Walkie talkies use radio frequency modulation and transmission to enable communication. They were first developed in the late 1930s and used heavily by the military during World War II due to their portability. Walkie talkies use a transceiver that combines a transmitter and receiver in a single unit. The audio signal is modulated onto a radio carrier wave using a modulation method like frequency modulation. This modulated signal is transmitted through an antenna to another walkie talkie where it is demodulated to recover the original audio. Frequency modulation is preferred over amplitude modulation for walkie talkies as it provides better sound quality and range for communications over longer distances.
In this ppt you will know about walkie - talkie and its uses , advantages ,why walkie talkie used ,block diagram of walkie - talkie and circuit description of walkie - talkie, which will helpful to you for presentation and also you can improve your knowledge.
Topics covered in this presentation:
Radio & Microwave Communication.
2. Spectrum Management.
3. Digital Microwave Systems.
4. Fading and measures to counter Fading effect.
5. Digital Microwave link – Performance Objectives.
6. Modulation Methods.
7. A word about BWA
8. Other wireless communication Applications
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
In this ppt you will know about walkie - talkie and its uses , advantages ,why walkie talkie used ,block diagram of walkie - talkie and circuit description of walkie - talkie, which will helpful to you for presentation and also you can improve your knowledge.
Topics covered in this presentation:
Radio & Microwave Communication.
2. Spectrum Management.
3. Digital Microwave Systems.
4. Fading and measures to counter Fading effect.
5. Digital Microwave link – Performance Objectives.
6. Modulation Methods.
7. A word about BWA
8. Other wireless communication Applications
What is GSM?
The Global System for Mobile communications is a digital cellular communications system. It was developed in order to create a common European mobile telephone standard but it has been rapidly accepted worldwide.
Formerly it was “Groupe Spéciale Mobile” (founded in 1982)
now: Global System for Mobile Communication.
Services:
Tele-services
Bearer or Data Services
Supplementary services
Applications:
Mobile telephony
GSM-R
Telemetry System
- Fleet management
- Automatic meter reading
- Toll Collection
- Remote control and fault reporting of DG sets
Value Added Services
Advantages:
Better Quality of speech
Data transmission is supported
New services offered due to ISDN compatibility
International Roaming possible
Large market
Crisper, cleaner quieter calls
disadvantages:
Dropped and missed calls
Less Efficiency
Security Issues
conclusion
The mobile telephony industry rapidly growing and that has become backbone for business success and efficiency and a part of modern lifestyles all over the world.
In this session I have tried to give and over view of the GSM system. I hope that I gave the general flavor of GSM and the philosophy behind its design.
The GSM is standard that insures interoperability without stifling competition and innovation among the suppliers to the benefit of the public both in terms of cost and service quality.
Frequency-Shift Keying, also known as FSK is a type of digital frequency modulation. It is also often called as binary frequency shift keying or BFSK
Similar to analog FM, it is a constant-amplitude angle modulation.
This presentation will discuss the concepts behind FSK
Ground wave propagation, Sky wave propagation, Space Wave propagation, Multi hop propagation, Duct wave propagation, LOS propagation, Ionospheric Layers
Loss of strength, A periodic reduction in the received strength of a radio transmission.
This is about the phenomenon of loss of signal in telecommunications.Fading refers to the
time variation of the received signal power caused by changes in the transmission medium or path.
Frequency-Shift Keying, also known as FSK is a type of digital frequency modulation. It is also often called as binary frequency shift keying or BFSK
Similar to analog FM, it is a constant-amplitude angle modulation.
This presentation will discuss the concepts behind FSK
Ground wave propagation, Sky wave propagation, Space Wave propagation, Multi hop propagation, Duct wave propagation, LOS propagation, Ionospheric Layers
Loss of strength, A periodic reduction in the received strength of a radio transmission.
This is about the phenomenon of loss of signal in telecommunications.Fading refers to the
time variation of the received signal power caused by changes in the transmission medium or path.
This presentation deals with topics such as Electromagnetic Spectrum, Wireless Propagation, Signals, Signal propagation effects, Spread spectrum and cellular systems.
AM – Frequency spectrum – vector representation – power relations – generation of AM – DSB, DSB/SC, SSB, VSB AM Transmitter & Receiver; FM and PM – frequency spectrum – power relations : NBFM & WBFM, Generation of FM and DM, Armstrong method & Reactance modulations : FM & PM frequency.
