Vish Khandelwal asked:


 

What is a Neural Network?

 

First of all, when we are talking about a neural network, we should more properly say "artificial neural network" (ANN), because that is what we mean most of the time. Biological neural networks are much more complicated than the mathematical models we use for ANNs. But it is customary to be lazy and drop the "A" or the "artificial".

An Artificial Neural Network (ANN) is an information processing paradigm that is inspired by the way biological nervous systems, such as the brain, process information. The key element of this paradigm is the novel structure of the information processing system. It is composed of a large number of highly interconnected processing elements (neurons) working in unison to solve specific problems. ANNs, like people, learn by example. An ANN is configured for a specific application, such as pattern recognition or data classification, through a learning process. Learning in biological systems involves adjustments to the synaptic connections that exist between the neurons. This is true of ANNs as well.

 

 

Historical Background of Neural Networks

 

Neural network simulations appear to be a recent development. However, this field was established before the advent of computers, and has survived at least one major setback and several eras.

Many importand advances have been boosted by the use of inexpensive computer emulations. Following an initial period of enthusiasm, the field survived a period of frustration and disrepute. During this period when funding and professional support was minimal, important advances were made by relatively few reserchers. These pioneers were able to develop convincing technology which surpassed the limitations identified by Minsky and Papert. Minsky and Papert, published a book (in 1969) in which they summed up a general feeling of frustration (against neural networks) among researchers, and was thus accepted by most without further analysis. Currently, the neural network field enjoys a resurgence of interest and a corresponding increase in funding.

 

The history of neural networks that was described above can be divided into several periods:

 

First Attempts: There were some initial simulations using formal logic. McCulloch and Pitts (1943) developed models of neural networks based on their understanding of neurology. These models made several assumptions about how neurons worked. Their networks were based on simple neurons which were considered to be binary devices with fixed thresholds. The results of their model were simple logic functions such as "a or b" and "a and b". Another attempt was by using computer simulations. Two groups (Farley and Clark, 1954; Rochester, Holland, Haibit and Duda, 1956). The first group (IBM reserchers) maintained closed contact with neuroscientists at McGill University. So whenever their models did not work, they consulted the neuroscientists. This interaction established a multidiscilinary trend which continues to the present day.

 

Promising & Emerging Technology: Not only was neroscience influential in the development of neural networks, but psychologists and engineers also contributed to the progress of neural network simulations. Rosenblatt (1958) stirred considerable interest and activity in the field when he designed and developed the Perceptron. The Perceptron had three layers with the middle layer known as the association layer.This system could learn to connect or associate a given input to a random output unit.

Another system was the ADALINE (ADAptive LInear Element) which was developed in 1960 by Widrow and Hoff (of Stanford University). The ADALINE was an analogue electronic device made from simple components. The method used for learning was different to that of the Perceptron, it employed the Least-Mean-Squares (LMS) learning rule.

 

Period of Frustration & Disrepute: In 1969 Minsky and Papert wrote a book in which they generalised the limitations of single layer Perceptrons to multilayered systems. In the book they said: "…our intuitive judgment that the extension (to multilayer systems) is sterile". The significant result of their book was to eliminate funding for research with neural network simulations. The conclusions supported the disenhantment of reserchers in the field. As a result, considerable prejudice against this field was activated.

 

Innovation: Although public interest and available funding were minimal, several researchers continued working to develop neuromorphically based computaional methods for problems such as pattern recognition.

During this period several paradigms were generated which modern work continues to enhance.Grossberg’s (Steve Grossberg and Gail Carpenter in 1988) influence founded a school of thought which explores resonating algorithms. They developed the ART (Adaptive Resonance Theory) networks based on biologically plausible models. Anderson and Kohonen developed associative techniques independent of each other. Klopf (A. Henry Klopf) in 1972, developed a basis for learning in artificial neurons based on a biological principle for neuronal learning called heterostasis.

Werbos (Paul Werbos 1974) developed and used the back-propagation learning method, however several years passed before this approach was popularized. Back-propagation nets are probably the most well known and widely applied of the neural networks today. In essence, the back-propagation net. is a Perceptron with multiple layers, a different thershold function in the artificial neuron, and a more robust and capable learning rule.

Amari (A. Shun-Ichi 1967) was involved with theoretical developments: he published a paper which established a mathematical theory for a learning basis (error-correction method) dealing with adaptive patern classification. While Fukushima (F. Kunihiko) developed a step wise trained multilayered neural network for interpretation of handwritten characters. The original network was published in 1975 and was called the Cognitron.

 

Re-Emergence: Progress during the late 1970s and early 1980s was important to the re-emergence on interest in the neural network field. Several factors influenced this movement. For example, comprehensive books and conferences provided a forum for people in diverse fields with specialized technical languages, and the response to conferences and publications was quite positive. The news media picked up on the increased activity and tutorials helped disseminate the technology. Academic programs appeared and courses were inroduced at most major Universities (in US and Europe). Attention is now focused on funding levels throughout Europe, Japan and the US and as this funding becomes available, several new commercial with applications in industry and finacial institutions are emerging.

Today: Significant progress has been made in the field of neural networks-enough to attract a great deal of attention and fund further research. Advancement beyond current commercial applications appears to be possible, and research is advancing the field on many fronts. Neurally based chips are emerging and applications to complex problems developing. Clearly, today is a period of transition for neural network technology.

 

Why use neural networks?

 

Neural networks, with their remarkable ability to derive meaning from complicated or imprecise data, can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computer techniques. A trained neural network can be thought of as an "expert" in the category of information it has been given to analyse. This expert can then be used to provide projections given new situations of interest and answer "what if" questions.

Other advantages include:

 

Adaptive learning: An ability to learn how to do tasks based on the data given for training or initial experience. Self-Organisation: An ANN can create its own organisation or representation of the information it receives during learning time. Real Time Operation: ANN computations may be carried out in parallel, and special hardware devices are being designed and manufactured which take advantage of this capability. Fault Tolerance via Redundant Information Coding: Partial destruction of a network leads to the corresponding degradation of performance. However, some network capabilities may be retained even with major network damage.

 

          Neural networks versus conventional computers

 

Neural networks take a different approach to problem solving than that of conventional computers. Conventional computers use an algorithmic approach i.e. the computer follows a set of instructions in order to solve a problem. Unless the specific steps that the computer needs to follow are known the computer cannot solve the problem. That restricts the problem solving capability of conventional computers to problems that we already understand and know how to solve. But computers would be so much more useful if they could do things that we don’t exactly know how to do.

Neural networks process information in a similar way the human brain does. The network is composed of a large number of highly interconnected processing elements(neurones) working in parallel to solve a specific problem. Neural networks learn by example. They cannot be programmed to perform a specific task. The examples must be selected carefully otherwise useful time is wasted or even worse the network might be functioning incorrectly. The disadvantage is that because the network finds out how to solve the problem by itself, its operation can be unpredictable.

On the other hand, conventional computers use a cognitive approach to problem solving; the way the problem is to solved must be known and stated in small unambiguous instructions. These instructions are then converted to a high level language program and then into machine code that the computer can understand. These machines are totally predictable; if anything goes wrong is due to a software or hardware fault.

