New laser will be powerful enough to rip apart space itself  

Posted by technology2day

New laser will be powerful enough to rip apart space itself

 

The European Commission has approved the construction of three gigantic new research lasers, with the option for a fourth that would, for an instant, be several hundred times more powerful than the entirety of the power generated by our civilization. The hope is that this will be enough energy to actually conjure virtual particles out of nothingness.

At peak power, the fourth laser in Europe's Extreme Light Infrastructure project (or ELI) will combine ten beams into a single pulse measuring 200 petawatts. 200 petawatts is significantly more power that our entire race generates at any given moment, and in fact more total power than Earth receives from the sun.
Needless to say, this is not the type of laser that you just turn on and wave around for your cat to chase. The only way that this massive amount of power is able to be harnessed is if the amount of time that it's being used for is insanely small. The 200 petawatt pulses will only last 1.5 x 10^-14 second, which is about the same amount of time that it takes for light to travel from one side of a human hair to the other, if you shave the hair down by 90%.
The point of all this is to try to explore some of the weirdness of quantum mechanics, which suggests that space is actually a giant party of random particles that are popping in and out of existence too fast for us to see. The hope is that a laser this powerful might actually be able to tear apart the vacuum of space-time itself, revealing the matter and antimatter underneath.

what is solid state electronics  

Posted by technology2day

what is solid state electronics

Integrated circuit technology and its later development, Micro systems technology, make good use of a multitude of processes and analysis methods developed and refined during the second half of the last century. The impact on society from this evolution has been tremendous.

Electrical and Electronics Engineer,s Careers  

Posted by technology2day



 
Electrical and Electronics Engineer,s Careers

Electrical and electronics engineers are involved in a wide variety of technology ranging from huge global positioning systems which can pinpoint the location of a moving vehicle to gigantic electrical power generators. These engineers are responsible for designing, developing, testing as well supervising the production of electrical and electronic equipment and machinery. Broadcast and telecommunication systems, electric motors, controls of machinery, lights and wiring in building complexes, vehicles, aircraft, radar and navigation systems, power generation, control and transmission devices which are used by electric utilities are all examples of equipment built by these engineers. They may also work in fields which relate to computers and IT. However, those engineers who deal exclusively with computer hardware are called computer hardware engineers- an engineering specialty with is discussed separately in the Handbook.

Electrical and electronics engineers may choose to specialize in various areas like power generation, transmission and distribution; communications; manufacture of electrical equipment etc or a one particular specialty within these area; foe e.g. industrial robot control systems or aviation electronics. These engineers are involved in designing new products, writing requirements for their performance, as well as developing maintenance schedules and charts. Testing equipment and machinery, solving operation problems, estimating time and cost of electrical and electronic products also come under their job.
In 2002, electrical and electronics engineers had around 292,000 jobs and constituted the largest branch of engineering. Most of these engineers were employed in professional, scientific, and technical services firms as well as government agencies. Manufacturers of computer and electronic equipment and machinery also employed these engineers. The remaining engineers were absorbed by firms which deal in wholesale trade, communications, and utilities.
Electrical and Electronics Engineering Job and Employment Opportunities

Favorable employment opportunities are predicted for electrical and electronic engineers. Job opportunities which would result from retirement and transfers of existing electrical and electronic engineers are in proportion with the degree granted to these graduates and thus demand for these workers roughly equals their supply.
Although the employment opportunities for electrical and electronic engineers are predicted to grow through 2012, their growth rate is slower than the growth of other occupations. Even though there is a rise in demand for electrical and electronic products, (including advanced communication goods) defense-related electronic products, and consumer electronics equipment, competition from abroad and increased use of electronic and electrical engineering services in foreign countries, hinder domestic employment. The growth rate of employment opportunities are predicted to be highest in the service industries which provide electronic engineering expertise.
It is imperative that electrical and electronic engineers continue their education. Those who do not keep abreast of latest advances in technology are at the risk of either loosing jobs or loosing good promotion opportunities
Electronics Engineer Job Description
The job duties and responsibilities of electronics engineer include:
• Researching, designing, developing and testing electronic products and components
• Designing electronic circuit, components and integrated systems
• Drawing plans and specifications for projects
• Taking care that the projects fulfill electrical safety regulations
• Designing test control apparatus and tools
• Handling the design of electrical devices
• Keeping abreast of the developments in the field of technology
• Writing technical reports
• Writing specifications of electronic products
• Developing user-friendly interfaces
Education Requirement


To enter this field, you are required to have a Bachelor’s degree in electrical engineering. A considerable experience in designing electronic systems is also necessary for this job. You may also require a combination of experience and training. There are a few colleges that provide training. Some colleges conduct work-study programs in which students can avail the opportunity of on-the-job training. If you want to do a job related to research or teaching you will need a Master’s degree. These engineers also need a license if their work influences the life and property of others or they provide services to public. Such types of engineers require degree from an engineering school, four years experience and passing grade on the state examination.
Skills Required


• Outstanding skills in math, science and technology and the field of IT
• Skills to develop and maintain budgets
• Aptitude to clearly explain the design ideas
• Ability to design electronic circuits
• Extra-ordinary communication skills
• Ability to maintain good working relations with the personnel
• Skills to analyze needs of electronic system
• Decision-making skills
• Ability to understand the electrical safety and health rules
Getting Job


You can find the job easily but extensive efforts will be required on your part. You will have to search internet, job ads on newspaper and read professional journals. You may also try your luck by applying to the private organizations and government agencies. Civil service examination will have to be passed to get a government job. Wherever you apply for the job, you will have to prepare a resume first and then apply for a job. You
can find a number of electronics engineer resumes on different sites for your help and guidance. After reading one or two resumes, you will be able to compose your own.
                     Advancement Opportunities
Electronic engineers can be promoted to managers and executives. Those who get extra training may be promoted to highest paid specialists. Experienced engineers can start their own engineering firm.
Salary


The salary of electronics engineers vary according to their experience.

