A scattering communication device based on a single-frequency conversion method

Abstract

This invention discloses a scattering communication device based on a single-conversion frequency conversion method, belonging to the field of scattering communication technology. It mainly includes a modulation and demodulation unit, a frequency conversion component, a power amplifier, and an RF front-end. It adopts a frequency division duplex mode, with both the transmit and receive channels using a single-conversion frequency conversion method to achieve adaptive transmission of voice, video, images, and other IP data. This invention can be used in scattering communication devices in the C, X, and Ku bands, adapting to different transmission environments and requirements. Compared with traditional scattering communication devices using a double-conversion frequency conversion method, it can improve system integration and flexibility, simplify circuit design, and reduce system costs.

Description

Technical Field

[0001] This invention relates to the field of scattering communication technology, specifically to a scattering communication device based on a single-frequency conversion method, which has the advantages of high flexibility and low cost. Background Technology

[0002] Scatter communication is a type of beyond-line-of-sight wireless communication that utilizes the forward bending effect of inhomogeneities in the atmospheric medium on radio waves. Scatter communication technology boasts excellent characteristics such as large communication capacity, strong resistance to interference from airborne particles, and long transmission distances.

[0003] Traditional scatter communication often employs a two-stage frequency conversion method. This involves modulating and demodulating the output intermediate frequency (IF) signal, then up-converting it to an intermediate frequency (IF) signal within a frequency converter, and finally up-converting the IF signal to a radio frequency (RF) signal. The receiving process follows the same logic. This method requires two stages of frequency conversion circuitry, resulting in high cost and weight. Current demands for cost and weight reduction in scatter communication equipment necessitate more efficient frequency conversion methods to adapt to the rapid development of scatter communication. Summary of the Invention

[0004] To address the requirements of low cost and lightweight scattering communication, this invention proposes a scattering communication device based on a single-frequency conversion method. By outputting an L-band signal in the digital domain and then converting the signal to the radio frequency operating band required by the system through a single frequency conversion, reliable long-distance communication can be achieved.

[0005] The objective of this invention is achieved as follows:

[0006] A scattering communication device based on a single-conversion method includes a modulation and demodulation unit, a frequency conversion component, a power amplifier, and a radio frequency front end.

[0007] The signal transmission process is as follows: The modulation and demodulation unit connects to the external voice and service terminals. After service processing, encoding, modulation, and digital up-conversion, the signal is sent to the DAC to output an L-band analog signal. The L-band signal is sent to the frequency conversion component through an RF cable. In the frequency conversion component, the signal is first filtered and amplified, and then mixed with the local oscillator signal to generate a C-band RF signal. The power amplifier receives the C-band RF signal from the frequency conversion component, amplifies it, and then transmits the amplified RF signal through a coupler and an isolator via the RF front end.

[0008] The signal receiving process is as follows: The frequency conversion component receives the radio frequency signal output by the low noise amplifier of the radio frequency front end, amplifies and filters it, and then mixes it with the received local oscillator signal to generate an L-band signal, which is then sent to the modulation and demodulation unit. The modulation and demodulation unit receives the L-band analog signal sent by the frequency conversion component, performs ADC, digital down-conversion, demodulation and decoding on it, and then outputs voice and service information respectively after service processing.

[0009] Furthermore, the radio frequency front end includes a coaxial switch, a duplexer, and a low-noise amplifier, enabling the system to share an antenna for transmission and reception, perform frequency division duplexing, and isolate the transmission and reception signals from each other; and the device model can be flexibly configured according to system needs to achieve automatic switching between high and low transmission and reception frequencies.

[0010] The coaxial switch has four ports; two of the ports are connected to the two ports of the duplexer, and the other two ports are connected to the power amplifier and the low-noise amplifier, respectively.

[0011] The modulation and demodulation unit includes an FPGA and an RF direct sampling chip; the RF direct sampling chip is used to perform DAC and ADC functions and integrates a high-performance clock generation module.

[0012] The FPGA of the modulation and demodulation unit provides a reference clock for the up and down conversion circuits. The I and Q signals of the modulation output are filtered by the FIR filter, multiplier interpolation and digital upconversion of the RF direct sampling chip to become L-band signals. After digital downconversion, multiplier decimation and FIR filtering, the L-band signals are sent to the FPGA for demodulation.

[0013] Furthermore, the frequency conversion component includes a transmit link, a receive link, and a frequency source circuit, which performs up-conversion and amplification functions between L-band and C-band signals. The frequency source provides corresponding local oscillator signals to the transmit and receive links via bus control.

[0014] The L-band signal enters from the intermediate frequency input port of the frequency converter component. After filtering, amplification, and mixing, it generates a C-band radio frequency signal. The radio frequency signal is selected by a switch and then output from the corresponding frequency channel. The C-band radio frequency signal enters from the radio frequency input port of the frequency converter component. It is first selected by a switch and then enters the corresponding frequency channel. After mixing, filtering, and amplification, it is output from the intermediate frequency output port.

