Scatter communication equipment based on one-time frequency conversion mode

Abstract

The invention discloses scatter communication equipment based on a one-time frequency conversion mode, and relates to the technical field of scatter communication. The device mainly comprises a modulation-demodulation unit, a frequency conversion assembly, a power amplifier and a radio frequency front end, adopts a frequency division duplex mode, and adopts a one-time frequency conversion mode for receiving and transmitting channels to realize self-adaptive transmission of IP data such as voices, videos, images and the like. The dual-frequency-conversion scatter communication device can be used for scatter communication devices in frequency bands such as C, X and Ku, can adapt to different transmission environments and requirements, and can improve the integration level and flexibility of a system, simplify the circuit design and reduce the system cost compared with a traditional secondary-frequency-conversion scatter communication device.

Description

Technical Field

[0001] The present invention relates to the technical field of scattering communication, and in particular to a scattering communication device based on a single frequency conversion mode, which has the advantages of high flexibility and low cost. Background Art

[0002] Scattering communication is a kind of over-the-horizon wireless communication that uses the forward bend transmission effect of the inhomogeneous body in the atmospheric medium on the radio wave. Scattering communication technology plays an important role in the field of modern military and civilian communications due to its excellent characteristics such as large communication capacity, strong three-way resistance and long transmission distance.

[0003] Traditional scatter communication mostly uses a secondary frequency conversion method, that is, the modulation and demodulation output intermediate frequency signal, which is first up-converted to an intermediate frequency signal in the frequency converter, and then up-converted to an RF signal. The receiving process is similar. This method requires a two-stage frequency conversion circuit, which is costly and heavy. Currently, the cost and weight requirements for scatter communication equipment are getting higher and higher, so a more efficient frequency conversion method is needed to adapt to the rapid development of scatter communication. Summary of the invention

[0004] In view of the low cost and lightweight requirements of scattering communication, the present invention proposes a scattering communication device based on a single frequency conversion method, which outputs an L-band signal in the digital domain and then converts the signal to the RF working frequency band required by the system after a single frequency conversion, thereby achieving long-distance reliable communication.

[0005] The object of the present invention is achieved in that: A scattering communication device based on a single frequency conversion method includes a modulation and demodulation unit, a frequency conversion component, a power amplifier and a radio frequency front end. The signal transmission process is as follows: the modulation and demodulation unit is connected to the external voice and service terminal, and after service processing, coding, modulation and digital up-conversion, it is sent to the DAC to output an L-band analog signal; the L-band signal is sent to the frequency conversion component through the RF cable, and is first filtered and amplified in the frequency conversion component, and then mixed with the local oscillator signal to generate a C-band RF signal; the power amplifier receives the C-band RF signal sent by the frequency conversion component, amplifies it, and the amplified RF signal is transmitted through the RF front end after passing through the coupler and isolator; The signal receiving process is as follows: the frequency conversion component receives the RF signal output by the low noise amplifier of the RF front end, amplifies and filters it, mixes it with the received local oscillator signal, generates an L-band signal and sends it 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 business information respectively after business processing.

[0006] Furthermore, the RF front end includes a coaxial switch, a duplexer and a low noise amplifier, so as to realize the functions of the system's shared antenna for transmission and reception, frequency division duplexing and isolation of transmission and reception signals; and the local device model can be flexibly set according to system needs to realize automatic switching of high and low frequency segments 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.

[0007] According to the scattering communication device based on the single frequency conversion method of claim 1, it is characterized in that the modulation and demodulation unit includes an FPGA and a radio frequency direct acquisition chip; the radio frequency direct acquisition chip is used to complete the 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 modulated output I and Q signals are converted into L-band signals through FIR filtering, multiple interpolation and digital up-conversion of the RF direct sampling chip. After the L-band signal is digitally down-converted, multiple extracted and FIR filtered, the I and Q signals are sent to the FPGA for demodulation.

[0008] Furthermore, the frequency conversion component includes a transmitting link, a receiving link and a frequency source circuit, which completes the up-down conversion and amplification functions between the L-band signal and the C-band signal. The frequency source provides corresponding local oscillator signals for the transmitting link and the receiving link through bus control.