Historical Earnings Information


In 2002, the median salaries received by electrical engineers were $68,180 annually. The middle 50 percent received salaries between $54,550 and $84,670 while the lowest 10 percent earned below $44,780. The highest 10 percent earned above $100,980. In 2002, the median annual earnings in the industries which employed the largest numbers of electrical engineers were:
• Scientific research and development services – $77,410
• Semiconductor and other electronic component manufacturing – $72,670
• Electric power generation, transmission, and distribution – $71,640
• Navigational, measuring, electro-medical, and control instruments manufacturing – $70,430
• Architectural, engineering, and related services – $66,980
In 2002, the median earnings of electronics engineers (except computer engineers) were $69,930 annually. The middle 50 percent received salaries between $55,930 and $85,980. The lowest 10 percent received salaries below $46,310, and the highest 10 percent earned above $103,860. In 2002, the median annual earnings in the industries which employed the largest numbers of electronics engineers were:
• Federal government – $78,830
• Architectural, engineering, and related services – $72,850
• Navigational, measuring, electro-medical, and control instruments manufacturing – $70,950
• Semiconductor and other electronic component manufacturing – $70,800
• Wired telecommunications carriers – $62,670
In a 2003 slaary survey conducted by the National Association of Colleges and Employers, candidates with a bachelor’s degree in electrical/electronics and communications engineering earned starting salaries of $49,794 on an average in a year; those with a master’s degree earned around $64,556; and those with a Ph.D. received $74,283on an average.
Seasoned Engineers may earn even more.

Electrical and Electronic Engineering Study

Why Study Electronics Engineering Technology?
As an Electronics Engineering Technology student, you will be able to develop a background in the areas of circuit analysis, interfacing and installation of electronic systems, communications systems, use of specialized equipment including oscilloscopes, spectrum analyzers, HART analyzers, and many other types of instrumentation. For example, in depth courses provide you with the capability of doing functional design and building up of circuits for sensor interfacing, communications over air, cable and fiber.
You will be prepared for a technical career in a wide variety of electronics, electrical, and related fields. You may find employment in areas related to automation engineering, computer electronics, telecommunications, power systems, general manufacturing, product design and testing, quality assurance, field engineering, prototype fabrication, process management, and customer service. You may be able to pursue the professional engineer license.
Choosing an Electronic Engineering Course
Electronics is fundamental to many of the things we take for granted today. Everything from mobile phones to aircraft and medical equipment relies on electronics, and it is difficult to think of any area of life that has not been affected by developments in electronics.
Technology, and particularly electronics, is developing at a more rapid pace than ever before. This makes the job of the Electronic Engineer both exciting and challenging, but it also means that there are great rewards for engineers, both in terms of remuneration and job satisfaction.
An International Career

Today, engineering in general - and electronics in particular - is an international business. Most of the well-known companies in electronics operate not just in several countries, but across continents, and many smaller companies depend on international trade for their business. In order to compete in this situation, companies recruit engineers from around the world. To succeed, engineers need to have internationally recognised qualifications.

