This document discusses several topics related to optical fiber communication systems including:
1. Factors that limit the performance of amplified fiber links such as transmission distance, data rate, and component costs.
2. System requirements including transmission distance, data rate, fiber type, and receiver sensitivities.
3. Key components of fiber optic systems and their specifications including lasers, detectors, and other elements.
4. Performance limiting factors for terrestrial and undersea lightwave systems.
5. Physical phenomena that degrade receiver sensitivity in realistic lightwave systems including modal noise and dispersion broadening.
Introduction to basics of wireless networks such as
• Radio waves & wireless signal encoding techniques
• Wireless networking issues & constraints
• Wireless internetworking devices
Hello everyone. This is a short presentation on path loss and shadowing. I have not covered all the topics but a brief idea is given on path loss and wireless channel propagation models.
Hope you find it useful.
Thanks
Introduction to basics of wireless networks such as
• Radio waves & wireless signal encoding techniques
• Wireless networking issues & constraints
• Wireless internetworking devices
Hello everyone. This is a short presentation on path loss and shadowing. I have not covered all the topics but a brief idea is given on path loss and wireless channel propagation models.
Hope you find it useful.
Thanks
The attached narrated power point presentation attempts to explain the methods of computation of total power loss and system rise time in a fiber optic link. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
Unit II- TRANSMISSION CHARACTERISTIC OF OPTICAL FIBER tamil arasan
Attenuation - Absorption losses, Scattering losses, Bending Losses, Core and Cladding losses, Signal Distortion in Optical Wave guides-Information Capacity determination -Group Delay-Material Dispersion, Wave guide Dispersion, Signal distortion in SM fibers-Polarization Mode dispersion, Intermodal dispersion, -Design Optimization of SM fibers-RI profile and cut-off wavelength.
In this chapter we examine the capacity of a single-user wireless channel where transmitter and/or receiver have a single antenna. We will discuss capacity for channels that are both time invariant and time varying. We first look at the well-known formula for capacity of a time-invariant additive white Gaussian noise (AWGN) channel and then consider capacity of time-varying flat fading channels. We will first consider flat fading channel capacity where only the fading distribution is known at the transmitter and receiver. We will also treat capacity of frequency-selective fading channels. For time -invariant frequency-selective channels the capacity is known and is achieved with an optimal power allocation that water-fills over frequency instead of time. We will consider only discrete-time systems in this chapter.
The attached narrated power point presentation attempts to explain the methods of computation of total power loss and system rise time in a fiber optic link. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
Unit II- TRANSMISSION CHARACTERISTIC OF OPTICAL FIBER tamil arasan
Attenuation - Absorption losses, Scattering losses, Bending Losses, Core and Cladding losses, Signal Distortion in Optical Wave guides-Information Capacity determination -Group Delay-Material Dispersion, Wave guide Dispersion, Signal distortion in SM fibers-Polarization Mode dispersion, Intermodal dispersion, -Design Optimization of SM fibers-RI profile and cut-off wavelength.
In this chapter we examine the capacity of a single-user wireless channel where transmitter and/or receiver have a single antenna. We will discuss capacity for channels that are both time invariant and time varying. We first look at the well-known formula for capacity of a time-invariant additive white Gaussian noise (AWGN) channel and then consider capacity of time-varying flat fading channels. We will first consider flat fading channel capacity where only the fading distribution is known at the transmitter and receiver. We will also treat capacity of frequency-selective fading channels. For time -invariant frequency-selective channels the capacity is known and is achieved with an optimal power allocation that water-fills over frequency instead of time. We will consider only discrete-time systems in this chapter.
Optical Fiber Communication Part 3 Optical Digital ReceiverMadhumita Tamhane
Current generated by photodetector is very weak and is adversely effected by random noises associated with photo detection process. When amplified, this signal further gets corrupted by amplifiers. Noise considerations are thus important in designing optical receivers.
Most meaningful criteria for measuring performance of a digital communication system is average error probability, and in analog system, it is peak signal to rms noise ratio. ...
the power point presentation explain wave nature of light .in present ppt explain interference and diffraction of light and also explain the basic difference between interference and differaction
Transmission system used for optical fibers Jay Baria
In this presentation I have explained various types of transmission system used for optical transmission and also described about the budget method that has to be followed while selecting an source for optical fibers and also about the factors that should be consider while selecting an source.
The attached narrated power point presentation attempts to explain the various digital communication techniques as applied to optical communications. The material will be useful for KTU final year B tech students who prepare for the subject EC 405, Optical Communications.
Fundamental of Radio Frequency communications.pptginanjaradi2
Fundamentals of Radio Frequency (RF) communications encompass the principles and techniques used to transmit and receive information wirelessly using electromagnetic waves within the radio frequency spectrum. Here's a breakdown of the key components:
1. **Electromagnetic Spectrum**: RF communications utilize a portion of the electromagnetic spectrum. This spectrum ranges from low frequencies used for power transmission to high frequencies used in technologies like microwaves and beyond. RF typically occupies the frequency range from about 3 kHz to 300 GHz.
2. **Modulation**: Modulation is the process of impressing information onto a radio wave by varying one or more of its properties such as amplitude, frequency, or phase. Common modulation techniques include Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM).
3. **Transmitters**: Transmitters generate radio frequency signals carrying the information to be transmitted. They typically consist of an oscillator to produce the carrier frequency, modulation circuitry to impress the information onto the carrier, and amplifiers to boost the signal for transmission.
