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EAN-139780750259200   EAN-13 barcode 9780750259200
Product NameCoastlines (The Geography Detective Investigates)
LanguageEnglish
CategoryBook / Magazine / Publication
Short DescriptionPaperback
Amazon.comA Buy on Amazon ~ 0750259205
SKU7953746
Price New40.74 US Dollars    (curriencies)
Price Used40.68 US Dollars    (curriencies)
Width8.74 inches    (convert)
Height9.02 inches    (convert)
Length0.24 inches    (convert)
Weight5.6 ounces    (convert)
AuthorJen Green
Page Count32
BindingPaperback
Published04/09/2009
Long DescriptionPupils are encouraged to ask questions and to collect, record and analyse evidence. Contains detective work boxes that assist students in performing projects and surveys that can be done in their local area. Focus On panels provide further insight into the subject.
Created11-16-2012 3:06:10pm
Modified01-12-2014 11:55:50pm
MD5c1ab4349c666247fc031717e3cd75549
SHA256698f9e6843ddbc0a66fcd761cb45a4b1fa3f7b3e0ea5f819d31b2b10ce0efda3
Search Googleby EAN or by Title
Query Time0.0018508

Barcodes are a graphical representation of information that can be easily read by machines. People read text easy enough but machines find this to be too complex so we use barcodes to simplify the process.

Barcodes can store numbers, letters and all the special characters. What can be stored in the barcode depends on which type of barcode is being used. But the basics of how a barcode works is the same regardless of what type of code it is, what information is stored in the barcode or what type of scanner is being used.

barcode scanIt all starts with the scan. The scanner, regardless of which type you are using, will examine the barcode image. The lines (or blocks in the case of 2D barcodes) will either reflect or absorb light. When we look at the barcode, we tend to see the dark stripes and think of those as the important parts. Those are the parts that absorb the light and the white parts reflect the light. So the scanners tend to see the barcodes in reverse of how we think of them. But the dark and light portions of the code on their own don't automatically become the information stored in the code. In most cases, it is the relative placement and size of each dark and light stripe (or block) that make up the information. There are also special markers that help the scanner know which direction the barcode is facing when it is scanned. This allows the scanning process to work even if the barcode is upside down when it is scanned. The scanner simply processes the scanned data in reverse in this case.

barcode oscolloscopeTaking a look at an oscolloscope screen as a scanner passes over barcode, you can see that the stripes reflect back light and the scanner registers the changes as high and low levels. So what looks like a simple image is really a rather complex set of layered encryption to store the data. The encryption isn't done to hide the information in this case. Instead it is done to make it easy for the machine to read the information. Since the base language of machines is binary (1 and 0) it is easy for them to read this type of information even if it takes several steps to turn this back into something that people can understand.

binaryThe size of each high and low are combined to make binary data. A series of 1 (one) and 0 (zero) values which are strung together then decoded into the actual information. Up to this point, the process is the same for all barcodes regardless of how they are stored. Getting the lines or dots into binary is the easy part for the machine. The next step is to make this binary code into something useful to people. That step depends on  which type of barcode is being scanned. Each type of barcode has its own encoding methode. Just like human languages, what seems to be two similar words (or barcodes in this case) could actually be two very different values even though they have the same basic letters (or bars).

So you can see that the scanning devices need to know not only how to turn the bars or dots into binary, but after they have done that they need to know how to turn that binary string into the original information. But regardless of the encoding process the basic steps are the same. Process the light and dark areas, convert them to binary, decode the binary, pass the information on to the receiving device which is normally a computer program of some sort.

Once the decoded data reaches the computer program, there is no telling how the information is to be used. The grocery store will use the information to keep track of the products you purchased as you go through the register. A manufacturer will use the code to identify where they are storing their parts. And shipping companies use the codes to keep track of the packages they are delivering.

Now that you know a little about the mechanical portion of the process, take some time to learn about the different types of barcode scanners and the different ways the information can be encoded into barcodes.

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