Qualifications themselves are only one of the benefits to be gained from study abroad. A successful career depends on who you know as well as what you know, and the people that you study with are likely to become important contacts once you leave university. If you choose a suitable course, the people who are classmates today will be the leaders of tomorrow.
Britain has long been recognised for its success in engineering and technology innovation, and this reputation is built on an excellent education system. The engineering knowledge you gain in a British university is, of course, the same as you would in any other country, but there are differences in the way these are taught and learnt from many others. You need to be aware of these differences of approach and expectation before you start to study.
In most courses in Britain, there is a lot of emphasis placed on learning to think for yourself and study on your own. This can come as a shock to students who are used to being given all of the information they need, but independent learning skills are vital once you start a real job, solving problems that have never been encountered before. Fortunately, courses develop these skills gradually, with plenty of support available to ensure your confidence is built up.
Engineering courses in Britain are shorter than in many other countries, being three or four years in length. Most students complete the course within this time, since it is unusual for students to repeat years. So although course fees may seem high, the overall cost of study in Britain can be lower than elsewhere.
Choosing a Course
Deciding what to study and where to study it is a big decision, both in terms of time and money, and so it is vital that you choose the right course and the right university. To make the right decision you have to take account of many different factors, as outlined below.
Looking at the lists of courses available, it is easy to be confused by the wide choice, ranging from straightforward Electronic Engineering to more specialist courses, such as communications, semiconductor devices or microelectronics. There is also a wide range of joint courses, combining electronics with computer science or language studies, for instance.
An Electronic Engineering course will cover all of the key knowledge and skills required to become a successful engineer, including the skills required to rapidly become familiar with new developments, while a more specialist course may neglect some of these topics in order to cover the more specialist subjects. This can be an advantage for those wanting to follow a career in the particular specialisation, but if you do not know which specialisation would suit you best, then a more general course may be more appropriate.
Fortunately, many courses begin by covering general Electronic Engineering, but allow specialisation in later stages of the course. A typical course may be fairly general for the first two years, with specialisation available in the third and fourth years. While following a joint course will give additional skills, it will allow less time for the core electronics knowledge, and so choosing an unrelated subject can leave the graduate not fully qualified in either of the subjects contributing to the degree.
Quality Courses
Besides deciding which type of course would suit you best, it is important to choose the right university. Each university sets its own curriculum, decides the teaching methods that will be used, and the qualifications required for entry. The facilities available within each university, the qualifications of the staff, and the specialisations available will also differ. It can be difficult to know which universities will offer the best education, especially as each institution wishes to promote its own courses. Although the reputation of a university may give an indication of the quality of education, the fact that they have a good reputation does not necessarily mean that the Electronic Engineering course will be equally good. Similarly, some of the best universities for the study of electronics are not generally recognised.
In order to help choose a suitable course, there are a number of sources of independent information. The British Government established the Quality Assurance Agency to assess the quality of education provided by each university in particular subjects. In order to make these assessments, a panel of experts visit the university to observe teaching, talk to students, graduates and their employers. They then award a grade out of 24 points. The panel also produce a report covering each of the six areas of the assessment. The assessments for Electronic Engineering, involving 76 institutions, were carried out between 1996 and 1998. The reports on each institution are publicly available on the QAA Website: www.qaa.ac.uk.
A total of ten universities gained the maximum possible grade (24 out of 24), but it is important to look at the individual reports, since these specify what the courses aim to achieve. The assessment is a judgement of how well these aims are achieved.
A second factor to consider in quality of courses is accreditation by professional bodies. In the case of Electronic Engineering, this is the Institution of Engineering and Technology (IET). The IET looks at both the subject matter and the way it is taught, and can award accreditation for three different levels of course. Accredited Master of Engineering (MEng) and Bachelor of Engineering (BEng) honours courses lead eventually to chartered engineer status, while other degree courses can lead to Incorporated Engineer status. Although accreditation of a course means that it has met the required standard, if a course is not accredited this does not necessarily mean that it is not a good course. A course can only be fully accredited once students have graduated, and so it may take four to five years before a new course can be accredited. Courses that address new technologies may be very relevant to industry, but because they are new, they may not be accredited. Courses that combine electronics with other disciplines may also not be accredited because they do not contain sufficient core Electronic Engineering material, but this does not mean they are not worth considering if the subject is what you want to study.
The choice of whether to study an MEng or BEng (honours) course can be a difficult one. MEng courses tend to last four years, while BEng's are generally one year shorter. This does save money on fees and living expenses, but if your eventual aim is to gain chartered status, a further year of academic study is required following graduation from a BEng.
Your choice of university may also take account of the cost of living. This can vary a great deal depending on the location of the university. Although London, for example, has many attractions for students, the costs of accommodation, transport and food all tend to be higher than in other parts of the country. Worrying about money and the need to work can be a big distraction from your academic work.
With the choice of different subjects, course structures and universities open to students of Electronic Engineering, it can seem overwhelming. You should try to decide what you really want to get out of your course. Then look for independent information, try to talk to someone who has studied at the universities you are interested in and, if you are unsure about what a particular course involves, or whether a particular university would suit you, then contact the Department with your questions. You will be able to learn a lot from the way they answer, both about the courses and the way that they treat students.

Why should You study Electrical and Electronic Engineering? 

• You enjoy maths and science and want to make the most of your excellent grades.
• You want to learn more about quantum effects and their application in security and computing.
• You’re fascinated by electricity, energy and electronics.
• You want to reduce our carbon footprint by developing more efficient renewable energy solutions, rolling out smart energy grids, and designing hybrid and all-electric vehicles.
• You love the latest gadgets and want to design mobile phones, set-top boxes, music players and 3D TVs.
• You’re inquisitive and want to explore how things work, invent things, and design things that benefit society.
• You want to develop innovative real-time software solutions that run on embedded computers and processors.
• You’re passionate about medical electronics, and want to contribute to the development of life-saving instrumentation.
• The Internet amazes you and you want to learn more about terabit optical communications and gigabit wireless handsets.
• You’re creative and want to work in the digital media industry.
• You’re looking for generous sponsorship options, interesting summer placements, and exceptional employment prospects.
• With an electrical and electronic engineering degree you’ll have no trouble earning money. The technology is all-pervasive and present in every aspect of modern life.
• Electrical and electronic engineering is embedded in all other engineering disciplines (particularly mechanical and aerospace).
• The skills we teach are portable and starting salaries are up to £29k a year.

