Dual-mode underwater wireless optical communication system based on LED array

Abstract

The invention relates to the field of underwater wireless optical communication, and discloses a dual-mode underwater wireless optical communication system based on an LED array, which comprises a transmitting module, a receiving module, a selection control module and the LED array. The LED array is connected with the transmitting module and the receiving module through the selection control module, and in the transmitting mode, the LED array converts electric signals into optical signals and outputs the optical signals. And in the receiving mode, the photoelectric detector converts the optical signal into a photocurrent signal. The selection control module can switch working modes of the LED array according to communication requirements, dual-mode communication is achieved, and the system has flexibility and expandability. Compared with a traditional underwater wireless optical communication system needing an independent transmitting end light source and an independent receiving end detector, the underwater wireless optical communication system has the advantages that signal receiving and transmitting are integrated on one device, cost and complexity are remarkably reduced, a solution which is small in size, easy to deploy and low in cost is provided for underwater communication, and the underwater wireless optical communication system has remarkable engineering application value.

Description

1. Technical Field

[0001] The present invention belongs to the technical field of underwater wireless optical communication, and particularly relates to a dual-mode communication system based on an LED array. 2. Background Art

[0002] In recent years, with the continuous development of the marine industry, efficient and reliable underwater communication technology has become one of the core requirements in the field of ocean engineering. As an important branch of underwater wireless communication technology, underwater visible light communication has advantages such as high bandwidth, low latency, low power consumption, and high security, and has a wide range of applications in fields such as marine environmental monitoring and underwater resource exploration.

[0003] In the existing underwater optical communication technology, although the communication system based on highly collimated laser beams can achieve long-distance transmission, it has high requirements for the alignment of the transceiver ends and high costs. In contrast, low-cost light-emitting diodes (LEDs) have a large divergence angle, which can significantly reduce the link alignment requirements. For practical applications, the underwater wireless optical communication system based on LEDs has the characteristics of high cost performance and moderate data rate. However, traditional underwater wireless optical communication systems usually require separate transmitters and receivers, resulting in problems such as large volume, high cost, and high system complexity in actual deployment. Therefore, how to design an underwater wireless optical communication system with small volume, high integration, and low cost has become an urgent problem to be solved in this field. Interestingly, LEDs and photodetectors have physical similarities, and LEDs can also work in the photovoltaic mode for the detection of optical signals. Based on this characteristic, LEDs can be used in wireless optical communication systems to detect signals without additional photodetectors.

[0004] In order to achieve underwater wireless optical communication with small volume and easy deployment, a dual-mode communication system based on an LED array is proposed, which integrates the signal transmission and reception on one device, significantly reducing the cost and complexity. This highly integrated dual-mode transceiver can be conveniently deployed in sensor nodes and underwater vehicles, and has broad application scenarios. 3. Summary of the Invention

[0005] The object of the present invention is to solve the problem that the existing underwater wireless optical communication system requires a separate light source and photodetector, resulting in a large system volume and high cost. An underwater wireless optical communication system using an LED array that can work both in the transmission mode and the reception mode as the transceiver end is provided. Combined with the design of a selection control module, it can effectively improve the system integration, reduce the cost and complexity, and can achieve reliable short-distance and easy-alignment communication underwater.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A dual-mode underwater wireless optical communication system based on an LED array, comprising: a transmitting module, a receiving module, a selection control module, and an LED array;

[0008] The transmitting module is used to convert digital signals into electrical signals; the receiving module is used to convert photocurrent signals into digital signals; the selection control module is used to select the LED array to operate in the transmitting mode or the receiving mode; the LED array is used to convert electrical signals into optical signals and transmit them in the transmitting mode, and is used to convert optical signals into photocurrent signals and transmit them to the receiving module in the receiving mode;

[0009] Further, the transmitting module includes a signal generator, a pre-equalizer, a power amplifier, an adjustable electrical attenuator, a biaser, and a DC power supply; among them, the signal generator, the pre-equalizer, the power amplifier, the adjustable electrical attenuator, the biaser, and the selection control module are connected in sequence, and the biaser is supplied with a bias current by the DC power supply; the pre-equalizer is a bridge-T circuit hardware pre-equalizer, which can compensate for the distortion of the device and the channel to the signal, improve the transmission rate and the response bandwidth of the LED, and make the amplitude-frequency response of the system flatter; the RF DC port of the biaser is connected to the selection control module;

