A Long Travel

Chapter 1

(Everything started with my mum’s buying a ticket for England.)

Dear Pessimistic,

Last week my mother said that ‘You should go to overseas because you need experience, i think your English level will be better than present.’ I never think about that until today because i think it’s craziness. I never go to anywhere without my mother! I’m too addicted to my home and my mother! I know you’ll say ‘what happened today?’ I say, today i went to school and came back, i did my homeworks innocently. Then my sweet mother came from work. When she came, she was smiling. And she said ‘I have a suprise, i think you’ll like it!’ I was curious. ‘What, what is it mumy?’ She smiled subtly. ‘After dinner honey, i’m too hungry!’ I couldn’t be patient, you know Pess i’m always impatient. Whatever; my mother ate dinner and it was time to learn news. ‘Sueda today i took a ticket to England it’s in three days at 3 pm.’ She was calm and i was shocked. Pessimistic in your opinion what should i do? I mean should i go or shouldn’t i go? It is 11 pm. I should sleep. I think morning with clean mind, i can decide more easily.

(After two days, my mother comes my room in the morning.)
My Mother: ‘Time to wake up my sleepy doughter!’
Me: Mom, 5 more minutes…
My Mother: No, i know very well these 5 minutes! And also we have to prepare your suitcase! We are too late!
Me (with a sleeply voice) : For what mumy? I think for sleep…
My Mother: Do you forget Sueda? Your plane’s flying 7 hours later?
Is it a joke?

History of Books

The history of the book is an academic discipline that studies the production, transmission, circulation and dissemination of text from antiquity to the present day. The scope of the history of the book, or book history as it is also known, includes the history of ideas, history of religion, bibliography as well as practices of conservation and curation.

Origins and antiquity

Writing is a system of linguistic symbols which permit one to transmit and conserve information. Writing appears to have developed between the 7th millennium BC and the 4th millennium BC, first in the form of early mnemonic symbols which became a system of ideograms or pictographs through simplification. The oldest known forms of writing were thus primarily logographic in nature. Later syllabic and alphabetic or segmental writing emerged.

The book is also linked to the desire of humans to create lasting records. Stones could be the most ancient form of writing, butwood would be the first medium to take the guise of a book. The words biblos and liber first meant "fibre inside of a tree". In Chinese, the character that means book is an image of a tablet of bamboo. Wooden tablets (Rongorongo) were also made onEaster Island.

Silk, in China, was also a base for writing. Writing was done with brushes. Many other materials were used as bases: bone, bronze, pottery, shell, etc. In India, for example, dried palm tree leaves were used; in Mesoamerica another type of plant,Amate. Any material which will hold and transmit text is a candidate for use in bookmaking.

Clay Tablets

Clay tablets were used in Mesopotamia in the 3rd millennium BC. The calamus, an instrument in the form of a triangle, was used to make characters in moist clay. The tablets were fired to dry them out. At Nineveh, 22,000 tablets were found, dating from the 7th century BC; this was the archive and library of the kings of Assyria, who had workshops of copyists and conservationists at their disposal. This presupposes a degree of organization with respect to books, consideration given to conservation, classification, etc. Tablets were used right up until the 19th century in various parts of the world, including Germany, Chile, and the Saharan Desert.

Wax Tablets

Romans used wax-coated wooden tablets (pugillares) upon which they could write and erase by using a stylus. One end of the stylus was pointed, and the other was spherical. Usually these tablets were used for everyday purposes (accounting, notes) and for teaching writing to children, according to the methods discussed by Quintilian in his Institutio Oratoria X Chapter 3. Several of these tablets could be assembled in a form similar to a codex. Also the etymology of the word codex (block of wood) suggest that it may have developed from wooden wax tablets.

Printing press
The invention of the printing press by Johannes Gutenberg around 1440 marks the entry of the book into the industrial age. The Western book was no longer a single object, written or reproduced by request. The publication of a book became an enterprise, requiring capital for its realization and a market for its distribution. The cost of each individual book (in a large edition) was lowered enormously, which in turn increased the distribution of books. The book in codex form and printed on paper, as we know it today, dates from the 15th century. Books printed before January 1, 1501, are called incunables. The spreading of book printing all over Europe occurred relatively quickly, but most books were still printed in Latin. The spreading of the concept of printing books in the vernacular was a somewhat slower process.

