Optical Fibre Communication - Lab Report Example

Abstract This laboratory report seeks to find out and explain the nature of the waveforms when input frequencies of the oscilloscope are either increased or reduced while keeping the power supply at a constant voltage level of 5 volts. The report shows the equipments needed to carry out the experiment, the role of the equipments and gives a vivid procedure on how the research was conducted. It finally represents the results achieved and attempts to provide an explanation of how the results were arrived at and what they mean. Table of contents Title Page Abstract 2 Contents 3 List of Figures 4 Introduction 5 Design 7 Equipments Required 7 Setting up Experiment 5 Figures representing experiment 6 Results 10 3.1 Waveform when input frequency is set to 100 Hz. 10 3.2 Waveform when input frequency is set to 1 KHz 11 3.3 Waveform when input frequency is set to 10 KHz 11 4. Discussion 12 5. Conclusions 12 6. References 13 List of figures Figure Number and Title Page Figure 3.1 showing waveform when input frequency is 100 Hz. 10 Figure 3.2 showing waveform when input frequency is 1 KHz. 11 Figure 3.3 showing waveform when input frequency is 10 kHz. 12 Introduction and literature review There are many laboratory experiments that employ the use of the oscilloscope and the function generators to understand their general functionality. Oscilloscopes are signal analyzers that show images of the person carrying out the experiment of signals commonly in the form of voltage against time. Users use the pictures retrieved from the oscilloscope to understand the frequency of the graph, the amplitude of the graph and the general shape of the graph that will vary depending on what the experiment intends to find out. Function generators, on the other hand, are sources of signals whose voltage is set by the person carrying out the research. It runs for a predefined period. The resultant signals are in the form of rectangular waves or sine waves and are used to control other equipments like a clock to work as a timing signal or used to send a radioactive signal back and forth. Function generators have characteristic features whether analogue or digital the digital type that includes: Selecting the type of the waveform. They are commonly the sine, square and triangular waves. A means to choose the waveform frequency. Standard rates range between 0.01Hz to 100MHz. The way to choose the amplitude for the waveform chosen. A minimum of two outputs. The primary output is where the user is doing the experiment finds the waveform they want. The second output, being used in this research is the Aux (TTL) which produces a square wave that has a standard of 0 up to 5 voltage signal levels. It is what we are employing to synchronize the oscilloscope to the variable primary output signal. This experiment also involved the use of the transmitter. SFH750V transmitter emits 650 nm with the capability of outputting 20 UV of light. The device has a spectral width of 35 nm and requires a current, depending on the required intensity, of 10 to 45 mA. The transmitter is a four-pin device (only two of which are active) and comprises of a LED, glass-bead focusing and a threaded chamber into which an optical fibre is inserted. The experiment also required us to have a receiver. The one we found useful here was a photodiode receiver. It is designed to be most sensitive at 850 nm, but will detect a 650 nm signal. When used to detect a signal, a photo-diode has to be used in reverse-bias mode. Fibre optics It is known to be a transparent, flexible fibre and is made out of a glass. Its purpose is to guide a wave through the pipe between two ends. It achieves the application in the communications industry because of better performance compared to electrical copper wires. They have fewer losses and better immunity when it comes to electromagnetic interference. Fibre cables come in many configurations that include multi-mode and mono-mode designs. Multi-mode is better in terms of operation in comparison to mono-mode. In this regard, they are well suited for computer networks and long distance communication. They offer a broader bandwidth, low attenuation, electric insulation and reduce costs incurred from theft. On the other hand, fibres can be used in sensors to make strain gauges, temperature and pressure. Fibre optic transmits light in