[0010] Further, the receiving module includes a low-noise amplifier and an oscilloscope. The low-noise amplifier can effectively amplify weak signals without significantly increasing noise. Among them, the signal input end of the low-noise amplifier is connected to the selection control module;

[0011] Further, the selection control module is designed with a single-pole double-throw (SPDT) toggle switch. Among them, the single-pole end is connected to the LED array, and the double-throw ends are respectively connected to the transmitting module and the receiving module; the selection control module provides instructions for the change of the working mode of the LED array. By the selection control module, the LED array corresponds to different switch paths, and the working mode of the LED array is quickly switched, so that the electro-optical and optoelectronic conversions can be completed respectively in the transmitting and receiving modes;

[0012] Further, the LED array module is composed of 4 small-packaged red-band LEDs closely arranged in an array. Among them, the 4 LEDs are connected in series. The LED array design can improve the transmitted optical power and extend the transmission distance in the transmitting mode, and can increase the detection area and improve the detection efficiency in the receiving mode;

[0013] The principle of the system is that the LED is composed of a PN structure formed by a P-type semiconductor and an N-type semiconductor, which can emit light under the condition of forward conduction voltage and can also work in the photovoltaic mode for the detection of optical signals; among them, the selected red-band LED has a main emission wavelength of 630 nm and a relatively wide emission spectrum. The effective range of the sensitivity spectrum of the red LED as a photodetector covers the peak position of the emission spectrum when it is used as a light source.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] Traditional underwater wireless optical communication systems usually require separate transmitting and receiving ends. The underwater wireless optical communication system of the present invention uses the same LED array as the light source of the transmitting end and the photodetector of the receiving end, without the need for an additional detector, significantly reducing the complexity and cost of the system. In addition, the array of red LEDs as the transceiver can increase the transmission power and detection area, enabling easy alignment and highly reliable communication in the underwater environment. At the same time, the underwater wireless optical communication system of the present invention can flexibly operate the LED array in the transmitting mode or the receiving mode through the transmission selection control module, facilitating changes according to actual needs, and having flexibility and scalability. The present invention provides a solution for underwater communication with small volume, easy deployment, and low cost, and has significant engineering application value. 4. Description of the Drawings

[0016] Figure 1 It is a conceptual diagram of the dual-mode underwater wireless optical communication system based on an LED array of the present invention;

[0017] Figure 2 It is a flowchart of the dual-mode underwater wireless optical communication system based on an LED array of the present invention;

[0018] Figure 3 It is a schematic circuit diagram of the selection control module of the dual-mode underwater wireless optical communication system based on an LED array of the present invention;

[0019] Figure 4 It is a printed circuit board model of the LED array as the transceiver in the present invention;

[0020] Figure 5 It is the relationship between the data rate and the bit error rate of the dual-mode underwater wireless optical communication system based on an LED array measured in the experiment of the present invention. 5. Specific Embodiments

[0021] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will be described in detail with reference to specific embodiments and the accompanying drawings;

[0022] First of all, it should be noted that all kinds of electronic components used in the present invention are mature technologies and corresponding products can be purchased from the market; those skilled in the art can fully reproduce the present invention based on their understanding of the application documents and their knowledge of wireless communication technology and digital signal processing technology.

[0023] Such as Figure 1As shown in the figure, a dual-mode underwater wireless optical communication system based on LED array is composed of a transmitting module, a receiving module, a selection control module and an LED array. Thanks to the LED replacing the photodetector, the whole system is almost symmetrical in the design of the framework. The transmitting module includes a signal generator, a pre-equalizer, a power amplifier, an adjustable electric attenuator, a bias device, and a DC power supply; the receiving module includes a low noise amplifier and an oscilloscope; the selection control module is a control circuit board designed with a single-pole double-throw switch. The circuit diagram of the selection control module is shown in the figure. Figure 3 As shown; the LED array module is an array composed of four red LEDs arranged closely;