E-Resources

It is difficult to predict the future of the book. A good deal of reference material, designed for direct access instead of sequential reading, as for example encyclopedias, exists less and less in for the form of books and increasingly on the web. Leisure reading materials are increasingly published in e-reader formats.

Although electronic books, or e-books, had limited success in the early years, and readers were resistant at the outset, the demand for books in this format has grown dramatically, primarily because of the popularity of e-reader devices and as the number of available titles in this format has increased. Another important factor in the increasing popularity of the e-reader is its continuous diversification. Many e-readers now support basic operating systems, which facilitate email and other simple functions. The iPad is the most obvious example of this trend, but even mobile phones can host e-reading software.

E-book readers such as the Sony Reader, Barnes & Noble's Nook, and the Amazon Kindle have increased in popularity each time a new upgraded version is released. The Kindle in particular has captured public attention not only for the quality of the reading experience but also because users can access books (as well as periodicals and newspapers) wirelessly online (a feature now available in all other e-reader devices). Apple has also entered this arena with applications for the iPhone and iPad which enable e-book reading.

https://en.wikipedia.org/wiki/History_of_books

Information

Information, in its most restricted technical sense, is a sequence of symbols that can be interpreted as a message. Information can be recorded as signs, or transmitted as signals. Information is any kind of event that affects the state of a dynamic system that can interpret the information.

Conceptually, information is the message (utterance or expression) being conveyed. Therefore, in a general sense, information is "Knowledge communicated or received concerning a particular fact or circumstance", or rather, information is an answer to a question.^{[citation needed]} Information cannot be predicted and resolves uncertainty. The uncertainty of an event is measured by its probability of occurrence and is inversely proportional to that. The more uncertain an event, the more information is required to resolve uncertainty of that event. The amount of information is measured in bits.
Example: information in one "fair" coin flip: log₂(2/1) = 1 bit, and in two fair coin flips is log₂(4/1) = 2 bits.
The concept that information is the message has different meanings in different contexts. Thus the concept of information becomes closely related to notions of constraint, communication, control, data, form, instruction, knowledge, meaning,understanding, mental stimuli, pattern, perception, representation, and entropy.

Citation: http://en.wikipedia.org/wiki/Information

History of Paper

Paper was invented by the ancient Chinese in the 2nd century BC during the Han Dynasty and spread slowly to the west via the Silk Road. Papermaking and manufacturing in Europe started in the Iberian Peninsula, today's Portugal and Spain and Sicily in the 10th century, and spread to Italy and South France reaching Germanyby 1400. Earlier, other paper-like materials were in use like papyrus, parchment and vellum.

In medieval Europe, the hitherto handcraft of papermaking was mechanized by the use of waterpower, the first water papermill in the Iberian Peninsula having been built in the Portuguese city of Leiria in 1411, and other processes. The rapid expansion of European paper production was truly enhanced by the invention of the printing press and the beginning of the Printing Revolution in the 15th century.

The word "paper" is etymologically derived from papyros, Ancient Greek for theCyperus papyrus plant. Papyrus is a thick, paper-like material produced from the pith of the Cyperus papyrus plant which was used in ancient Egypt and other Mediterranean cultures for writing long before the making of paper in China. Papyrus however is a "lamination of natural plants, while paper is manufactured from fibres whose properties have been changed by maceration or disintegration.

Citation: http://en.wikipedia.org/wiki/History_of_paper

Image

An image (from Latin: imago) is an artifact that depicts or records visual perception, for example a two-dimensional picture, that has a similar appearance to some subject – usually a physical object or a person, thus providing a depiction of it.

Capturing an image of the environment with a mobile phone camera

Characteristics

Images may be two-dimensional, such as a photograph, screen display, and as well as a three-dimensional, such as a statue or hologram. They may be captured by optical devices – such as cameras, mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena, such as the human eye or water surfaces.

The word image is also used in the broader sense of any two-dimensional figure such as a map, a graph, a pie chart, or an abstract painting. In this wider sense, images can also berendered manually, such as by drawing, painting, carving, rendered automatically by printing or computer graphics technology, or developed by a combination of methods, especially in a pseudo-photograph.

A volatile image is one that exists only for a short period of time. This may be a reflection of an object by a mirror, a projection of a camera obscura, or a scene displayed on a cathode ray tube. A fixed image, also called a hard copy, is one that has been recorded on a material object, such as paper or textile by photography or any other digital process.

