any such actual embodiments in order to achieve the specific goals of the developer, and these decisions may vary from embodiment to embodiment.

[0032] It is also necessary to explain here that, in order to avoid obscuring the present application due to unnecessary details, only the device structure closely related to the scheme according to the present application is shown in the drawings, while other details that are not closely related to the present application are omitted.

[0033] It should be understood that the present application is not limited to the described implementation forms due to the following description with reference to the accompanying drawings. In this article, where feasible, the embodiments can be combined with each other, features between different embodiments can be replaced or borrowed, and one or more features can be omitted in one embodiment.

[0034] According to the baseband sampling theorem, when the sampling rate Fs is greater than twice the signal bandwidth, any bandwidth-limited signal can be reconstructed. Figure 1 The original signal time domain waveform is shown in Figure 2. S The time domain signal is sampled for the sampling period (T S =1 / F S ), Fs is the sampling rate, the most common sampling method is sample and hold, Figure 2 The output signal schematic diagram of the DAC module is shown, which can be understood as the convolution of the sampling pulse sequence and the unit amplitude rectangular pulse with a pulse width of Ts.

[0035] Figure 3 The schematic diagram of the reconstructed signal in the frequency domain is shown. When the high-speed DAC module outputs a signal with a frequency of Fc, image frequency components such as Fs-Fc, Fs+Fc, 2Fs-Fc, 2Fs+Fc, etc. are generated in the frequency domain at the same time.

[0036] In most applications, DAC is used to generate the original baseband signal, and the remaining image frequency components are useless signals and need to be filtered out by filters. In fact, according to the frequency of the required signal, the image frequency can also be output as the final useful signal. This application uses this principle to perform "up-conversion" inside the high-speed DAC module to generate a broadband modulated signal in the X-band.

[0037] The present application provides a satellite-borne X-band miniaturized digital transmission transmitter, which uses the mirror frequency output by a high-speed DAC module to generate an X-band modulated signal. The satellite-borne X-band miniaturized digital transmission transmitter is designed based on this principle, which can simplify the hardware architecture and improve the integration of the entire device.

[0038] Figure 4 The hardware block diagram of the satellite-borne X-band miniaturized data transmission transmitter provided according to an embodiment of the present application is shown. The satellite-borne X-band miniaturized data transmission transmitter includes: an FPGA module, a high-speed DAC module, an X-band bandpass filter and an X-band amplifier;

[0039] The FPGA module is used to modulate and digitally up-convert the baseband signal to obtain the processed digital signal;

[0040] The high-speed DAC module is used to up-convert the processed digital signal to an intermediate frequency and output an intermediate frequency signal and multiple image frequency components;

[0041] The X-frequency bandpass filter is used to perform frequency selective filtering on the intermediate frequency signal and multiple image frequency components to obtain a signal after frequency selective filtering;

[0042] The X-band amplifier is used to perform power amplification processing on the signal after the frequency selection filtering processing, and output an X-band modulated signal.

[0043] In this embodiment, the image frequency output by the high-speed DAC module is used to generate an X-band modulation signal. When generating the X-band modulation signal, the microwave modulation up-conversion module and the local oscillator signal required for the modulation up-conversion are no longer required. The image frequency in the output signal of the high-speed DAC module is used to directly generate the X-band modulation signal, which greatly improves the system integration and reduces the hardware cost. Compared with the traditional solution, it has obvious advantages in terms of single-machine weight and overall machine integration. In addition, due to the use of the high-speed DAC module, the X-band miniaturized data transmitter of this embodiment can achieve the transmission of data at a rate of hundreds of Mbps.

[0044] In one embodiment, the frequency of the signal after the frequency-selective filtering process is Fs+Fc, where Fc is the intermediate frequency carrier frequency and Fs is the sampling rate. Figure 5 The schematic diagram of generating X-frequency modulation signal is shown. Further, the sampling rate of the high-speed DAC module is 6Gsps, and the intermediate frequency carrier frequency is 1.5GHz to 2.5GHz, which can be determined according to the final required X-band carrier frequency. The DAC will also generate a corresponding modulation signal at the frequency Fs+Fc (about 8GHz).