Neural networks and conventional algorithmic computers are not in competition but complement each other. There are tasks are more suited to an algorithmic approach like arithmetic operations and tasks that are more suited to neural networks. Even more, a large number of tasks, require systems that use a combination of the two approaches (normally a conventional computer is used to supervise the neural network) in order to perform at maximum efficiency.

 

 

 

 

 

 

Neural Networks in Practice

 

Given this description of neural networks and how they work, what real world applications are they suited for? Neural networks have broad applicability to real world business problems. In fact, they have already been successfully applied in many industries.

 

Since neural networks are best at identifying patterns or trends in data, they are well suited for prediction or forecasting needs including:

 

 

sales forecasting

industrial process control

customer research

data validation

risk management

target marketing

But to give you some more specific examples; ANN are also used in the following specific paradigms: recognition of speakers in communications; diagnosis of hepatitis; recovery of telecommunications from faulty software; interpretation of multimeaning Chinese words; undersea mine detection; texture analysis; three-dimensional object recognition; handwritten word recognition; and ****** recognition.

 

 

 

 

 

Human and Artificial Neurones – investigating the similarities

 

How the Human Brain Learns?

 

Much is still unknown about how the brain trains itself to process information, so theories abound. In the human brain, a typical neuron collects signals from others through a host of fine structures called dendrites. The neuron sends out spikes of electrical activity through a long, thin stand known as an axon, which splits into thousands of branches. At the end of each branch, a structure called a synapse converts the activity from the axon into electrical effects that inhibit or excite activity from the axon into electrical effects that inhibit or excite activity in the connected neurones. When a neuron receives excitatory input that is sufficiently large compared with its inhibitory input, it sends a spike of electrical activity down its axon. Learning occurs by changing the effectiveness of the synapses so that the influence of one neuron on another changes.

 

 

 

 

 

 

Components of a neuron

 

 

 

 

 

The synapse

 

  From Human Neurones to Artificial Neurones

 

We conduct these neural networks by first trying to deduce the essential features of neurones and their interconnections. We then typically program a computer to simulate these features. However because our knowledge of neurones is incomplete and our computing power is limited, our models are necessarily gross idealisations of real networks of neurones.

 

The neuron model

 

Architecture of neural networks

Feed-forward networks

 Feed-forward ANNs  allow signals to travel one way only; from input to output. There is no feedback (loops) i.e. the output of any layer does not affect that same layer. Feed-forward ANNs tend to be straight forward networks that associate inputs with outputs. They are extensively used in pattern recognition. This type of organisation is also referred to as bottom-up or top-down.

 

Feedback networks

Feedback networks (figure 1) can have signals travelling in both directions by introducing loops in the network. Feedback networks are very powerful and can get extremely complicated. Feedback networks are dynamic; their ’state’ is changing continuously until they reach an equilibrium point. They remain at the equilibrium point until the input changes and a new equilibrium needs to be found. Feedback architectures are also referred to as interactive or recurrent, although the latter term is often used to denote feedback connections in single-layer organisations.



 

 

 

 

Applications of neural networks

Neural Networks in Practice

Given this description of neural networks and how they work, what real world applications are they suited for? Neural networks have broad applicability to real world business problems. In fact, they have already been successfully applied in many industries.

Since neural networks are best at identifying patterns or trends in data, they are well suited for prediction or forecasting needs including:

sales forecasting

industrial process control

customer research

data validation

risk management

target marketing

But to give you some more specific examples; ANN are also used in the following specific paradigms: recognition of speakers in communications; diagnosis of hepatitis; recovery of telecommunications from faulty software; interpretation of multimeaning Chinese words; undersea mine detection; texture analysis; three-dimensional object recognition; hand-written word recognition; and ****** recognition.

Neural networks in medicine

 

Artificial Neural Networks (ANN) are currently a ‘hot’ research area in medicine and it is believed that they will receive extensive application to biomedical systems in the next few years. At the moment, the research is mostly on modelling parts of the human body and recognising diseases from various scans (e.g. cardiograms, CAT scans, ultrasonic scans, etc.).

Neural networks are ideal in recognising diseases using scans since there is no need to provide a specific algorithm on how to identify the disease. Neural networks learn by example so the details of how to recognise the disease are not needed. What is needed is a set of examples that are representative of all the variations of the disease. The quantity of examples is not as important as the ‘quantity’. The examples need to be selected very carefully if the system is to perform reliably and efficiently.

Modelling and Diagnosing the Cardiovascular System

Neural Networks are used experimentally to model the human cardiovascular system. Diagnosis can be achieved by building a model of the cardiovascular system of an individual and comparing it with the real time physiological measurements taken from the patient. If this routine is carried out regularly, potential harmful medical conditions can be detected at an early stage and thus make the process of combating the disease much easier.

A model of an individual’s cardiovascular system must mimic the relationship among physiological variables (i.e., heart rate, systolic and diastolic blood pressures, and breathing rate) at different physical activity levels. If a model is adapted to an individual, then it becomes a model of the physical condition of that individual. The simulator will have to be able to adapt to the features of any individual without the supervision of an expert. This calls for a neural network.

Another reason that justifies the use of ANN technology, is the ability of ANNs to provide sensor fusion which is the combining of values from several different sensors. Sensor fusion enables the ANNs to learn complex relationships among the individual sensor values, which would otherwise be lost if the values were individually analysed. In medical modelling and diagnosis, this implies that even though each sensor in a set may be sensitive only to a specific physiological variable, ANNs are capable of detecting complex medical conditions by fusing the data from the individual biomedical sensors.

Electronic noses

ANNs are used experimentally to implement electronic noses. Electronic noses have several potential applications in telemedicine. Telemedicine is the practice of medicine over long distances via a communication link. The electronic nose would identify odours in the remote surgical environment. These identified odours would then be electronically transmitted to another site where an door generation system would recreate them. Because the sense of smell can be an important sense to the surgeon, telesmell would enhance telepresent surgery.

For more information on telemedicine and telepresent surgery

 

Electronic noses

ANNs are used experimentally to implement electronic noses. Electronic noses have several potential applications in telemedicine. Telemedicine is the practice of medicine over long distances via a communication link. The electronic nose would identify odours in the remote surgical environment. These identified odours would then be electronically transmitted to another site where an door generation system would recreate them. Because the sense of smell can be an important sense to the surgeon, telesmell would enhance telepresent surgery.

For more information on telemedicine and telepresent surgery

    Neural Networks in business

 

 

Business is a diverted field with several general areas of specialisation such as accounting or financial analysis. Almost any neural network application would fit into one business area or financial analysis.

There is some potential for using neural networks for business purposes, including resource allocation and scheduling. There is also a strong potential for using neural networks for database mining, that is, searching for patterns implicit within the explicitly stored information in databases. Most of the funded work in this area is classified as proprietary. Thus, it is not possible to report on the full extent of the work going on. Most work is applying neural networks, such as the Hopfield-Tank network for optimization and scheduling.