A mental image exists in an individual's mind. Like something one remembers or imagines. The subject of an image need not be real; it may be an abstract concept, such as a graph, function, or "imaginary" entity. For example, Sigmund Freud claimed to have dreamed purely in aural-images of dialogs. The development of synthetic acoustic technologies and the creation of sound art have led to a consideration of the possibilities of a sound-image made up of irreducible phonic substance beyond linguistic or musicological analysis.

A still image is a single static image, as distinguished from a kinetic image (see below). This phrase is used in photography, visual media and the computer industry to emphasize that one is not talking about movies, or in very precise or pedantic technical writing such as a standard.

A film still is a photograph taken on the set of a movie or television program during production, used for promotional purposes.

The top image is captured using photography. The bottom image isrendered. Images are produced by capturing or rendering.

Imagery (literary term)

Imagery is in literature a "mental picture" which appeals to the senses. It can both be figurative and literal.

Moving image

A moving image is typically a movie (film) or video, including digital video. It could also be an animated display such as a zoetrope.

Citation: http://en.wikipedia.org/wiki/Image

Popcorn! Really? Popcorn!?

Popcorn! How in the world did I get the idea to write about popcorn? Seriously! I like a good bowl of popcorn from time to time. There is nothing like the smell that fills the room, the creamy butter that you can melt and dump on top of the lonely little white kernels, and every once in a while you get that annoying piece stuck on the back of your throat and you honestly feel like you are going to die because you can't cough enough to get it off your throbbing tonsils. I have always eaten popcorn the same way. Lots of Butter, and medium salt. That's my normal menu when it comes to popcorn. But this month my popcorn world was flipped upside down. I went to a popcorn stand that I thought was just the normal popcorn, but when I took my first bite, something amazing happened in my field of taste buds. It was no normal piece of popcorn, not even close! It was this amazing burst of creamy ranch flavor that I was not expecting, but after I finished my bag I was shocked! I was excited! I was pumped up and couldn't wait to get another bag of that flavor of popcorn. So here is the flavor I am trying to pour on you today. When life seems to be the same day after day, don't be afraid to switch up the flavor. There are so many things that life has to offer, and so many opportunities, but sometimes it means switching your flavor.

Citation: http://pastorkevinwilson.blogspot.com/?expref=next-blog

Elephant

The class teacher asks students to name an animal that begins with an “E”. One boy says, “Elephant.”

Then the teacher asks for an animal that begins with a “T”. The same boy says, “Two elephants.”

The teacher sends the boy out of the class for bad behavior. After that she asks for an animal beginning with “M”.

The boy shouts from the other side of the wall: “Maybe an elephant!”

Citation: http://academictips.org/blogs/funny-short-stories/

Writing Letters to Son

One student fell into a cycle of classes, studying, working and sleeping.

Didn't realize how long he had neglected writing home until he received the following note:

"Dear Son, Your mother and I enjoyed your last letter. Of course, we were much younger then, and more impressionable. Love, Dad."

Citation: http://www.ahajokes.com/true004.html

History of Mobile Phones

The history focuses on communication devices which connect wirelessly to the public switched telephone network. Thetransmission of speech by radio has a long and varied history going back to Reginald Fessenden's invention and shore-to-ship demonstration of radio telephony. The first mobile telephones were barely portable compared to today's compact hand-held devices. Along with the process of developing more portable technology, drastic changes have taken place in the networking of wireless communication and the prevalence of its use.

Handheld mobile phone

Prior to 1973, mobile telephony was limited to phones installed in cars and other vehicles. Motorola was the first company to produce a handheld mobile phone. On 3 April 1973 when Martin Cooper, a Motorola researcher and executive, made the first mobile telephone call from handheld subscriber equipment, placing a call to Dr. Joel S. Engel of Bell Labs. The prototype handheld phone used by Dr. Cooper weighed 1.1 kg and measured 23 cm long, 13 cm deep and 4.45 cm wide. The prototype offered a talk time of just 30 minutes and took 10 hours to re-charge.

John F. Mitchell, Motorola's chief of portable communication products and Cooper's boss in 1973, played a key role in advancing the development of handheld mobile telephone equipment. Mitchell successfully pushed Motorola to develop wireless communication products that would be small enough to use anywhere and participated in the design of the cellular phone.