[0015] Compared with the scattering communication device using the double-conversion method, the present invention has the following advantages:

[0016] First, it moves problems that originally needed to be handled in the analog domain to the digital domain, offering high flexibility; the digital NCO module can achieve perfect orthogonality without the need for IQ calibration.

[0017] Secondly, the entire device only requires one frequency conversion, which simplifies the circuit design of the frequency conversion components and reduces the cost and weight of the device. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the device architecture provided in an embodiment of the present invention;

[0020] Figure 2 This is a signal processing flowchart provided in an embodiment of the present invention. Detailed Implementation

[0021] To achieve the present invention, the following will be combined with the appendix. Figure 1 , 2 Further details will be provided.

[0022] Reference Figure 1 The diagram illustrates the architecture of a scattering communication device based on a single-frequency conversion method, which mainly includes a modulation and demodulation unit, a frequency conversion component, a power amplifier, and a radio frequency front end.

[0023] This scattering communication device provides an external management network port for monitoring and management by higher-level authorities. The monitoring function of the entire device is completed by the monitoring software within the modem unit. The monitoring software interacts with the baseband software through shared memory, monitors the frequency converter and power amplifier through the RS485 interface, and monitors the RF front-end through TTL level.

[0024] The modulation and demodulation unit connects to external voice and service terminals. After service processing, encoding, modulation, and digital up-conversion, the signal is sent to the DAC and outputs an L-band analog signal. Simultaneously, it receives the L-band analog signal from the frequency conversion component, performs ADC, digital down-conversion, demodulation, and decoding on it, and then outputs voice and service information respectively after service processing.

[0025] The L-band signal is fed into the frequency converter via an RF cable. In the frequency converter, it is first filtered and amplified, then mixed with the transmitted local oscillator signal to generate a C-band RF signal output. Simultaneously, the frequency converter receives the weak RF signal from the low-noise amplifier, amplifies and filters it, and then mixes it with the received local oscillator signal to generate an L-band signal, which is then sent to the modulation / demodulation unit via an RF cable.

[0026] The power amplifier receives a small C-band radio frequency signal from the frequency converter, amplifies it after passing through an isolator, and then outputs the amplified radio frequency signal after sampling through a coupler and isolator. The detection and control circuit performs power detection and reporting of both the transmitted and reflected radio frequency signals, which can provide a basis for fault diagnosis.

[0027] The amplified RF signal enters the RF front-end, where, depending on the device model, it is switched to the matching transmit / receive frequency band via a coaxial switch. During transmission, the signal is filtered by a duplexer and then fed to the antenna; during reception, the duplexer couples in the weak received signal, amplifies it with a low-noise amplifier, and outputs it to the frequency converter; simultaneous bidirectional communication is possible.

[0028] The frequency conversion component converts the input L-band signal into a radio frequency signal in one step, including but not limited to the C-band, and may also be the X-band, Ku-band, etc.

[0029] The power amplifier's transmission power can be configured according to system needs to better adapt to the transmission characteristics of scatter communication and realize the system's communication capabilities.

[0030] The RF front-end includes a coaxial switch, a duplexer, and a low-noise amplifier, all connected internally by RF cables, enabling a miniaturized and lightweight design. For systems with high power requirements, the RF front-end can be implemented using waveguide switches.

[0031] Reference Figure 2 This diagram illustrates a signal processing flowchart for a modulation and demodulation unit in a scattering communication device based on a single-conversion frequency conversion method. The FPGA modulates and outputs two signals, I and Q. First, FIR filtering and multiplier interpolation are performed. Then, based on the system's intermediate frequency (IF) configuration (NCO1), the transmission frequency control word is calculated. The FPGA writes this frequency control word into the TX register, and controls the output frequency (fclk1) through six address bits. NCO1 can be configured within the range of 10MHz to 6000MHz.

[0032] Simultaneously receiving L-band analog signals, the signal is first converted to a digital signal by an ADC. Then, based on the system's received intermediate frequency (IF) configuration (NCO2), the received frequency control word is calculated. The FPGA then converts this frequency into an analog signal output via a DAC. The FPGA provides a reference clock (Refclk2) for the up-conversion circuit, writing the rate control word into the RX register to achieve data frequency shifting. Finally, after decimation and FIR filtering, the I and Q signals are sent to the FPGA for demodulation. The FPGA provides a reference clock (Refclk2) for the down-conversion circuit; NCO2 can be configured within the range of 10MHz to 6000MHz.