[0009] The L-band signal enters from the intermediate frequency input port of the frequency conversion component, and after filtering, amplification and mixing, a C-band RF signal is generated. The RF signal enters the corresponding frequency channel after being switched on and then output; the C-band RF signal enters from the RF input port of the frequency conversion component, and first enters the corresponding frequency channel after being switched on and then mixed, filtered and amplified before being output from the intermediate frequency output port.

[0010] Compared with the scattering communication equipment of the secondary frequency conversion method, the present invention has the following advantages: First, the problem that originally needed to be processed in the analog domain is moved to the digital domain for solution, which is highly flexible; the digital NCO module can achieve perfect orthogonality without the need for IQ calibration.

[0011] Second, the entire device only requires one frequency conversion, which simplifies the frequency conversion component circuit design and reduces equipment cost and weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0013] Figure 1 is a schematic diagram of a device architecture provided by an embodiment of the present invention; Figure 2 It is a signal processing flow chart provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to implement the present invention, the following Figure 1 , 2 Further detailed explanation is given.

[0015] Reference Figure 1 , which illustrates an architecture diagram of a scattering communication device based on a single frequency conversion method, mainly including a modulation and demodulation unit, a frequency conversion component, a power amplifier and a radio frequency front end.

[0016] The scattering communication equipment provides a management network port to accept upper-level monitoring and management. The monitoring function of the entire equipment is completed by the monitoring software in the modem unit. The monitoring software interacts with the baseband software through shared memory, monitors the frequency conversion components and power amplifiers through the RS485 interface, and monitors the RF front end through the TTL level.

[0017] The modulation and demodulation unit is connected to the external voice and service terminals, and after service processing, coding, modulation and digital up-conversion, it is sent to the DAC and outputs the L-band analog signal. At the same time, it 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 the voice and service information respectively after service processing.

[0018] The L-band signal is sent to the frequency conversion component through the RF cable, where it is first filtered and amplified, and then mixed with the transmitting local oscillator signal to generate a C-band RF signal output. At the same time, the frequency conversion component receives the weak RF signal output by the low-noise amplifier, amplifies and filters it, and then mixes it with the receiving local oscillator signal to generate an L-band signal that is sent to the modulation and demodulation unit through the RF cable.

[0019] The power amplifier receives the C-band RF small signal sent by the frequency conversion component, and then amplifies the power after passing through the isolator. The amplified RF signal is sampled by the coupler and isolator and then output. The detection control circuit completes the power detection and reporting of the transmitted and reflected RF signals, which can provide a basis for fault diagnosis.

[0020] After being amplified by the power amplifier, the RF signal enters the RF front end. According to the current device model, the coaxial switch in the RF front end switches to the matching transmit and receive frequency band. When transmitting, it is filtered by the duplexer and fed to the antenna; when receiving, the duplexer couples the weak receive signal, amplifies it by the low noise amplifier, and outputs it to the frequency conversion component; two-way communication can be carried out simultaneously.

[0021] The frequency conversion component converts the input L-band signal into a radio frequency signal once, including but not limited to the C-band, and may also be the X-band, Ku-band, etc.

[0022] The transmission power of the power amplifier can be configured according to system requirements to better adapt to the transmission characteristics of scattering communication and realize the communication capability of the system.

[0023] The RF front end includes a coaxial switch, a duplexer and a low noise amplifier, which are connected internally with RF cables to achieve a miniaturized and lightweight design. If the system requires high power, the RF front end can be implemented using a waveguide switch.

[0024] Reference Figure 2 , mainly illustrates a signal processing flow chart of the modulation and demodulation unit of a scattering communication device based on a single frequency conversion method. FPGA modulates and outputs the I and Q signals, first performs FIR filtering and multiple interpolation, then configures NCO1 according to the system's intermediate frequency, calculates the frequency control word, and writes this frequency control word into the TX register. The output frequency fclk1 is controlled through 6 address bits. NCO1 can be configured within 10MHz~6000 MHz.

[0025] At the same time, the L-band analog signal is received, and the ADC is first converted into a digital signal. Then, according to the system's intermediate frequency, NCO2 is configured to calculate the receiving frequency control word. The FPGA converts this frequency into an analog signal output through the DAC. The FPGA provides a reference clock Re for the up-conversion circuit and writes the rate control word into the RX register to achieve data frequency shifting. Finally, after multiple extraction 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, and NCO2 can be configured within 10MHz~6000 MHz.

