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137 Cards in this Set
- Front
- Back
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Benefits of using Questionnaires |
- Large numbers of people can be asked the same questions, therefore comparisons are easy to make - Cheaper than interviews - Response can be anonymous |
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Limitations of using Questionnaires |
- Must be designed very carefully. Questions need to be unambiguous. - Cannot guarantee 100% return rate - may be lower with some groups |
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Benefits of using Interviews |
- A rapport can be developed with the people who will use the system - Questions can be adjusted or added as the interviews proceed |
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Limitations of using Interviews |
- Can be time consuming and costly - It might not be possible to interview everyone |
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Benefits of Meetings |
- A group of people can attend a meeting with different views being expressed - Can be used to gather or give information - Body language can be seen |
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Limitations of Meetings |
- The discussions can lose focus resulting in the questions not being fully answered - Some staff may not attend because jobs still need to be completed |
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Benefits of Document/Record analysis and inspection |
- Good for obtaining factual information |
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Limitations of Document/Record analysis and inspection |
- Cannot be used when input, output and information are not document-based |
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Benefits of Observation |
- All aspects of work loads, methods of working, delays and 'bottlenecks' can be identified |
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Limitations of Observation |
- Can be time consuming and costly - Problems may not occur during observation - Users may put on a performance when being observed |
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Areas of the System Life Cycle |
1. Definition of the problem 2. Investigation and analysis 3. Design 4. Implementation 5. Testing 6. Installation 7. Documentation 8. Evaluation and maintenance |
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Inputs of the System life cycle |
1. Definition of the Problem - none. 2. Investigation and analysis - Feasibility study. 3. Design - Requirements specification. 4. Implementation - Designs. 5. Testing - Completed system/test plans. 6. Installation - Working system. |
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Outputs of the System life cycle |
1. Definition of the Problem - Feasibility study. 2. Investigation and analysis - Requirements specification. 3. Design - Designs. 4. Implementation - Completed system. 5. Testing - Working system/test logs. 6. Installed system. |
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What is prototyping? |
A software development methodology which focuses on the early delivery to end users of an incomplete, but working, system which can then be changed following feedback from the client. |
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Evolutionary prototyping |
An initial prototype is developed and evaluated by the end users. Using this feedback a second prototype is developed and then evaluated. This process continues with each prototype and evaluation making the system closer to what the end users require. |
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Throw-away prototyping |
A working model of various parts of the system is developed after a short investigation. The prototype is developed and evaluated by the end users but is not used in the final solution - it is thrown away. This enables the end users to give, and receive quick feedback, which means that any refinements can be done early in the development. |
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Benefits of prototyping |
- Reduced time and costs - Improved and increased user involvement - Earlier feedback from end users can be obtained by the designer - The avoidance of the expense and difficulty of changing a finished software product |
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Disadvantages of prototyping |
- End-user confusion between the prototype and the finished system - Excessive development time of the prototype |
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What is Rapid Application Development (RAD)? |
The main aim is to produce a software solution in less than six months. It is a software methodology based on a system life cycle that is iterative and evolutionary. |
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What are the main features of RAD? |
- The use of joint application design (JAD) workshops - these aim to develop a set of requirements that should not change before the system is implemented. - The use of timeboxing - the requirements of the system are defined in small 'chunks', each of which is considered using a JAD. Each 'chunk' is allocated a timescale which must not be exceeded. |
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Benefits of RAD |
- End users are involved at all stages with the system being implemented within 6 months
- End users are involved in the evaluations so this should ensure that the final system fully meets their defined requirements - End users do not have to define all the requirements of the system at the beginning of the process |
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Disadvantages of RAD |
- The solution developed using RAD may, on the surface, meet the end-user requirements but the functionality may not be acceptable - The project manager, who is overseeing the development of the system, will need to keep a very tight control over the whole development process and the team, if the system is to be developed within the six month deadline required by RAD |
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Contents of the Requirements Specification |
- What the system is to do and how this is to be achieved - A description of all the interactions the end users will have with the software - The defined functional requirements - The defined non-functional requirements - The objectives of the system - The scope of the system - The proposed timescale for the project - End-user defined constraints including budget, time, hardware and software choices - A contract |
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Who writes the requirements specification? |
Systems analyst after investigations have been carried out |
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Contents of the System Specification |
- The facilities and outputs the new system will provide - Operation requirements - what operations the system should carry out - Information requirements - what information the system should provide to the end users - Volume requirements - for example, how much volume of processing is to be handled - General systems requirements - EG: degree of data accuracy needed, security issues, need for an audit trail, flexibility of the system, ability of the system to adapt to growth and change |
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Contents of the Design Specification |
- The purpose of the system - Assumptions, limitations or constraints - The inputs - documents and screens/interface - The outputs - documents and screens/interface - Error messages - The colours/font/sizes, including the consideration of the corporate image/house style to be used - Validation rules - Processing requirements/queries - Data structures - Modelling diagrams e.g. data-flow diagrams, entity-relationship diagrams and state-transition diagrams - The hardware - The software/programming language to be used - Test plan |
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Who writes the design specification? |
Systems designer |
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What sort of data should be tested? |