Digital cellular networks – 2G

Main articles: 2G, 2.5G, and 2.75G

Two 1991 GSM mobile phones with several AC adapters

In the 1990s, the 'second generation' mobile phone systems emerged. Two systems competed for supremacy in the global market: the European developed GSM standard and the U.S. developed CDMA standard. These differed from the previous generation by using digital instead of analog transmission, and also fast out-of-band phone-to-network signaling. The rise in mobile phone usage as a result of 2G was explosive and this era also saw the advent of prepaid mobile phones.

In 1991 the first GSM network (Radiolinja) launched in Finland. In general the frequencies used by 2G systems in Europe were higher than those in America, though with some overlap. For example, the 900 MHz frequency range was used for both 1G and 2G systems in Europe, so the 1G systems were rapidly closed down to make space for the 2G systems. In America the IS-54 standard was deployed in the same band as AMPS and displaced some of the existing analog channels.

In 1993, IBM Simon was introduced. This was possibly the world's first smartphone. It was a mobile phone, pager, fax machine, and PDA all rolled into one. It included a calendar, address book, clock, calculator, notepad, email, and a touchscreen with a QWERTY keyboard. The IBM Simon had a stylus you used to tap the touch screen with. It featured predictive typing that would guess the next characters as you tapped. It had apps, or at least a way to deliver more features by plugging a PCMCIA1.8 MB memory card into the phone.

Coinciding with the introduction of 2G systems was a trend away from the larger "brick" phones toward tiny 100 – 200 gramhand-held devices. This change was possible not only through technological improvements such as more advanced batteries and more energy-efficient electronics, but also because of the higher density of cell sites to accommodate increasing usage. The latter meant that the average distance transmission from phone to the base station shortened, leading to increased battery life whilst on the move.

Personal Handy-phone System mobiles and modems used in Japan around 1997–2003

The second generation introduced a new variant of communication called SMS or text messaging. It was initially available only on GSM networks but spread eventually on all digital networks. The first machine-generated SMS message was sent in the UK on 3 December 1992 followed in 1993 by the first person-to-person SMS sent in Finland. The advent of prepaid services in the late 1990s soon made SMS the communication method of choice amongst the young, a trend which spread across all ages.

2G also introduced the ability to access media content on mobile phones. In 1998 the first downloadable content sold to mobile phones was the ring tone, launched by Finland's Radiolinja (now Elisa). Advertising on the mobile phone first appeared in Finland when a free daily SMS news headline service was launched in 2000, sponsored by advertising.

Mobile payments were trialed in 1998 in Finland and Sweden where a mobile phone was used to pay for a Coca Cola vending machine and car parking. Commercial launches followed in 1999 in Norway. The first commercial payment system to mimic banks and credit cards was launched in the Philippines in 1999 simultaneously by mobile operators Globe and Smart.

The first full internet service on mobile phones was introduced by NTT DoCoMo in Japan in 1999.

Mobile broadband data – 3G

Main article: 3G

As the use of 2G phones became more widespread and people began to utilize mobile phones in their daily lives, it became clear that demand for data (such as access to browse the internet) was growing. Furthermore, experience from fixed broadband services showed there would also be an ever increasing demand for greater data speeds. The 2G technology was nowhere near up to the job, so the industry began to work on the next generation of technology known as 3G. The main technological difference that distinguishes 3G technology from 2G technology is the use of packet switching rather than circuit switching for data transmission. In addition, the standardization process focused on requirements more than technology (2 Mbit/s maximum data rate indoors, 384 kbit/s outdoors, for example).

Inevitably this led to many competing standards with different contenders pushing their own technologies, and the vision of a single unified worldwide standard looked far from reality. The standard 2G CDMA networks became 3G compliant with the adoption of Revision A to EV-DO, which made several additions to the protocol while retaining backwards compatibility:

·         Introduction of several new forward link data rates that increase the maximum burst rate from 2.45 Mbit/s to 3.1 Mbit/s

·         Protocols that would decrease connection establishment time

·         Ability for more than one mobile to share the same time slot

·         Introduction of QoS flags

All these were put in place to allow for low latency, low bit rate communications such as VoIP.