Maximizing Your Streaming Experience with XCIPTV- Tips for 2024.pdfXtreame HDTV
In today’s digital age, streaming services have become an integral part of our entertainment lives. Among the myriad of options available, XCIPTV stands out as a premier choice for those seeking seamless, high-quality streaming. This comprehensive guide will delve into the features, benefits, and user experience of XCIPTV, illustrating why it is a top contender in the IPTV industry.
As a film director, I have always been awestruck by the magic of animation. Animation, a medium once considered solely for the amusement of children, has undergone a significant transformation over the years. Its evolution from a rudimentary form of entertainment to a sophisticated form of storytelling has stirred my creativity and expanded my vision, offering limitless possibilities in the realm of cinematic storytelling.
From Slave to Scourge: The Existential Choice of Django Unchained. The Philos...Rodney Thomas Jr
#SSAPhilosophy #DjangoUnchained #DjangoFreeman #ExistentialPhilosophy #Freedom #Identity #Justice #Courage #Rebellion #Transformation
Welcome to SSA Philosophy, your ultimate destination for diving deep into the profound philosophies of iconic characters from video games, movies, and TV shows. In this episode, we explore the powerful journey and existential philosophy of Django Freeman from Quentin Tarantino’s masterful film, "Django Unchained," in our video titled, "From Slave to Scourge: The Existential Choice of Django Unchained. The Philosophy of Django Freeman!"
From Slave to Scourge: The Existential Choice of Django Unchained – The Philosophy of Django Freeman!
Join me as we delve into the existential philosophy of Django Freeman, uncovering the profound lessons and timeless wisdom his character offers. Through his story, we find inspiration in the power of choice, the quest for justice, and the courage to defy oppression. Django Freeman’s philosophy is a testament to the human spirit’s unyielding drive for freedom and justice.
Don’t forget to like, comment, and subscribe to SSA Philosophy for more in-depth explorations of the philosophies behind your favorite characters. Hit the notification bell to stay updated on our latest videos. Let’s discover the principles that shape these icons and the profound lessons they offer.
Django Freeman’s story is one of the most compelling narratives of transformation and empowerment in cinema. A former slave turned relentless bounty hunter, Django’s journey is not just a physical liberation but an existential quest for identity, justice, and retribution. This video delves into the core philosophical elements that define Django’s character and the profound choices he makes throughout his journey.
Link to video: https://youtu.be/GszqrXk38qk
Panchayat Season 3 - Official Trailer.pdfSuleman Rana
The dearest series "Panchayat" is set to make a victorious return with its third season, and the fervor is discernible. The authority trailer, delivered on May 28, guarantees one more enamoring venture through the country heartland of India.
Jitendra Kumar keeps on sparkling as Abhishek Tripathi, the city-reared engineer who ends up functioning as the secretary of the Panchayat office in the curious town of Phulera. His nuanced depiction of a young fellow exploring the difficulties of country life while endeavoring to adjust to his new environmental factors has earned far and wide recognition.
Neena Gupta and Raghubir Yadav return as Manju Devi and Brij Bhushan Dubey, separately. Their dynamic science and immaculate acting rejuvenate the hardships of town administration. Gupta's depiction of the town Pradhan with an ever-evolving outlook, matched with Yadav's carefully prepared exhibition, adds profundity and credibility to the story.
New Difficulties and Experiences
The trailer indicates new difficulties anticipating the characters, as Abhishek keeps on wrestling with his part in the town and his yearnings for a superior future. The series has reliably offset humor with social editorial, and Season 3 looks ready to dig much more profound into the intricacies of rustic organization and self-awareness.
Watchers can hope to see a greater amount of the enchanting and particular residents who have become fan top picks. Their connections and the one of a kind cut of-life situations give a reviving and interesting portrayal of provincial India, featuring the two its appeal and its difficulties.
A Mix of Humor and Heart
One of the signs of "Panchayat" is its capacity to mix humor with sincere narrating. The trailer features minutes that guarantee to convey giggles, as well as scenes that pull at the heartstrings. This equilibrium has been a critical calculate the show's prosperity, resounding with crowds across different socioeconomics.
Creation Greatness
The creation quality remaining parts first rate, with the beautiful setting of Phulera town filling in as a scenery that upgrades the narrating. The meticulousness in portraying provincial life, joined with sharp composition and solid exhibitions, guarantees that "Panchayat" keeps on hanging out in the packed web series scene.