- Normal data - Extreme data - Erroneous data |
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A test plan should cover... |
- The requirements - Pathways - Validation routines - A comparison of the actual performance against the design specification |
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Who are the project team? |
- Project manager - Systems analyst - Systems designer - Programmer - Tester |
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What does the project manager do? |
- Plan and control the whole project - (if required) Is responsible for identifying and rectifying potential problems and issues |
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What does the systems analyst do? |
- Analyse and investigate the existing system - Results of their analysis will enable the system's analyst to assess the suitability of the current system for upgrading |
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What does the systems designer do? |
- Builds on the results of the findings of the systems analyst to design the new system - Their role is central to the process of designing, developing and implementing their desired requirements of the system |
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What does the programmer do? |
- Creates software that is required for the system being developed - A programmer can be specialist in one area (language) - Can also be generalist who writes code for many types of software |
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What does the tester do? |
- Developing and using test plans - Must ensure the system is free from bugs and errors |
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What techniques can be used in the design stage of the system life cycle to complete data modelling? |
- Entity Relationship Diagram - Data Flow Diagram - State Transition Diagram - Flowchart |
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What does an ERD include? |
- Entities - a 'thing' that can be uniquely identified - Attributes - the information that is held on a system about an entity, for example, for a product - product number, description, supplier.... - Primary key - a unique field in a table, that identifies each occurrence of an entity - Foreign key - the primary key from a different table - Relationships - how entities are linked. There are three types, 1:M, 1:1, M:M |
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What is a data flow diagram? |
- Shows who/what the system interacts with in the form of external entities - Focuses on the processes that transform incoming data flows (inputs) into outgoing data flows (outputs) - Shows how the processes create and use data that is held in data stores - Does not show the hardware or software required to operate the system - Shows the data stores that are used and the direction of flow of data and information - Has rules about how the components can be linked - Can be shown as Level 0, or context diagram, giving a summary of the system - Can be level 1, providing an overview of what is happening within the system, represented in the L0 by the central process box |
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What is a state transition diagram? |
- Defines every state of a system diagrammatically - Shows each state as a location, and the transitions between them as arrows. Each arrow is labelled with the reason for the state transition - Enables the state of a system to be followed as different stimuli arrive - Shows the actions (outputs) associated with each transition - Is formal, so tools can be built which can execute them - Is ideal for describing the behaviour of a single object - Is not good at describing behaviour that involves several objects |
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What is a flowchart? |
- Good for providing a general outline of the processing that is involved in the system under investigation - Does not relate very well to the actual software system which is eventually developed - Uses different shaped symbols to represent different actions - Can be used to model all kinds of systems not just computer systems - Can be used to break a process into small steps or to give an overview of a complete system - Can be easily understood by people who are not involved in the IT industry - Does not translate easily into code - Can sometimes become so complex it is hard to follow - Used by the analyst to give a generalised overview of a system or the functions which make up a specific process |
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What tools can a project manager use to plan a project? |
- Critical Path Analysis - Gantt Charts |
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What does Critical Path Analysis involve? |
- Identifies the critical path for a project - the order in which the component parts have to be completed and, usually, the path that takes maximum time - Defines the path that should be taken to ensure the project is successful and completed on time - Enables resources to be allocated provisionally - Enables slack, lead and lag time to be built in and to cover any slippage in the project - Provides a firm idea of when tasks and the project should be completed |
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What do Gantt Charts involve? |
- Show how long each activity/task is expected to take and the order in which these will occur - Enable the modelling of how long the overall project will take and where the projected pressure points are - Show the critical path as the longest sequence of dependent tasks |
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What do Gantt Charts contain? |
They contain: Milestones - important checkpoints and interim goals for a project Resources - people/equipment needed Status - shows the progress of each task Dependencies - activities which are dependent on other activities being completed first or at the same time |
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What are the three types of processing system? |
1. Batch 2. Interactive 3. Real-time |
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What is a batch processing system? |
Processes batches of data at regular intervals. Processing: processed when the system is not busy and offline Response time: Delayed - there is a delay between the data being input and the results User interface: usually code based |
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What is an interactive processing system? |
Handles transactions one at a time. Processing: Each transaction is completed before moving on to the next Response time: dependent on action from end user User interface requirements: Graphical User interface (GUI) |
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What is a real-time processing system? |
Processes data at the time it is required. Processing: Data is processed as soon as it is received by the processor Response time: Very quick, based on user requirements, but usually lower than four seconds User interface: usually based on the internal requirements of the user |
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What should the designer consider when designing a human-computer interface (HCI)? |
- Use of colour - Layout - Quantity of information on the screen - Font - Complexity of the language - Type of controls |
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What are the types of operating system? |
- Single-user - Multi-user - Multi-tasking - Interactive - Real-time - Batch - Distributed |
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What is a single-user system? |
Provides access to the OS for one user at a time. It can support more than one user account, but only one account can be used at any one time. |
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What is a multi-user system? |
More than one user can access the system at the same time. Access to this OS is usually provided by a network. |
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What is a multi-tasking system? |
The processor does more than one task at a time. For example, enabling a user to write a letter and use the internet at the same time. |
