We have seen the use of facial recognition technology in many movies. A photo of the person to be identified will be obtained from some hidden camera. It will then be run in through the police database so as to find a match with their existing records. At last a match will be found and the criminal will be caught red handed. Though this may seem fascinating in movies, it may not be the same in real world.

The facial recognition system was equipped in cameras and was placed in some streets so as to cut down the number of crimes in the area. But, the technology failed to provide results as the people around the streets wore masks, prohibiting the cameras from getting a clear enough shot to identify anyone.

The facial recognition software’s have been upgraded well enough to provide 99% accuracy at present. In this post, we will discuss about the origin of this technology and also their enhancing capabilities for both governmental and personal use.

From the phrase facial recognition, it is understood that the software used for this purpose mainly recognizes a number of distinguished features of the face. All the features added together make almost 80 nodal points. The software used for facial recognition recognizes and distinguishes the face from its background by some of the common nodal points given below.

• Distance between the eyes
• Nose width
• Depth of the eye sockets
• Cheekbone shape
• Length of jaw-line

The above nodal points are measured altogether to provide a common numerical code known as the face print.

Early Stages

As explained earlier, the software that is needed for the technology could only compare a 2-D image of a person with the existing database. The software was very weak in technicality as correct results were difficult to obtain if the photo was not taken in the correct lighting and with good facial expressions. As these types of photos are taken instantly and in a secretive manner there would be changes in orientation and click angles. When these photos were compared with the database, no results were ever found. Thus, this system was mostly rejected by all authorities.

3-D Facial Recognition Technology

To get a better understanding, take a look at the image below.

Facial Recognition System

The above explained problems were all resolved with the evolution of 3-D Facial Recognition Technology. As a 3-D image of a person’s face helps to point out clearly the different nodal points, this method proved to be more accurate. All the valleys and bumps of the face are more apparent and this helps a lot in comparing with the database.

The 3-D method also removes the disadvantage of correct lighting aspects. Thus, the photo of the person can be taken even in improper lighting and that too in any angle [in a range of almost 90 degrees]. Given below are the different steps that take place when the identity of a person is verified with an existing database.

Detecting the person

To know the proper working of this process, take a look at the image shown below.

The image that is to e compared with the database is obtained either as a photo [2-D] or as a video image [3-D].

Alignment of image

For a 2-D image, the system can be accurate only if the angular position of the face towards the camera is at least 35 degrees. But for a 3-D image, the system can be accurate even if the angular position of the face towards the camera is at 90 degrees. The size and pose can also affect the accuracy.

Measurement of face

The face recognition software makes templates on the different curves of the face. The face will be measured in micrometer scales.

Transfer of Measurement

The measurement taken is then transferred into a unique code. This code makes each template unique and thus represents the different features of the face.

Matching with database

The comparison of the image with the database can occur in two ways. If both the image taken and the image in the database are 3-D, then there is no problem in the matching process.

But, as the database in most government offices and other places are present in 2-D form, the comparison becomes more complex. The 3-D image has to be converted to a 2-D image before comparison. A 3-D image will be live and moving when compared to a still and stable 2-D image. So, when a 3-D image is take, it is converted to 2-D by taking measurements from some distinguished points from the face. These measurements will then be converted to an algorithmic form and thus will be converted to a 2-D image.

Comparison

The comparison can be classified into two according to its purpose. One of them is verification and the other is identification.

If a person is to be identified as one who claims to be an employee of a particular office, it is called verification. This type of comparison will with the database will only take place in a 1:1 ratio. That is,

For the identification of a thief or a culprit, the image received will be compared to all the images in the database in a 1: N ratio. Take a look at the comparison process shown in the image below.

The comparison process is usually done in three different templates. They are

Vector Template – This template is used for quick search with the database in both the 1:1 and 1:N ratio.

Local Feature Analysis [LFA] – This template mostly follows the vector template. This search is a little more complex.

Surface Texture Analysis [STA] – This is the most complex search template of all the three. It comes after the LFA and the search is based on the skin features of the image, which contains the most detailed information.

