Low-cost software radio system applied to teaching

Abstract

A low-cost software radio system applied to teaching comprises an antenna, a switch and a core board, and the core board is connected with an ADC module, a DAC module and an OLED module. The antenna and the switch are mutually connected, the switch is connected with a receiver and a transmitter, the receiver and the transmitter are used for transmitting, receiving and conditioning of signals, and the core board is used for modulation and demodulation of baseband signals and user operation; in conclusion, through low-cost hardware construction, the experiment cost of the system is greatly reduced, the experiment requirements of most subjects of majors such as communication engineering and electronic information engineering can be met, the combination part of theory and practice is greatly improved, and the practical ability of students is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of communication, and in particular relates to a low-cost software radio system used for teaching. Background Art

[0002] With the rapid development of society, university-related majors such as communications and electronics have developed rapidly, which has put forward higher requirements for teaching and experiments. At the same time, due to the deep theoretical depth and complex practical process of professional courses, it is difficult for many universities to design experimental courses that deeply combine theory and practice. The existing software radio solutions all use Xilinx's Zynq system FPGA+AD9361 solution, or directly use the RFSoC solution. Both solutions are extremely costly and are not conducive to the large-scale purchase and popularization of experimental equipment. Therefore, it is necessary to design an easy-to-implement low-cost software radio system to cooperate with the experiments of related courses such as signal systems, communication principles, and digital signal processing, so as to improve the experimental level of related majors and strengthen the methodology of combining professional theory with practice for design. Utility Model Content

[0003] The utility model aims to provide a low-cost software radio system for teaching, so as to solve the technical problem that the existing radio system is expensive and not suitable for mass purchase and popularization of modern experimental equipment.

[0004] In order to solve the above technical problems, the utility model adopts the following technical solutions:

[0005] A low-cost software radio system for teaching includes an antenna, a switch and a core board, wherein the core board is connected with an ADC module, a DAC module and an OLED module;

[0006] The antenna and the switch are connected to each other, the switch is connected to the receiver and the transmitter, the receiver and the transmitter are used for signal transmission and reception conditioning, and the core board is used for baseband signal modulation and demodulation and user operation;

[0007] The receiver includes an RF radio frequency filter, an LNA low noise amplifier, an up-converter and a VGA variable gain amplifier which are sequentially connected in series with the switch, and the up-converter is connected to a local oscillator;

[0008] The transmitter comprises a power amplifier, a transmitting end bandpass filter, a down converter, a low-pass filter and a modulator which are sequentially connected in series with a switch, and the down converter is connected with a local oscillator.

[0009] Compared with the prior art, the beneficial effects of the utility model are as follows: the utility model comprises two parts, a transmitter and a receiver, capable of two-way communication, and does not use expensive zero-IF agile frequency-changing chips such as AD9361. The signal processing structure uses an ordinary single-chip microcomputer as the main processing module, which greatly reduces the cost. The core processing module used can be quickly replaced by devices such as FPGA, which is convenient for processing high-speed wireless signals and has stronger adaptability. Through low-cost hardware construction, the experimental cost of this system is greatly reduced, which can meet most of the subject experimental requirements of majors such as communication engineering and electronic information engineering, greatly improve the combination of theory and practice, and enhance students' practical ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0011] Figure 1 This is an architecture diagram of a low-cost software radio system used for teaching in the utility model;

[0012] Figure 2 This is a schematic diagram of the principle of a low-cost software radio system used for teaching in the utility model;

[0013] Figure 3 The utility model is a work flow chart of a low-cost software radio system used for teaching. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0015] The present invention is further described in detail below in conjunction with the embodiments.

[0016] like Figure 1-3 As shown, a specific embodiment of a low-cost software radio system for teaching provided by the utility model is as follows:

[0017] A low-cost software radio system for teaching includes an antenna 1, a switch 2 and a core board 100, wherein the core board 100 is connected with an ADC module, a DAC module and an OLED module;

[0018] The antenna 1 and the switch 2 are connected to each other, and the switch 2 is connected to a receiver 101 and a transmitter 102, the receiver 101 and the transmitter 102 are used for signal transmission and reception conditioning, and the core board 100 is used for baseband signal modulation and demodulation and user operation;

[0019] The receiver 101 comprises an RF radio frequency filter 3, an LNA low noise amplifier 4, an up converter 5 and a VGA variable gain amplifier 6 which are sequentially connected in series with the switch 2, and the up converter 5 is connected to a local oscillator 7;

[0020] The transmitter 102 includes a power amplifier 8 , a transmitting end bandpass filter 9 , a down converter 10 , a low pass filter 11 and a modulator 12 which are sequentially connected in series with the switch 2 . The down converter 10 is connected to the local oscillator 7 .