Expectation and Delivery
As the delivery date draws near, expectation for "Panchayat" Season 3 is at a record-breaking high. The authority trailer has previously created critical buzz, with fans enthusiastically anticipating the continuation of Abhishek Tripathi's excursion and the new undertakings that lie ahead in Phulera.
All in all, the authority trailer for "Panchayat" Season 3 recommends that watchers are in for another drawing in and engaging ride. Yet again with its charming characters, convincing story, and ideal mix of humor and show, the new season is set to enamor crowds. Write in your schedules and prepare to get back to the endearing universe of "Panchayat."
From the Editor's Desk: 115th Father's day Celebration - When we see Father's day in Hindu context, Nanda Baba is the most vivid figure which comes to the mind. Nanda Baba who was the foster father of Lord Krishna is known to provide love, care and affection to Lord Krishna and Balarama along with his wife Yashoda; Letter’s to the Editor: Mother's Day - Mother is a precious life for their children. Mother is life breath for her children. Mother's lap is the world happiness whose debt can never be paid.
In the vast landscape of cinema, stories have been told, retold, and reimagined in countless ways. At the heart of this narrative evolution lies the concept of a "remake". A successful remake allows us to revisit cherished tales through a fresh lens, often reflecting a different era's perspective or harnessing the power of advanced technology. Yet, the question remains, what makes a remake successful? Today, we will delve deeper into this subject, identifying the key ingredients that contribute to the success of a remake.
Scandal! Teasers June 2024 on etv Forum.co.zaIsaac More
Monday, 3 June 2024
Episode 47
A friend is compelled to expose a manipulative scheme to prevent another from making a grave mistake. In a frantic bid to save Jojo, Phakamile agrees to a meeting that unbeknownst to her, will seal her fate.
Tuesday, 4 June 2024
Episode 48
A mother, with her son's best interests at heart, finds him unready to heed her advice. Motshabi finds herself in an unmanageable situation, sinking fast like in quicksand.
Wednesday, 5 June 2024
Episode 49
A woman fabricates a diabolical lie to cover up an indiscretion. Overwhelmed by guilt, she makes a spontaneous confession that could be devastating to another heart.
Thursday, 6 June 2024
Episode 50
Linda unwittingly discloses damning information. Nhlamulo and Vuvu try to guide their friend towards the right decision.
Friday, 7 June 2024
Episode 51
Jojo's life continues to spiral out of control. Dintle weaves a web of lies to conceal that she is not as successful as everyone believes.
Monday, 10 June 2024
Episode 52
A heated confrontation between lovers leads to a devastating admission of guilt. Dintle's desperation takes a new turn, leaving her with dwindling options.
Tuesday, 11 June 2024
Episode 53
Unable to resort to violence, Taps issues a verbal threat, leaving Mdala unsettled. A sister must explain her life choices to regain her brother's trust.
Wednesday, 12 June 2024
Episode 54
Winnie makes a very troubling discovery. Taps follows through on his threat, leaving a woman reeling. Layla, oblivious to the truth, offers an incentive.
Thursday, 13 June 2024
Episode 55
A nosy relative arrives just in time to thwart a man's fatal decision. Dintle manipulates Khanyi to tug at Mo's heartstrings and get what she wants.
Friday, 14 June 2024
Episode 56
Tlhogi is shocked by Mdala's reaction following the revelation of their indiscretion. Jojo is in disbelief when the punishment for his crime is revealed.
Monday, 17 June 2024
Episode 57
A woman reprimands another to stay in her lane, leading to a damning revelation. A man decides to leave his broken life behind.
Tuesday, 18 June 2024
Episode 58
Nhlamulo learns that due to his actions, his worst fears have come true. Caiphus' extravagant promises to suppliers get him into trouble with Ndu.
Wednesday, 19 June 2024
Episode 59
A woman manages to kill two birds with one stone. Business doom looms over Chillax. A sobering incident makes a woman realize how far she's fallen.
Thursday, 20 June 2024
Episode 60
Taps' offer to help Nhlamulo comes with hidden motives. Caiphus' new ideas for Chillax have MaHilda excited. A blast from the past recognizes Dintle, not for her newfound fame.
Friday, 21 June 2024
Episode 61
Taps is hungry for revenge and finds a rope to hang Mdala with. Chillax's new job opportunity elicits mixed reactions from the public. Roommates' initial meeting starts off on the wrong foot.