The first pre-commercial trial network with 3G was launched by NTT DoCoMo in Japan in the Tokyo region in May 2001. NTT DoCoMo launched the first commercial 3G network on 1 October 2001, using the WCDMA technology. In 2002 the first 3G networks on the rival CDMA2000 1xEV-DO technology were launched by SK Telecom and KTF in South Korea, and Monet in the USA. Monet has since gone bankrupt. By the end of 2002, the second WCDMA network was launched in Japan by Vodafone KK (now Softbank). European launches of 3G were in Italy and the UK by the Three/Hutchison group, on WCDMA. 2003 saw a further 8 commercial launches of 3G, six more on WCDMA and two more on the EV-DO standard.

During the development of 3G systems, 2.5G systems such as CDMA2000 1x and GPRS were developed as extensions to existing 2G networks. These provide some of the features of 3G without fulfilling the promised high data rates or full range of multimedia services. CDMA2000-1X delivers theoretical maximum data speeds of up to 307 kbit/s. Just beyond these is the EDGEsystem which in theory covers the requirements for 3G system, but is so narrowly above these that any practical system would be sure to fall short.

The high connection speeds of 3G technology enabled a transformation in the industry: for the first time, media streaming of radio (and even television) content to 3G handsets became possible, with companies such as RealNetworks and Disney among the early pioneers in this type of offering.

In the mid-2000s (decade), an evolution of 3G technology began to be implemented, namely High-Speed Downlink Packet Access(HSDPA). It is an enhanced 3G (third generation) mobile telephony communications protocol in the High-Speed Packet Access(HSPA) family, also coined 3.5G, 3G+ or turbo 3G, which allows networks based on Universal Mobile Telecommunications System(UMTS) to have higher data transfer speeds and capacity. Current HSDPA deployments support down-link speeds of 1.8, 3.6, 7.2 and 14.0 Mbit/s. Further speed increases are available with HSPA+, which provides speeds of up to 42 Mbit/s downlink and 84 Mbit/s with Release 9 of the 3GPP standards.

By the end of 2007, there were 295 million subscribers on 3G networks worldwide, which reflected 9% of the total worldwide subscriber base. About two thirds of these were on the WCDMA standard and one third on the EV-DO standard. The 3G telecoms services generated over 120 Billion dollars of revenues during 2007 and at many markets the majority of new phones activated were 3G phones. In Japan and South Korea the market no longer supplies phones of the second generation.

Although mobile phones had long had the ability to access data networks such as the Internet, it was not until the widespread availability of good quality 3G coverage in the mid-2000s (decade) that specialized devices appeared to access the mobile internet. The first such devices, known as "dongles", plugged directly into a computer through the USB port. Another new class of device appeared subsequently, the so-called "compact wireless router" such as the Novatel MiFi, which makes 3G internet connectivity available to multiple computers simultaneously over Wi-Fi, rather than just to a single computer via a USB plug-in.

Such devices became especially popular for use with laptop computers due to the added portability they bestow. Consequently, some computer manufacturers started to embed the mobile data function directly into the laptop so a dongle or MiFi wasn't needed. Instead, the SIM card could be inserted directly into the device itself to access the mobile data services. Such 3G-capable laptops became commonly known as "netbooks". Other types of data-aware devices followed in the netbook's footsteps. By the beginning of 2010, E-readers, such as the Amazon Kindle and the Nook from Barnes & Noble, had already become available with embedded wireless internet, and Apple Computer had announced plans for embedded wireless internet on its iPad tablet devices beginning that Fall.

Native IP networks – 4G

Main article: 4G

By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications like streaming media. Consequently, the industry began looking to data-optimized 4th-generation technologies, with the promise of speed improvements up to 10-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard (offered in the U.S. by Sprint) and the LTE standard, first offered in Scandinavia by Telia Sonera.

One of the main ways in which 4G differed technologically from 3G was in its elimination of circuit switching, instead employing an all-IP network. Thus, 4G ushered in a treatment of voice calls just like any other type of streaming audio media, utilizing packet switching over internet, LAN or WAN networks via VoIP.

Satellite mobile

Main article: Satellite phone

Earth-orbiting satellites can cover remote areas out of reach of wired networks or where construction of a cellular network is uneconomic. The Inmarsat satellite telephone system, originally developed in 1979 for safety of life at sea, is now also useful for areas out of reach of landline, conventional cellular, or marine VHF radio stations. In 1998 the Iridium satellite system was set up, and although the initial operating company went bankrupt due to high initial expenses, the service is available today.