4. **Receivers**: Receivers capture radio frequency signals, extract the desired information, and convert it into a usable form. Receivers include components such as antennas to capture the incoming signal, amplifiers to boost weak signals, demodulators to extract the information from the carrier, and filters to remove unwanted noise and interference.
5. **Antennas**: Antennas are crucial components for both transmitting and receiving RF signals. They convert electrical signals into electromagnetic waves for transmission and vice versa for reception. Antennas come in various designs optimized for different applications, such as dipole antennas, patch antennas, and parabolic antennas.
6. **Propagation**: RF signals propagate through the atmosphere, and their behavior is influenced by factors such as frequency, distance, terrain, and environmental conditions. Understanding propagation characteristics is essential for designing efficient communication systems.
7. **Propagation Models**: Propagation models describe how RF signals propagate in different environments. These models help engineers predict signal strength, coverage areas, and potential sources of interference. Common models include free-space path loss, multipath fading, and terrain-based models.
8. **Spectrum Management**: Since the radio frequency spectrum is a finite and shared resource, its allocation and usage are regulated by government agencies such as the Federal Communications Commission (FCC) in the United States. Spectrum management involves allocating frequency bands to different users, enforcing regulations to prevent interference, and promoting efficient spectrum utilization.
9. **Applications**: RF communications find applications in various fields, including broadcasting, telecommunications, wireless networking.
3. From an architectural standpoint, it is
classified as,…
POINT TO POINT LINKS
DISTRIBUTION NETWORKS
LOCAL AREA NETWORKS
4. • They transport information, available in the form
of a digital bit stream
• The link length can vary from less than a
kilometer to 1000’s of kilometer
• They are used for high speed transmission
• Optical regenerators should perform,
1. Re-amplification
2. Re-shaping
3. Re-timing
6. o Attenuation
o Distance Bandwidth Product
o Cost of the connectors
o Splicing
Then decide,
• single or multimode fiber
• step or graded index fiber
10. PN = (PT /N)(1−δ )log2N
where ,
δ is the insertion loss of each directional coupler.
δ = 0.05
PT =1 Mw
PN = 0.1 μW
N can be as large as 500
11. PN = PTC[(1−δ )(1−C)]N−1
where ,
PT is the transmitted power
C is the fraction of power coupled out at each tap
δ accounts for insertion losses, assumed to be the
same at each tap
N should not exceed 60.
12.
13.
14.
15. Link Power Budget
◦ There is enough power margin in the system
to meet the given BER
Rise Time Budget
◦ Each element of the link is fast enough to
meet the given bit rate
19. Type of detector
APD: High sensitivity but complex, high bias
voltage (40V or more) and expensive
PIN: Simpler, thermally stable, low bias
voltage (5V or less) and less expensive
Responsivity (that depends on the avalanche
gain & quantum efficiency)
Operating wavelength and spectral selectivity
Speed (capacitance) and photosensitive area
Sensitivity (depends on noise and gain)
20. Wavelength LED Systems LASER
Systems.
800-900 nm 150 Mb/s.km 2500 Mb/s.km
(Typically
Multimode
Fiber)
1300 nm (Lowest 1500 Mb/s.km 25 Gb/s.km
dispersion) (InGaAsP Laser)
1550 nm (Lowest 1200 Mb/s.km Up to 500
Attenuation) Gb/s.km
(Best demo)
21. If the signal is detected by a receiver that
requires a minimum average power at the bit
rate B, the maximum transmission distance is
limited
The system requirements typically specified in
advance are the bit rate B and the
transmission distance L
The performance criterion is specified through
the bit-error rate (BER), a typical requirement
being BER < 10−9.
22. • When the dispersion-limited transmission
distance is shorter than the loss-limited
distance of the system is said to be dispersion
limited.
BL ≤ (4|D|σλ )−1
• A solution to the dispersion problem is
offered by dispersion-shifted fibers for
which dispersion and loss both are minimum
near 1.55 μm.
23. o The purpose of the power budget is to ensure
that enough power will reach the receiver to
maintain reliable performance during the entire
system lifetime
o The minimum average power required by the
receiver is the receiver sensitivity
o It is expressed in dBm
24. • Used to ensure that the system is able to operate
properly at the intended bit rate
• Even if the bandwidth of the individual system
components exceeds the bit rate, it is still possible
that the total system may not be able to operate at
that bit rate
• It is used to allocate the bandwidth among
various components
25. • The rise time Tr of a linear system is defined as the
time during which the response increases from 10 to
90% of its final output value when the input is
changed abruptly.
• When the input voltage across an RC circuit
changes instantaneously from 0 to V0, the output
voltage changes as,
Vout(t) =V0[1−exp(−t/RC)]
26.
27. Here we focus on the factors that limit the
performance of amplified fiber links
It depends on following factors,
1. Performance - limiting factor
2. Terrestrial light wave systems
3. Undersea light wave systems
28.
29. The sensitivity of the optical receiver in a realistic
lightwave system is affected by several physical
phenomena which, in combination with fiber
dispersion, degrade the SNR at the decision circuit
30. Among the phenomena that degrade the receiver
sensitivity are,
1. Modal noise
2. Dispersion broadening
3. Intersymbol interference
4. Mode-partition noise
5. Frequency chirp
6. Reflection feedback.