[0033] The RF direct sampling chip performs DAC and ADC functions, supporting direct sampling input and output of RF signals up to 6GHz. The ADC / DAC sampling rate can be configured with four ratios: 2 / 3 / 4 / 6. In this solution, the DAC sampling rate is 7.2Gsps and the ADC sampling rate is 2.4Gsps. The digital transceiver channel design incorporates decimation and interpolation factors based on the final equivalent output rate. Both the receive link decimation factor and the transmit link interpolation factor are relatively independent and configurable. A high-performance clock generation module is integrated on-chip, eliminating the need for the user to provide a high-frequency sampling clock.

[0034] A frequency conversion component for a scattering communication device based on a single-conversion method includes a transmit link, a receive link, and a frequency source circuit, which performs single-conversion and amplification functions between L-band signals and C-band radio frequency signals. The frequency source provides corresponding local oscillator signals to the transmit and receive links via bus control.

[0035] For the transmission link, the L-band signal enters from the intermediate frequency input port of the frequency converter component, and after bandpass filtering, intermediate frequency amplification and digital control attenuation, it enters the mixer. The transmission frequency source generates local oscillator signals LO1 and LO2, which are mixed with the L-band signal to generate high and low band radio frequency signals. The radio frequency signal is selected by a switch and enters the corresponding frequency radio frequency channel. After filtering, the corresponding C-band radio frequency signal is output from the radio frequency output port.

[0036] For the receiving link, the C-band RF signal enters from the RF input port of the frequency converter component, and after being selected by the switch and filtered, it enters the mixer. The receiving frequency source generates local oscillator signals LO3 and LO4, which are mixed with the corresponding C-band signals to generate L-band signals. After filtering, amplification and secondary filtering, the L-band signals are output from the intermediate frequency output port.

[0037] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A scattering communication device based on a single-frequency conversion method, comprising a modulation / demodulation unit, a frequency conversion component, a power amplifier, and a radio frequency front-end, characterized in that, The signal transmission process is as follows: The modulation and demodulation unit is connected to the external voice and service terminals. After service processing, encoding, modulation, and digital up-conversion, the signal is sent to the DAC and outputs an L-band analog signal. The L-band analog signal is sent to the frequency conversion component through the RF cable. In the frequency conversion component, the signal is first filtered and amplified, and then mixed with the local oscillator signal to generate a C-band RF signal. The power amplifier receives the C-band RF signal from the frequency conversion component, amplifies it, and the amplified RF signal is transmitted through the RF front end after passing through a coupler and an isolator. The signal receiving process is as follows: The frequency conversion component receives the radio frequency signal output from the low noise amplifier of the radio frequency front end, amplifies and filters it, and then mixes it with the received local oscillator signal to generate an L-band analog signal, which is then sent to the modulation and demodulation unit; The modulation and demodulation unit receives the L-band analog signal sent by the frequency conversion component, performs ADC, digital down-conversion, demodulation and decoding on it, and then outputs voice and service information respectively after service processing; The modulation and demodulation unit includes an FPGA and an RF direct sampling chip; the RF direct sampling chip is used to perform DAC and ADC functions and integrates a high-performance clock generation module. The FPGA of the modulation and demodulation unit provides a reference clock for the up and down conversion circuits. The I and Q signals of the modulation output are filtered by the FIR filter of the RF direct acquisition chip, multiplier interpolation and digital up conversion into L-band analog signals. The L-band analog signal is first converted into a digital signal by an ADC. Then, the receiving frequency control word is calculated based on the NCO2 configuration according to the system's receiving intermediate frequency. The FPGA writes this frequency control word into the RX register to realize data frequency shifting. The frequency conversion component includes a transmitting link, a receiving link, and a frequency source circuit, which is used to perform up-conversion and amplification functions between L-band analog signals and C-band signals; the frequency source circuit provides corresponding local oscillator signals to the transmitting link and the receiving link through bus control. The L-band analog signal enters from the intermediate frequency input port of the frequency converter component, and after filtering, amplification and mixing, it generates the C-band radio frequency signal. The radio frequency signal is then selected by a switch and output to the corresponding frequency channel. The C-band radio frequency signal enters from the radio frequency input port of the frequency converter component, is first selected by a switch to enter the corresponding frequency channel, and then is mixed, filtered and amplified before being output from the intermediate frequency output port.

2. The scattering communication device based on a single-frequency conversion method according to claim 1, characterized in that, The radio frequency front end includes a coaxial switch, a duplexer, and a low-noise amplifier, enabling the system to share an antenna for transmission and reception, perform frequency division duplexing, and isolate the transmission and reception signals from each other; and the device model can be flexibly set according to system needs to achieve automatic switching between high and low frequency bands for transmission and reception. The coaxial switch has four ports; two of the ports are connected to the two ports of the duplexer, and the other two ports are connected to the power amplifier and the low-noise amplifier, respectively.

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