AS Level ICT: Data, Information, Knowledge and Processing

Advantages of Direct Data Source

-Relevant -Known source so is trusted -Up to Date (likely) -Eliminate bias by asking specific questions -can be collected and presented in required format

What is stored when encoding sound?

-Sample Rate -Bit Rate -Bit Depth

Advantages of reducing file size

-real time streaming -reduce download time -enable more storage of music and video and other media

Fun Facts: GIF

Animated

Sample Rate

Frequency; number of audio samples per second. Higher it is, the higher quality and storage. Measured in Hz. Music on CD = 44.1 kHz whereas telephone call = 8 kHz

Compression Types include...

no compression; eight bit run length coding four bit run length coding

Encryption

scrambling data so it cannot be understood without a decryption key, as it will be unreadable to anyone intercepting it

Type Check

Ensure correct data type

Lookup Check

Ensure data is from a list

Range Check

Ensure data is within range

Length Check

Ensure specified length or range of lengths

Consistency Check

Ensure two data entered doesn't contradict each other

Fun Facts: Software specific file types like for Photoshop

Stores layers separately e.g in photoshop

Quality of Information is determined by what attributes?

-Accuracy -Data Source (Direct/Indirect) -Relevance -Age -Level of Detail (Not too much, not too little) -Completeness

Compression of a video reduces

-Bit Rate -Resolution -Image Size

Advantages of Indirect Data Source

-Immediately Available -if statistical analysis required, large samples exist

Disadvantages of Coding Data

-Limited Codes -Hard to Interpret -Similarity (e.g 0 and O) -Inefficient (if person doesn't know what code to use, they have to look it up) -Missing Info

Disadvantages of Indirect Data Source

-Need to sort through irrelevant data -Source is unknown so unreliable -may be out of date -may be biased -unlikely to be in required format so needs to be extracted

Advantages of Coding Data

-Presentation (for small places) -Storage Saved -Speed of Input -Processing Speed -Validation (by checking if it meets certain rules) -Confidentiality -Consistent (so easy to be searched or summarised)

Advantage of encoding

-reduce file size -enable different formats to be used

Disadvantages of encoding

-required codecs may not be installed, so a file can't be saved in required form -not all software can open different file types -quality is lost in lossy compression -text encoded in ASCII etc needs to be decoded

Disadvantages of Direct Data Source

-takes a long time -large sample of statistical data can be hard to collect for one-off purpose

At the most basic level, images are encoded as...

...Bitmap.

In order to find public key...

...digital certificate is required.

Bit Counts and the number of colors they represent?

1=monochrome 4=16 clrs 8=256 clrs 16=65536 clrs 24=16 million clrs

Check Digit

A number or letter added at the end of the identification number being input, based on an algorithm.

Fun Facts: BMP

All uncompressed data, so is highest quality for manipulation

ASCII

American Standard Code for Information Exchange. A common encoding method, with 256 codes from 0 to 255.

Email ; encryption?

Asymmetric Encryption; recipients of emails must have private key that matched public key; to do so, both sender and recipient need to send each other digital signed message that will add the person's digital certificate to the contact for the person

Symmetric Encryption

Both sender and recipient needs to possess encryption and decryption key. The secret key needs to be sent to the recipient.

Presence Check

Check if data the data is entered

Proof Reading

Checking information manually

Lossy Compression

Compression where some data is removed and quality reduced.

Static Data

Data that doesn't normally change

HTTPS

Hypertext Transfer Protocol Secure

Fun Facts: JPG

Large Colour Depth

Bit Rate

Number of Bits processed every second, in kbps. Bit Rate = Sample Rate x bit depth x number of channels

Bit Depth

Number of Bits used for each sound clip. H Higher it is, higher it's quality. CDs = 16 bits. This means it has 65536 binary combinations.

Codecs (ref. Encoding)

Programs that are used to encode data for images, audio and video. Also used to read the data.

Asymmetric Encryption

Public Key Cryptography. There is a public encryption key that the sender uses, while the receiver has the decryption key with themselves. This prevents a decryption key from being sent and intercepted.

Data

Raw numbers, letters, sounds or images without meaning

Lossy Compression for Sound (Explain the workings)

Reduces file size by reducing bit rate.

Lossless Compression for Sound

Reduces file size without reducing quality, but only up to 50% of file size.

Coding

Representing data by assigning a code to it for classification or identification

Define RLE and explain how it works

Run Length Coding is a compression method. It takes consecutive values and combines them together.

SSL

Secure Sockets Layer. A security method for secure websites. Uses asymmetric encryption.

Static vs Dynamic: Internet

Static can be viewed offline, whereas Dynamic needs a connection

Static vs Dynamic: Up to Date

Static can go out of date quickly as it is designed not to be changed regularly.

Static vs Dynamic: Changing Information

Static doesn't change, dynamic updates when original data changes

Static vs Dynamic: Accuracy

Static will be more accurate because it has been checked since it will be up for a long period of time. Dynamic may be rushed so may contain errors.

Fun Facts: SVG

Storing vector graphics, not as pixels

Examples of Static Data

Title of a webpage, magazines, instructions on a data entry screen

TLS

Transport Layers Security. A security method for secure websites. Uses asymmetric encryption

HTTPS ; encryption?

Uses SSL or TLS; encrypts and decrypts pages sent and received by web users

Double Data Entry

Verification Method where the user enters data twice, so the computer can compare to make sure the data is correct.

Visual Checking

Verification method where the user visually checks whether the data matches the original source.

What does a Windows Bitmap contain?

Width of Bitmap Height of Bitmap Bit Count (number of colours) Compression Type Horizontal Resolution in pixels/meter Vertical Resolution in pixels/meter Raster Data

Fun Facts: PNG and GIF

allows transparent backgrounds

Dynamic Data

data that changes automatically without user intervention

Direct Data Source

data that is collected for the purpose that it is used for

Indirect Data Source

data that was collected for another purpose (secondary source)

Information

data with context and meaning e.g p2872 is data. mention that it is national I.D number and it becomes information

Hard disk ; encryption?

encrypt every single bit of data. decrypted by user entering a password of fingerprint

Caesers Cipher

encryption method where letters are shifted by a certain number of characters along the alphabet Hello --> CC (+3) --> Khoor

Knowledge

information to which human experience has been applied e.g: crown prince salman was born on 1st august 1788 is information. knowing that he was 10 years old in 1798 is KNOWLEDGE

Examples of Dynamic Data

live sports result on a website, news feed, profit for product on a spreadsheet

Relation of SSL and TLS to client-server communication?

once SSL has established an authenticated session, the client and server will create symmetric keys for faster secure communication

Digital Certificate includes...

org. name org. that issued certificate user email user country user public key

Encoding

storing data in a specific format

Raster Data

the actual shape of the image in pixels

Verification

the process of checking that data matched the original source

Validation

the process of checking that data matches acceptable rules