[0021] The following is an introduction to each component. First, the antenna 1 is used to receive wireless signals. Generally speaking, in order to achieve effective signal reception and transmission, the size of the antenna 1 must be comparable to the radio wavelength. Typically, there are: QUOTE , where L is the length of antenna 1 and λ is the wavelength of the radio wave;

[0022] RF filter 3: Filter out interference signals and noise signals. Since the radio spectrum in free space is occupied by various communication services, in order to obtain useful signals with the best signal-to-noise ratio, filters must be used to shield signals in useless frequency bands. At the same time, since it is necessary to amplify weak wireless signals in space, some stronger signals can easily exceed the linear range of the amplifier, reducing the amplification factor of useful signals. Therefore, the analog filter at the receiving end plays an important role in improving the signal-to-noise ratio and reducing interference. Commonly used analog filters include Butterworth, Chebyshev, Bessel and Elliptic.

[0023] Low noise amplifier: amplifies weak electromagnetic signals in space so that they can be collected by ADC at baseband;

[0024] Local oscillator 7: used as a carrier signal in the spectrum shifting process in the receiver 101, down-converting the signal in the RF domain to the baseband;

[0025] Mixer: A component equivalent to a multiplier in the spectrum shifting process, but due to the existence of the local oscillator input, a filter needs to be connected to its subsequent stage;

[0026] Power amplifier 8: used to amplify the small RF signal, thereby achieving long-distance transmission in the wireless space. In practical applications, the power amplifier works in Class C working state, using a smaller conduction angle to achieve higher power and efficiency;

[0027] Transmitter bandpass filter 9: This part is closely following the output end of the modulated signal and is used to filter out harmonics and noise signals in the analog signal;

[0028] Local oscillator 7: acts as a carrier signal in the up-conversion process in the transmitter 102, and is used to achieve spectrum shifting of the signal.

[0029] The core board 100 is mainly used for signal acquisition, demodulation, modulation and signal generation. It also includes a simple human-computer interaction interface and debugging interface. The core board 100 mainly includes three parts: main control chip, signal conditioning, and human-computer interaction:

[0030] (1) Main control chip

[0031] As the core of the whole system, the main control chip is responsible for processing digital signals and interactive logic. The peripheral circuit design of the main control chip needs to have strong reliability and debuggability, so when designing the structure, it is necessary to reserve sufficient redundancy for power supply and clock, and bring out as many debugging interfaces as possible.

[0032] (2) Signal conditioning

[0033] There are four main types of signal conditioning objects: IQ signals sent from the receiving board to the main control, modulated signals sent from the main control to the transmitting board, demodulated analog signals, and original analog signals. The main tasks of signal conditioning include filtering, amplification, attenuation, and amplitude adjustment, thereby fully exerting the full performance of ADC and DAC and improving the dynamic range and signal-to-noise ratio of the entire system.

[0034] (3) Human-computer interaction

[0035] The human-computer interaction part is mainly divided into parameter reception and display, so as to realize the operator's function of receiving the demodulated signal and adjusting the relevant parameters. For the signal path of the analog signal after demodulation, the operator observes the way of converting the demodulated signal into the analog signal output by the conditioned operational amplifier and power amplifier.

[0036] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0037] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-cost software radio system for teaching, characterized by: It includes an antenna, a switch and a core board, and the core board is connected with an ADC module, a DAC module and an OLED module; The antenna and the switch are connected to each other, the switch is connected to the receiver and the transmitter, the receiver and the transmitter are used for signal transmission and reception conditioning, and the core board is used for baseband signal modulation and demodulation and user operation; The receiver includes an RF radio frequency filter, an LNA low noise amplifier, an up-converter and a VGA variable gain amplifier which are sequentially connected in series with the switch, and the up-converter is connected to a local oscillator; The transmitter comprises a power amplifier, a transmitting end bandpass filter, a down converter, a low-pass filter and a modulator which are sequentially connected in series with a switch, and the down converter is connected with a local oscillator.

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