[0045] In one embodiment, Figure 6 FIG. 1 shows a flow chart of the FPGA module according to an embodiment of the present application modulating the baseband signal and digitally up-converting the baseband signal. Figure 6 , the FPGA module performs AOS (Advanced Orbiting Systems) framing, signal coding, constellation mapping, shaping filtering and digital up-conversion on the baseband signal, and then outputs the processed digital signal to the high-speed DAC module. Here, AOS framing is performed according to the frame format requirements specified by the CCSDS (Consultative Committee for Space Data Systems) standard, and channel coding can use LDPC (Low-density Parity-check) or RS+convolutional concatenated code. The baseband data is constellated according to the specified modulation method, and the mapped data is shaped and digitally up-converted. The shaping filter is implemented by the table lookup method. The core of the table lookup method is the data in the table, which are the convolution values ​​of the required filter impulse response and the input code element.

[0046] In one embodiment, the satellite-borne X-band miniaturized digital transmission transmitter further includes: a DAC sampling clock, which is used to generate a sampling clock required for the operation of the high-speed DAC module.

[0047] In a second aspect, an embodiment of the present application further provides a method for generating an X-band modulated signal. The method is based on the satellite-borne X-band miniaturized data transmission transmitter provided in the aforementioned embodiment, and the method includes:

[0048] Step S1, modulating and digitally up-converting the baseband signal to obtain a processed digital signal;

[0049] Step S2, up-converting the processed digital signal to an intermediate frequency, and outputting an intermediate frequency signal and a plurality of image frequency components;

[0050] Step S3, performing frequency selective filtering on the intermediate frequency signal and the multiple image frequency components to obtain a signal after the frequency selective filtering processing;

[0051] Step S4, performing power amplification processing on the signal after the frequency selection filtering processing, and outputting an X-band modulated signal.

[0052] In summary, the satellite-borne X-band miniaturized digital transmitter of the present application adopts a new X-band modulation signal generation method, which greatly simplifies the hardware architecture and reduces the implementation cost. It can be subsequently applied to the design of satellite-borne X-band transmitters to improve the integration of the whole machine and reduce the size and weight of a single machine.

[0053] The above are only various implementations of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A satellite-borne X-band miniaturized data transmitter, characterized in that: include: FPGA module, high-speed DAC module, X-band bandpass filter and X-band amplifier; The FPGA module is used to modulate and digitally up-convert the baseband signal to obtain a processed digital signal; The high-speed DAC module is used to up-convert the processed digital signal to an intermediate frequency, and output an intermediate frequency signal and a plurality of image frequency components; The X-band bandpass filter is used to perform frequency selective filtering on the intermediate frequency signal and the multiple image frequency components to obtain a signal after the frequency selective filtering process; The X-band amplifier is used to perform power amplification processing on the signal after the frequency selection filtering processing, and output an X-band modulated signal; The frequency of the signal after the frequency selection filtering is Fs+Fc, where Fc is the intermediate frequency carrier frequency and Fs is the sampling rate; The sampling rate of the high-speed DAC module is 6Gsps, and the intermediate frequency carrier frequency is 1.5GHz to 2.5GHz.

2. The satellite-borne X-band miniaturized data transmitter according to claim 1, characterized in that: The baseband signal is modulated, including: AOS framing, signal coding, constellation mapping and shaping filtering.

3. The satellite-borne X-band miniaturized data transmitter according to claim 1, characterized in that: Also includes: A DAC sampling clock is used to generate a sampling clock required for the high-speed DAC module to operate.

4. A method for generating an X-band modulation signal, characterized in that: include: Modulate and digitally up-convert the baseband signal to obtain a processed digital signal; Up-converting the processed digital signal to an intermediate frequency, and outputting an intermediate frequency signal and a plurality of image frequency components; Performing frequency selective filtering on the intermediate frequency signal and the multiple image frequency components to obtain a signal after the frequency selective filtering processing; Performing power amplification processing on the signal after the frequency selection filtering processing, and outputting an X-band modulated signal; The frequency of the signal after the frequency selection filtering is Fs+Fc, where Fc is the intermediate frequency carrier frequency and Fs is the sampling rate; The sampling rate is 6Gsps, and the intermediate frequency carrier frequency is 1.5GHz to 2.5GHz.

5. The method according to claim 4, characterized in that The baseband signal is modulated, including: AOS framing, signal coding, constellation mapping and shaping filtering.

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