[0024] Figure 2 The present invention is a flow chart of a dual-mode underwater wireless optical communication system based on an LED array. For the transmitting module, the original data is loaded onto a signal generator. The electrical signal output by the signal generator passes through a pre-equalization circuit and then adjusts the signal amplitude through an amplifier and an adjustable electrical attenuator, so that the modulated signal fully covers the linear range of the LED. Finally, a bias device is used to superimpose a DC bias on the signal and input it into the selection control module. For the receiving module, the weak photocurrent signal detected by the red LED array is amplified by a low-noise amplifier and then collected and processed by an oscilloscope. For selecting the transmitting control module, a single-pole double-throw button switch design is used to control the link on and off. When the transmitting end is selected, the signal superimposed with the DC bias is used to drive the LED array to emit light; when the receiving end is selected, the LED converts the optical signal into a photocurrent signal and inputs it into the low-noise amplifier of the receiving module for amplification. Figure 4 This is a printed circuit board model of the LED array in the present invention. The array design can increase the emission light power and extend the transmission distance in the emission mode, and can increase the detection area and improve the detection efficiency in the receiving mode.

[0025] At the transmitting end, the control module is selected to connect the LED array to the transmitting module to transmit the light signal. At the receiving end, the control module is selected to connect the LED array to the receiving module to realize the photoelectric detection function. The relationship between the communication rate and the hard decision bit error rate of the system is tested. Figure 5 As shown in the figure, it can be seen that as the data rate increases, the bit error rate gradually increases; the system can achieve a bit error rate of less than 3.8×10 -3 The experiment verifies the feasibility of the present invention.

[0026] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and many variations are possible. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A dual-mode underwater wireless optical communication system based on an LED array, characterized in that, It includes a transmitting module, a receiving module, a selection control module, and an LED array; The transmitting module converts digital signals into electrical signals and sends them to the selection control module; the receiving module converts the received photocurrent signals into digital signals; the selection control module is used to control whether the LED array is connected to the transmitting module or the receiving module; the LED array converts electrical signals into optical signals for output in the transmitting mode, and acts as a photodetector to convert optical signals into photocurrent signals in the receiving mode; the LED array, the transmitting module, and the receiving module are connected through the selection control module.

2. The dual-mode underwater wireless optical communication system based on an LED array according to claim 1, characterized in that The transmitting module includes a signal generator, a pre - equalizer, a power amplifier, an adjustable electrical attenuator, a bias unit, and a DC power supply; among them, the signal generator, the pre - equalizer, the power amplifier, the adjustable electrical attenuator, the bias unit, and the selection control module are connected in sequence, and the bias unit is supplied with bias current by the DC power supply; the RF - DC port of the bias unit is connected to the selection control module.

3. A dual-mode underwater wireless optical communication system based on an LED array according to claim 1, characterized in that, The receiving module includes a low - noise amplifier and an oscilloscope, where the signal input port of the low - noise amplifier is connected to the receiving end of the selection control module.

4. A dual-mode underwater wireless optical communication system based on an LED array according to claim 1, wherein The selection control module is designed with a single - pole double - throw switch. Among them, the single - pole end is connected to the LED array, and the double - throw ends are respectively connected to the transmitting module and the receiving module. Through the selection control module, the working mode of the LED array can be quickly switched, so that the same LED array can work both in the transmitting mode and in the receiving mode.

5. A dual-mode underwater wireless optical communication system based on an LED array according to claim 1, characterized in that, The LED array is connected in series with 4 LEDs in the red - light band, and the 4 LEDs are closely arranged to form an array.

6. The dual-mode underwater wireless optical communication system based on an LED array according to claim 5, wherein The LEDs in the red - light band can act as photodetectors to detect signals in their emission band.

7. A dual-mode underwater wireless optical communication system based on an LED array according to claim 1, wherein At the transmitting end, through the selection control module, the LED array is connected to the transmitting module, and the LED array emits optical signals. After being transmitted through the underwater channel, they reach the target surface of the LED array at the receiving end. At the receiving end, through the selection control module, the LED array is connected to the receiving module, and the LED array works in the receiving mode, converting the detected optical signals into photocurrent and inputting them into the receiving module.

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