[0026] The RF direct sampling chip completes the DAC and ADC functions, and supports direct sampling input and output of RF signals up to 6GHz. There are four types of multiples corresponding to the ADC / DAC sampling rate: 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 designs the extraction and interpolation multiples according to the final equivalent output rate. The extraction multiples of the receiving link and the interpolation multiples of the transmitting link are relatively independent and configurable. A high-performance clock generation module is integrated on the chip, and the user does not need to provide a high-frequency sampling clock.

[0027] A frequency conversion component of a scattering communication device based on a single frequency conversion method includes a transmitting link, a receiving link and a frequency source circuit, which completes the single frequency conversion and amplification function between L-band signals and C-band radio frequency signals. The frequency source provides corresponding local oscillator signals for the transmitting link and the receiving link through bus control.

[0028] For the transmission link, the L-band signal enters from the intermediate frequency input port of the frequency conversion component, enters the mixer after bandpass filtering, intermediate frequency amplification and digitally controlled attenuation, and the transmission frequency source generates local oscillator signals LO1 and LO2, which are mixed with the L-band signal to generate high-band and low-band RF signals. The RF signal enters the corresponding frequency RF channel through the switch selection, and then outputs the corresponding C-band RF signal from the RF output port after filtering; For the receiving link, the C-band RF signal enters from the RF input port of the frequency conversion component, enters the mixer after switch selection and filtering, and the receiving frequency source generates local oscillator signals LO3 and LO4, which are mixed with the corresponding C-band signal to generate L-band signal. The L-band signal is filtered, amplified and filtered twice before being output from the intermediate frequency output port.

[0029] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A scattering communication device based on a single frequency conversion method, comprising a modulation and 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 terminal, and after service processing, coding, modulation and digital up-conversion, it is sent to the DAC to output an L-band analog signal; the L-band signal is sent to the frequency conversion component through the RF cable, and is first filtered and amplified in the frequency conversion component, and then mixed with the local oscillator signal to generate a C-band RF signal; the power amplifier receives the C-band RF signal sent by the frequency conversion component, amplifies it, and the amplified RF signal is transmitted through the RF front end after passing through the coupler and isolator; The signal receiving process is as follows: the frequency conversion component receives the RF signal output by the low noise amplifier of the RF front end, amplifies and filters it, mixes it with the received local oscillator signal, generates an L-band signal and sends it 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 business information respectively after business processing.

2. A scattering communication device based on a single frequency conversion method according to claim 1, characterized in that: The RF front end includes a coaxial switch, a duplexer and a low noise amplifier, which realizes the functions of sharing a common antenna for system transmission and reception, frequency division duplexing and mutual isolation of transmission and reception signals; and the local device model can be flexibly set according to system needs to realize automatic switching of high and low frequency segments of 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.

3. The scattering communication device based on a single frequency conversion method according to claim 1, characterized in that: The modulation and demodulation unit includes an FPGA and a radio frequency direct acquisition chip; the radio frequency direct acquisition chip is used to complete the 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 modulated output I and Q signals are FIR filtered, multiple interpolated and digitally up-converted by the RF direct sampling chip to become L-band signals. The L-band analog signal is first converted into a digital signal through ADC, and then NCO2 is configured according to the system's receiving intermediate frequency to calculate the receiving frequency control word. FPGA converts this frequency and finally converts it into an analog signal output through DAC.

4. The scattering communication device based on a single frequency conversion method according to claim 1, characterized in that: The frequency conversion component includes a transmitting link, a receiving link and a frequency source circuit, which is used to complete the up-down frequency conversion and amplification functions between the L-band signal and the C-band signal; the frequency source circuit provides corresponding local oscillator signals for the transmitting link and the receiving link through bus control; The L-band signal enters from the intermediate frequency input port of the frequency conversion component, and after filtering, amplification and mixing, a C-band RF signal is generated. The RF signal enters the corresponding frequency channel after being selected by the switch and then output; The C-band RF signal enters from the RF input port of the frequency conversion component, first enters the corresponding frequency channel through the switch, and then is mixed, filtered and amplified before being output from the intermediate frequency output port.

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