Data Transmission

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Data Transmission

Data transmission is the process of sending data from one device to another.

How is data transmitted?

Data is sent over a network (like the internet).
Data is broken down into small units called packets.
- This is more efficient and reliable than sending one large block of data.
- If a packet is lost, only that one packet needs to be resent, not the entire message.

Structure of a data packet

The header contains the important information needed to get the packet to its destination:
- Destination address (the IP address of where it is going)
- Originator’s address (the IP address of where it came from)
- Packet number (the sequence order of the data)
The payload is the actual data being sent.
- Example: text, video, image data
The trailer is the end of the packet.
- It checks for errors during transmission.

Methods of data transmission

Serial data transmission
- Data is sent one bit at a time over a single channel.
- Reliable over long distances (less chance of data synchronisation errors).
- Slower than parallel transmission.
- Common in USB connections.
Parallel data transmission
- Data is sent several bits at the same time using multiple channels.
- Much faster over short distances.
- Less reliable over long distances (more data synchronisation issues).
- Used inside computer circuits.

Transmission Directions

Transmission directions describe how data flows between devices: either one-way only, half-two-way but one at a time, or two-way at the same time.

Transmission directions 1

Simplex data transmission
- Data can be sent in one direction only.
- Simple to implement, requires less bandwidth, but communication is one-way only.
- Used in broadcasting, such as a radio or TV, where there is no need for a return signal.

Transmission directions 2

Half-duplex data transmission
- Data flows both ways, but only one direction at a time.
- Allows for two-way communication, but is slow for continuous dialogue.
- Used in walkie-talkies, where one person speaks at a time.

Transmission directions 3

Full-duplex data transmission
- Data can be sent and received in both directions at the same time.
- Fastest method for two-way communication.
- Requires more complex hardware and more bandwidth.
- Used in telephone calls or video conferencing, where both sides can speak and listen at the same time.

1Computer Systems

1.1Data Representation

1.1.1Binary Numbers

1.1.2Negative Binary Numbers

1.1.3Hexadecimal

1.1.4Using Hexadecimal

1.1.5Converting Binary & Hexadecimal

1.1.6Converting Denary & Hexadecimal

1.1.7Capacity

1.1.8Calculating Capacity Requirements

1.1.9Binary in Computer Systems

1.1.10Data Compression

1.1.11Run Length Encoding

1.1.12File Formats

1.2Data Transmission

1.2.1Packet Switching

1.2.2Data Transmission

1.2.3Universal Serial Bus (USB)

1.2.4Parity Check

1.2.5Checksum & Echo Checks

1.2.6Encryption

1.3Hardware

1.4Software

1.4.1Operating Systems

1.4.2Interrupts

1.4.3High-Level Languages

1.4.4Low-Level Languages

1.5The Internet & its Uses

1.5.1The Internet

1.5.2Uniform Resource Locators (URLs)

1.5.3DNS

1.5.4HTML

1.5.5Cookies

1.5.6Web Hosting

1.5.7Digital Currency

1.6Cyber Security

1.6.1Forms of Attack

1.6.2Penetration Testing

1.6.3Types of Malware

1.6.4How Malware Spreads

1.6.5Protecting Against Malware

1.6.6Information Security

1.6.7Structured Query Language (SQL) Injection

1.6.8Firewalls

1.6.9Authentication: User Access Levels

1.6.10Authentication: Passwords

1.6.11Social Engineering

1.6.12Phishing

1.6.13Denial of Service Attacks

1.7Automated & Emerging Technologies

1.7.1Automated Systems

1.7.2Robotics

1.7.3Artificial Intelligence

2Algorithms, Programming & Logic

2.1Algorithm Design & Problem Solving

2.1.1Computational Thinking - Abstraction

2.1.2Computational Thinking - Decomposition

2.1.3Computational Thinking - Algorithmic Thinking

2.1.4Pseudocode

2.1.5Flow Diagrams

2.1.6Interpreting, Correcting & Completing Algorithm

2.1.7Correcting Algorithms

2.1.8Completing Algorithms

2.1.9Testing

2.1.10Types of Testing

2.1.11Test Plans

2.1.12Validation & Sanitation

2.1.13Authentication & Contingencies

2.2Programming

2.2.1Programming Fundamentals - Variables & Constants

2.2.2Programming Fundamentals - Comments

2.2.3Programming Fundamentals - Input & Output

2.2.4Data Types

2.2.5Casting

2.2.6Controlling Program Flow - Sequence

2.2.7Controlling Program Flow - Selection

2.2.8Controlling Program Flow - Iteration

2.2.9Modularity - Subroutines

2.2.10Modularity - Scope

2.2.11Arrays

2.3Databases

2.3.1Structuring Data - Records

2.3.2Structuring Data - Databases

2.3.3SQL

2.4Boolean Logic

2.4.1Binary Systems

2.4.2Logic Circuits

2.4.3Truth Tables

2.4.4Evaluating Expressions

2.4.5Boolean Operators

2.4.6End of Topic Test - Logic

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