When these templates are combined in the facial recognition software, the system is able to recognize and identify the person even if there are changes in his expressions like smiling, frowning and also blinking. Even a moustache growth or beard will not affect the accuracy of the software.

But, there are disadvantages as well. A glare from the person wearing eyeglasses can cause problems. If the person is disguised as one with long hair in such a way that it covers the front part of the face, it will be difficult to identify him. Very poor lighting during the time of photography may cause the face to be under exposed. This can also be a problem.

Uses of Facial Recognition System

This technology was first used by law enforcement agencies so as to identify people from huge crowds. This system was also adopted to catch people trying to fraud while voting. The system was also used in airports to check whether the foreigners visiting the country had any resemblance to criminals or suspects.

Another important application of this technology is in ATM’s and check-cashing security. Before transacting the money, a photograph of the person is taken and is verified with the database to see whether the customer is valid. Thus identity theft and fraudulent transactions can be avoided. This system is very useful as there will be no need of personal identification number for any person. But this type of a transaction process is yet to come in many places.

Hi all Readers,

We always try to publish useful circuits and topics for our readers. After publishing an article we usually measure how well it was received among our readers. We have two options for measuring success of an article published; first being the number of page views it has got and the second being the number of comments. Among our team we believe the second measure that’s “number of comments” is the best available criteria for calculating success of an article.

A “comment” is an opinion made by a valuable reader about a particular article. It may be a positive acknowledgment, a criticism, a doubt, a correction, sometimes a suggestion and sometimes an answer to a doubt. What ever it may be we believe comments make an article rich. Comments give article a Life! Web 2.0 makes possibility for a great user interaction compared to old ages of static web!

What are the advantages of “Comment-ing” on an article ?

• Reader can instantly publish his opinion about the article
• Reader can ask any doubt of his and get an answer very quickly
• Reader can criticize and point out the mistakes
• Reader can share similar thoughts or advanced concepts of the same
• Reader can help other people by clearing their doubts – by taking part in interaction

I am going to list all the published articles in Circuits Today which has got at least 15+ Comments. We consider these articles as really successful  and this list may be helpful for our daily readers to have further interaction; hence improve their knowledge.

1. Infrared motion detector circuit – Enjoys 1st position with 81 comments so far. This is a VERY HOT topic.

2. 150 Watt amplifier circuit -  Stands 2nd with 75 comments. Another HOT & Active topic.

3.  Automatic LED Emergency Light -  Now on 3rd position with 73 comments. This HOT discussion is on a race!

4. 100 Watt inverter circuit – 62 Comments

5. Long Range FM Transmitter – 52 Comments

6. Battery charger circuit using SCR – 50 Comments

7. Single Chip FM Radio circuit – (35)

8. 100 Watt sub woofer amplifier -(30)

9.  AM Transmitter circuit – (28)

10. Remote control tester circuit – (27)

11. Simple Water Level Indicator

12. Lead acid battery charger circuit

13. Fire alarm circuit

14. TV transmitter circuit

15. 2 km FM transmitter

16. Simple Electronic Combination Lock using IC LS 7220

17.  High & Low voltage cut-off with delay& alarm

18. Light activated switch circuit

19. 50 W transistor amplifier

20. Air flow detector circuit

So that’s it! 20 HOT& Active posts listed above. Choose one that you like and be a part of it!!

Direct To Home Technology

Overview

Direct to home technology refers to the satellite television broadcasting process which is actually intended for home reception. This technology is originally referred to as direct broadcast satellite (DBS) technology. The technology was developed for competing with the local cable TV distribution services by providing higher quality satellite signals with more number of channels.

In short, DTH refers to the reception of satellite signals on a TV with a personal dish in an individual home. The satellites that are used for this purpose is geostationary satellites. The satellites compress the signals digitally, encrypt them and then are beamed from high powered geostationary satellites. They are received by dishes that are given to the DTH consumers by DTH providers.