Monday, 24 June 2024
Episode 62
Taps seizes new information and recruits someone on the inside. Mary's new job
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Tom Selleck Net Worth: A Comprehensive Analysisgreendigital
Over several decades, Tom Selleck, a name synonymous with charisma. From his iconic role as Thomas Magnum in the television series "Magnum, P.I." to his enduring presence in "Blue Bloods," Selleck has captivated audiences with his versatility and charm. As a result, "Tom Selleck net worth" has become a topic of great interest among fans. and financial enthusiasts alike. This article delves deep into Tom Selleck's wealth, exploring his career, assets, endorsements. and business ventures that contribute to his impressive economic standing.
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Early Life and Career Beginnings
The Foundation of Tom Selleck's Wealth
Born on January 29, 1945, in Detroit, Michigan, Tom Selleck grew up in Sherman Oaks, California. His journey towards building a large net worth began with humble origins. , Selleck pursued a business administration degree at the University of Southern California (USC) on a basketball scholarship. But, his interest shifted towards acting. leading him to study at the Hills Playhouse under Milton Katselas.
Minor roles in television and films marked Selleck's early career. He appeared in commercials and took on small parts in T.V. series such as "The Dating Game" and "Lancer." These initial steps, although modest. laid the groundwork for his future success and the growth of Tom Selleck net worth. Breakthrough with "Magnum, P.I."
The Role that Defined Tom Selleck's Career
Tom Selleck's breakthrough came with the role of Thomas Magnum in the CBS television series "Magnum, P.I." (1980-1988). This role made him a household name and boosted his net worth. The series' popularity resulted in Selleck earning large salaries. leading to financial stability and increased recognition in Hollywood.
"Magnum P.I." garnered high ratings and critical acclaim during its run. Selleck's portrayal of the charming and resourceful private investigator resonated with audiences. making him one of the most beloved television actors of the 1980s. The success of "Magnum P.I." played a pivotal role in shaping Tom Selleck net worth, establishing him as a major star.
Film Career and Diversification
Expanding Tom Selleck's Financial Portfolio
While "Magnum, P.I." was a cornerstone of Selleck's career, he did not limit himself to television. He ventured into films, further enhancing Tom Selleck net worth. His filmography includes notable movies such as "Three Men and a Baby" (1987). which became the highest-grossing film of the year, and its sequel, "Three Men and a Little Lady" (1990). These box office successes contributed to his wealth.
Selleck's versatility allowed him to transition between genres. from comedies like "Mr. Baseball" (1992) to westerns such as "Quigley Down Under" (1990). This diversification showcased his acting range. and provided many income streams, reinforcing Tom Selleck net worth.
Television Resurgence with "Blue Bloods"
Sustaining Wealth through Consistent Success
In 2010, Tom Selleck began starring as Frank Reagan i
Skeem Saam in June 2024 available on ForumIsaac More
Monday, June 3, 2024 - Episode 241: Sergeant Rathebe nabs a top scammer in Turfloop. Meikie is furious at her uncle's reaction to the truth about Ntswaki.
Tuesday, June 4, 2024 - Episode 242: Babeile uncovers the truth behind Rathebe’s latest actions. Leeto's announcement shocks his employees, and Ntswaki’s ordeal haunts her family.
Wednesday, June 5, 2024 - Episode 243: Rathebe blocks Babeile from investigating further. Melita warns Eunice to stay clear of Mr. Kgomo.
Thursday, June 6, 2024 - Episode 244: Tbose surrenders to the police while an intruder meddles in his affairs. Rathebe's secret mission faces a setback.
Friday, June 7, 2024 - Episode 245: Rathebe’s antics reach Kganyago. Tbose dodges a bullet, but a nightmare looms. Mr. Kgomo accuses Melita of witchcraft.
Monday, June 10, 2024 - Episode 246: Ntswaki struggles on her first day back at school. Babeile is stunned by Rathebe’s romance with Bullet Mabuza.
Tuesday, June 11, 2024 - Episode 247: An unexpected turn halts Rathebe’s investigation. The press discovers Mr. Kgomo’s affair with a young employee.
Wednesday, June 12, 2024 - Episode 248: Rathebe chases a criminal, resorting to gunfire. Turf High is rife with tension and transfer threats.
Thursday, June 13, 2024 - Episode 249: Rathebe traps Kganyago. John warns Toby to stop harassing Ntswaki.
