Applied Instrumentation Lab (8EI7)

Applied Instrumentation Lab8EI7

Experiment No. 1Object: - Setting Analog and Digital Link using Optical Fiber Apparatus: - Optical Fiber Trainer with power supply cord, Optical fiber cable 650 nm, Cathode Ray Oscilloscope (CRO), Connecting ProbesTheory: - Fiber optic links can be used for transmission of digital as well as analog signals. Basically a fiber optic link contains three main elements transmitter and optical fiber & a receiver. The transmitter module takes the input signal in electrical form and then transforms it into optical (light) energy containing the same information. The optical fiber is the medium, which carries this energy to the receiver. At the receiver, Light is converted back into electrical form with the same pattern as originally fed to the transmitter.

Analog Link:-

Emitter circuit Detector circuit

GndFunction Generator AC Amplifier 1 KHz Circuit

Fig. 1.1 Setting up Optical Fiber Analog Link

Observation: -

Input Voltage(V)Output Voltage(V)Time(ms)

Fig. 1.2 Connection diagram of analog link set upProcedure: - 1. Connect the power supply cord to the main power plug and to trainer.2. Ensure that all switch faults are OFF.3. Make the following connections as shown in fig. 1.2 a. Connect the function generator 1 KHz sine wave output to the emitter 1s input.b. Connect the fiber optic cablebetween the emitters output and detectors input.c. Detector 1s output to the ACamplifier 1s input.4. On the board switch emitter 1sdriver to analog mode.5. Switch ON the power supply of trainer and CRO.6. Observe the input to emitter (TP5) with the output from ACamplifier 1(TP 28) and note that the two signals are same. Digital Link: -

Emitter circuit Detector circuit

GndComparatorFunctionGenerator 1 KHz AC amplifier Circuit

Fig. 1.3 Setting up Optical Fiber Digital Link

Fig. 1.4 Connection diagram of digital link set up

Procedure: -

1. Connect the power supply cord to the main power plug and to trainer.2. Ensure that all switch faults are OFF.3. Make the following connections as shown in fig. 1.4. a. Connect the function generator 1 KHz sine wave output to the emitter 1s input.b. Connect the fiber optic cablebetween the emitters output and detectors input.c. Detector 1s output to the comparator 1s input.d. Comparators 1s output to AC amplifier 1s input. 4. On the board switch emitter 1sdriver to digital mode.5. Switch ON the power supply of trainer and CRO.6. Monitor both the inputs to comparator 1 (TP 13 & 14). Slowly adjust the Comparators bias preset, until DC level on the input (TP13) lays mid way between the high and low level of the signal on the positive input (TP 14). 7. Observe the input to emitter 1 (TP 5) with the output from AC amplifier 1 (TP 28) and note that the two signals are same.

Observation: -

Input Voltage(V)Output Voltage(V)Time(ms)

Result: - Thus we have setting up the analog and digital link in optical fiber.

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