    Marketing

There is a marketing application which has been integrated with a neural network system. The Airline Marketing Tactician (a trademark abbreviated as AMT) is a computer system made of various intelligent technologies including expert systems. A feedforward neural network is integrated with the AMT and was trained using back-propagation to assist the marketing control of airline seat allocations. The adaptive neural approach was amenable to rule expression. Additionaly, the application’s environment changed rapidly and constantly, which required a continuously adaptive solution. The system is used to monitor and recommend booking advice for each departure. Such information has a direct impact on the profitability of an airline and can provide a technological advantage for users of the system. [Hutchison & Stephens, 1987]

While it is significant that neural networks have been applied to this problem, it is also important to see that this intelligent technology can be integrated with expert systems and other approaches to make a functional system. Neural networks were used to discover the influence of undefined interactions by the various variables. While these interactions were not defined, they were used by the neural system to develop useful conclusions. It is also noteworthy to see that neural networks can influence the bottom line.

 

 

 

Are there any limits to Neural Networks?

 

The major issues of concern today are the scalability problem, testing, verification, and integration of neural network systems into the modern environment. Neural network programs sometimes become unstable when applied to larger problems. The defence, nuclear and space industries are concerned about the issue of testing and verification. The mathematical theories used to guarantee the performance of an applied neural network are still under development. The solution for the time being may be to train and test these intelligent systems much as we do for humans. Also there are some more practical problems like:

the operational problem encountered when attempting to simulate the parallelism of neural networks. Since the majority of neural networks are simulated on sequential machines, giving rise to a very rapid increase in processing time requirements as size of the problem expands.

Solution: implement neural networks directly in hardware, but these need a lot of development still. instability to explain any results that they obtain. Networks function as "black boxes" whose rules of operation are completely unknown

 

 

The Future

Because gazing into the future is somewhat like gazing into a crystal ball, so it is better to quote some "predictions". Each prediction rests on some sort of evidence or established trend which, with extrapolation, clearly takes us into a new realm.

Prediction 1:

Neural Networks will fascinate user-specific systems for education, information processing, and entertainment. "Alternative ralities", produced by comprehensive environments, are attractive in terms of their potential for systems control, education, and entertainment. This is not just a far-out research trend, but is something which is becoming an increasing part of our daily existence, as witnessed by the growing interest in comprehensive "entertainment centers" in each home.

This "programming" would require feedback from the user in order to be effective but simple and "passive" sensors (e.g fingertip sensors, gloves, or wristbands to sense pulse, blood pressure, skin ionisation, and so on), could provide effective feedback into a neural control system. This could be achieved, for example, with sensors that would detect pulse, blood pressure, skin ionisation, and other variables which the system could learn to correlate with a person’s response state.

Prediction 2:

Neural networks, integrated with other artificial intelligence technologies, methods for direct culture of nervous tissue, and other exotic technologies such as genetic engineering, will allow us to develop radical and exotic life-forms whether man, machine, or hybrid.

Prediction 3:

Neural networks will allow us to explore new realms of human capabillity realms previously available only with extensive training and personal discipline. So a specific state of consiously induced neurophysiologically observable awareness is necessary in order to facilitate a man machine system interface.

 

Conclusion

The computing world has a lot to gain fron neural networks. Their ability to learn by example makes them very flexible and powerful. Furthermore there is no need to devise an algorithm in order to perform a specific task; i.e. there is no need to understand the internal mechanisms of that task. They are also very well suited for real time systems because of their fast responseand computational times which are due to their parallel architecture.

Neural networks also contribute to other areas of research such as neurology and psychology. They are regularly used to model parts of living organisms and to investigate the internal mechanisms of the brain.

Perhaps the most exciting aspect of neural networks is the possibility that some day ‘consious’ networks might be produced. There is a number of scientists arguing that conciousness is a ‘mechanical’ property and that ‘consious’ neural networks are a realistic possibility.

Finally, I would like to state that even though neural networks have a huge potential we will only get the best of them when they are intergrated with computing, AI, fuzzy logic and related subjects.

 

Ryan asked:


The only knowledge you will have when you are out to buy a desktop will be the type of desk top you wish to acquire. In the desktop market however you will find wide range of configurations, different shapes and sizes and fast changing specifications of features.

The following guide has been prepared to ensure that you are able to arrive at the right specification of the desired features. Links are provided with each feature to arrive at variety of models available with that feature.

Find by features

Processor- CPUs are the main feature which decides what you can do, how much you can do and how fast you can do with your system. Processor specification states the brand, the processor type and the processor speed. The common understanding till some time ago was that higher the processor speed better will be the performance. Not so any longer. The major processor manufacturers Intel and AMD have revolutionized the processor market with dual core and quad core processors all in a single piece of silicon.

Single core chips like AMD Sempron, and Intel Celeron D don’t cost much and are configured in low priced desktops because of their low performance and low speed. They still run the show the reason being most software is designed for execution on a single thread (one stream of data) or processor core.

http://www.reviewgist.com/desktop-reviews?processorType=AMD+Sempron

http://www.reviewgist.com/desktop-reviews?processorType=Intel+Celeron+D

The AMD Athlon 64 isn’t fast but it satisfies all computing requirements. The price too has come down with the launch of newer processors. http://www.reviewgist.com/desktop-reviews?processorType=AMD+Athlon+64

Dual processor is two processor cores on a single piece of silicon. The advantage of having multiple processors is ability to handle more than one thread. When multiple applications are running at a time, the multiple processors are parallel processing and this increases the speed of performance. Customers intending to multi task, 3D gaming with desktops must insist on dual core processor type.

AMD Athlon 64 X2 – http://www.reviewgist.com/desktop-reviews?processorType=AMD+Athlon+64+X2

The Intel Core 2 Duo processors are fast and power efficient and can run the most intense applications. It is configured in low end systems as well as in gaming PCs.

http://www.reviewgist.com/desktop-reviews?processorType=Intel+Core+2+Duo

http://www.reviewgist.com/desktop-reviews?processorType=Intel+Core+Duo

Processor speed is another specification of the processor that needs attention before purchase, as this feature too determines what use you can put your desktop to. The processor executes instructions received from RAM. So if the desktop is intended for complicated calculations and drawings for graphic images and games a faster processor will be required.

1.5 to 2 GHz- Processor speed in this range would suffice the needs of students or small offices. http://www.reviewgist.com/desktop-reviews?processorSpeed=1.5-to-2

2.2 to 2.7 GHZ- http://www.reviewgist.com/desktop-reviews?processorSpeed=2.2-to-2.7

2.8 to 3.4 GHz- Processors with 3 GHz and higher speeds like Pentium 4 and equivalent AMD processors are ideal for desktop multimedia and Gaming PCs. http://www.reviewgist.com/desktop-reviews?processorSpeed=2.8-to-3.4

Memory- The next in the feature list of all desktops is the Memory. The specifications state the space and type. Space mentioned in MBs or GBs. There should be enough memory to run all the software you intend to use, so check out the requirements of the intended software before you decide on space specification of RAM. Larger the memory, faster the processor will operate as it permits larger amount of data to be transferred.

