optical communications

1. Send Message With Optic
Communication
2016Amir hosein Ataei 1
Change the symbols sent according to the entropy of the
transmit to reduce power as well as increase the
transmit rate

2. Introduction
• Due to the widespread use of networks and
communications in technology, it is therefore
very important to solve their problems today.
•The seminar that was reviewed during the
semester is aimed at expediting common network
protocols (Mesh Protocol, Hub Protocol, etc.) and
addressing their disadvantages, including (error,
noise, distortion), due to magnetic fields, reducing
power and increasing transmission rates.
•As you know, the most important parameter is high
speed communication with minimum error.
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3. work explanation
• This circuit can receive analog or digital
signal and transmit it through the OLT to the
optical pulse through the laser then receive
the optical pulse and then convert it to
electrical signal by the comparator.
OLT/
comparator
OLT/
comparator
Input Signal
Laser Detector
Output Signal
•This circuit is called Full Duplex.
Detector Laser
Block Diagram
OLT : Optical Line Terminal 3

4. ❖If the input signal is analog, it is converted
to an optical pulse by sequential sampling.
❖This method is the link between the wired
connection and its conversion into optical pulse
which reduces the network traffic and
minimizes the error.
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5. Schematic Circuit
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6. Circuit Function Description
• This circuit uses the Atmega32A
microcontroller, which uses a 4 * 4 Keypad to
generate characters. It scans the Micro
Keypad and stores the characters regularly,
then codes in the majority method and
assigns more 0-bit usernames to lower power
consumption. The transmitting frequency is
1MHz and each bit of data is sent every
20ms. The receiver has a 16 * 2 lcd to display
the transmitted information so 32 characters
are scanned and sent each time.
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7. How to get information
❖Each time the information is transmitted by a
Phototransistor in the same way that the Base
Laser excites the transistor, so that its
Collector current travels to the Emitter and is
compared to an Op-Amp with reference
voltage and then transmits the electric pulse to
the Micro.
Op-Amp Circuit
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8. Investigating topologies
Disadvantages Advantages Topology
Too many connections Minimum traffic Mesh
Blocking the Hub will disrupt the
entire network (all traffic is on
the Hub)
Minimum connections Hub
High traffic Each system is a Repeater Ring
High traffic and error Very low cost Bus
✓All protocols are noisy against fields caused by electricity.
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9. • The main purpose of this project is to solve the
problems of computer communication systems,
such as: low speed, long-distance signal loss,
distortion in the signal and noise, such as
auditory noise due to parallel cables passing
through each other and their magnetic fields.
✓For example: Data cables with power cables.
Cross Talk Noise
Project Development
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10. • One of the problems we face is
the effect of the magnetic field
caused by the power cable and
the deformation of the signal,
which is sometimes not resolved
by the Notch filter.
•Another problem is the
distance between the
transmitter and receiver.
✓Optimal fiber is one of the
best solutions.
Notch Filter
Optic Fiber 10

11. • If our transmission media is airborne in this
method due to the presence of flying objects, the
communication between the receiver and the
receiver may be faulty, so we recommend
switching the transmission medium to fiber optic
via Patch Cord.
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12. Advantages of Optical Fiber
I. We need less Repeater during shipping.
II. It is immune to the magnetic fields caused by
the flow of cables.
III. We send data from the cable system more
quickly so network traffic is down and data
can be transmitted faster.
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13. Project Optimization
• Zero-level transmissions can be problematic
when the propagation environment of this
method is airborne, so that changing the
environment can affect the Op-Amp circuit at
this time.
•We use PAM modulation to resolve this
problem.
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14. Pulse Amplitude Modulation
• The modulation is assigned to the zero level
and one voltage level each, meaning that the
other Op-Amp circuit has no problem
detecting the input signal by converting the
signal received by the comparator to the two
reference voltages and converting it into a
digital signal. Note that in this method the bit
zero is not due to error.
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15. ❖In this modulation the system error decreases
sharply but slightly increases power consumption.
❖Due to the use of lasers,
we cannot bring the zero
level down to 3v because the
Forward Voltage Laser is
about 2.7v and it should also
be higher than this voltage as
this level is the comparison
level between 0 and 1. 15

16. Multi Mode
❖The system can send multiple data at
different wavelengths via a patch cord, which
reduces cost;
❖1. LEDs can be used instead of lasers.
❖(But decreases working distance in MM)
❖2. The number of lines decreases.
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17. 1 17

18. 2 18

19. How to code in the Huffman
method
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20. 20

21. Huffman problems
• The source code is encoded by a fixed length,
majority method by field data collection.
•Another drawback of the Huffman method in this
circuit is that it has a higher bitrate value than the
bit rate due to the use of long-range lasers, which
increases the noise level which is not desirable.
•Because of this, the majority method was used
because the Huffman variable-length encoding results
in changes in the number of bandwidths required,
which is a problem with changing the timing sent per
different data.
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22. 22

23. 1
2 23

24. 24

25. entropy
• As can be seen, the untransformed source
entropy is less than the encoded entropies
(constant and invariant length), which is good
for the analog signal property.
✓To send numbers in this way, we compute the
probability of field numbers and we conclude
that the numbers are among the last values of
the probability table.
•Encoded sources are seen to have more
entropy, but in addition to our entropy slightly
changing, the advantages of digitally
transmitting data are high noise and bandwidth.
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26. Why Can Bit Zero Be So Influential?
• Due to the use of the Op-Amp circuit at the input of the
received signal and comparing that signal to a reference
level because:
• 1- Input signal amplification.
• 2- Compare the level of logical 0 and 1.
✓If a slight change in the ambient light level occurs when
the transmitter laser (which means the signal is zero),
the transceiver's transistor photocurrent may change the
signal level and eventually result in the transmitted data
becoming a conversion This was made easier by
adjusting the Multiturn connected to the Op-Amp and by
an ambient light detector such as the TSL230.
TSL230
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27. Power consumption
• In the majority-way classification, we
use code that has zero bits more than
one bit to consume less power.
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28. 0 / 1 {Codes} in visual basic
attached
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29. END