Friday, June 14, 2024 - Episode 250: Babeile is cleared to investigate Rathebe. Melita gains Mr. Kgomo’s trust, and Jacobeth devises a financial solution.
Monday, June 17, 2024 - Episode 251: Rathebe feels the pressure as Babeile closes in. Mr. Kgomo and Eunice clash. Jacobeth risks her safety in pursuit of Kganyago.
Tuesday, June 18, 2024 - Episode 252: Bullet Mabuza retaliates against Jacobeth. Pitsi inadvertently reveals his parents’ plans. Nkosi is shocked by Khwezi’s decision on LJ’s future.
Wednesday, June 19, 2024 - Episode 253: Jacobeth is ensnared in deceit. Evelyn is stressed over Toby’s case, and Letetswe reveals shocking academic results.
Thursday, June 20, 2024 - Episode 254: Elizabeth learns Jacobeth is in Mpumalanga. Kganyago's past is exposed, and Lehasa discovers his son is in KZN.
Friday, June 21, 2024 - Episode 255: Elizabeth confirms Jacobeth’s dubious activities in Mpumalanga. Rathebe lies about her relationship with Bullet, and Jacobeth faces theft accusations.
Monday, June 24, 2024 - Episode 256: Rathebe spies on Kganyago. Lehasa plans to retrieve his son from KZN, fearing what awaits.
Tuesday, June 25, 2024 - Episode 257: MaNtuli fears for Kwaito’s safety in Mpumalanga. Mr. Kgomo and Melita reconcile.
Wednesday, June 26, 2024 - Episode 258: Kganyago makes a bold escape. Elizabeth receives a shocking message from Kwaito. Mrs. Khoza defends her husband against scam accusations.
Thursday, June 27, 2024 - Episode 259: Babeile's skillful arrest changes the game. Tbose and Kwaito face a hostage crisis.
Friday, June 28, 2024 - Episode 260: Two women face the reality of being scammed. Turf is rocked by breaking
Experience the thrill of Progressive Puzzle Adventures, like Scavenger Hunt Games and Escape Room Activities combined Solve Treasure Hunt Puzzles online.
240529_Teleprotection Global Market Report 2024.pdfMadhura TBRC
The teleprotection market size has grown
exponentially in recent years. It will grow from
$21.92 billion in 2023 to $28.11 billion in 2024 at a
compound annual growth rate (CAGR) of 28.2%. The
teleprotection market size is expected to see
exponential growth in the next few years. It will grow
to $70.77 billion in 2028 at a compound annual
growth rate (CAGR) of 26.0%.
Meet Dinah Mattingly – Larry Bird’s Partner in Life and Loveget joys
Get an intimate look at Dinah Mattingly’s life alongside NBA icon Larry Bird. From their humble beginnings to their life today, discover the love and partnership that have defined their relationship.
Create a Seamless Viewing Experience with Your Own Custom OTT Player.pdfGenny Knight
As the popularity of online streaming continues to rise, the significance of providing outstanding viewing experiences cannot be emphasized enough. Tailored OTT players present a robust solution for service providers aiming to enhance their offerings and engage audiences in a competitive market. Through embracing customization, companies can craft immersive, individualized experiences that effectively hold viewers' attention, entertain them, and encourage repeat usage.
Meet Crazyjamjam - A TikTok Sensation | Blog EternalBlog Eternal
Crazyjamjam, the TikTok star everyone's talking about! Uncover her secrets to success, viral trends, and more in this exclusive feature on Blog Eternal.
Source: https://blogeternal.com/celebrity/crazyjamjam-leaks/
Young Tom Selleck: A Journey Through His Early Years and Rise to Stardomgreendigital
Introduction
When one thinks of Hollywood legends, Tom Selleck is a name that comes to mind. Known for his charming smile, rugged good looks. and the iconic mustache that has become synonymous with his persona. Tom Selleck has had a prolific career spanning decades. But, the journey of young Tom Selleck, from his early years to becoming a household name. is a story filled with determination, talent, and a touch of luck. This article delves into young Tom Selleck's life, background, early struggles. and pivotal moments that led to his rise in Hollywood.
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Early Life and Background
Family Roots and Childhood
Thomas William Selleck was born in Detroit, Michigan, on January 29, 1945. He was the second of four children in a close-knit family. His father, Robert Dean Selleck, was a real estate investor and executive. while his mother, Martha Selleck, was a homemaker. The Selleck family relocated to Sherman Oaks, California. when Tom was a child, setting the stage for his future in the entertainment industry.