Though DBS and DTH present the same services to the consumers, there are some differences in the technical specifications. While DBS is used for transmitting signals from satellites at a particular frequency band [the band differs in each country], DTH is used for transmitting signals over a wide range of frequencies [normal frequencies including the KU and KA band]. The satellites used for the transmission of the DTH signals are not part of any international planned frequency band. DBS has changed its plans over the past few years so as to include new countries and also modify their mode of transmission from analog to digital. But DTH is more famous for its services in both the analog and digital services which includes both audio and video signals. The dishes used for this service is also very small in size. When it comes to commercial use, DBS is known for its service providing a group of free channels that are allowed for its targeted country.

DTH in India

India is one of the biggest DTH service providers in the world. The requirement is very high because of the high population and the increased number of viewers. The low cost of DTH when compared to other local cable providers is also one main reason for this substantial growth.

In India the DTH requirement is more than in any country as the population of viewers is at very high rate.

The idea of DTH was first provided to India in 1996. But it was not approved then as there were concerns about national security. But the laws were changed by the year 2000 and thus DTH was allowed. According to the new rule, DTH providers are required to set up new stations within 12 months of getting the license. The cost of the license is almost $2.15 million in India with a validity of 10 years for renewal. The latest reports suggest that almost 25% of the total Indian population use this facility while others use local TV connections.

Some of the common DTH providers in India are

1. TATA Sky

2. BIG TV

3. Sun Direct DTH

4. Dish TV

5. Airtel DTH

6. Videocon DTH

Working of DTH

To know the working of DTH better, take a look at the diagram below.

For a DTH network to be transmitted and received, the following components are needed.

• Broadcasting Centre
• Satellites
• Encoders
• Multiplexers
• Modulators
• DTH receivers

It must be noted the channels that are broadcasted from the broadcasting centre hare not created by the DTH providers. The DTH providers pay other companies like HBO, Sony MAX and so on for the right to broadcast their channel to the DTH consumers through satellite. Thus the DTH provider acts as a mediator r broker between the consumers and the programme channels.

The broadcast centre is the main part of the whole system. It is from the broadcast station that the signals are sent to the satellites to be broadcasted. The broadcast station receives the signals from various program channels.

The satellite receives the signal from the broadcast centre and compresses the signals and makes them suitable for re-transmission to the ground.

The DTH providers give dish receivers for the viewers to receive the signal from the satellites. There may be one or multiple satellites that send the signals at the same time. The receiver receives the signal from them and is passed on to the Set Top Box [STB] receiver in the viewer’s house.

The STB receiver changes the signal in a form suitable for our television and then passes it on to our TV.

Advantages of DTH Technology

• The main advantage is that this technology is equally beneficial to everyone. As the process is wireless, this system can be used in all remote or urban areas.
• High quality audio and video which are cost effective due to absence of mediators.
• Almost 4000 channels can be viewed along with 2000 radio channels. Thus the world’s entire information including news and entertainment is available to you at home.
• As there are no mediators, a complaint can be directly expressed to the provider.
• With a single DTH service you will be able to use digital quality audio, video and also high speed broadband.

Almost all the electronic circuits mentioned in this site are designed and built on a PCB board. But you cannot build these electronic circuits if you do not know the basics of soldering.  If you do not know to solder well, the solder joints will not be perfect and thus the circuit will have serious flaws. In this post, we will discuss about the soldering tools or soldering kits that are used for this purpose. We will also have a step by step procedure on how to solder a circuit board.

Soldering Tools

The basic tools that are used for this purpose are

• Soldering Iron
• Solder Wire [Alloy]
• Flux
• PCB and the components that are to be soldered

The soldering iron is the heat source tool for the process. It should be of high quality. Of course the price may increase with the quality, but the soldering will be perfect. Usually a 25 Watt soldering iron is adequate for the process. A higher watt device may bring too much heat to the PCB and will surely damage the sensitive components. A lesser watt device may not have adequate heat and thus is prone to be extensively used. This may also cause extensive heat damage.

The solder wire is used to fix the components like resistors, capacitors and so on to the PCB in the given fields. The leads of the devices are connected to the track of the PCB by melting the soldering wire to the junction. When the heat from the soldering iron touches the soldering wire it starts melting and this melted wire when introduced to the junction, joins the components to the track firmly.

