Highly robust underwater optical communication system

The present invention belongs to the technical field of underwater communication, and provides a novel highly robust underwater optical communication system which comprises a sending module and a receiving module. The novel highly robust underwater optical communication system realizes highly robust underwater optical communication under strong interference of sunlight and artificial light sources. The system uses a new physical method irrelevant to frequency, and can be used with existing MIMO and CDMA to obtain better communication effects. The circularly polarized light is used for signal transmission, thereby avoiding the problem of channel misalignment caused by the rotation of a platform underwater. At the same time, good polarization maintaining of a marine environment makes the signal characteristics difficult to lose.

TECHNICAL FIELD

The present invention belongs to the technical field of underwater communication, and particularly relates to a novel highly robust underwater optical communication system.

BACKGROUND

The underwater wireless communication technology is a key technology for building an underwater sensor network and realizing information collection and transmission. The exploration of high-speed and effective underwater wireless communication technology is important to the establishment and normal operation of an underwater sensor network system. An underwater visible light communication technology transmits information using high-speed bright and dark flashing signals that cannot be recognized by the naked eyes and issued by light emitting diodes, has the characteristics of high bandwidth, low delay, small volume and low power consumption, and can be effectively applied to the scenario of short-distance underwater communication. In recent years, underwater optical communication systems have become a research hotspot, have made certain progress in the fields of anti-interference, robustness and high-bandwidth transmission, and have been regarded as the optimal solution for underwater short-distance, high-bandwidth and low-delay communication. However, at present, the problem of poor anti-interference still exists in underwater optical communication. In the process of underwater communication, under the effects of absorption and scattering of environmental water bodies, plankton, organic matter and suspended particles, different degrees of interference are generated for light waves, thereby attenuating light intensity, greatly affecting the quality of optical communication and causing extremely high error rate. In addition, ambient light (natural light and artificial light) also greatly affects the underwater optical communication. A high-bandwidth and low-delay underwater optical communication system that can be used in complex environments is urgently needed, so as to achieve high-speed information transmission.

SUMMARY

To satisfy the needs in the background, the present invention provides a highly robust underwater optical communication system.

A novel highly robust underwater optical communication system comprises a sending module and a receiving module.

The sending module comprises a lens group1, an optical receiver2, a differential amplifier3, a comparator4and an embedded microcontroller unit5; during signal reception, an optical signal passing through an environmental channel passes through the lens group1; the lens group1separates reference light from signal light; two lights respectively enter the corresponding receiver2; the receiver2converts an optical analog signal into an electrical analog signal; two electrical analog signals are inputted into the differential amplifier3; after the signal light and the reference light are differentially amplified, a differential signal is sent into the comparator4; the comparator4converts the analog signals into digital signals; the digital signals are inputted into the embedded microcontroller unit5, and finally decoded to obtain target data.

The receiving module comprises the embedded microcontroller unit5, a signal inverter6, high-power LED modulation circuits7, a high-power LED8and the lens group1; when the system sends the signals, the embedded microcontroller unit5groups the information to be sent, and then encodes the grouped information; the encoded information is sent into the signal inverter6; the signal inverter6respectively outputs a positive phase signal and a reverse phase signal to two corresponding high-power LED modulation circuits7; the high-power LED modulation circuits7modulate the high-power LED8to convert the digital signals into optical signals; the light emitted by the high-power LED8passes through the lens group1; and the omnidirectional signal light is converted into linearly polarized light, and the linearly polarized light is converted into circularly polarized light and transmitted into the environment.

The lens group1comprises a polarizer9and a quarter wave plate10; during signal transmission, the signal light passes through the polarizer9to convert the omnidirectional light into linearly polarized light, and then convert the linearly polarized light into circularly polarized light through the quarter wave plate10; during signal reception, the circularly polarized light with signals passes through the quarter wave plate10to convert the circularly polarized light into the linearly polarized light; the converted light passes through the polarizer9; and the polarizer9filters out signals of ambient light and an orthogonal channel, and retains the optical signal of the channel.

The optical receiver2is used to receive visible light in a wave band of 400-760 nm and convert the visible light into an analog quantity.

In a sending mode, the embedded microcontroller unit5encodes the data, and inputs a digital quantity into the signal inverter6; the signal inverter6outputs the positive phase signal and the reverse phase signal; and in a receiving mode, the embedded microcontroller unit5receives the digital signals transmitted by the comparator4and decodes the digital signals to obtain target data.

The output power of the high-power LED8is 30 W, which meets the switching rate of 10 MHz.

The encoding adopts a differential mode to remove signal interference; two channels for encoding respectively encode the signals clockwise and counterclockwise; and two signals have the same amplitude and opposite phases. The method can more accurately identify the signals and remove ambient light interference.

The beneficial effects of the present invention are: the system of the present invention provides a highly robust underwater optical communication system, which realizes highly robust underwater optical communication under strong interference of sunlight and artificial light sources. The system uses a new physical method irrelevant to frequency, and can be used with existing MIMO and CDMA to obtain better communication effects. The circularly polarized light is used for signal transmission, thereby avoiding the problem of channel misalignment caused by the rotation of a platform underwater. At the same time, good polarization maintaining of a marine environment makes the signal characteristics difficult to lose.

In the figures:1lens group;2optical receiver;3differential amplifier;4comparator;5embedded microcontroller unit;6signal inverter;7high-power LED modulation circuit;8high-power LED;9polarizer;10quarter wave plate;11sending module;12receiving module. In the encoded schematic diagrams, FIG. (a) and FIG. (b) are encoded schematic diagrams of a sending end; in the codes, the circle is clockwise (counterclockwise) circularly polarized light; and FIG. (c) and FIG. (d) are schematic diagrams of differential communication principles.

DETAILED DESCRIPTION

Specific embodiments of the present invention are further described below in combination with the technical solutions and the drawings of description.

As shown inFIG. 2, when the system sends the signals, the embedded microcontroller unit groups the information to be sent, and then encodes the grouped information; the encoded information is sent into the signal inverter6; the signal inverter6respectively outputs the positive phase signal and the reverse phase signal to two modulation circuits7; the modulation circuits modulate the high-power LED8to convert the digital signals into optical signals; the light emitted by the high-power LED8passes through the lens group1; and the omnidirectional signal light is converted into linearly polarized light, and the linearly polarized light is converted into circularly polarized light and transmitted into the environment.

During signal reception, an optical signal passing through an environmental channel passes through the lens group1; the lens group1separates reference light from signal light; two lights respectively enter the corresponding receiver2; the signal receiver converts an optical analog signal into an electrical analog signal; two analog signals are inputted into a high-speed differential amplifier3; the signal light and the reference light are differentially amplified; a differential signal is sent into a high-speed comparator4; the high-speed comparator converts the analog signals into digital signals; the digital signals are inputted into the embedded microcontroller unit, and finally decoded to obtain target data.