Citation: http://en.wikipedia.org/wiki/History_of_mobile_phones

Radio

Radio is the wireless transmission of signals through free space byelectromagnetic radiation of a frequency significantly below that ofvisible light, in the radio frequency range, from about 30 kHz to 300 GHz. These waves are called radio waves. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.

Information, such as sound, is carried by systematically changing (modulating) some property of the radiated waves, such as their amplitude, frequency, phase, or pulse width. When radio waves strike an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be extracted and transformed back into its original form.

Radio band

Main article: Radio frequency

Light Comparison
Name	Wavelength	Frequency (Hz)	Photon Energy (eV)
Gamma ray	less than 0.01 nm	more than 10 EHZ	100 keV - 300+ GeV
X-Ray	0.01 to 10 nm	30 PHz - 30 EHZ	120 eV to 120 keV
Ultraviolet	10 nm - 400 nm	30 EHZ - 790 THz	3 eV to 124 eV
Visible	390 nm - 750 nm	790 THz - 405 THz	1.7 eV - 3.3 eV
Infrared	750 nm - 1 mm	405 THz - 300 GHz	1.24 meV - 1.7 eV
Microwave	1 mm - 1 meter	300 GHz - 300 MHz	1.24 meV - 1.24 µeV
Radio	1 mm - km	300 GHz - 3 Hz	1.24 meV - 12.4 feV

Radio frequencies occupy the range from a few hertz to 300 GHz, although commercially important uses of radio use only a small part of this spectrum. Other types of electromagnetic radiation, with frequencies above the RF range, are infrared, visible light,ultraviolet, X-rays and gamma rays. Since the energy of an individual photon of radio frequency is too low to remove an electron from an atom, radio waves are classified as non-ionizing radiation.

Telephony

Mobile phones transmit to a local cell site (transmitter/receiver) that ultimately connects to the public switched telephone network (PSTN) through an optic fiber or microwave radio and other network elements. When the mobile phone nears the edge of the cell site's radio coverage area, the central computer switches the phone to a new cell. Cell phones originally used FM, but now most use various digital modulation schemes. Recent developments in Sweden (such as DROPme) allow for the instant downloading of digital material from a radio broadcast (such as a song) to a mobile phone.

Satellite phones use satellites rather than cell towers to communicate.

Video

Television sends the picture as AM and the sound as AM or FM, with the sound carrier a fixed frequency (4.5 MHz in the NTSC system) away from the video carrier. Analog television also uses a vestigial sideband on the video carrier to reduce the bandwidth required.

Digital television uses 8VSB modulation in North America (under the ATSC digital television standard), and COFDM modulation elsewhere in the world (using the DVB-T standard). A Reed–Solomon error correction code adds redundant correction codes and allows reliable reception during moderate data loss. Although many current and future codecs can be sent in the MPEG transport stream container format, as of 2006 most systems use a standard-definition format almost identical to DVD: MPEG-2 video in Anamorphic widescreen and MPEG layer 2 (MP2) audio. High-definition television is possible simply by using a higher-resolution picture, but H.264/AVC is being considered as a replacement video codec in some regions for its improved compression. With the compression and improved modulation involved, a single "channel" can contain a high-definition program and several standard-definition programs.

Navigation

All satellite navigation systems use satellites with precision clocks. The satellite transmits its position, and the time of the transmission. The receiver listens to four satellites, and can figure its position as being on a line that is tangent to a spherical shell around each satellite, determined by the time-of-flight of the radio signals from the satellite. A computer in the receiver does the math.

Radio direction-finding is the oldest form of radio navigation. Before 1960 navigators used movable loop antennas to locate commercial AM stations near cities. In some cases they used marine radiolocation beacons, which share a range of frequencies just above AM radio with amateur radio operators. LORAN systems also used time-of-flight radio signals, but from radio stations on the ground.

VOR (Very High Frequency Omnidirectional Range), systems (used by aircraft), have an antenna array that transmits two signals simultaneously. A directional signal rotates like a lighthouse at a fixed rate. When the directional signal is facing north, an omnidirectional signal pulses. By measuring the difference in phase of these two signals, an aircraft can determine its bearing or radial from the station, thus establishing a line of position. An aircraft can get readings from two VORs and locate its position at the intersection of the two radials, known as a "fix."

