The History of Video Conferencing ? Moving Ahead at the Speed of Video

No new technology develops smoothly, and video conferencing had more than its share of bumps along the way before becoming the widely used communications staple it is today. The history of video conferencing in its earliest form goes back to the 1960's, when AT&T introduced the Picturephone at the World's Fair in New York. While viewed as a fascinating curiosity, it never became popular and was too expensive to be practical for most consumers when it was offered for $160 a month in 1970.
Commercial use of real video conferencing was first realized with Ericsson's

demonstration of the first trans-Atlantic LME video telephone call. Soon other companies began refining video conferencing technologies, including such advancements as network video protocol (NVP) in 1976 and packet video protocol (PVP) in 1981. None of these were put into commercial use, however, and stayed in the laboratory or private company use.
In 1976, Nippon Telegraph and Telephone established video conferencing (VC) between Tokyo and Osaka for company use. IBM Japan followed suit in 1982 by establishing VC running at 48000bps to link up with already established internal IBM video conferencing links in the United States so that they could have weekly meetings.
The 1980's introduce commercial video conferencing
In 1982, Compression Labs introduces their VC system to the world for $250,000 with lines for $1,000 an hour. The system was huge and used enormous resources capable of tripping 15 amp circuit breakers. It was, however, the only working VC system available until PictureTel's VC hit the market in 1986 with their substantially cheaper $80,000 system with $100 per hour lines.
In the time in between these two commercially offered systems, there were other video conferencing systems developed that were never offered commercially. The history of video conferencing isn't complete without mentioning these systems that were either prototypes or systems developed specifically for in-house use by a variety of corporations or organizations, including the military. Around 1984, Datapoint was using the Datapoint MINX system on their Texas campus, and had provided the system to the military.
In the late 1980's, Mitsubishi began selling a still-picture phone that was basically a flop in the market place. They dropped the line two years after introducing it. In 1991, the first PC based video conferencing system was introduced by IBM ? PicTel. It was a black and white system using what was at the time an incredibly inexpensive $30 per hour for the lines, while the system itself was $20,000. In June of the same year, DARTnet had successfully connected a transcontinental IP network of over a dozen research sites in the United States and Great Britain using T1 trunks. Today, DARTnet has evolved into the CAIRN system, which connects dozens of institutions.
CU-SeeMe revolutionizes video conferencing
One of the most famous systems in the history of video conferencing was the CU-SeeMe developed for the MacIntosh system in 1992. Although the first version didn't have audio, it was the best video system developed to that point. By 1993, the MAC program had multipoint capability, and in 1994, CU-SeeMe MAC was true video conferencing with audio. Recognizing the limitations of MAC compatibility in a Windows world, developers worked diligently to roll out the April 1994 CU-SeeME for Windows (no audio), followed closely by the audio version, CU-SeeMe v0.66b1 for Windows in August of 1995.
In 1992, AT&T rolled out their own $1,500 video phone for the home market. It was a borderline success. That same year, the world's first MBone audio/video broadcast took place and in July INRIA's video conferencing system was introduced. This is the year that saw the first real explosion in video conferencing for businesses around the globe and eventually led to the standards developed by the ITU.
International Telecommunications Union develops coding standards
The International Telecommunications Union (ITU) began developing standards for video conferencing coding in 1996, when they established Standard H.263 to reduce bandwidth for transmission for low bit rate communication. Other standards were developed, including H.323 for packet-based multi-media communications. These are a variety of other telecommunications standards were revised and updated in 1998. In 1999, Standard MPEG-4 was developed by the Moving Picture Experts Group as an ISO standard for multimedia content.
In 1993, VocalChat Novell IPX networks introduced their video conferencing system, but it was doomed from the start and didn't last. Microsoft finally came on board the video conferencing bandwagon with NetMeeting, a descendent of PictureTel's Liveshare Plus, in August of 1996 (although it didn't have video in this release). By December of the same year, Microsoft NetMeeting v2.0b2 with video had been released. That same month, VocalTec's Internet Phone v4.0 for Windows was introduced.
VRVS links global research centers
