Experiment on Optical Fiber Transmission - Lab Report Example

Lab Report: Optical Fibre Communication This project gives practical evidence of properties of optical fibre as a modern means of telecommunication (Agrawal 2010, p34). It also provides details of the fundamental elements of a general communication system of optical fibre, using the technology of logic gates and transistors. The results of changing the varying the frequency of the output signal, the independent variable, on the values of the input signal is shown in forms of waves of various frequencies and wavelengths. This project shows the use of normal visible light as input signal and coding them by simple low and high pulses of the Transistor to transistor logic for the production of signal. Contents Title Page Abstract 1 Contents 2 List of Figures 3 List of Tables 3 1. Introduction 4 2. Design 5 2.1 Experiment Setting 5 2.2 Inspection and Calibration Setup 6 2.3 Recording Output Data 6 2.8. Output Data Record 3. Results 7 3.1 Results for 1 kHz Signal 7 3.2 Results for the 10 kHz Signal 7 3.3 Results for the 10 kHz Signal 7 3.4 Qualitative Results for all frequencies 8 3.5. Data for all the frequencies 4. Discussion 9 5. Conclusions 9 6. References 10 List of Figures Figure Number and Title Page Figure 2: Oscilloscope Output for 1 kHz 5 Figure 3: Oscilloscope Output for 1 kHz 6 Figure 4: Received Signal for all the Frequencies 8 List of Tables Table Number and Title Page Table 1 The results at 100 Hz 4 Table 2: Results for 1 kHz 5 Table 2: Results for 10 kHz 6 Table 3: The Data at 10 kHz 7 1. Introduction Optical fibre is popular as a global means of telecommunication. The study of the signal generation and wavelength regulation in fibre optic systems is vital in the design and improvement of systems by optimizing the configuration properties. Fibre Optic communication system uses the physical principle of light reflection. As light travels through various media, depending on the density of the medium, the light goes through total internal reflection. This takes place when light is propagated inside a transmission medium with a greater optical density than that of the medium outside. This property depends on the difference of the speed of light inside various mediums. The ratio of the speeds between the mediums and the speed of light in a vacuum is referred to as the refractive index of that specific material or the medium. Refraction of light is controlled by the following model: N1 / N2 = sinθ1 / sinθ2 In this model, N1 is the refractive index of material 1 and N2 is the refractive index of material 2 which the light passes through. Angle θ1 represents the angle of incident while θ2 represents the angle of refraction in the boundary between the two light transmitting materials. When light moves from a medium with a higher refractive index than that of a lower refractive index, the angle of refraction can be shown to be 90º at critical angle θc. This is represented in the model below. θ = sin -1(N1 / N2), where (N1 > N2) Above the incident angle, in the boundary between the materials of higher refractive index and that of low refractive index, there is a total internal reflection of the light. Therefore, the fibre is made as thin as possible to maximize the size of the incident angle and ensure that it is always higher than the critical angle. Even though it is possible to direct the inside an optical fibre, it is vital to decide on the way the input signal ought to be reduced on the basis of its frequency of that signal. This is a safe way of transmission in information systems considering that the higher the frequency, the larger the amount of information in a period of time. The Transistor to Transistor Logic signal producer gives a clear on and off signal appearing as square waveforms. According to Mirabito and Morgenstern 2004, p58), these waves can be changed to binary signals and be applicable in computer information systems and data communication. If the signal clarity and signal strength reduces, there is a considerable data loss as well as distortion of information. 2. Design 2.1 Experiment Setting This project uses the SFH750V transmitter and SFH250V photodiode receiver. After the identification of the two components, the next step was the pin-out configurations of their properties. It used a column shaped breadboard to connect the cathode and the node terminals of the SFH750V transmitting component to a power supply circuit of 5V, and having a reasonable resistor of 330 ohms in a serial arrangement. The same power producing system was used to supply power to the receiver with a resistor of 470 ohms in a serial arrangement. This ensures that the diode is in a reverse bias. The receiving and the transmitting components have the optical fibre carefully linking them by the entry of the optical fibre inside the threaded cavity of every component. This is followed by the gentle tightening of the holder nut. After confirmation of the proper working order of the transmitter it was linked to the signal generating system of the Transistor to transistor Logic. The linking media is the coaxial wire cable with a power of 5V supplied though it (Thyagarajan and Ghatak 2007, p34). The output of this signal generating system put in the first channel digital oscilloscope. The second channel used the output signals from the photo-diode receiver component. For the purpose of comparison, this provided room for display of both the output and the input signal on the same screen and concurrently as demonstrated in figure 1 below. This experiment compared the received signals as well as the transmitted of three separate wave frequencies (1 KHz, 10 kHz and 100 Hz) of the Transistor and Transistor Logic signal increases in a scale 10 units every time. Figure 1: Oscilloscope output Signal of 100 Hz 2.2 Inspection and Calibration Setup When the SFH750V transmitter component is connected to power, the visual inspection and calibration is done to confirm that the Light Emitter Diode LED is powered and table (Bates 2001, p54). In linking of the fibre between the receiver and transmitter, it is vital to confirm working of the SFH750V transmitter component and the light output signal at the optical fibre end without which there will be no transmission of any output signal (Hecht 2002, p65). The oscilloscope setup permitted an easy calibration for the transmitted signal as well as the received signals. 