Study Electrical and Electronic Engineering

World's Best Universities: Engineering Top 100

TOP TEN






OTHER,S




11 Tsinghua University China
12 Carnegie Mellon University (CMU) United States
13 Georgia Institute of Technology United States
14 University of Toronto Canada
15 University of California, Los Angeles (UCLA) United States
16 University of Illinois at Urbana-Champaign (UIUC) United States
17 Kyoto University Japan
18 Delft University of Technology (TU Delft) Netherlands
19 University of Michigan United States
20 Cornell University United States
21 Princeton University United States
22 Harvard University United States
23 Tokyo Institute of Technology Japan
24 KAIST - Korea Advanced Institute of Science & Technology South Korea
25 University of Manchester United Kingdom
26 Hong Kong University of Science and Technology (HKUST) Hong Kong
27 University of Texas at Austin (UT Austin) United States
28 Purdue University United Statess
29 McGill University Canada
30 University of British Columbia (UBC) Canada
31 École Polytechnique Fédérale de Lausanne (EPFL) Switzerland
32 University of Melbourne Australia
33 Peking University China
34 University of California, San Diego (UCSD) United States
35 École Polytechnique, ParisTech France
36 Technische Universität München (TUM) Germany
37 Nanyang Technological University (NTU) Singapore
38 Seoul National University (SNU) South Korea
39 University of Waterloo Canada
40 RWTH Aachen Germany
41 National Taiwan University (NTU) Taiwan
42 University of New South Wales (UNSW) Australia
43 Shanghai Jiao Tong University (SJTU) China
44 University of Sydney Australia
45 Australian National University (ANU) Australia
46 University of Edinburgh United Kingdom
47 Indian Institute of Technology Bombay (IITB) India
48 Technische Universität Berlin Germany
49 Universität Karlsruhe Germany
50 Eindhoven University of Technology (TU Eindhoven) Netherlands
51 UCL (University College London) United Kingdom
52 University of Hong Kong (HKU) Hong Kong
53 University of Southampton United Kingdom
54 Indian Institute of Technology Delhi (IITD) India
55 University of Auckland New Zealand
56 Columbia University United States
57 Technion - Israel Institute of Technology Israel
58 Monash University Australia
59 Osaka University Japan
60 University of Wisconsin-Madison United States
61 KTH, Royal Institute of Technology Sweden
62 University of Queensland (UQ) Australia
63 University of California, Santa Barbara (UCSB) United States
64 Indian Institute of Technology Kanpur (IITK) India
65 Politecnico di Milano Italy
66 University of Washington United States
67 National Tsing Hua University Taiwan
68 Indian Institute of Technology Madras (IITM) India
69 Technical University of Denmark Denmark
70 Hong Kong Polytechnic University Hong Kong
71 University of Science and Technology of China China
72 University of Pennsylvania (UPenn) United States
73 Northwestern University United States
74 University of Alberta Canada
75 Technische Universität Darmstadt Germany
76 Katholieke Universiteit Leuven Belgium
77 Chalmers University of Technology Sweden
78 École Normale Supérieure de Paris (ENS Paris) France
79 Zhejiang University China
80 University of Minnesota United States
81 Yale University United States
82 Virginia Polytechnic Institute (virginia Tech) United States
83 University of Bristol United Kingdom
84 Universität Stuttgart Germany
85 Chinese University of Hong Kong (CUHK) Hong Kong
86 University of Chicago United States
87 Pennsylvania State University (Penn State) United States
88 Johns Hopkins University United States
89 RMIT University Australia
90 Indian Institute of Technology Kharagpur (IITKGP) India
91 University of Birmingham United Kingdom
92 Texas A&M University United States
93 Bandung Institute of Technology (ITB) Indonesia
94 Tohoku University Japan
95 Universität Politecnica de Catalunya Spain
96 Lomonosov Moscow State University Russia
97 University of Maryland, College Park United States
98 Vienna University of Technology Austria
99 Trinity College Dublin Ireland
100 Politecnico di Torino Italy
Source www.usnews.com
Best University Of Engineering In Bangladesh

1 Bangladesh University of Engineering and Technology
2 Ahsanullah University of Science and Technology
4 American International University-Bangladesh
5 North South University
6 East West University
7 Shahjalal University of Science and Technology
8 Islamic University of Technology
9 Khulna University of Engineering and Technology
l0 Daffodil International University
11 Independent University, Bangladesh
12 Chittagong University of Engineering and Technology
13 BRAC University
14 Rajshahi University of Engineering & Technology
15 Khulna University
16 Dhaka University of Engineering & Technology, Gazipur
17 University of Information Technology & Sciences
18 The University of Asia Pacific
19 International Islamic University, Chittagong
20 International University of Business Agriculture and Technology
21 University of Liberal Arts Bangladesh
22 Noakhali Science and Technology University