1 GB of RAM gives good performance and is the minimum requirement to run Windows Vista. 2 GB is the minimum requirement for multimedia.

128 to 256 MB- http://www.reviewgist.com/desktop-reviews?installedRAM=128-to-256

512 to 1024 MB- Home users and Home office would require 512 MB or more http://www.reviewgist.com/desktop-reviews?installedRAM=512-to-1024

The two types of memory are DDR SDRAM and DDR2 SDRAM. The DDR2 version is faster of the two. These memory types are categorized according to features like bandwidth and clock speed. Memory can be upgraded by Dual Inline Memory Module (DIMM).

Hard drive- Definitely you would want to store all the data you work with and create, the Operating Systems used and all your applications.

20 to 40 GB- A 40 GB hard drive provides enough storage for home, family and office applications but not for the demanding gaming and multi media applications. http://www.reviewgist.com/desktop-reviews?hardDriveCapacity=20-to-40

80 to 160 GB- For gaming and digital music hard drive requirement can be within this range.http://www.reviewgist.com/desktop-reviews?hardDriveCapacity=80-to-160

250 to 320 GB- if you are dabbling with huge amounts of data like digital images and multi media files check for models in the range of 200 to 350 GB. http://www.reviewgist.com/desktop-reviews?hardDriveCapacity=250-to-320

Higher GB up to 500GB storage drives too is available.

Desktops come with hard drives of 3.5inch size. Hard drives have an in built motor that spins in speed range of 5,400 to 15,000 revolutions per minute; most models have speed of 7200rpm. The advantage associated with higher speeds is faster access and storing of more data.

Size and Shape- Desktops come in a variety of shapes and sizes. The small form factor cases have a number of features for basic functioning however upgrading with expansion cards is not possible. The all-in-one model has both display and computer enclosed in a single box, hence ideal for space constraint situations.

The disadvantage is the computer may get obsolete before the display. The Mid tower case and Full-tower case are more popular these days because of their sleek look. Lot of interior space and slots are available for expansion and up-gradation with hard drives and optical drives. There are plenty of ports for connecting peripherals like printers and digital cameras.

Find by Type

Budget desktops- The budget desktops appeal to the home and student customers. Desktops within $400 come with features that serve the everyday requirement of word processing, spreadsheets, letterbox and web surfing. The processors from AMDs like the Sempron or the lower end processors of Athlon series and Intel’s Pentium 4 fit into this kind of budget. Lenovo ThinkCentre A60 (9631D4U) PC Desktop

IBM ThinkCentre S50 Refurbished Intel Desktop Computer – Intel P4 2.6GHz, 512MB DDR, 40GB HDD, DVD-R (J156-4384)

If you intend to use for gaming, raise the budget say within 500 to 600$ and you can have 3 GHz processor, 512MB Memory, a thin TFT screen and 120 GB hard drive. You can even upgrade the model. Upgrading the RAM is possible with a small amount. Check these models:

http://www.reviewgist.com/desktop-reviews?Price=434.5-to-665.5

Business Desktops- Business desktops need to come with a certain amount of quality, only that much that you need and that too at a competitive price. Security features, warranty details and availability of onsite service must be given priority. Desktops configured with power saving features of dual core processors by both AMD and Intel will give good value for money. You can consider these models:

Dell XPS 700 (XPS700-6366PB1) PC Desktop

Lenovo 3000 J115 PC Desktop

Gaming Desktops- You need speed to conquer your gaming opponent and Intel Core2Duo can be ideal or still better the AMD Athlon 64 X2s processors. The AMD’s dual cores stand better chance because most gaming applications are not designed to take advantage of the multi threading capabilities of Intel processors. You can also opt for the high speed hard drives. Check out the models at:

http://www.reviewgist.com/desktop-reviews?processorType=Intel+Core+2+Duo

http://www.reviewgist.com/desktop-reviews?processorType=AMD+Athlon+64+X2

Media Center and Digital Entertainment Desktops- You will need these types of desktops for storing and sharing music, photos, editing videos, creating movie DVDs and music CDs. For such peak performance the features required are fastest processors, biggest hard drives and brightest displays. And if you have deep pockets check out the models at

Dell XPS 700 (XPS700-2KX3WB1) PC Desktop

Hewlett Packard Compaq dc7600 (EH798UC) PC Desktop

Find by Price

230 to 400 $- In such a low range you will be surprised and satisfied to get desktops that have powerful processors and graphic cards. They have enough features to support general business tasks and office computing chores.

http://www.reviewgist.com/reviews?search=desktop&Price=250-to-400

400 to 600 $- Ideally suited for office computing, networking, home or small office users. These inexpensive desktops offer great features and performance for the money spent.

http://www.reviewgist.com/desktop-reviews?Price=407.3-to-616

600 to 1600 $ – Sturdy structure, lot of options for upgrading and can fast adapt to changing business needs and good multi-media control buttons.

http://www.reviewgist.com/desktop-reviews?Price=620.2-to-1600

Arthur Raise asked:


The market today is flooded with options and even when you want to purchase a camcorder you can be confused by the number of brands and configurations. When you want to but a camcorder, think about what you intend to use the camcorder for and how extensive your use will be. Don’t just buy the most expensive because it takes your fancy.

The World Wide Web is the most comprehensive source for buying camcorders. Online e-commerce sites offer a wide range of camcorders manufactured by leading brands Sony, Panasonic, Nikon, and more. Always comparison shop this will give you an idea of not just costs but features. Make the effort of reading consumer reviews and feedback. Take a look at auctions, sales, and discount offers. Many a time retailers offer huge discounts on overstocked camcorders.

Be an internet savvy shopper. Protect your privacy and only buy from reputed websites. Read how to protect yourself online on the federal consumer site. Only buy from a website that has a secure payment gateway. Check whether the online site that sells camcorders has a return policy and states clearly about shipping costs and time.

When buying a camcorder think about:

1. There are many options in camcorder types; you could buy an analogue camcorder or a digital camcorder. An analogue camcorder will allow you to watch the playback of what you record while a digital one will allow you to edit the film on your computer apart from playback.

2. Think seriously whether you want a camcorder to record home events and travel experiences or because you want to be a serious filmmaker. Study the various modes like sports mode or night vision one.

3. Make a budget camcorders can cost between USD 300-3000 so you need to decide how much you really want to spend. Never spend more than you can afford.

4. Ask about the features there are camcorders that have state of art features as well as ones that are automatic just aim and shoot.

5. Visit online and offline shops and make a survey of features, warrantees, as well as prices. Often online stores have camcorders at lower retail prices than retail stores.

6. Before you choose a brand or model be sure you understand its features. Surf the internet and understand the terminology. See: http://camcorders.about.com/od/camcorderglossary/Camcorder_Glossary.htm .

7. Find out what accessories you will need to use the camcorder efficiently.

8. Read articles and tips written by experts on how to film using a camcorder. Read through the instruction manual carefully and ask the seller to clarify any queries you may have.

Films shot with a camcorder can be posted on video blogs. There are sites devoted to camcorder films and its use. Read expert guidelines and advise. Become an expert camcorder user and enjoy hours of creative filming.