2.3 Output Data Record The recording of the amplitudes of the transmitted and the received signals of the peak voltage was done for all the frequencies being considered in a table form. A screen capture of the oscilloscope result display for two of the frequencies was taken to assist in drawing the waveforms of the output signals, noting the phase difference between the transmitted signal and the received signals. 3. Results 3.1 Results of the 100 Hz Signal Table 1 displays the results of the 100 Hz transmitted signal, with the transmitted signal being at the voltage of 30 Volts while the received signal peak voltage of 10 Volts. Channel Number Y Gain Number of grid lines Peak Voltage (Volts) 1 20.00 1.5 30.00 2 10.00 1 10.00 Table 1 The results at 100 Hz 3.2 Results for 1 kHz Signal Table 2 below shows the data for 1 kHz signal, using the same peak voltage of the transmitted signal (30 Volts) and the received signals (10 Volts). Channel Y Gain Number of grid lines Peak to Peak Voltage (V) 1 20.00 1.5 30.00 2 10.00 1 10.00 Table 2: Results for 1 kHz 3.3 Results for the 10 kHz Signal Table 3 below displays the data for the 10 kHz, using the same peak voltage of 10 and 30 Volts. These data were of similar trends as those of the lesser frequencies. Channel Y Gain Number of grid lines Peak Voltage (Volts) 1 20.00 1.5 30.00 2 10.00 1 10.00 Table 3: The Data at 10 kHz 3.4 Data for all the frequencies From the experiment, it was evident that the Channel 1 and channel 2 had a phase difference of π radians in all the applied frequencies (Atkins, Simpkins and Yablon 2003, p976). Figure 1 above displays the results of the oscilloscope at a frequency of 100 Hz. Channel 1 shows the upper wave as squares of the signal produced by a Transistor to Transistor Logic. Channel 2 is represented by the lower waveform which is the received input signal. It also shows as a square wave but with one square of a very short wave length. The signal of mid frequency wave of 1 kHz, the channel 1 output signal appeared in square wave as presented in figure 2 below. There generated more rounding in the output signal for Channel 2. The waveform was produced with is more saw or tooth like ripples as shown in figure 2 below. Figure 2: Oscilloscope Output for 1 kHz Figure 3: Oscilloscope Output for 1 kHz For the greater range signal of 10 KHz frequency, the transmitted signal appeared in square wave. The output signal was received in the shape of saw tooth as presented in figure 3 above. A summary of the reproduction of the three output waveforms are presented in figure 4 below. Figure 4: Received Signal for all the Frequencies 4. Discussion The major issue exposed by this project is perhaps the dire urgency of the need to optimize the recovery of received signal. Figure 4 shows waveforms in which majority of the deformed wave in this project precisely demonstrates the distinct peak values. It also shows the troughs that make the waves frequencies into various ranges to support the movement of data in the communication channels. The figure proceeds to indicate the fact that limiting wave frequency where waveforms are not resolvable. More experiment is needed with greated frequencies to demonstrate this possibility. The results of prolonging the fibre while dispersing the signal is of great necessity. This however requires longer portions of the optical fibre to make remarkable difference considering that the unit of measurement of bandwidths for the optical fibres is MHz for every km. The waveform created by dispersing and increasing the bandwidth reduced the strength of the signal during the experiment. The distortion of the output signal ns caused by the transmission medium absoring and scatering the light, or through bad connections in the transmitter and the receiver components. As usual, telecomunication channels operate with many optical fibres. With this, it is important for the core of the optical fibre to be covered using a cladding to prevent the cable from lossing total internal reflection, causing a considerable loss of data and information. This is possible if any two neighbourig fibres of equal optical densities comes into contact with one another. 5. Conclusions This project showed the efects of the received signals on the signal and information distortion, by changing the frequencies of the output signals transmitted. Higher frequencies cause more distortion of the transmitted signals waveforms. The project further demonstrated the fact that binary data is able to be transmitted through optical fibre and the pronciple of total internal reflection higher speeds. Various frequencies of the waveforms of the transmited and received signals demonstrated the fact that it is necessary to have reliable recovery of signal as well as the higher limit of frequencies for the transmited signals. 6. References Hecht J. 2002. Understanding Fiber Optics (4th ed.). Prentice Hall. Thyagarajan, K. and Ghatak, A K. 2007. Fiber Optic Essentials. Wiley-Interscience. pp. 34. Bates, R J. 2001. Optical Switching and Networking Handbook. New York: McGraw-Hill. p. 10. Agrawal, G. 2010. Fiber-Optic Communication Systems (4 ed.). Wiley. Atkins, R. M. Simpkins, P. G. and Yablon, A. D. 2003. "Track of a fiber fuse: a Rayleigh instability in optical waveguides". Optics Letters 28 (12): 974–976 Mirabito, M M.A and Morgenstern, B L. 2004. 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