BEST Electrical and Electronic Engineering University Of Bangladesh


1 Bangladesh University of Engineering and Technology

2 Ahsanullah University of Science and Technology


4 Khulna University of Engineering and Technology

5 Chittagong University of Engineering and Technology

6 Rajshahi University of Engineering & Technology

7 Dhaka University of Engineering & Technology, Gazipur

4 American International University-Bangladesh



Keep your property where you can see it  

Posted by technology2day


  
Surveillance camera ensures your valuables aren't part of the vanishing act
A safe home is a happy one, but many off-the-shelf surveillance cameras are too expensive or simply impractical for home use. That's why designer Alberto Ricci Bitti created an automated and inexpensive surveillance camera that uses a flash card as recording media.
All the required functionalities fit inside a small 8-bit microcontroller and the design harnesses the potential of the ATmega32: almost every hardware component of the AVR is put to good use, resulting in a leaner, more cost-effective parts list. The camera only needs to be set up once and an IR remote and easy-to-use voice-prompt menu means this award-winning design will be the star of the show.
Video surveillance systems have rapidly grown from being a specialized equipment for high-risk areas (like banks and airports), to the point of being standard facilities of most places open to the public. Nowadays, no shopping centre, office, industry can afford lacking one. In conjunction with a time-lapse video recorder, these little cameras play an active role discouraging theft and collecting evidences and precious information about the offenders.
Despite their huge commercial success, video surveillance recorders have had little impact on residential markets. No doubt they would be useful at home as well as they are at work: according to the Police, most home thieves go unpunished, so in a sense homeowners must help for themselves.
I have always wanted a video recording system protecting my house, but commercially available systems didn't persuade me. Let's see why.
Standard systems won't do.
Commercially available systems are not designed for home use, and unfortunately don't adapt well to the new role. Problems start with the time-lapse recorder, which is a special recorder capable of recording several days of slow-frame-rate video on an ordinary VHS tape or a big hard disk. Most units are solidly built and usually they worth their money, nonetheless my concept of reliability for home use is "install and forget", which doesn't match hard disks or tape heads spinning forever.
If the price tag and periodic functionality inspections are OK for you, there is always the problem of placement. You need a out-of-sight place, spacious enough to accommodate the recorder and the video display, because images can only be inspected using the original recorder.
Another issue differentiating between commercial and residential systems is the way you run the wires from the camera to the recorder. For shops and offices you can easily pass the cable under the floor or over the ceiling, but if you live in a old brick house like me, you simply can't do it without cutting the walls. You can try RF-linked cameras, if you don't care wiping out all WiFi networks in your neighbourhood (and you are not concerned about exposing your privacy). Alternatively, you can use good WiFi cameras that by definition preserve the network, with only drawback of consuming most of the bandwidth for themselves...
My tailored solution.
The Witness Camera is a combination of a VGA CMOS camera, a passive-infrared movement sensor, a 1 GB SD-card (or bigger), and an AVR Mega32 microcontroller implementing a solid-state time-lapse recorder. It is a compact, complete, self-contained surveillance system designed with home users in mind. It can be installed in minutes wherever there is a mains plug, and it is affordable because of it is built using an handful of inexpensive parts.
 For most typical domestic environments, it can store more than one month of images at a maximum rate of a colour picture every 2 seconds (320x200 pixels, comparable to VHS-CCTV recorders), or 3 seconds (VGA, 640x480 pixels). Recording starts automatically upon detecting a movement. Alternatively you can set a timer, or supply an external trigger, and even do continuous recording.
You only need to setup the camera once. An infrared remote control and voice-prompt menus allow easy operation, even when the camera is concealed or installed in places like ceiling corners.
When the card is full, new images replace automatically older ones, so you get always the most recent snapshots. You won't even notice the system is working; there are no moving parts, no fans, no electrical power wasted.
In the (unfortunate) case you need to investigate the images, just take off the card from the camera and put it on any PC or laptop with an SD-card slot. Specialized software is not required: the Witnesscam records its files using a standard file system (FAT16 or FAT32) and image compression format (JPEG). Retrieval is immediate as the camera sorts the pictures in folders according by date and time.
How it works.
The Witness Camera operation is conceptually simple, but involves many ingredients. Some are physical components, the others are software blocks. To make things clear, I will introduce them gradually, according to the operating mode.
The most important hardware component is the ITC328 camera module. It consists of a VGA (640x480) CMOS colour sensor and a JPEG-compression chip. The compression engine includes a serial interface at 3.3V levels that can be connected directly to a microcontroller's UART. Issuing the appropriate commands you can take snapshots as JPEG-compressed byte streams. The camera comes in a handy module with everything including the lens, and a 4-pole connector for power and data.
The most important software component is the AVR-DOS file system. It is a library for driving mass storage devices, like SD and MMC cards, CompactFlash, and even  hard disks connected to the AVR microcontroller. It provides an high-level programming interface for accessing disks formatted according to FAT16 or FAT32 specifications, which means its files are directly compatible with PCs.  By linking AVR-DOS to your program you can  create and open files, write and read data, create and change directories with simple commands, like you would do on a PC. Restricting read/write access to one file at a time, the FLASH and RAM footprints are minimal (8kB and 1.3kB), making it possible to use a small 8-bit AVR device like the Mega32 for tasks usually accomplished by  16- or even 32-bit processors.
These two blocks are the foundation and starting point of the Witness Camera design. With the aid of  the simplified block diagram of Figure 1, let's see how these block interoperate during normal operation as a time-lapse recorder.