When the VOR station is collocated with DME (Distance Measuring Equipment), the aircraft can determine its bearing and range from the station, thus providing a fix from only one ground station. Such stations are called VOR/DMEs. The military operates a similar system of navaids, called TACANs, which are often built into VOR stations. Such stations are called VORTACs. Because TACANs include distance measuring equipment, VOR/DME and VORTAC stations are identical in navigation potential to civil aircraft.

Radar

Radar (Radio Detection And Ranging) detects objects at a distance by bouncing radio waves off them. The delay caused by the echo measures the distance. The direction of the beam determines the direction of the reflection. The polarization and frequency of the return can sense the type of surface. Navigational radars scan a wide area two to four times per minute. They use very short waves that reflect from earth and stone. They are common on commercial ships and long-distance commercial aircraft.

General purpose radars generally use navigational radar frequencies, but modulate and polarize the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of heavy storms, as well as land and vehicles. Some can superimpose sonar data and map data from GPS position.

Search radars scan a wide area with pulses of short radio waves. They usually scan the area two to four times a minute. Sometimes search radars use the Doppler effect to separate moving vehicles from clutter. Targeting radars use the same principle as search radar but scan a much smaller area far more often, usually several times a second or more. Weather radars resemble search radars, but use radio waves with circular polarization and a wavelength to reflect from water droplets. Some weather radar use the Doppler effect to measure wind speeds.

Data (digital radio)

Most new radio systems are digital, see also: Digital TV, Satellite Radio, Digital Audio Broadcasting. The oldest form of digital broadcast was spark gap telegraphy, used by pioneers such as Marconi. By pressing the key, the operator could send messages in Morse code by energizing a rotating commutating spark gap. The rotating commutator produced a tone in the receiver, where a simple spark gap would produce a hiss, indistinguishable from static. Spark-gap transmitters are now illegal, because their transmissions span several hundred megahertz. This is very wasteful of both radio frequencies and power.

The next advance was continuous wave telegraphy, or CW (Continuous Wave), in which a pure radio frequency, produced by a vacuum tube electronic oscillator was switched on and off by a key. A receiver with a local oscillator would "heterodyne" with the pure radio frequency, creating a whistle-like audio tone. CW uses less than 100 Hz of bandwidth. CW is still used, these days primarily by amateur radio operators (hams). Strictly, on-off keying of a carrier should be known as "Interrupted Continuous Wave" or ICW or on-off keying (OOK).

Radio teletype equipment usually operates on short-wave (HF) and is much loved by the military because they create written information without a skilled operator. They send a bit as one of two tones using frequency-shift keying. Groups of five or seven bits become a character printed by a teleprinter. From about 1925 to 1975, radioteletype was how most commercial messages were sent to less developed countries. These are still used by the military and weather services.

Aircraft use a 1200 Baud radioteletype service over VHF to send their ID, altitude and position, and get gate and connecting-flight data. Microwave dishes on satellites, telephone exchanges and TV stations usually use quadrature amplitude modulation(QAM). QAM sends data by changing both the phase and the amplitude of the radio signal. Engineers like QAM because it packs the most bits into a radio signal when given an exclusive (non-shared) fixed narrowband frequency range. Usually the bits are sent in "frames" that repeat. A special bit pattern is used to locate the beginning of a frame.

Communication systems that limit themselves to a fixed narrowband frequency range are vulnerable to jamming. A variety of jamming-resistant spread spectrum techniques were initially developed for military use, most famously for Global Positioning System satellite transmissions. Commercial use of spread spectrum began in the 1980s.Bluetooth, most cell phones, and the 802.11b version of Wi-Fi each use various forms of spread spectrum.

Systems that need reliability, or that share their frequency with other services, may use "coded orthogonal frequency-division multiplexing" or COFDM. COFDM breaks a digital signal into as many as several hundred slower subchannels. The digital signal is often sent as QAM on the subchannels. Modern COFDM systems use a small computer to make and decode the signal with digital signal processing, which is more flexible and far less expensive than older systems that implemented separate electronic channels.

COFDM resists fading and ghosting because the narrow-channel QAM signals can be sent slowly. An adaptive system, or one that sends error-correction codes can also resist interference, because most interference can affect only a few of the QAM channels. COFDM is used for Wi-Fi, some cell phones, Digital Radio Mondiale, Eureka 147, and many other local area network, digital TV and radio standards.

 Citation: http://en.wikipedia.org/wiki/Radio