The Virtual Room Videoconferencing System (VRVS) project at Caltech-CERN kicked off in July of 1997. They developed the VRVS specifically to provide video conferencing to researchers on the Large Hadron Collider Project and scientists in the High Energy and Nuclear Physics Community in the U.S. and Europe. It has been so successful that seed money has been allotted for phase two, CalREN-2, to improve and expand on the already in-place VRVS system in order to expand it to encompass geneticists, doctors, and a host of other scientists in the video conferencing network around the world.
Cornell University's development team released CU-SeeMe v1.0 in 1998. This color video version was compatible with both Windows and MacIntosh, and huge step forward in pc video conferencing. By May of that year, the team has moved on to other projects.
In February of 1999, Session Initiation Protocol (SIP) was launched by MMUSIC. The platform showed some advantages over H.323 that user appreciated and soon made it almost as popular. 1999 was a very busy year, with NetMeeting v3.0b coming out, followed quickly by version three of the ITU standard H.323. Then came the release of iVisit v2.3b5 for both Windows and Mac, followed by Media Gateway Control Protocol (MGCP), version 1. In December, Microsoft released a service pack for NetMeeting v3.01 (4.4.3388) and an ISO standard MPEG-4 version two was released. Finally, PSInet was the first company to launch H.323 automated multipoint services. Like we said, 1999 was a very busy year.
SIP entered version 1.30 in November of 2000, the same year that standard H.323 hit version 4, and Samsung released their MPEG-4 streaming 3G video cell phone, the first of its kind. It was a hit, particularly in Japan. Rather predictably, Microsoft NetMeeting had to release another service pack for version 3.01.
In 2001, Windows XP messenger announced that it would now support Session Initiation Protocol. This was the same year the world's first transatlantic tele-surgery took place utilizing video conferencing. In this instance, video conferencing was instrumental in allowing a surgeon in the U.S. to use a robot overseas to perform gall bladder surgery on a patient. It was one of the most compelling non-business uses in the history of video conferencing, and brought the technology to the attention of the medical profession and the general public.
In October of 2001, television reporters began using a portable satellite and a videophone to broadcast live from Afghanistan during the war. It was the first use of video conferencing technology to converse live with video with someone in a war zone, again bringing video conferencing to the forefront of people's imaginations.
Founded in December of 2001, the Joint Video Team completed basic research leading to ITU-T H.264 by December of 2002. This protocol standardized video compression technology for both MPEG-4 and ITU-T over a broad range of application areas, making it more versatile than its predecessors. In March of 2003, the new technology was ready for launch to the industry.
New uses for video conferencing technologies
2003 also saw the rise in use of video conferencing for off-campus classrooms. Interactive classrooms became more popular as the quality of streaming video increased and the delay decreased. Companies such as VBrick provided various MPEG-4 systems to colleges across the country. Desktop video conferencing is also on the rise and gaining popularity.
Companies newer to the market are now refining the details of performance in addition to the nuts and bolts of transmission. In April of 2004, Applied Global Technologies developed a voice-activated camera for use in video conferencing that tracks the voice of various speakers in order to focus on whoever is speaking during a conference call. In March 2004, Linux announced the release of GnomeMeeting, an H.323 compliant, free video conferencing platform that is NetMeeting compatible.
With the constant advances in video conferencing systems, it seems obvious that the technology will continue to evolve and become an integral part of business and personal life. As new advances are made and systems become more reasonably priced, keep in mind that choices are still determined by network type, system requirements and what your particular conferencing needs are.



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How Video Conferencing Works ? Multimedia, Interactive Communication Across the Miles

You may think you understand video conferencing pretty well until someone who isn't at all familiar with it approaches you for a simple definition. When they ask, "What exactly is video conferencing?" you could suddenly realize you're at a loss for words.
The simplest definition of how video conferencing works is simply by the integration of video, audio and peripherals to enable two or more people to communicate simultaneously over some type of telecommunications lines. In other words, you are transmitting synchronized images and verbal communications between two or more locations in lieu of them being in the same room. How video conferencing works is a little bit harder to explain than answering the question, "What is video conferencing?"