its axis through total internal reflection of the light. The core is encompassed by a cladding layer made of dielectric materials. Total internal reflection occurs when refractive index of the core of the fiber cable has to be greater as compared to the refractive index of the cladding. The fibre transmission system is coupled with decoders and encoders at each end of the cable. The electrical signal at the input is converted into a light signal and directed into the fibre cable for transmission. The power of the input signal is dependent on the input signal power and frequency. Research has shown that light travels faster in a vacuum followed by in the air. The glass used in the fibre is designed in such ways as to minimize losses and hence an efficient way to transmit information at great speeds over a longer distance. Design Equipment Required In the design stage of our experiment, we organized the equipments required and set up the experiment. The equipments used in this experiment included:- SFH750V transmitter SFH250V receiver 8-inch length of plastic fiber bread-board power supply 330Ω and 470 kΩ resistors a function generator (with fixed TTL output signal) Oscilloscope and assorted leads. 2.2 Setting up the experiment To get the experiment up and running, we followed the following procedure: - First, we set the power source to 5 volts. - It was then placed the transmitter device on the breadboard. It was made sure that the A and C terminals were not on the same breadboard column. The anode was connected to the 330Ω resistor as shown in figure 1. -Using a wire, a connection was made on one end of the resistor which was on the positive terminal of the power supply. Next, using another cable, a connection was made to the negative terminal to the power supply and to the cathode node of the transmitter. - The screw terminal was checked if the LED was on. It was to be indicated by a red light from the LED. - The receiver was placed on the breadboard. While doing this, it was ensured that the A and C terminals were not shorted. - The cathode was connected to the 470 Ω resistors to achieve the reverse-biased connection of the device. - Then a connection was put on the remaining end of the resistor and the positive terminal together to the power supply using a wire as shown in figure 2. -Using a wire, a connection to the negative terminal of the power supply was made to the anode of the receiver. - It was then checked to confirm that the LED of the transmitter was still on. - Next It was placed on one end of the fiber into the wires threaded cavity. It was affected by temporarily removing the transmitter from the breadboard and replacing it thereafter. - The fiber was pushed gently to the furthest point to allow and tightened the threaded nut. The precaution tied to this was the use of our fingers only and consequently there was no need for the pliers. - It was then checked to ensure that the opposite end of fiber was reached by the light. -After seeing the light, the floating end of the fiber was placed into the receiver's threaded cavity and tightened up the threaded nut as it was initially. - The end of the 330Ω resistor was connected to the 5 V power supply. The power supply was however still needed to provide ground to the transmitter and the 5V to the receiver. - It was turned on for the function generator and set the frequency to 100 Hz. - What followed was connecting a coaxial cable to the TTL output of the generator. - This was followed by connecting the positive end to the end of the 330Ω resistor of the transmitter that we had disconnected from the power supply. - What followed was to connect the shielding of the coaxial cable to the negative terminal of the 5 v power supply. - The output of the oscilloscope was connected to channel 1 from the function generator and adjusted until the 100 Hz TTL square wave was visible. - Channel 2 of the oscilloscope was connected to the cathode of the receiver. - After confirming that the signal displayed was a square wave with slightly rounded edges, theform was sketched and noted the voltage. - After recording, the input frequencies was altered to 1 KHz, 10 KHz and recorded the corresponding waveforms of the two input frequencies respectively. 