Yankee Stadium implemented a wireless infrared LAN to connect cash registers to a central server for food ordering. Infrared was chosen for its low cost and ability to operate within the stadium without interfering with games. However, infrared has short range and low speeds, limiting its use to this localized application within the stadium.
In telecommunications and computer networking, a communication channel or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel. A channel is used to convey an information signal, for example a digital bit stream, from one or several senders (or transmitters) to one or several receivers. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second.Communicating data from one location to another requires some form of pathway or medium. These pathways, called communication channels, use two types of media: cable (twisted-pair wire, cable, and fiber-optic cable) and broadcast (microwave, satellite, radio, and infrared). Cable or wire line media use physical wires of cables to transmit data and information. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass.
These are examples of commonly used channel capacity and performance measures:
Spectral bandwidth in Hertz
Symbol rate in baud, pulses/s or symbols/s
Digital bandwidth bit/s measures: gross bit rate (signalling rate), net bit rate (information rate), channel capacity, and maximum throughput
Channel utilization
Link spectral efficiency
Signal-to-noise ratio measures: signal-to-interference ratio, Eb/No, carrier-to-interference ratio in decibel
Bit-error rate (BER), packet-error rate (PER)
Latency in seconds: propagation time, transmission time
Delay jitter
Chapter 4-Transmission Media - guided and unguided .pptxssuser32eccd
transmission medium is the physical path between transmitter and receiver
guided media – guided along a solid medium
unguided media – atmosphere, space, water
characteristics and quality determined by medium and signal
guided media - medium is more important
unguided media - bandwidth produced by the antenna is more important
key concerns are data rate and distance
It includes defination and components of network, types of network according to area coverage, along with major types of transmission/communication media.
In telecommunications and computer networking, a communication channel or channel, refers either to a physical transmission medium such as a wire, or to a logical connection over a multiplexed medium such as a radio channel. A channel is used to convey an information signal, for example a digital bit stream, from one or several senders (or transmitters) to one or several receivers. A channel has a certain capacity for transmitting information, often measured by its bandwidth in Hz or its data rate in bits per second.Communicating data from one location to another requires some form of pathway or medium. These pathways, called communication channels, use two types of media: cable (twisted-pair wire, cable, and fiber-optic cable) and broadcast (microwave, satellite, radio, and infrared). Cable or wire line media use physical wires of cables to transmit data and information. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass.
These are examples of commonly used channel capacity and performance measures:
Spectral bandwidth in Hertz
Symbol rate in baud, pulses/s or symbols/s
Digital bandwidth bit/s measures: gross bit rate (signalling rate), net bit rate (information rate), channel capacity, and maximum throughput
Channel utilization
Link spectral efficiency
Signal-to-noise ratio measures: signal-to-interference ratio, Eb/No, carrier-to-interference ratio in decibel
Bit-error rate (BER), packet-error rate (PER)
Latency in seconds: propagation time, transmission time
Delay jitter
Chapter 4-Transmission Media - guided and unguided .pptxssuser32eccd
transmission medium is the physical path between transmitter and receiver
guided media – guided along a solid medium
unguided media – atmosphere, space, water
characteristics and quality determined by medium and signal
guided media - medium is more important
unguided media - bandwidth produced by the antenna is more important
key concerns are data rate and distance
It includes defination and components of network, types of network according to area coverage, along with major types of transmission/communication media.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
for beginners, providing thorough training in areas such as SEO, digital communication marketing, and PPC training in Noida. After finishing the program, students receive the certifications recognised by top different universitie, setting a strong foundation for a successful career in digital marketing.
2. Transmission Media
• Two basic formats
– Guided media : wires, fiber optics
• Medium is important
– Unguided media : wireless, radio transmission
• Antenna is important
• Each have tradeoffs over data rate, distance
– Attenuation : weakening of signal over distance
3. Mini Electromagnetic Review
• Take a sound wave…
Frequency (hz) = Number of cycles/second
With a constant wave velocity, frequency = velocity / wavelength
For electromagnetic waves, f = c / w ; c = speed of light
4. Mini Electromagnetic Review
Same principle with electrical waves:
Station at 88.1 FM = 88.1 Mhz
88100000 = 3.0 * 10^8 / w
w = 3.0 * 10^8 / 88100000
= 3.4 meters
Time to travel this far is 1/f or
0.000000011 seconds
7. Twisted Pair
Pair of copper wires constitutes a single communication link.