Millions of people use video conferencing every day around the globe, but very few people know just how the technical aspects of the process work. The main ingredients of successful video conferencing are video cameras, microphones, appropriate computer software and computer equipment and peripherals that will integrate with the transmission lines to relay the information.
The analog information recorded by the microphones and cameras is broken down into discreet units, translating it to ones and zeros. A Codec encodes the information to a digital signal that can then be transmitted to a codec at the other end, which will retranslate these digital signals back into analog video images and audio sounds.
The theory's the same, the transmission has changed
In the earlier days of video conferencing, T1, ATM and ISDN lines were used almost exclusively but were really only practical for room-based video conferencing systems. These dedicated lines were expensive and only large corporations tended to have the facilities and money to invest in this type of set-up.
As the Internet became more a part of the everyday lives of all businesses, however, it changed how video conferencing was conducted. The TCP/IP connections of the Internet are much less expensive and can carry large quantities of information, including video packets for conferencing, relatively easily. Because of this, video conferencing has become much more prevalent in small businesses and in desktop packages that can be set up with software for computer-to-computer networking.
Compression makes video transmission practical
The problem that arises when you convert analog to digital for transmission is the loss of clarity in an image. Analog signals are a continuous wave of amplitudes and frequencies showing shades and ranges of color as well as depth and brightness. When you convert to digital, which is strictly 0's and 1's, you then need to develop a grid to represent values, intensities and saturations of different color values so that the image can be interpreted and reformed at the receiving end.
This vast amount of digital information requires huge bandwidth and means that the time it would take to transmit video images would be impractical for most applications. That's where compression is crucial. When determining how video conferencing works, one of the most important elements is the compression ratio.
The higher the compression ratio, the more quickly the information is capable of being transmitted. In many cases, however, this also means some loss in clarity or audio/video quality. For instance, a compression ratio of 4:1 would be terribly slow but have a fantastic picture quality. But by the time it was transmitted, everyone at the other end would probably have left the room for a cup of coffee. Lossy compression discards unneeded or irrelevant sections of a signal in order to transmit only the essentials, speeding up the transmission time significantly but sometimes resulting in loss of quality.
Compression can either be intra-frame or inter-frame for material that is repetitive or redundant, such as that wall behind the conference participant. Since the wall remains static and never changes, this image is redundant and can be eliminated from transmissions to an extent with proper compression. Intra-frame compression assumes the redundancy will be present in parts of a frame that are close to each other. Inter-frame compression assumes that there is redundancy over time (i.e., like that wall). Either of these can achieve a fairly high degree of accuracy and reduce the bandwidth needed for transmittal of signals.
A newer version of compression/decompression is SightSpeed technology, developed by Cornell University. SightSpeed compresses only images considered essential and eliminating what is considered 'filler,' relying on the brain to fill in the decompression at the other end. Based on an artificial intelligence model, SightSpeed achieves compression of about 90:1, compared to the typical 15:1 for video conferencing.
Any video conferencing session you use will provide compression of the transmission signal. The key is determining the balance between speed and video picture quality that is right for your needs.
Point to point video conferencing
Point to point video conferencing is just what it sounds like ? a link between two different points on the planet, or two different video conferencing terminals. It could be between an office in New York City and a conference room in Munich. Point to point video conferencing can easily be initiated by someone on one end contacting the other end as though making a standard telephone call. There are no special arrangements to be made other than knowing that the participants will be there.
Multipoint conferencing is more complex