RAYMOND NWAMBUONWO asked:


When shopping for digital camcorders, several choices are available. Some of these options involve the products features, characteristics and price ranges. This objectiveness also exists when one is purchasing any product ranging from sneakers to furniture and from toys to SUVs. Another way that a type of commodity is differentiated is through the company that produces it. Today, Sony is one of the most trusted names in electronic equipment, which includes its line of Sony digital camcorders.

Sony was actually started with the name Tokyo Telecommunications Engineering Corporation. Mr. Morita Akio and Ibuka Masaru founded the company in 1946, and then changed the name to Sony in 1958. “Sony” is a combination of a Latin word that is the root of the word “sound;” the English word “sunny;” and the term “Sonny-boys,” which in Japanese refers to a nerd.

The first significant consumer product that the company sold was an audio tape recorder that Sony put on the market in 1950. Sony is renowned worldwide for manufacturing the first transistor radio that can fit in a pants pocket (1957), the portable tape player known as the Walkman (1979), and the famous Playstation video game system (1994).

Right before the first Sony digital camcorders were released, the company made two groundbreaking camcorders. Sony introduced its Betacam in 1982. This camcorder was produced for professional recording via television. The initial units were analog, though the Digital Betacam was added to the arsenal of Sony digital camcorders, in 1994. Many of Sony’s digital video tape recorders (vtr) can play back all of Sony’s analog and digital Betacam formats.

In 1983 Sony’s Betamovie, based on its Betamax format, became the first domestic camcorder. The compact video head drum of this analog camcorder was subsequently used for camcorders manufactured afterwards. Today’s users of Sony digital camcorders would find the Betamovie to be bulky. In fact, one could not hold it by using a single hand, so users oftentimes laid the camcorder on their shoulder. Nevertheless, camcorders that followed the Betamovie were even bulkier, as Betamovie units lacked playback and rewind features.

Many Sony digital camcorders are offered on the market today. These fantastic products vary significantly in appearances, features, and price. The primary groups of Sony digital camcorders include: hard disk camcorders, dvd camcorders, hi8 Camcorders, high definition (hd) camcorders, minidv (digital video) camcorders.

Since its inception in 1946, the Sony Corporation has become a leader and innovator in the world of digital electronic equipment. Following the tradition of the Betacam and Betamovie, today’s Sony digital camcorders connote the best of their company and the best of the industry.

JR Lang asked:


Ten years ago the only video cameras that were available were the analog type that were so big and bulky that they had to be carted around on a trolley while professionals used them to shoot video for television. Camcorders have come a long way, they are smaller, slimmer, user-friendly and have tons of options that are available on many different models. Also with today’s digital technology comes the digital camcorder, which makes shooting and editing a movie a simple and fun activity for many people.

When buying a camcorder it is important to choose one that fits with you. Store counters are filled with a great variety of brands and models each with an array of features and formats. It is important to understand these features when buying a camcorder and buying the right camcorder which fits your purpose and budget.

The following guide to buying a camcorder details these features and will give you the guidance needed to buy the right camcorder the first time.

While analog camcorders still exist, digital camcorders are the camcorders of the day. Digital camcorders provide a superb recording quality by recording audio and video digitally without any loss in quality. In fact the quality far outweighs analog in yielding excellent color and clarity with 500 lines of resolution. And while digital camcorders are more expensive than analog, the price difference has shrunk enough in the past couple of years to make it very worthwhile to purchase the digital type.

Digital camcorders display recorded images by using the fantastic flat LCD screen feature. These screens can be rotated about 290 degrees along the vertical line, and horizontally about 90 degrees. These screens have made digital camcorders very popular with consumers since the recording process becomes so easy and fun when you are able to see what is being recorded on the LCD screen in real time. Also it is important to note that the DVD camcorders LCD displays a list of the recorded scenes for quick, easy searching.

When buying a camcorder you want to get an LCD screen that is as large as you can afford. The larger the screen the more you can see what you are recording in real time. One thing to keep in mind is the larger the screen the more battery power it will draw.

Another feature of LCD screens is the viewfinder, which is intended for shooting in bright sunlight and helps to save power. The panel size of LCD screens is presented in inches ranging from 1.8 to 3.5 inch screens

Camcorders have two types of zoom capabilities, digital and optical, and many camcorders come with both. The digital zoom enlarges images by magnifying the actual pixels. The finished image is thus affected and lacks clear definition. Pixilation is the term that defines this process of blurring. This option can be turned off on most models of camcorders and should be for optimal image quality.

The optical zoom feature actually utilizes the movement of the lens. The focal length is changed and image that passes through the lens is captured with optical zoom. Higher optical zoom ratings give better image quality.

Very often the audio that is recorded with your camcorder is just as important as the video. Mostly camcorders have the same audio quality. Some problems may occur, such as recording of tape motor noise, no sound at all, noise from hand movement and even times when the camcorder will record the wrong thing. The best thing you can do when buying a camcorder is to look for options, and make sure that the camcorder has a microphone jack to which you can attach an external microphone as opposed to relying on the camcorders internal microphone. An external microphone will be of great benefit at those times when you are recording something like a concert, wedding or graduation speech because the external microphone will allow you adjust the channels to fit with the sound levels you are recording.

There are several media formats available with digital camcorders. When buying a camcorder this feature is very important to look at and choose the right format that fits your needs and budget. This is the feature which determines how the video is recorded and what kind of storage device is used.

DVD Camcorders – Before discussing the actual DVD media camcorders, first let’s take a look at the different types of DVD formats of which there are three: DVD-R, DVD-RW, and DVD-RAM. DVD-R is a recordable DVD format with a write-once only capability. DVD-RW is a recordable DVD but it allows rewrites and so provides unlimited writing to same disk. DVD-RAM – DVD Random Access Memory is a DVD disc, which can be recorded with information, erased, and recorded again. DVD-RAM is considered a highly reliable format, as the discs have built-in error control and a defect management system. Therefore, DVD-RAM is perceived to be better than the other DVD technologies.

There are two versions of DVD camcorders. The first one works with rewritable DVD-RAM discs requiring a DVD player with RAM playback or a PC with a DVD-RAM drive. The second works by using the more popular DVD-RW and DVD-R discs that work with most ordinary DVD players and allow for actual recording of images to the DVD disk. A great feature of this recording format is the ability to edit in-camera and with repeated playbacks the disk does not degrade.

MiniDV Camcorders are types of camcorder that store recorded data to MiniDV cassettes. The video and sound quality is exceptionally good. The MiniDV camcorders are small, sleek and stylish because of the small size of MiniDV cassettes.

MicroMV digital camcorders use tapes that are much smaller than MiniDV tapes and also use more of compression technology. The MicroMV is compressed much more that the MiniDV and records very high quality video as well as possess the capability of full digital editing. The MicroMV is also very compact, lightweight and ultra small.

Flash Media Camcorders record images to an internal Flash drive and Flash Memory cards. Flash Memory cards include: SD, Compact Flash, Memory Stick and Memory Stick Duo.