Education and Early Interests
Growing up, young Tom Selleck was an active and athletic child. He attended Grant High School in Van Nuys, California. where he excelled in sports, particularly basketball. His tall and athletic build made him a standout player, and he earned a basketball scholarship to the University of Southern California (U.S.C.). While at U.S.C., Selleck studied business administration. but his interests shifted toward acting.
Discovery of Acting Passion
Tom Selleck's journey into acting was serendipitous. During his time at U.S.C., a drama coach encouraged him to try acting. This nudge led him to join the Hills Playhouse, where he began honing his craft. Transitioning from an aspiring athlete to an actor took time. but young Tom Selleck became drawn to the performance world.
Early Career Struggles
Breaking Into the Industry
The path to stardom was a challenging one for young Tom Selleck. Like many aspiring actors, he faced many rejections and struggled to find steady work. A series of minor roles and guest appearances on television shows marked his early career. In 1965, he debuted on the syndicated show "The Dating Game." which gave him some exposure but did not lead to immediate success.
The Commercial Breakthrough
During the late 1960s and early 1970s, Selleck began appearing in television commercials. His rugged good looks and charismatic presence made him a popular brand choice. He starred in advertisements for Pepsi-Cola, Revlon, and Close-Up toothpaste. These commercials provided financial stability and helped him gain visibility in the industry.
Struggling Actor in Hollywood
Despite his success in commercials. breaking into large acting roles remained a challenge for young Tom Selleck. He auditioned and took on small parts in T.V. shows and movies. Some of his early television appearances included roles in popular series like Lancer, The F.B.I., and Bracken's World. But, it would take a
4. • There were some methods for communications
like communication via smoke , mors alphabet,
walkie talkie etc.
• All of them has some receivers, transmitters , and
more important than all of them , has some
signals with some frequencies.
5. • Let’s compare the communication via smoke
with walkie talkie.
• In the smoke communication , telling a situation to the
other people depends on the time interval between
smokes. Different intervals for different situations. This
means there are some frequencies for some situations and
if there are frequencies there is a signal . This signal is
called the smoke signal.
6. • In the mors alphabet, walkie talkie or the other
modern communication systems , there are
electrical signals with some frequencies.
• Shortly , the most important similarity is the
signals and frequencies.
7. • Walkie Talkies were first patented
in 1938 by Al Gross. They were first
used by the military only most likely
because they were so expensive and
very large and heavy for the average
person to buy and use.
8. • In fact, someone needed to carry part of the walkie talkie on their
back because it was so large. It is not so clear who should get
credit for the invention of the device.
• Around the same time Al Gross was working on his model,
Donald Hings was working on his version of the walkie talkie
which he called a “packset”. Hings invention was used during
War World Two starting in 1942 and was very important in the
war effort.
9. • After World War Two the use of the hand held radio
spread throughout different public sectors. With more
compact designs police and fireman began to rely more on
the devices for communication. Later walkie talkie use
moved from public to private sectors and to everyday use
for the average person or even toys for children.
10.
11. • The walkie talkie communication system consists of two
receiver and two transmitter circuits. One receiver and one
transmitter circuits are for each walkie talkies. The general
structure of this system :
13. • A transducer is a device that converts a signal
in one form of energy to another form of energy.
Microphone and the loudspeaker are the
transducers.
• After the sound is converted to the electrical
signal, amplifier amplifies it in the transmitter
circuit. Modulation is the carrying the message
signal with the carrier signal . Modulator makes
this duty.
• In the receiver circuit , demodulator seperates the
message signal from modulated signal , and
amplifier increases the message signal to be
heard easily. Loudspeaker converts the electrical
signal to the sound.
• Transducer and the receiver must be in the same
frequency interval to communicate each other.