Multipoint conferencing is more complicated because it has to coordinate several different locations simultaneously. Since you can't be in direct contact with several places at once while they are all in contact with others, you need one source that will tie them all together. In video conferencing, this is called a multipoint bridge or multipoint conferencing unit (MCU).
An MCU enables multi-location video conferencing by providing a sort of "central processing center" for all of the locations through which all the information flows. The MCU receives all information from the various locations and then sends it out to each location. In some cases the MCU is located on a particular PC, and in other cases it is located on a remote server (the most common structure, particularly for more powerful MCU networks).
Audio is usually sent and received simultaneously in all locations with an MCU with no problem because of the relatively small bandwidth needed for transmittal. It is broadcast in what is called "full duplex" mode, meaning everyone can talk and hear at the same time with no cutting off when one person or another speaks.
Video transmission, however, can be broadcast in a number of ways with an MCU depending upon the quality of the software and the complexity of the system. Some common types of video transmission for video conferencing include:
• Continuous Presence video conferencing, which allows up to four conference sites to be seen simultaneously on split screens. This is usually used if you have a small group or individuals in separate locations and will primarily be seeing close-up shots.
• Universal Control video conferencing is controlled by the initiating conference site. The primary site determines who sees what at all other sites.
• Voice Activated video conferencing is by far the most common type used today. The image with these systems shifts to the site that is currently activating the microphone so that you can always see whoever is speaking. However, if there is a good deal of background noise participants should mute their microphones when they aren't talking in order to avoid the image jumping about needlessly.
Overcoming the language barrier
Obviously, communicating through video conferencing can't be achieved unless both ends of the conference are "speaking the same language." That is, whatever is being transmitted electronically will need to be reassembled properly and heard and seen clearly at the other end. The Codec system (Coder-Decoder) is useless if both ends aren't using the same virtual language to interpret the signals.
The International Telecommunications Union (ITU) developed a set of standards in 1996 dubbed H.323 to outline specific guidelines for Video Conferencing standards and protocols so that compliance and support across networks would be easier to achieve and maintain. Since then, many manufacturers and developers of video conferencing tools have adopted the H.323 guidelines as their own.
Web conferencing solutions such as Click to Meet, Lotus's SameTime, and WebEx also offer corporate solutions that are based on Internet video conferencing. These systems have shared protocols that can be downloaded and used anywhere at any location for subscribers through the Internet. These are becoming more popular with companies who like the convenience and user-friendliness. They will no doubt become more and more refined over time, vying with and perhaps surpassing the H.323 standards.
Overcoming firewall issues
There are, of course, obstacles to overcome when you take a look at how video conferencing works. After all, you're sending vast amounts of translated data either directly or through a gatekeeper system (the MCU) that is switching and transferring information between a variety of computers. Just about any business these days has a firewall system to provide security and protect the system from potential viruses. Trouble is, many firewalls also block the transmission of data for video conferencing.
Recent innovations have largely circumvented these problems by designing firewall solutions that recognize video conferencing signaling requests and allow the information packets to bypass the firewall or router without disabling the firewall protection for other traffic. Even with this, however, there may be occasions when packets are dropped because of heavy traffic on the system, so investing in a firewall system that can handle substantial traffic is essential to quality video conferencing performance.
How video conferencing works will certainly evolve over time and improve in the coming years, but a basic understanding of what it is and how it works now will help you make the best choice for you when you're ready to begin using video conferencing yourself.
This article on the "How Video Conferencing Works" reprinted with permission.



