VLC-BASED LIGHT SPOTLIGHTING SYSTEM

Abstract:

LiFi is a high speed and wireless communication system that allows us to utilize the light we use for a different purpose connectivity. LiFi enabled LED lights modify illumination levels so that when we turn on our bulbs, not only is light transferred throughout the room, but so is data. This modulation happens so fast that the eye cannot perceive it. Visible light spotlight is a very current technology that creates focused beam of light similar to sound beams coming out of directional speaker.

By shining optics to one site, particular listeners can be targeted with sound without others nearby hearing it. It uses an arrangement of non-linear optics converters and some fancy mathematics. But it is factual and is find to knock and socks any conventional loud speaker.

This light device comprise a audio playback that fires out of earshot ultrasound pulses with very small wavelength which act in a manner very similar to that of a narrow column.

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The ultrasound beam converted into light signals and acts as an airborne speaker and as the beam moves through the air gradual distortion takes place in an expected way due to property of non-linearity of air. This results in audible components that can be precisely controlled and accurately predicted. Visible light spotlight is made up of an amplifier, a sound processor and the transducer. In transmitter side LED used as a source and it is controlled by sound record & playback moduleWTV040S. The receiver side avalanche photo detector will receive the light signal and it is controlled by PIC16F877A.

Introduction

The Visible light communication (VLC) can be implemented in two ways, first way is the signal can be feed to the transmitter the LED can be emitted the signal and then the signal can be received by the optical receiver. Second way is the data will be encoded so that the error can be minimized. In VLC implementation is allows the multimedia contents such as text, audio, voice, video, audio and video or image.

In proposed system the audio is transmitted by encoding and modulating the intensity of the light, which is received by avalanche photo detector and the light signal is demodulated into electronic form. This modulation is performed in such a way that it is not perceptible to the human eye. The received signal given to the controller then it is amplified by amplifier circuit. It is directly connected to the speaker.

Literature Review

In VLC consist of different way of transmission system[1-3]. In Ref.[1], in this paper only design for protecting arts and statue in the museum using VLC. The system design against from the theft, human contacts, photographing and fading. The main advantage of this paper is using three types of sensors[touch sensor, PIR, LASER] and sensing data can be transmitted to the receiver. When the arts may be damaged the sensor is activated then transmitted the data.

In Ref.[2], this paper discussed about Short range of audio signal transmission. Here we are using 3W white phosphor LED used as a source it covers very distance (20cm). In the system we using AFE circuit for error minimizing in received data.

In Ref.[3], the paper explains the image sensor based Optical Wireless Communication System(OWCS) for automotive application. The vehicle light act as a transmitter and the camera Image Sensor(IS) act as a receiver. The image pixels are communicated with PIN diode technology. This technology uses 1-bit flag image.

WTV-SR is one of the members of recording serial products. WTV-SR module can record as well as fixed voice playback, recording content uploaded and a variety of control modes can be chose. With the master chip and plug-in SPI-FLASH, it has a great advantage in the duration time of recording and cost performance.It can record up to 252 segment voice and recording time up to 1600 seconds. It supports audible recording at 10KHz or 14KHz sample rate.

Adapter

An adapter is a device that converts attributes of one electrical device or system to those of an otherwise incompatible device or system. Some modify power or signal attributes, while others merely adapt the physical form of one electrical connector to another.

In a computer, an adapter is often built into a card that can be inserted into a slot on the computer's motherboard. The card adopts information that is exchanged between the computer's microprocessor and the devices that the card supports.

PIC Assembled PCB:

The microcontroller is a device that can perform a specific function according to the coding/program burnt into its program memory. This board is build with PIC16F877A as a microcontroller unit and it is specially designed for connecting digital and analog sensor which has input voltage range 5 or 12V DC as well as it can be interfaced with serial communication devices, relay boards.

PIC assembled PCB

Single Relay:

Relays are simple switches which are operated both electrically and mechanically. Relays consist of a n electromagnet and also a set of contacts. The switching mechanism is carried out with the help of the electromagnet. The main operation of a relay comes in places where only a low-power signal can be used to control a circuit.

An isolation circuits used to prevents reverse voltage from the relay which protects the controller and transistor from the microcontroller unit.

Single Relay Board

PIC16F877A Controller:

PIC means Peripheral Interface Controller. The PIC family having different series. The series are 12-Series, 14-Series, 16-Series, 18-Series, and 24-series. We used 16 Series PIC microcontrollers.

The main features of PIC microcontroller is high performance RISC CPU, 35 single word instruction to learn, fully static design and high speed CMOS FLASH/EEPROM technology. The operating speed is DC-20MHz clock input DC-200ns instruction cycle.

Voltage Regulator 7805:

Regulator regulates the output voltage to be always constant. The output voltage is maintained irrespective of the fluctuations in the input AC voltage. The 7805 provides circuit designers with an easy way to regulate DC voltage to 5V. Encapsulated in a single chip/package (IC), the 7805 is a positive voltage DC regulator that has only 3 terminals. They are: Input voltage, Ground, Output voltage.

System Design

In the proposed system the process of voice communication through the visible light on the transmitter side voice is used as the input signal. This signal is converted to an electrical signal through condenser or microphone. This electrical signal is amplified by the amplifier circuit and feed into the power LED. The light signal from the LED various according to the intensity of the voice signal. The louder is voice the glow of the LED will be more. At the receiver side avalanche photo detector will receive the light signal and correspondingly generated an electrical signal proportional to it. This electrical signal is processed by a demodulated circuit, which is then feed to a speaker and it produces the audio signal which was at the input of transmitter side.

Transmitter Unit

The audio signal is given to the input of microphone, it is stored by Sound Record & Playback ModuleWTV040S. The signal is stored in the EEPROM. This module consist of channel selection for storing purpose. The voice signal is converted into digital form then give to the LiFi drive. LiFi drive consist of audio amplifier and local oscillator. Finally the digital voice signal is encoded then it is transmitted by high beam light.

Receiver Unit

The light signal is received by avalanche photo detector then the signal is decoded. The decoded signal is given to the PIC microcontroller in the receiver pin. The B0 pin is connected to the relay circuit. It is used to prevents reverse voltage which protects the controller and transistor from the microcontroller unit. After that the low level signal is given to the amplifier circuit. Finally the amplified signal is connected to the speaker or headset jumper.

Conclusion

This paper is describes the VLC based spotlighting for Location Identification. Its applicable for predefined purpose only like Laboratory, Industry, Museum, Flights, Airport, Hotels etc. In this paper highlighting the proposed system only for the predefined functions but after doing changes, we can use this system for internet access from cloud.