HDD Camcorders, or hard disk drive camcorders are compact and record in MPEG-2 video as well as other encoded formats and recorded data is stored to an internal hard disk. The upside of this format is the ability to store huge amounts of video data by using compression. The video is saved to the internal hard disc within the camcorder and then downloaded to a computer and burnt onto to a DVD. The HDD camcorder has no moving parts and so there is less chance of mechanical breakdown.

Digital 8 Camcorders record digital video to Hi-8 videotapes. Digital 8 is a consumer digital videotape format developed by Sony, and introduced in 1999. Digital8 equipment uses the same videocassettes as analog Hi8 equipment, but differs in that the audio/video signal is encoded digitally. Picture quality is fairly good and this format allows playback of analog videotapes recorded on Hi-8 camcorders.

VHS Camcorders are types of camcorders that record video digitally to VHS videotapes. Picture quality is good and this format allows playback of analog videotapes.

HDV Camcorders, are the newest standard in high definition recording and viewing. High Definition Video camcorders usually utilize MiniDV tapes or Hard Disk Drives which yields a full high definition 1920 by 1080 resolution. This resolution provides a superb high-def video picture quality, which looks great on a high definition television. When buying a camcorder with this capability it is important to know that for editing high-def video a computer is required with a fast processor and lots of memory to meet the requirements of video editing software.

Hitachi has manufactured the world’s first full HD digital camcorder which both records and saves image data in the Full HD format on both the hard drive and on Blu-ray Discs, which are the next standard for recordable media.

When buying a camcorder a key feature to consider is built in stabilization. Unless you are shooting video with the camcorder sitting on a tripod, which most home users do not do for everyday shoots, the hand must be stable while holding the camera to avoid image distortion caused by unsteadiness or jerking of the hand. This feature helps to fix these errors caused by jerking of the camera in the hand while shooting.

The stabilization feature comes in two types, Optical and Electronic. Superior to the electronic technique, the Optical Image Stabilization technique is where a part of the lens is moved in the camcorder to compensate for the shake.

With the Electronic Image Stabilization technique the camcorders internal computer shifts the image electronically in the opposite direction of the shake. This is achieved by slightly zooming in on the image. Poor electronic techniques can cause loss of sharpness or resolution.

Controls and Camcorder Size. When buying a camcorder you do not want to compromise usability for size. While a small camcorder maybe cute and convenient to carry, it is important to make sure that it is also user-friendly. You want to be able to reach and use the controls of a camcorder with ease while recording, if the camcorder is so small that you cannot easily access the control buttons the recording experience will be hindered and it will also become a hassle.

The battery a digital camcorder uses is also a vital feature to consider when buying a camcorder. Does the camcorder come with a rechargeable battery? How long recording time is available on a fully charged battery? The best option is to purchase a camcorder which has a rechargeable battery. Generally different models of camcorders have different battery capacity which allow for varying amount of recording time on a fully charged battery.

The two most common rechargeable batteries are the NiCd and the Lithium Ion. The lithiums are usually preferred because they take a charge quicker, are lighter than others and have a longer life span. Most full charges give a battery 6 hours of life.

The brand of camcorder will of course play a role when buying a camcorder. There are plenty of manufacturers of digital camcorders including but not limited to Canon, Panasonic, Sony Hitachi, JVC and Sharp. Canon has some of the best high-def machines on that market today, JVC has a couple of great budget models and Sony is best known for their handycam, which provides superb picture quality in compact machine.

In the end, the most important factor to consider when buying a camcorder is your personal use, the features you desire and price. Ratings of brands are available and the list of key features and specifications should be looked at to determine if the brand and model fits your needs and budget.

Digital camcorders are not cheap, in fact they are often thought of as a hefty investment that could range anywhere between $280 to over $2500 retail price. Something to consider is that in todays world with the Internet providing a stage where millions of sellers and merchants compete for your business it is easy to save significant amounts of money by avoiding retail merchants and purchasing discount digital camcorders.

JR Lang asked:


The word camcorder comes from combining the two words, camera and recorder. How a camcorder works is by recording audio and video and then saving those to a storage device, there by creating your own movies/videos and capturing life on video.

Earlier models of camcorders only used analog and recorded to VHS videotapes, and they were so big and bulky that they had to be carted around on a trolley. These camcorders were mostly used by professionals for broadcasting via television. But those days are over. With the advance of technology came digital and with digital came the digital camcorder.

Today digital camcorders are available in small hand held devices that allow everyone to record and make video recordings, and they are quickly making their way to more and more homes, where families use them to capture their lives on film.

To understand how camcorders work is to look at the three components that they are comprised of: Lens, Imager and Recorder.

The lens of a camcorder is the light path of the camera that consists of a number of adjustments where the camcorder works to allow the user to capture pictures and videos exactly as desired.

These adjustments include parts like aperture, which allows one to control and adjust the light. The zoom function, that is used to adjust the field-view area covered by the lens. And the shutter speed that helps capture any form of motion.

The imager, which is the camcorders eye, works by housing the photosensitive devices. This is how camcorders work to develop the electronic video signal from the light captured in quite a complex electronic process.

How camcorders work for recording is the recorder, which, provides complex signaling functions that capture the video signals and transfers them to the recording medium, such as DVD. The recording and storage device is an important feature to the usability of camcorders.

Camcorders display the recorded images via the magnificent flat LCD screen feature that comes with most camcorders today. These screens can be rotated about 290 degrees along the vertical line, and horizontally about 90 degrees. These screens have made digital camcorders very popular by consumers since the recording process becomes so easy and fun when you are able to see what is being recorded on the LCD screen in real time.

One of the most popular camcorders today is the DVD type, which can replay video on a home DVD player via the digital camcorders recording and hence burning directly to DVD.

The convenience of recording directly to the high-resolution DVD format is incomparable. Also, instant access to any scene eliminates the time and hassle of fast-forwarding and rewinding, as with tape formats. These camcorders work by allowing the DVD format to save memories securely in high-resolution. Also it is important to note that the DVD type camcorders LCD displays a list of the recorded scenes for quick, easy searching.

DVD camcorders provide superb recording quality by digitally recording to a DVD disc and not on tape. Another benefit of recording with a DVD camcorder is its flexibility. You can use your camera to record at home, use it as a storage medium, or in the office connected to your PC. Images recorded onto DVD-RAM or DVD-R discs can also be played on a DVD recorder or DVD player, so you don’t have to hook the camcorder up to a TV to watch your recordings.

There are two versions of DVD digital camcorders: one that works with rewritable DVD-RAM/R discs requiring a DVD player with RAM playback or a PC with a DVD-RAM drive, and the second works by using the more popular DVD-R/RW discs that work with most ordinary DVD players.

There are several other recording and writing formats available in digital camcorders. MiniMV, MicroMV, HDD, HDV, Digital 8, VHS and Flash Memory Drive.

Camcorders are wireless and they work by getting their electricity source from special batteries. Generally different models of camcorders have different battery capacity which allow for varying amount of recording time on a fully charged battery. The two most common rechargeable batteries are the NiCd and the Lithium Ion. The lithiums are usually preferred because they take a charge quicker, are lighter than others and have a longer life span. Most full charges give a battery 6 hours of life.