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Seven Steps to a Vital Videoconference

When it's time for your fifteen minutes of fame will you be ready? With videoconferencing becoming common place in 21st century communication, executives, entrepreneurs, and leaders need to be media savvy. Here's how to put your best face forward:



1. Prepare. It's not enough to show up to speak. Practice with the technology an hour before your presentation and rehearse your message points. Don't wing it.

2. Pause and Listen. Expect time delays. A weak video signal could cause a delay or echo. Allow ample time for your message to reach the other site and wait for a response before you resume making new remarks.

3. Use Small Gestures. Actions are amplified on videoconference. Wild, sweeping movements can result in distorted, fuzzy images.

4. Appoint a Moderator. The moderator facilitates the meeting, introduces guests, and keeps the presentation movoing. The moderator or a designated person operates the technology to free speakers to focus on the message.

5. Dress for TV. Avoid distracting jewelry, shiny clothing, and large, bold patterns. Keep another shirt or blouse in the office for late day videoconferences. Perspiration stains and wrinkles will be noticeable on video. Keep powder handy for shiny noses and bald spots.

6. Create a Connection. Begin with hello. The wave is a standard greeting in videoconferencing. Use the zoom function on the camera to establish eye contact. It's difficult to communicate without viewing facial expressions from the remote site.

7. Minimize Distractions. Keep noise down by restricitng movement in and out of the room. Turn off all beepers and cell phones at the beginning of the meeting. Place a "Do Not Enter" sign on the door and change activities frequently to maintain attention and avoid the boredom factor.

Nothing can replace in-person communication. But if you master the techniques of online communication, videoconferencing is the next best thing to being there.

Copyright Diane DiResta, 2004. All rights reserved.

Diane DiResta is President of DiResta Communications, Inc.,a New York City based consultancy. She is author of Knockout Presentations: How to Deliver Your Message with Power, Punch, and Pizzazz (Chandler House Press) http://www.diresta.com



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Paid to Click lewat Donkey Mails

lang : indonesia
Dari sekian banyak tawaran dari situs-situs MLM banyak kita temukan kata paid to click , paid to sign up , paid game dsb. artinya ketika kita mengklick ,sign up atau main game maka kita akan mendapatkan bagian ( uang ) walapun itu sedikit demi sedikit .namun banyak juga situs yang bertujuan untuk mencari keuntunan dengan cara menipu . Mereka membuat situs yang sama dengan yang aslinya tapi sebenarnya situs tersebut palsu , dengan cekatan mereka meniru mulai dari tampilan , isi , bahkan nama situs sehingga orang lain bisa tertipu dengan mendaftar dan mentransfer atau menyimpan uangnya di situs tersebut .
sebenarnya dari situs tersebut ada yang mengandung unsur judi ( gambling) misalnya lotere , head or tails game , jackpot dsb. namun banyak orang yang tidak peduli dengan itu walaupun mereka tahu tapi tidak mau tahu , ada juga orang yang tidak tahu-menahu atau tidak mengerti dengan sistem semacam ini .
Dengan banyaknya situs semacam itu saya menjadi penasaran dan mencoba sebuah situs yang menawarkan hal semacam itu seperti donkey mail . ternyata setelah saya mencoba fitur paid to click , paid to sign up saja saya bisa mendapatkan beberapa sen yang bisa saya kumpulkan dan saya cairkan lewat rekening egold. Sekarang saya percaya bahwa dari sekian banyak situs yang menawarkan hal semacam ada yang benar dan ada yang menipu ( scam ) .
tapi saya sarankan kalau ada yang ingin mencoba , jangan sekali -kali masuk situs yang mengandung unsur gambling ( judi) seperti lotere , atau game yang menawarkan keberuntungan semata tanpa ada suatu kerja keras yang lazim ( mengundi nasib ).
Ada juga yang menawarkan hasil yang lebih banyak seperti google adsense. Semua percaya bahwa mencari uang itu tidak mudah semudah apa yang banyak di tawarkan dengan hasil yang sangat menggiurkan . Disini kita dituntut untuk bekerja keras tapi tidak menggunakan otot fisik tapi otak . yang paling penting adalah strategi

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Power Inverter

Converting 12 volts dc into a well-regulated 220 v ac at high efficiency is especially desirable when the input power source is derived from solar cells or a car battery. Often, too, output harmonics generated by the conventional square-wave inverter must be reduced to a point
where it does not create other practical drawbacks. These design requirements are met with this inverter, which maintains efficiency and reduces harmonics at all power levels by ensuring that the driving current is almost linearly proportional to the output power and by producing a three-level output waveform that more closely approximates a sine wave. As shown, the CD4013 dual flip-flop generates a l00-hertz pulse train (duty cycle is 1/6) and a 50-Hz square wave (the oscillator is easily modified for 60 Hz), both of which are independent of input voltage and load variations. The AND gates formed by the diode-resistor networks at the output of the flip-flops apply these signals to the power transistor drive circuitry (BC548, MJE801, etc.), which, configured in a two-phase switched-mode arrangement that sends a pulse through
the primary of the line transformer every quarter cycle at 50 Hz, generates a three-level waveform.