Twists minimize the effects of electromagnetic interference
- emit less emag energy
- less susceptible to emag energy
8. Twisted Pair - Applications
• Most common medium
• Telephone network
– POTS
– Between house and local exchange (subscriber loop), also
called the end office. From the end office to Central Office
(CO) class 4 CO class 1 via Public Switched Telephone
Network (PSTN)
• Within buildings
– To private branch exchange (PBX)
• For local area networks (LAN)
– 10Mbps or 100Mbps
– Possible to rev up to 1Gbps – Gigabit Ethernet
9. Twisted Pair - Pros and Cons
• Cheap
• Easy to work with
– Can use as digital or analog
• Limited bandwidth/data rate
– Generally 1Mhz and 100Mbps
• Short range
– 2km for digital, 5km for analog
• Direct relationship between data rate and range
– Gigabit Ethernet
• 1000Mbps over 4 Cat5 UTP up to 100 meters
– IEEE 802.3ab standard in 1999
• 1000Mbps over 1 Cat5 UTP up to 24 meters
10. Unshielded and Shielded TP
• Unshielded Twisted Pair (UTP)
– Ordinary telephone wire
– Cheapest
– Easiest to install
– Suffers from external EM interference
• Shielded Twisted Pair (STP)
– Metal braid or sheathing that reduces interference
– More expensive
– Harder to handle (thick, heavy)
11. UTP Categories
• Cat 1
– Used for audio frequencies, speaker wire, etc. Not for
networking.
• Cat 2
– Up to 1.5Mhz, used for analog phones, not for
networking
• Cat 3
– EIA 568-A Spec from here on up
– up to 16MHz
– Voice grade found in most offices
– Twist length of 7.5 cm to 10 cm
• Cat 4
– up to 20 MHz
– Not frequently used today, was used for Token Ring
12. UTP Categories Cont.
• Cat 5
– up to 100MHz
– Twist length 0.6 cm to 0.85 cm
– Commonly pre-installed in new office buildings
• Cat 5e “Enhanced”
– Up to 100Mhz
– Specifies minimum characteristics for NEXT (Near End Crosstalk)
and ELFEXT (Equal level far end crosstalk)
• Coupling of signal from one pair to another
• Coupling takes place when transmit signal entering the link
couples back to receiving pair, i.e. near transmitted signal is
picked up by near receiving pair
• Cat 6
– Proposed standard up to 250Mhz
• Cat 7
– Proposed standard up to 600Mhz
16. Coaxial Cable Applications
• Most versatile medium
• Television distribution
– Cable TV
• Long distance telephone transmission
– Can carry 10,000 voice calls simultaneously
– Being replaced by fiber optic
• Short distance computer systems links
• Local area networks
– More expensive than twisted pair, not as popular for
LANs
17. Coaxial Cable Characteristics
• Analog – Broadband Coaxial Cable
– Amplifiers every few km, closer if higher frequency
– Up to 500MHz
– Cable TV, Cable Modems (~10Mbps)
• Digital – Baseband Coaxial Cable
– Repeater every 1km
– Closer for higher data rates
Name Type Mbps m In…
RG-58 Coax 10 185 10Base2, “ThinNet”
RG-8 Coax 10 500 10Base5, “ThickNet”
19. Optical Fiber
Breakthrough in data transmission systems!
Core: Thin strands of glass
Cladding: Glass with different optical properties than core
Jacket: Plastic/Insulation
20. Optical Fiber - Benefits
• Greater capacity
– Data rates of hundreds of Gbps
– Tbps demonstrated using WDM
• Smaller size & weight
– Order of magnitude smaller than TP/Coax
• Lower attenuation
• Electromagnetic isolation
– Not vulnerable to interference, impulse, crosstalk!