2.3 Figures representing the experiment Results Waveform when input frequency is set to 100 Hz Figure 3.1 showing waveform when input frequency is 100 Hz. Figure 3.2 showing waveform when input frequency is 1 KHz. 3.3 Waveform when input frequency is set to 10 KHz Figure 3.3 showing waveform when input frequency is 10 KHz. Discussion The primary issue that this test has highlighted is the requirement for the enhancement of sign recuperation. From the waveforms in figures, there is the most mutilated wave of this trial plainly has the discernable tops and troughs of the waves making the recurrence ranges suitable for data transmission. Anyhow it additionally demonstrates that there may be a constraining recurrence whereon the wave example is unresolvable. Further investigation at higher frequencies would be expected to affirm this. From the output represented above the attenuation, levels are not dependent on the input frequency. Analysing each of the 10 kHz, 1 kHz and 100 Hz reveals that they all had input level voltage of 1v and dropped to 50mv as a recorded by channel 2 on the output. Moreover, higher frequency led to more interference on the waveform developed as seen from the shape on the waveform. At 100Hz and 1 kHz, the waveform on the input and output side are identical, indicating a conservation of the bandwidth levels of the transmission. On the other hand, 10 kHz had a slight difference in the bandwidth of entry and the output bandwidth. The impact of expanding the length of the optical fiber on the scattering of the sign would likewise be intriguing, however this would likely oblige long segments of fiber to deliver huge changes as transmission capacities of optical strands are regularly measured in Mhz every km. And the contortion of the wave structure brought about by scattering and expanded data transfer capacity, the quality of the sign was debilitated in this trial as shown by the lessening in the crest to top voltage of the got signal. Conclusion The objectives of the experiment with respect to the increase of frequency were successfully executed. It was determined that at low-frequency levels, interference of the wave under transmission is minimal while, at higher frequencies, the transmission of the wave undergoes the interference and may result in a different waveform from the original. The experiment session had errors that required averting in future to minimise errors. Considering the rated amount of frequency at 1 kHz while the oscilloscope reads 1.4Hz is erroneous. In future, use of superior measurement devices in a laboratory session with minimal interference will help to come up with correct illustrations about the fibre and communication characteristics. Fibre optic cables have minimal losses and attenuation compared to copper wires. List of references Corning, 2014. CORNING. [Online] Available at: HYPERLINK "http://www.corning.com/opticalfiber/" http://www.corning.com/opticalfiber/ [Accessed 3 DEC 2014]. IBM Corporation, 2014. Understanding Optical Communication. [Online] Available at: HYPERLINK "http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&sqi=2&ved=0CGsQFjAN&url=http%3A%2F%2Fwww.redbooks.ibm.com%2Fredbooks%2Fpdfs%2Fsg245230.pdf&ei=82V_VIWLAoPC7AbprICwAg&usg=AFQjCNHA7drqwpTzcGFA4gy-j7SbV_hH1Q&sig2=b38wDoAYssyUv-K" http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&sqi=2&ved=0CGsQFjAN&url=http%3A%2F%2Fwww.redbooks.ibm.com%2Fredbooks%2Fpdfs%2Fsg245230.pdf&ei=82V_VIWLAoPC7AbprICwAg&usg=AFQjCNHA7drqwpTzcGFA4gy-j7SbV_hH1Q&sig2=b38wDoAYssyUv-K [Accessed 3 DEC 2014]. Rouse, M., 2014. Optical fibre. [Online] Available at: HYPERLINK "http://searchtelecom.techtarget.com/definition/optical-fiber" http://searchtelecom.techtarget.com/definition/optical-fiber [Accessed 3 DEC 2014]. University of Texas, 2014. Fiber Optics Communication. [Online] Available at: HYPERLINK "www.utdallas.edu/.../FIBEROPTICS.pdf" www.utdallas.edu/./FIBEROPTICS.pdf [Accessed 3 DEC 2014]. Yasin, Z., 2014. SLAC National Accelerator Laboratory. [Online] Available at: HYPERLINK "https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&sqi=2&ved=0CFAQFjAJ&url=https%3A%2F%2Fwww.slac.stanford.edu%2Fslac%2Fsass%2Ftalks%2Fopticalfiber.pdf&ei=82V_VIWLAoPC7AbprICwAg&usg=AFQjCNGE2Pu1PZYkfue-p1u7ZephK6mfuA&sig2=qnhH" https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&sqi=2&ved=0CFAQFjAJ&url=https%3A%2F%2Fwww.slac.stanford.edu%2Fslac%2Fsass%2Ftalks%2Fopticalfiber.pdf&ei=82V_VIWLAoPC7AbprICwAg&usg=AFQjCNGE2Pu1PZYkfue-p1u7ZephK6mfuA&sig2=qnhH [Accessed 3 DEC 2014]. Read More