The soldering wire is actually an alloy of tin and lead in the ratio 60:40. This is the best ratio that is considered for soldering in PCB’s. There are other proportions of this alloy and they are considered low quality as the tin content with respect to lead will be lower.

A high quality solder wire will have a melting point of about 250 degree Celsius and will have a very high conductivity along with a shiny appearance.  When a high quality solder wire is used to connect the components to the PCB, there is to be no fear of corrosion in future.

Flux is another important component that is used in soldering purposes. It is sealed to the core of the solder wire before soldering. The flux is used to reduce the surface tension of the solder wire in its melting point. Thus, it acts as a wetting agent and wets the parts that are to be joined to the PCB. This also helps in the proper heat transfer from the solder iron to the solder wire.

Another main use of the flux is to prevent oxidation of both the solder wire and the components that are added to the PCB. The Tin-Lead alloy that is used as solder wire may have no problem when attached to copper. But they do not attach so well, when in contact with the oxides of copper. The oxides of copper mostly form when the temperature is increased for soldering. The flux can prevent the formation of metal oxide as they are nearly inert at room temperature and become strongly reduced when the temperature increases. The use of flux causes the rise of smoke when the soldering process continues. During this time the flux acts as a catalyst and helps in removing the oxidants and thus cause a better solder joint.

Soldering Technique

If you are a beginner, your initial soldering results may be just average and unprofessional in looks. You can only master the technique by practice. Here is the step by step procedure for soldering.

1. First of all keep the solder iron plugged in for about a minute and a half before starting to use it. By that time the solder iron may get heated to the optimum temperature [250 degree Celsius].
2. Bend the leads of the different devices that are to be connected to the PCB. For a clean bend, the approximate distance of bend is about 2mm from its body ends.
3. If you are connecting a resistor to the PCB, find its spot and place it into the hole of the PCB.
4. After placing the resistor flip the PCB in such a way that the inserted leads looks towards you.
5. Take the soldering iron in the right hand and the solder wire in the left hand.  The solder wire must be placed on your finger tips with about 3 inches extending from your finger grip.
6. Bring both the solder iron tip and the solder wire tip close to the base of the lead of the resistor and copper track of the PCB. Make them come in contact at the same instant at the junction.
7. You will notice that the solder wire starts to melt as soon as the contact is made.
8. When the wire starts melting keep pushing it till the joint has been filled up with the molten alloy.
9. Move away the solder wire and the solder iron simultaneously and allow the molten wire to solidify.  Thus one lead of the resistor has been connected to the PCB. Do the same step for the other lead and also for all other components.

The setp by step procedure is also shown in the figures given below.

Soldering Techniques

Precautions to be taken while Soldering

For a good heat transfer, the solder wire and the solder iron must be well cleaned before starting. It must also be pre-tinned with solder. In order to avoid the overheating of PCB, the components are usually elevated above the PCB. After the component is inserted in the PCB hole, the excess lead is cut off, thus leaving a length of about the radius of the pad.

After soldering, the soldered joints must also be cleaned after it has been solidified.

Some components that are to be soldered may be heat sensitive. For such components a heat sink may be used on the leads which will reduce the heat transfer to the components. The only problem is that for such components more heat will be required from the solder iron to complete the joint.

De-soldering and Re-soldering

There may be cases where a soldered PCB may be taken for re-soldering. The problem is that the solder that is already used has some dissolved base metals that make it unfit for reuse. If you try to re-solder onto it, the new solder will not properly bond with the base metal and will cause the formation of a brittle cold solder joint with a crystalline appearance.

So before re-soldering it is good practice to de-solder and thus remove the solder from the joint. For this purpose there are de-soldering equipments called solder suckers. By doing this a lot of flux is released which will clear the dissolved base metals and all other contaminants from the copper trace. Thus a bright, shiny, clean junction will be ready to be re-soldered.

Take a look at the post below to know the exact method of desoldering.