This diagram introduces a second hardware block, the PIR (Passive Infra-Red) movement sensor model ITM256. This module can sense people up to 5 meters/16 feet  away, by measuring changes in the infrared radiation caused by human body temperature. It is a cheap mass-production part from the burglar alarm market, including a Nicera RE200B thermopile and a KC778B companion chip in dice form, under the familiar epoxy blob. A Fresnel lens with an angle of 60º snaps in the PCB, which connects to the outside world by means of a short 3-pole cable (power, ground and signal).
The PIR triggers a software block, the recorder, which is in charge of deciding if and how many pictures to take according to its trigger inputs and operating mode. The recorder controls the camera driver (another software module) in order to get the JPEG byte stream. The real-time clock is an hardware feature of the AVR controller, and the recorder uses it both for time-stamping the JPEG files with current date and time, and as an interval timer if time-lapse photography mode is selected. After time-stamping, the recorder hands over picture data to the file system, which stores it permanently on the SD-card.
Having a file system in place opens up many possibilities to the world 8-bit microcontrollers. Once you try it, it's hard to go back. The capability of accessing huge data files is exploited also in the other operating mode of the Witnesscam, the setup mode.
During setup the user interacts by means of an infrared remote control (I have used an off-the-shelf universal remote), and the Witnesscam responds with voice prompts. The prompts guide the user through the editing of all the operating parameters (date, time, recording mode, picture resolution, number of frames to take each time the sensor triggers...).
The voice menu block is the software module running the user interface. It takes the pulse train from the infrared receiver as input, and after decoding it uses it to edit the settings from AVR's non volatile memory. During this process, it invokes the  speech synthesizer module, which provides the primitives needed to compose and play the messages.
The speech synthesizer takes advantage from the existing mass storage capabilities, using the file system in read mode. The flash disk must be prepared in advance with a special set of files with audio samples for each word or status messages to be pronounced, e.g. the file "15.PCM" stores the waveform samples for the word "fifteen". Reconstructing the audio signal is then a matter of opening the file and sending the samples to the AVR PWM feature.
Samples compression is unnecessary. Years ago, devoting more than one megabyte of flash for this purpose would have been regarded as extravagant opulence,  but today this figure represents about 0.1% of flash disk capacity! So this technique is cheaper than an LCD display, and ways more effective, because it's expected that the camera is concealed or placed out-of-the-way.
The complete picture.
The complete block diagram is the sum of the two previous diagrams plus some extra details. The software modules are drawn inside the AVR Mega32 body. For ease of reference, the relevant source file names are given in italics.
The complete block diagram isn't trivial. It  includes both hardware parts and software-only objects and libraries (file names in italics). The Mega32 is a perfect fit for this design, as almost all of its features are used.
This chart shows the file system exploded into its constituents: the AVR-DOS library, the underlying SD-MMC software driver which takes care of low-level access to the physical media, and the SD-card itself. The card talks to the AVR via the hardware SPI interface, which is notably fast in Mega devices.
There is a new file manager layer (file archive.bas) mediating between the recorder and the AVR-DOS file system. Its purpose is to provide  helper functions like determining the oldest files in the archive, deleting unused stuff to make room for new images, and creating an orderly set of  directories and files to archive the pictures according to the time stamp.
Another added functionality,  introduced in order to preserve disk integrity, is power monitoring. The system must cease any disk write in case of problems. It measures both main and battery voltages using the 10-bit AD converter of the AVR.
The remaining functions are not essential for the Witnesscam to work, but make development and use much easier. With the PC debug port you can log system operations messages (disk size and free space, JPG file size, read and write file access details, remote control codes received) for diagnostic purposes - or just for the pleasure of watching the internal clockwork in action.. I created the port bit-banging an I/O pin, a technique that works perfectly for low baud rates (9600) and allows setting of signal polarity. That is, you can connect the AVR pin straight to the RX pin on PC serial port, without any interface logic (a priceless trick for debug).
The AVR can drive LEDs from all of its general purpose I/O pins. I have provided two status indicators on the front panel. They are useful to verify the PIR sensor range and to check if disk is actually recording.
Notably,  I have introduced two extra LEDs inside the box, next to the SD-card slot. I call this the "disk semaphore": when the green light is on, it's safe to extract or insert the SD-card from its slot. A red light signals that a disk operation is  in progress, and you must wait before touching the SD-card. A simple algorithm inside the main recording loop determines what light to put on based on the status of the recorder, the card detect switch from the SD-card receptacle, and the lid detector switch that notifies the system when the camera case is opened.
BASIC instinct.
The most peculiar aspect of this design is that the firmware is written in BASIC. I'm a strong advocate of using C for embedded systems, and I use routinely the excellent GCC compiler for AVR development on PC and Linux platforms. But at the time I was waiting for the samples of the camera to arrive, I was asked to select a BASIC compiler and IDE for an educational board my company was developing.
BASCOM-AVR  from MCS electronics is a stable, popular product with a rock-solid user base, and a syntax similar to Visual Basic. The IDE installs with lots of examples, and you don't need anything else to make your applications. Actually, the IDE integrates  all sorts of accessories including a simulator, a chip programmer and (nice touch) a serial terminal.
While browsing the online help, my attention was caught by the AVR-DOS library supplied with the package. The help includes a schematic for wiring an SD or MMC card to the SPI, and a 3-line-long code snippet for writing a text file:
open "README.TXT" for output as #1