14. Types of Communication
A B
Simplex – A can talk to B
Radio, T.V. broadcasting, CD/DVD ROM
Simplest type, requires one transmitter and one receiver
Simplex
Duplex – A and B both can talk to each other simultaneously
Telephone, Telegraph
Complex, requires two transmitter and two receiver at both ends
Needs two different channels for simultaneous transmission
A B
Duplex
15. • A transceiver is a small unit that combines a transmitter and a
receiver
• A small hand-held unit of transceiver is popularly called a
walkie-talkie
• The usual controls on the small transceivers unit are off-on
switch with volume control, push-to-talk button, squelch control
(eliminates background noise) and jack for earphones
A B
Half-Duplex
Half-Duplex – A and B can both talk to each other but not simultaneously
Fax, CD/DVD RW
Needs one single channel for transmission
Compromise between two, don’t require separate transmitter and receiver
Same antenna and circuitry may be used for both transmission and reception
16.
17. WHAT IS THE MODULATION ?
• Modulation is the process of superimposing a
signal (message signal ) on a high frequency
signal (carrier signal ) to transmit easily.
s(t)
The wave you
want to transmit
c(t)
A wave that can be
transmitted
+
Signal Carrier r(t)
The actual wave
that is transmitted
=
Modulated signal
t t t
18. DEMODULATION
• Demodulation is the opposite of the modulation.
Demodulation is used in receiver. When the
modulated signal is come into the receiver , the
demodulator seperate the message signal from the
modulated signal.
r(t)
The received signal at
demodulator
Modulated signal s(t)
Output of the
demodulator
Original Signal
t t
Demodulation
20. AM vs FM
• In amplitude modulation (AM) , the message signal m(t)
is impressed on the amplitude of the carrier signal c(t).
Modulation is done with changing the amplitude of carrier
signal.
• In frequency modulation (FM) , the frequency of the
carrier is changed according to the variations in the
message signal.
21. • QUESTION IS WHAT TYPE OF
MODULATION SHOULD BE USED TO
TRANSMIT THE SIGNAL THROUGH THE
LONG DISTANCES ???
• IN ORDER TO ANSWER THIS
QUESTION , THE ADVANTAGES FM
AND AM MUST BE EXAMINED
22. ADVANTAGES OF FM
• Resilient to the noise : AM waves do not have constant
envelopes and therefore more affected by static or noise
than FM. Unwanted electromagnetic waves do not cause the
frequency of FM carrier wave to change.
• Resilient to signal strength variations
• Does not require linear amplifiers in the transmitter
• Enables greater efficiency than many other modes
23. ADVANTAGES OF AM
It is simple to implement
it can be demodulated using a circuit consisting of very few
components
AM receivers are very cheap as no specialized components
are needed.
.
24. SHORTLY ;
• Frequency modulated signal has wider coverage
than AM radio
• Frequency modulated signal has better sound
quality than AM radio
That’s why FM is more preferred than the
AM in walkie talkies.
25. Carrier Frequency bands
Name Freq.
Range
Wave
length
Application Propagation
ELF 300Hz
to 3kHz
100 km
to 1000km
Navigation, long distance
communication with
ships
Wave tube between earth surface and
the ionosphere
VLF 3kHz
to 30kHz
10km
to 100km
Navigation, long distance
communication
Ground propagation, stable
LF 30kHz
to
300kHz
1km
to 10km
Navigation, long distance
communication with
ships
Ground propagation, stable
MF 300kHz
to 3MHz
100m
to 1km
AM broadcasting, radio
navigation
Ground-wave, sky-wave propagation.
Fading
HF 3MHz
to
30MHz
10m
to 100m
Radio broadcasting,
fixed point-to-point
(around the world)
Large perturbation, reflection in
ionosphere
VHF 30MHz
to
300MHz
1m
to 10m
Radio and TV
broadcasting, mobile
services
Diffraction
UHF 300MHz
to 3GHz
10cm
to 100cm
Cellular telephony (GSM,
NMT, AMPS), digital TV,
fixed point-to-point,
satellite, radar
Shadowing by mountains and buildings
SHF 3GHz
To
30GHz
1cm
to 10cm
Broadband indoor
systems, microwave
links, satellite
communications
Attenuation due to rain, snow and fog
EHF 30GHz
to
300GHz
1mm
to 10mm
LOS communication
(short distance or
satellite)
Attenuation due to rain, snow and gases
26. • The carrier waves frequencies for radio broadcasting are assigned by
Federal Communications Commission (FCC)
FREQUENCY ALLOCATION
• Use of radio frequency bands of the electromagnetic spectrum is regulated
by governments in most countries, in a spectrum management process
known as frequency allocation or spectrum allocation.
• Radio propagation does not stop at national boundaries. Giving
technical and economic reasons, governments have sought to harmonise
the allocation of RF bands and their standardization.