Because the positive and negative output swings each last one third of a cycle, separated by sixth-period intervals at the zero crossings, third-harmonic attenuation is theoretically reduced to zero. By appropriate modulation of these zero-voltage intervals, good regulation is achieved at low loss without reintroducing excessive third harmonic energy. Although this method is not as
elegant as the transformerless method of summing phase-shifted square waves or stepped sine waves,’ it is much simpler. D1 and C1 ensure reliable startup. Current limiting is provided by Q1, which diverts drive current if output current soars. Output impedance is kept virtually constant
during all parts of the cycle, including zero-voltage periods, where Q2 saturates Q3, thus feeding an inductive current back into the battery via diodes D2 and D3. The zener diode provides spike suppression. A neon lamp or similar symmetrical-breakdown device allows simple voltage regulation. When Vout, soars, Ci attains breakdown before the normal zero-voltage period, and Q4 or Q5 diverts current. Because this is a switched-mode inverter, efficiency is excellent at nominal output power. But, in contrast to other inverters, its high-efficiency characteristic extends down to very low output-power levels. This is achieved by forcing output current to flow not only through the transformer’s secondary, but also through the baseemitter
junctions of the 2N5685 power transistors. Thus, base drive closely tracks the output power requirements. As long as the transformer winding ratio is compatible
with the gain needed to saturate the power transistors, significant power can be saved at the lower power levels. Efficiency exceeds 88% at 120 volt-amperes, 75% at 175
VA, and 50% at 15 VA. No-load loss is only 12 watts. Still better performance can be obtained by adopting the power Darlington configuration, as shown at the upper left. Using the Darlington, the inverter’s efficiency will be 89% at 150 VA, 70% at 225 VA, and 50% at 15
VA. Lower transformer step-up ratios further improve performance, because the output transistors switch more totally into saturation. Thus, 12-v dc-to-110-v ac and 24-v-dc-to-220-v-ac designs are more efficient than this 12-v-dc-to-220-v-ac circuit.

see the circuit diagram here

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Low Voltage Microcontroller

The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with
2K bytes of Flash programmable and erasable read-only memory (PEROM). The
device is manufactured using Atmel’s high-density nonvolatile memory technology
and is compatible with the industry-standard MCS-51 instruction set.

By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a powerful
microcomputer which provides a highly-flexible and cost-effective solution to many
embedded control applications.

The AT89C2051 provides the following standard features: 2K bytes of Flash, 128
bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt
architecture, a full duplex serial port, a precision analog comparator, on-chip oscillator
and clock circuitry.

In addition, the AT89C2051 is designed with static logic for operation
down to zero frequency and supports two software selectable power saving
modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial
port and interrupt system to continue functioning. The power-down mode saves the
RAM contents but freezes the oscillator disabling all other chip functions until the next
hardware reset.

Feature

• Compatible with MCS®-51Products
• 2K Bytes of Reprogrammable Flash Memory
– Endurance: 1,000 Write/Erase Cycles
• 2.7V to 6V Operating Range
• Fully Static Operation: 0 Hz to 24 MHz
• Two-level Program Memory Lock
• 128 x 8-bit Internal RAM
• 15 Programmable I/O Lines
• Two 16-bit Timer/Counters
• Six Interrupt Sources
• Programmable Serial UART Channel
• Direct LED Drive Outputs
• On-chip Analog Comparator
• Low-power Idle and Power-down Modes
• Green (Pb/Halide-free) Packaging Option Read More../ baca selanjutnya ...