print #1, "HALLO FILE!"

close #1


I couldn't resist trying it. I grabbed an SD-card from the nearest photo camera, the Atmel's STK300 evaluation board and a soldering iron. A few minutes later, Windows Notepad running on a 32-bit, 3 GHz machine was opening a file written by an 8-bit, 8 MHz AVR microcontroller. I was hooked.
BASCOM does a good work at simplifying hardware access. For small applications, it's a time saver. Do you need a real time clock? Just tell the compiler, and he will do the hard work of making timer interrupt code specific to the AVR flavour you selected. Do you need buffered serial I/O? Just select the buffer size and baud rate. The list of supported features is long - RC5 infrared remote control, ADC readout, timers and PWM setup, to name a few that were useful for the Witnesscam project. But also graphic and text LCD, 1-wire devices, SPI and I2C busses, PS2 mice, AT keyboards, and even a TCP/IP stack.
On the other extreme, as the complexity of your application increases, you will miss C type checking, aggregate types and support for modularity. Also, BASCOM error massages are obscure when not misleading, and lacking of automatic type conversions and true expression handling is an unnecessary pain. My advice is to stay on C if you expect to develop more than 64 kB of code; for smaller designs, like this one, it makes sense to opt for BASIC if you are exploiting most of the built-in features it offers. BASCOM supports structured programming, and with a bit of discipline you can write code as organized as you can do in C. See the sources for my best attempt at doing it!
Filled to capacity     
Keeping the disc filled to capacity, but not overfull, was a challenging problem.
In theory you can get disk occupation calling diskFree(), find the oldest file in the disk and delete it. In practice it turns out that both operations are time-consuming, so you must avoid them as much as possible. To complicate matters, file size isn't constant. It depends on the scene and how it gets compressed by the JPEG algorithm. It depends also on the time of acquisition, because storing a picture file may require creating new directories (hence more disk space) each time the year, month, day, or hour change. And users are free to select a different resolution or recording mode at any time, changing the space required to accommodate new files.
I developed an heuristics based on common-sense rules:
When the disk is only partially full, it is sufficient to check disk occupation only every now and then, and all files can be conserved without problems.
As disk occupation increases, the amount of space left need to be checked more frequently, and it's wise to start deleting some files.  As deleting files burns precious machine cycles, it's preferable to do it when the camera is idle, i.e. recording isn't triggered.
Should disk occupation reach its limits, disk occupation checks must be performed frequently. Deletion of oldest files must be performed anyway, even if the processor needs resources for recording, because of  the risk of getting out of disk space.
Careful section of the value for deleteWhenIdle and cleanupInterval improves recorder's performance in all but continuous recording modes, because all erasing is performed when there is nothing else to do. If you feel 1000 pictures is a large number, consider it represent a negligible percentage of full disk capacity. It takes time to get accustomed to the Gigabyte Age!
The flow chart in Figure 4 should shed some light on how the heuristics works. Experimentation in my house as PIR-triggered recorder resulted in all file erases performed during idle, calling diskFree()at most every 30 minutes.
Speech preparation.
The Witnesscam speech synthesizer plays a set of speech files to build its messages. You can record the files with your own voice if you want, but I was reluctant doing this, so I used computer-generated speech instead.
I would like to tank the people at AT&T Research Laboratories for giving me the permission of using samples from their Natural Voices system for this contest. Those unfamiliar with this technology can test their fantastic software online (http://www.research.att.com/~ttsweb/tts/), typing-in any text and listening for a warm, natural voice reading it.
I used the AT&T online demo tool to download a set of .WAV files with the words of interest. I selected a male voice (Mike) in order to reduce the content of high frequencies as possible. The Witnesscam dynamic range is 8 bit, and sample rate is 11,250 Hz, so I used a sound editing program (Cool Edit Pro) for down-sampling. I compressed the voice waveforms using the dynamic compressor tool in order to compensate for the reduced bit resolution (AT&T audio files are 16-bit). Then, I normalized the amplitudes, and saved each speech segment in a separate file as 8-bit "unsigned" samples - that is, raw numbers where silence corresponds to a value of 128.
At run time, the Witnesscam uses the file name to select the files to play. It expects to find them under a common folder named "speech". Sound playback technique is brutally tricky. The samples are banged straight to the PWM without buffering, the only timing coming from a busy-wait loop. Ironically, the unpredictable delays due to disk access add a pleasant chorus-like effect, making the voice warmer and fuller.
The circuit amplifying the PWM signal is even more brutal, using just one transistor and trusting the speaker elastic properties for filtering higher frequencies and moving the cone back to the positive direction. These shortcuts limit the kind of speaker to use: if it's too small, the Nyquist products will be audible, if it's too large,  it won't jump back in time for the next audio peak. I have experimented with various sizes from my junk box, and found that a 75mm/3" speaker works well - surprisingly well. A clear sign that speech is like no other sound, because the brain is capable to reconstruct the voice from very little information.