TAKE A LOOK : HOW TO DESOLDER ELECTRONIC CONNECTIONS

Soldering – Video

We have seen the working of electronic displays like Liquid Crystal Displays, SED TV’s, and Touch screen technology and so on. Even though we rely mostly on monitors nowadays we must not forget the fact that the basic display mechanism is paper the early 105 AD when the Chinese invented it. Before the invention of paper, the only way to print your writing was on silk scrolls, which only wealthy people could afford. This would have made literacy rate lesser.

People communicate through paper by writing on it with ink. They display their ideas with the help of words and images, which may differ in many languages as well. The paper technology has not yet been beaten by other display technologies in the matter of portability and price. But this technology also has some disadvantages like you cannot rewrite on top of the printed words and it is difficult to carry a large number of books.

Now, these disadvantages are also being minimised with the help of a new technology called electronic ink [e-ink]. In this post we will discuss about how e-ink is made, how large bundles of books can be carried easily and its efficiency in replacing other computer displays.

Making E-ink

E-ink may look similar to the regular ink, though they are different. In fact it can also be applied on the same material in which regular ink is applied. Although different companies manufacture E-ink in different ways, there are three basic components that give them the ability to rearrange upon command. They are

1. Millions of tiny microcapsules
2. The ink substance present in an oily form which fills the microcapsules
3. Negative charged pigmented chips or balls which float inside the microcapsules

When using the e-ink in a digital book, the pages will be made of an ultra-thin plastic material. The ink is allowed to spread through the entire page, and they will be separated by cells that somewhat resemble the cells on graph paper. They also resemble to the way in which pixels are arranged on a computer screen, with each cell connected to microelectronics which are embedded in this plastic sheet.  When this type of a design is setup the text or image that is to be displayed is done by applying a positive or negative charge to the microcapsules.

A company called Xerox from Palo Alto, CA is one of the major manufacturers of E-ink. To know the working of this technology in a better sense, the company has given a better example. You have to compare the microcapsules inside ink to clear beach balls. These beach balls should be filled with hundreds of tiny, white ping-pong balls. And instead of air, the beach ball is filled with a blue dye. If you notice this design from the top position, you can see that the beach ball is white in colour and that the smaller ping-pong balls are floating in the liquid. If you looked at the top of this beach ball, you would see the ping-pong balls floating in the liquid, and the beach ball would appear white. But if you looked at the bottom of the ball, it would appear blue.

If these beach balls were laid on a field and the ping-pong balls were made to move between the top and bottom of the beach balls, you could make the field change colour. This is the basic working of E-ink.

Now in reality, the microcapsules are very small that almost 100,000 microcapsules can be put in a square inch of paper. Their width does not exceed 100 microns and each microcapsule contains hundreds of smaller chips.

Given below is a diagram on how the pigment chips inside the E-ink reacts to the +ve and –ve charges.

From the figure you must have noticed that when a charge is applied to the microcapsules, the chips are forced to move to the top or pulled down to the bottom. When they move to the top, the chips make the capsules look white and when they are pulled down to the bottom, the capsules look dark. This is because the person seeing it only sees the dark ink. When these small black and white spots are arranged in patterns, words, sentences and images can easily be formed.

Uses of E-ink

The biggest advantage of E-ink is that it can be easily printed on surfaces like walls, billboards, clothes and so on. This idea has already caught the eye of many advertising agencies and you may have noticed advertisements on walls using this technology. The ink is so flexible that it is possible to develop roll-up displays for electronic devices. They also need very little power for its usage. When compared to LCD displays, they consume almost 100 times lesser power than LCD’s do.

Another advantage includes its readability. As the text is printed in format, it does not cause strain to the eyes. There are studies going on in increasing the resolution in products so that they can be viable in book or other small-print publications

One of the main use of this technology is its application in digital books which can typeset itself and that readers could go through it like it were made of regular paper. You could even borrow stories from the library by wireless transaction and after reading it you can send it back to the library. Nowadays you may have noticed the presence of E-books that are available in sites in downloadable format.

The above mentioned ways are applicable in the way you receive your newspaper as well. All you have to do is press a button on your computer that would update how many ever ‘e-newspapers’ you need. Thus you will have no worries on what to do with the lump of papers at your home. As papers are made from trees you are able to reduce the environmental pollution by lessening the cutting of trees.