Today digital camcorders are commonplace. They can be seen used everywhere, from family picnics and birthday parties to those news headlines you see where a passer by was able to capture some extraordinary event, such as natural disaster, cops beating a suspect or videos seen on the infamous YouTube website.

Regardless of how many features you choose or how complicated the digital camcorder is, most are very user-friendly, and their popularity is mainly centered in how digital camcorders provide a user-friendly video recording experience for anyone.

Digital camcorders come with various price tags from hundreds to thousands of dollars, depending on the features of the device, the clarity of sound and video quality provided, and the company manufacturing it. In todays world with the Internet providing a stage where millions of sellers and merchants compete for your business it is easy to save significant amounts of money by avoiding retail merchants and purchasing discount digital camcorders.

JR Lang asked:


Today there are many choices available when it comes to digital camcorders. The shelfs are full of brands and models each unique in their features and capabilities. Here is a list of the top 7 digital camcorders.

Canon Vixia HF10 – This is Canon’s first flash memory media digital camcorder. It delivers excellent High Definition quality video and performance while remaining compact and user-friendly. Specifications: High Definition Digital Camcorder, 16 GB Internal Flash Drive, full 1920×1080 capture and recording High Definition Video, 12 x optical/200x digital zoom lens. Retail: $1099.00

CANON VIXIA HF100 – Canon’s second Flash Media digital camcorder, same small package and continues to deliver excellent High Definition video quality. With it’s advanced Video Codec High Definition, the picture never fails to deliver a supreme high-def viewing experience.

Specifications: Digital Camcorder, Flash Card memory, full 1920×1080 capture and recording High Definition Video, 12 x high definition video zoom lens. Retail: $899.00

Canon DC-50 Digital CamcorderCanon DC-50 – Nice and simple. Canon delivers a simple DVD camcorder that produces great video. Specifications: DVD Digital Camcorder, 5.39 megapixels, 10 x optical zoom, DVD-R (8cm), DVD-RW (8 cm), DVD-R DL (8 cm). Retail: $799.00

Sony Handycam HDR-SR11 – This 60GB Hard Drive based High Definition Video digital camcorder features superb image quality and top notch performance. Specifications: 60GB Hard-Drive Digital Camcorder, full 1920×1080 capture and recording High Definition Video, 12 x optical zoom. Retail: $1199.00

Canon DC230 – A great budget model. While it has few frills, the long lens and good video quality makes the Canon DC230 stand above the rest of the inexpensive DVD type camcorders. Specifications: DVD Digital Camcorder, 1.07 megapixels, 35 x optical zoom, DVD-R (8cm), DVD-RW (8 cm), DVD-R DL (8 cm). Retail: $449.00

JVC GR-D250 – While JVC manufacturers offer several types of digital camcorders the GR-D250 stands out due to a budget price and a big zoom range. Specifications: MiniDV Digital Camcorder, 25 x optical zoom/800 x digital zoom. Retail: $279.00

Flip Ultra: You cannot write about top digital camcorders and not mention the Flip Ultra, the second and better version of the original Flip from Pure Digital. An innovation in video recording the Flip hit the market by storm and accounts for over 13% of all video camera sales. Major manufacturers are all ready mimicking the Flip by coming out with similar versions. The Flip Ultra can definitely be dubbed as the “simple and perfect” digital camcorder.

Specifications are pretty much nill with this one. The screen is tiny (1.5 inches) and doesn’t swing out for self-portraits. No still shots. There are no settings, no menu buttons, no light, no lens cap and no memory card. No optical zoom, only a 2 x digital zoom. The entire unit is pocket size, has three buttons, play, stop and trash. No battery pack, works with AA batteries, (alkalines last about 2 hours and rechargeables about 5 hours).

No tapes or disks, all footage is downloaded via attached USB plug, which pops out at 90 degrees to the camera body, plug that into the computer and download the footage. The Flip’s icon appears on your screen as though it’s a disk. When you open it, you find a folder full of video clips, which you can play, copy to your hard drive and burn to DVD and edit in most standard editing programs. All of this requires a one-time installation of a special codec (a video-format translator). You can also use a special cable to plug it into the TV and watch footage.

Also, you can take the Flip to a CVS or other participating store where they will make you a DVD for $13.

The entire filming process is: Press the red button once to record and once to stop. Press play to review the video and then trash to delete scene. Thats it?

Yes that’s it! It is the most simple of digital camcorders that fits anywhere and everywhere, and is light enough for a baby to hold. It’s size allows it to go anywhere, and everywhere where a traditional camcorder may not, like a purse, beach bag, or pocket. It’s rugged so you can take it skiing, to the playground, while playing a sport and virtually anywhere where you might need to shoot some clips. And if you get the acrylic accessory case (retails: $50) you can even take it UNDERWATER!

With all this simplicity, the Flip delivers an amazingly good picture quality. It has TV resolution (640 x 480 pixels, 30 frames per second). The picture is surprisingly good, not as good as high definition or tape digital camcorders but for the price and simplicity the Flip definitely earns a spot on the top digital camcorders list. The most amazing feature is the Flip’s low-light ability, which trumps even the most expensive of digital camcorders. Not only is the video grain-free, but recorded dim scenes actually look brighter than they looked to the ***** eye. Retail Price: $149.99 with max 60 minutes of footage.

Something to consider is that in todays’ world with the Internet providing a stage where millions of sellers and merchants compete for your business it is easy to save significant amounts of money by avoiding retail merchants and purchasing discount digital camcorders.

Evie Parrish asked:


Electronics are especially vulnerable to any kind of water damage or liquid spills. If your cellphone or laptop is water damaged, it can either malfunction, suffer from quality deterioration or be rendered useless and broken.

Quick action is needed when it comes to saving laptops and mobile phones from further water damage. Here are some helpful tips on how to prevent these equipment from being damaged further.

If your cellphone is water damaged:

* Remove it from the source of water and shake off excess water. Grab your cellphone quickly because if you leave it lying around in the source of water for more than 20 seconds, the water will seep inside.

* Do not put it inside a microwave or dry it with a hair dryer. People often commit this big no-no when they are faced with this situation. Exposing your cellphone to direct heat will damage it more and might cause it to short circuit.

* Turn off your water damaged cellphone and remove its batteries immediately.

* Dry your phone using a towel or paper towel. Let the phone sit on absorbent towels or paper. Replace the towel or paper every 4 to 6 hours. Remember that all traces of moisture and humidity should be expelled.

* Wait for one day of drying after testing your phone.

* If the water damage is extensive. Place it inside a zip lock bag and bring it to a cellphone repair professional in order to have it assessed. The professional will evaluate the extent of the damage and suggest tips on how to solve the problem.

On the other hand, if your laptop is water damaged:

* If water or any other liquid spilled on your laptop, shut it down quickly, remove its batteries and unplug it from the electricity source. If the water reaches the electrical circuits inside the laptop, it might short circuit.