• Greater repeater spacing
– Often 10’s of kilometers
• Hard to tap
21. Optical Fiber Transmission Modes
Gradient refraction in core allows light to curve helically, more coherent at end
Shrink core to allow only a single angle or mode, light reflect in only one pattern
Rays at shallow angles reflect; multiple propagation path spreads signal out over time
22. Wireless or Radiated
Transmission
• Unguided media
• Transmission and reception via antenna
– Desirable to make antenna one-quarter or one-half the
wavelength
• Directional
– Focused beam
– Careful alignment required
• Omnidirectional
– Signal spreads in all directions
– Can be received by many antennas
23. Frequencies
• 2GHz to 40GHz
– Microwave
– Highly directional
– Point to point
– Satellite
• 30MHz to 1GHz
– Omnidirectional
– Broadcast radio
• 3 x 1011 to 2 x 1014
– Infrared
– Local
• Higher frequencies Higher data rates
24. Terrestrial Microwave
• Typically parabolic dish, focused beam, line of
sight
• Max distance between antenna:
d=7.14 * Sqrt(hK) ; K=4/3,
; h=antenna ht in meters
; d=distance in km
so two 1 meter antenna can be 7.14*Sqrt(4/3)=8.2 km
apart
• Applications
– Long haul telecommunications, television. May need
repeaters
– Short range for BN or closed-circuit TV
25. Terrestrial Microwave
• Data rate increases with frequency
– 2 Ghz Band 7 Mhz Bandwidth 12 Mbps
– 6 Ghz Band 30 Mhz Bandwidth 90 Mbps
– 11 Ghz Band 40 Mhz Bandwidth 135 Mbps
– 18 Ghz Band 220 Mhz Bandwidth 274 Mbps
• Attenuation
– Loss varies with the square of the distance
– TP/Coax: loss varies with log of distance / linear in dB
– Therefore, we don’t need as many repeaters with microwave
• Interference and Raindrop Attenuation
– Frequency bands strictly regulated
– Use lower frequency to avoid raindrop problem
dB
d
Loss
2
4
log
10
26. Satellite Microwave
• Satellite is relay station
• Satellite receives on one frequency, amplifies or
repeats signal and transmits on another
frequency/frequencies (transponder channels)
• Typically geo-stationary orbit
– Height of 35,784km or 22,236 miles
– 4 degree spacing in 4/6Ghz Band
– 3 degree spacing in 12/14 Ghz Band
• Applications
– TV, telephone
– Private business networks
– VSAT (Very Small Aperture Terminal)
• Large corp. with distributed sites
• Small receiver to Ku-band satellite to Big earth hub
• Used by RCA in late 1994 for Direct Broadcast System
27. Satellite Transmission
Characteristics
• Optimum Frequency Range 1-10Ghz
– Below 1Ghz, natural noise. Above 10Ghz, attenuation
from the atmosphere
– Most applications use the 5.925-6.425 Ghz range
uplink, 4.2-4.7Ghz range downlink (4/6 Ghz Band)
• Propagation delay
– 35784000m / 3.0 * 108 m/s 0.12 seconds one way
– About quarter second propagation delay round trip,
noticeable for phone conversations, problem for two-
way communications
• Error /flow control?
• Low orbit satellites a solution? (Iridium, Tachyon)
28. Broadcast Radio
• 30Mhz to 2 Ghz
• Omnidirectional
– Use loop or wire antenna instead of dish
• Applications
– Range covers FM radio, UHF and VHF television
– 802.11b operates in the 2.4Ghz ISM band
• Due to lower frequencies than microwave, less
problems with attenuation
• Same equation for antenna distance, attenuation as
microwave
• Drawbacks
– Suffers from multipath interference, Reflections
– Possible security concerns
29. Infrared
• Modulate noncoherent infrared light
• Line of sight (or reflection)
• Blocked by walls
• Problems
– Short range, usually 50-75 feet maximum
– Low speed, 1-4 Mbps
• e.g. TV remote control, IRD port
– For networks, typically only used to connect wireless
hubs due to the need for direct line-of-sight
30. Media Selection
Network Transmission Error
Media Type Cost Distance Security Rates Speed
Twisted Pair LAN Low Short Good Low Low-high
Coaxial Cable LAN Mod. Short-Mod Good Low Low-high
Fiber Optics any High Mod.-long V. Good V.Low High-V.High
Network Transmission Error
Media Type Cost Distance Security Rates Speed
Radio LAN Low Short Poor Mod Low
Infrared LAN, BN Low Short Poor Mod Low
Microwave WAN Mod Long Poor Low-Mod Mod
Satellite WAN Mod Long Poor Low-Mod Mod
Guided Media
Radiated Media
31. Sample App:
Yankee Stadium Food
Service
“Food Service Without
Missing the Game,” Network
Computing (Oct 1, 1996)