Circuit implementation.
The final circuit of the Witness camera works out the details of interfacing the modules introduced by the block diagram, and supplying power as appropriate. The circuit develops around the AT Mega 32, and most interfacing resolves to straight connections, as all AVR I/O pins provide programmable pull-ups and respectable output current. One notable exception is the PIR movement sensor (Intertec's ITM256), which is a 5V part (opposed to the rest of the circuit that works at 3.3V), and needs an independent power regulator (IC3, an LM2936-Z5 low-dropout, low quiescent current regulator from National). A separate regulator is beneficial in this case, as it provides extra  power decoupling for some very sensitive analog amplification contained on the PIR module. A series resistor on the PIR output is an inexpensive way to adapt its 5V output to the 3.3V input level of the AVR.
The camera module (Intertec ITCM328) connects to the UART RX and TX pins. Communication runs at 115200 baud, thus I selected a 7.3728 MHz crystal for exact bit timing. Don't replace it with the more common 8MHz as the camera module is picky about baud rates. The SD-CARD connects directly to the SPI port pins. The card connector is a Yamaichi FPS009-3202. I like its space-saving outline, with most of its pin placed inside its body instead of sticking out.
The connector features also extra signals indicating card insertion status and the position of the write-protect tab of the card. I routed them to two spare I/O pins (internal pull-ups enabled). A different kind of switch, the micro switch detecting when the lid is opened, and the external trigger switch connect in the same way to the AVR.
However, I selected one of the three AVR interrupt pins for the external trigger,  in order to capture and flag automatically any transition. The same applies to the PIR input (think of it as an "internal" trigger) and the remote control input.
The latter pin comes from a Vishay TSOP34836 infrared receiver IC. This inexpensive part is mass produced for the consumer market (TV, VCRs, DVDs...) and is tuned for 36kHz infrared bursts (like the RC5 encoding required by the Witnesscam). You can replace it with similar parts from other manufactures; I selected it for its immunity to false triggers, which improves Witnesscam's overall performance.
As regards the outputs, four LEDs showing device status take half of the port A. A spare bit on port C drives the relay output by means of the typical transistor & diode network. I used a BC847 and 1N4001.
As previously detailed while describing the audio subsystem, the same conventional circuit drives the output speaker in an unorthodox way. I tried it for fun, and it worked so good that I didn't change it.
Another unorthodox section is the serial port built around port C, bit 5 of the AVR. Being a software implementation, its polarity is reversed compared to an hardware UART, so the usual additional polarity inversion circuitry is not required. You can connect it to a PC running a serial terminal program for debug or troubleshooting: connections to the PC DB9 pin are PC-TX to DB9-PIN3, PC-GND to DB9-PIN5.
Admittedly, this circuit doesn't meet RS232 specifications (no negative voltages, just 3.3V swing, imperfect timing during interrupts limiting speed to 9600 baud), nonetheless it's a zero-cost solution that does its job.
I've been less parsimonious with the power supply: it's easy to overlook power supply issues. The camera and the  flash disk have an impulsive behavior, consuming almost nothing when not in use and drawing intense bursts when writing or compressing an image. Thus I provided both a 100 µF electrolytic and a 0.1 µF ceramic capacitor for most parts. These caps are outlined in a separate section of the schematic diagram, take care to place the capacitors near to their respective owners.
DC power comes from a wall-wart adaptor and a battery pack. The batteries keep clock running (see the 32.768 kHz crystal), while ensuring completion of disk operations during power outages. A 15V varistor cuts power spikes, and diodes D1 and D2 mix the power sources prior to power regulators. The 1N5822 are Shottcky diodes in order to optimize the voltage drop. The 3.3V regulator is a LM1117-3.3 (National Semiconductor) low-dropout regulator.
The circuit monitors its own power to safeguard disk integrity. Two identical divider networks for battery power (R3-R4-C5), and mixed power (R7-R8-C8), reduce voltages to safe levels suitable for ADC pins. Don't omit the capacitors that smooth the measurements and provide a charge tank for sampling.
Almost all of the parts (with the notable exception of the camera, see the FAQ for details) can be obtained from RS Components: here are the part numbers:
Quantity RS Part # Part description
1 267-6930 8 ohm, 3 inch diameter loudspeaker
1 652-7494 Diode (LL4148 or 1N4001)
1 434-8104 100 nF ceramic capacitor (1206 case)
1 519-4059 100uF/25V electrolytic capacitor (TPH)
1 264-4040 15...22pF ceramic capcitor (1206 size)
1 464-8909 15Vdc transient suppressor
1 132-494 1K resistor for LED
1 150-710 microswitch, lever actuated
1 478-9268 32.768kHz CFPX-56 watch crystal
1 226-1695 7.3728 MHz crystal
1 237-647 Yamaichi FPS009-3001-BL SD/MMC card connector
1 533-5604 Ultra low dropout voltage regulator, TO92 case
1 533-9527 LM1117T-3.3 fixed voltage regulator
1 377-9664 Two pole toggle switch
1 461-3739 1000 ohm, 0.25W, 5% resistor (size 1206)
1 461-3723 100 ohm, 0.25W, 5% resistor (size 1206)
1 461-3745 10 kiloohm, 0.25W, 5% resistor (size 1206)
1 461-3751 100 kiloohm, 0.25W, 5% resistor (size 1206)
1 223-2300 2.2 kiloohm, 0.25W, 5% resistor (size 1206)
1 223-2085 50 ohm, 0.25W, 5% resistor (size 1206)
1 223-2186 330, 0.25W, 5% resistor (size 1206)
1 484-2252 BC817 transistor (SOT123 case)
1 826-515 Red LED, 3 mm
1 180-8502 Green LED, 3 mm
1 351-825 Subminiature relay, 10V coil
1 482-193 10-way box connector for programming
1 628-1485 Atmel AtMega32 AVR processor




CIRCUIT