* Turn your laptop upside down to prevent the water from reaching more internal parts.

* Use paper towels to remove excess water from the laptop.

* Examine your keyboard; tilt it on one side to get rid of any liquid that might be trapped.

* Use a clean, slightly damp piece of cloth to clean the screen.

* If you know how to disassemble your laptop, then do it. You can inspect the internal parts in order to assess the extent of the water damage. Take out the hard drive and remove as many drives as you can. If you do not know how to do this carefully, you can enlist the services of a professional to disassemble the laptop.

* If your laptop is damaged by a liquid other than water, you can use distilled water to rinse it. Using distilled water is more favorable than tap water because it will not leave any particle in the laptop that can cause more damage.

* Let your laptop dry. You can do this in two ways; you can either dry it naturally or dry it using light heat. If you want your laptop to dry naturally, you can prop it up and leave it for 24-48 hours in a dry place so that air can circulate for faster drying. If you want to use light heat in drying your laptop, you can place it in a shelf above your radiator. Do not place it under direct sunlight. You can also use a dehumidifier for faster drying.

Remember that cellphones and laptops are made with delicate materials so exercise caution in dealing with these equipment.

Roberto Sedycias asked:


Camcorder, as the name suggests is a device that combines both a video camera and a video recorder in a single unit. As compared to its previous technology that used separate devices for recording audio and video, a camcorder has a built-in recorder unit for recording both audio and video.

From the early generation of camcorder that used digital tape to store data to the more advanced ones that use non-removable media like hard disk drives to store, the camcorder has come a long way in the direction of technology and performance. The latest and sophisticated camcorders use two different storage media such as built-in HDD and memory card.

Major components:

Lens, imager and recorder are the three major components of the camcorders. Lens encompasses aperture, zoom and shutter. In a professional camcorder the lens is manually controlled for all optical functions. However, in a consumer unit it is generally controlled by the electronics of the camcorder. The prime function of lens is to gather and focus light on the imager. When the image is projected on the imager through the camera lens the light is converted to an electronic video signal. And last but not the least, it is the function of the recorder to write the video-signals to the recording medium. However, the record controlling system of the camcorders allows the user to control the device.

Classification:

The camcorders are classified as digital and analogue basing on their storage devices. The analogue components are with imager-chip. Betamax, VHS, Video8 are example of camcorders with analogue storage form. However, the digital camcorders include MiniDV, DVD, hard drive, digital8 as their memory. The digital storage allows perfect resolution of video without any colour jitter or fade. There are some camcorders using flash memory devices, small hard disks and Microdrives.

While considering the classification of camcorders according to consumer and professional aspects, the consumer camcorders emphasize on features like portability, price and ease of use. However, the professional camcorders excel in technical performance. They have many manually controlled technologies that the consumer camcorders lack despite of having ample of I/O options.

Uses of Camcorders:

Home:

Camcorders have become one of the popular gadgets in many homes like many other electronic devices. Unlike still photography a video coverage of personal celebrations like wedding, birthday and other personal events can make the memory live forever.

Media:

Any electronic media showcasing news, special events or any other live telecast can not do without camcorders. Camcorders have been proved as a feasible device to record and store events that can be telecasted from the studio later on.

Entertainment:

In many TV channels, where low budget TV shows are the target, camcorders feasibly cater to the requirements.

Politics:

The political protesters use camcorder as a useful device to make their point strong on the basis of proof. These days, even the police are using camcorders during riots or protests to track the troublemaker and take action against the real culprit.

A camcorder allows recording of video staring from 30 mins with VHS-C and mini DVD camcorders to several hours with hard disk and flash drive camcorders. The important mechanism involved in camcorders allows watching the recorded video on the device itself. The VHS-C tapes and the mini DVDs can be viewed using VCR and DVD player respectively. Camcorders with Hi8, Flash drive or hard disk require television to view the video or the video can be uploaded to the computer using video editing program.

Today, many brands of camcorders are available with different models. The change of technology has enhanced the features of camcorders in the aspect of performance, compactness and feasibility. The accessories are, to a large extent, responsible for the increasing functionality of the high-end device. For a novice user of camcorder, it is advisable to gather adequate knowledge before purchasing the sophisticated gadget.

MicheleGiove asked:


With the aid of a simple piece of software, any cellphone can turn into a device that would look good in a spy movie.

More and more often, we happen to read, on newspapers, magazines or websites, news about development of modern telecommunication technologies. A few weeks ago, for example, Italian newspapers were reporting the news of a father, who ended up under investigation for keeping his teenage kids under control through a cellphone which was turned into a real bug, able to transmit in real time, or record and transmit, whatever was happening around, even while apparently turned off.

This kind of devices, which for your ordinary Joe might be coming straight out of a 007 movie, are actually much more common, much easier, and last but not least, much less expensive than one could think.

As anyone may have noticed by observing the evolution of mobile technology in recent years, modern mobile phones are now much closer to portable computers than they are to an ordinary telephone.

And just like every PC, although with a different installation process, modern cellphones can host a wide array of software, either the normal utilities for the phone’s everyday activities (SMS, email, address book management, photo camera, MP3 player, etc), or specific products that make our phones a real multimedia station rather than a simple conversation device.

Ad esempio, oltre a programmi che, come detto sopra, possono trasformare il telephony in una microspia ricetrasmittente, spesso all’insaputa dell’utilizzatore, esistono anche altri programmi che rendono le nostre conversazioni sicure, codificando la trasmissione e rendendola inintelligibile a chi non sia in possesso dello stesso software e delle relativa chiave di decodifica.

For example, beside software that, as explained above, can turn our cellphone into a real bug, allowing third parties to listen, unbeknownst to the user, to any conversation around it even while turned off, there are also some utilities which, after being installed on a handset, make our conversations secure, by encrypting them, making any interception impossible and useless for any third party without having the relevant decryption key.

Just like a PGP key for email, this software allows to encrypt telephone communications (including SMS), by being installed on user’s handsets, along with a secret 256-bit key entered by all users. After installation the user can access the software from the Main Menu of the phone to place secure calls to other users. To place the call the user needs to enter the normal phone number of the caller from the dialer screen.

When the call is answered on the other end, the software checks for the correct keys on both ends and then initiates a 256-bit encrypted call. Missions and consultants in foreign countries do not need to be bothered of who is listening into their conversations, as they are over a data line which is heavily encrypted. At no point is any data sent over a voice channel or is in clear text type transfer.

This application ensures that information can be sent from anywhere in the world to headquarters within a few seconds. Some information requires to be sent instantaneously and requires an instant reaction. A simple call is to be placed to HQ and a conversation can take place to aid instant decision making.

The Encrypted Call Software is simple to configure. Just enter the 256-bit key on all phones that wish to communicate with each other and you are done. Simplicity of this software should not be mistaken for its performance. In the background the software uses Data Call facility provided by the network provider to seamlessly auto-adapt itself to any GSM network. The end user does not need to enter any complicated settings to make it operational, as an intelligent plug-and-play system ensures smooth operations.

For further protection, the key can be changed at any time. The software is only available for sale to Law Enforcement or related agencies.