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Optics
Fibroptonic
Ref : 202 012
3 Experiment no. 6
Optical transmission of logical information.
Figure 11: Oscillogram corresponding to the rapid switching to change from logic state 0
to state 1.
ENGLISH
3.1 Equipment:
•
Transmitter
•
Receiver
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Optical fibre connected to the transmitter and receiver
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6, 9 or 12 V DC power supply
•
Oscilloscope
3.2 Set-up:
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Power the transmitter and the receiver (red terminal to +, black terminal to -)
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Connect the fibre properly to the 2 units (see figure 4)
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Place the microphone switch on the EXT position.
3.3 Experiment:
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Toggle the other switch alternately (On – Off positions).
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When the switch is on ON, the green LED comes on, an infrared signal is sent
through the fibre. This signal is detected by the photoreceptor, the red LED comes
on.
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If we disconnect the optical fibre, the infrared signal cannot be detected: the red
LED goes off.
•
These 2 binary logic states (state 1: LED is on / state 0: LED is off) can be viewed
on the oscilloscope. For this, connect the yellow and black terminals of the receiver
to the oscilloscope (yellow: channel A and black to the ground of the device). The
selector switch of the oscilloscope must be on the DC position. When the LEDs are
on, the amplitude of the signal on the oscilloscope reaches 0.4 to 0.7 V (depends
on the supply voltage of the transmitter and receiver and on the length of the optical
fibre).
•
Figure 11 shows the appearance of a signal detected on the oscilloscope when the
switch of the transmitter unit is quickly toggled (On – Off).
State 1 : Green and red LED on
State 0 :LED off
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