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What is an interactive system? |
Provides direct user interaction whilst a programme is running. |
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What is a real-time system? |
Developed for real-time applications and typically used for embedded applications (systems within another application). |
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What is batch processing? |
Processes batches of data at regular intervals. The amount of data processed is usually large with the data being of identical type. |
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What is distributed processing? |
A number of computers connected together with each computer completing part of the processing. When all the processing has been completed, the results are combined to meet the requirements of the user. |
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What are the four main methods of dialogue? |
- Prompts - Nature of input - Methods of input - Feedback |
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What should the designer especially consider with an HCI? |
- Attention - Perception - Memory - Learning |
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What should the designer consider when designing a system model? |
The user's mental model. This is to ensure that the final product matches the user's requirements as closely as possible. |
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What is a model human processor (MHP)? |
Developed by Card, Moran and Newell. This concept attempts to portray the user of a computer system as a computer, including memory and processors. |
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What is the application of MHP? |
Examples of how the model can be applied to the design of a user interface include: - The use of a logical order to the inputs, possibly those required from the user - An on-screen flashing cursor used to show the user where data is to be input - An audible stimulus, for example, a beep sound, to indicate when an error has been made by the user |
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What is an intranet? |
A communication system that is restricted and internal to a company or organisation - usually over a LAN or a virtual private network (VPN). It provides an organisation with services that are only accessible by authorised users. It uses the internet protocol (IP) and includes access to web pages, email and collaborative working. |
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What is the internet? |
A global system of interconnected computer networks that use the IP. It provides access to information and resources from any connected computer anywhere in the world. It includes access to libraries, academic works, as well as internet email, chatting, online shopping etc. Its purpose is to link computers and information together. |
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What is an extranet? |
A private network that is built on top of, and uses the internet. It is commonly used to access a company or organisation's intranet. It is easiest if thought of as an intranet accessed from any computer connected to the internet. |
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What is a Local Area Network (LAN)? |
A set of computers that are: - Within a locally defined area and in close proximity to each other - Able to have direct connections between them - Connected only by cables that are owned by the user - Able to share local peripherals LAN - usually a small network, often within a school, library, small business etc. |
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What is a Wide Area Network (WAN)? |
A set of computers that are:
- Geographically remote - with large distances between them - Connected by equipment that is owned by a third party - telecommunication lines, satellites, etc... Most common example of a WAN is the internet. |
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What is a virtual network? |
A network that is run on top of a larger network - it is a subset. The virtual network is then secured and acts as a private network (VPN). The computers can be physically remote but act as though they are on a local network and access local resources. |
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What is a peer-to-peer network? |
All computers connected in it are of equal status. Any of the computers connected can provide printer or file-sharing resources. |
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What are the advantages of a peer-to-peer network? |
- Only normal computers are required: there is no need to purchase an expensive server - Each user manages their own computer. This means that a network manager is not required. - Set-up is done via wizards within software. No technical knowledge is required. - There is no reliance on a central computer so there is less to go wrong. |
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What are the disadvantages of a peer-to-peer network? |
- Each computer is fulfilling more than one role - it may be printing or file sharing. This increases the load. - Data can be stored on any computer - there is no organisation to data storage. - Security, anti-virus and back up are down to the individual user |
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What is a client-server network? |
A client-server network has a powerful controlling computer, otherwise known as the server. This central computer controls peripherals - printers, back up etc - and the security of the network. |
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What are the advantages of a client-server network? |
- Backup, security and anti-virus are centralised - The user does not do any of the management of the computers, there is usually a network manager to do this. - Network processing is done centrally, freeing the individual computers to do what the user wants. |
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What are the disadvantages of a client-server network? |
- The server costs money, as does the network operating system - A network manager is required and this costs money - There is a reliance on the central server - if it fails, no work can be done |
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What are the different network components? |
- Switch - Hub - Network Interface Card (NIC) - Wireless Access Point (WAP) - Router - Repeater - Bridge |
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What is a switch? |
A switch has a number of ports and it stores the addresses of all devices that are directly or indirectly connected to each port. As data comes into the switch, it is examine to see the final destination and then directed to the port to which the device it is seeking is connected. |
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What is a hub? |
This is a concentrator that connects lots of computers to the network through a single link. Signals received on any port are broadcast to all other ports. Hubs can be active (where they repeat signals sent through them) or passive (where they do not repeat but merely split signals sent through them). |
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What is a Network Interface Card (NIC)? |
This allows the device to be physically connected to the network and allows communication to pass to and from a computer. It contains a unique identifier or MAC code. |
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What is a Wireless Network Interface Card? |
This would perform the same function as an NIC but eliminate the need for a direct physical connection. It can be internal or external. |
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What is a Wireless Access Point (WAP)? |
If you have any NICs, then you need a device that will send and receive wireless signals. A WAP is connected into the physical network by a cable and positioned so that it can send and receive wireless signals. |
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What is a router? |
This is a device that routes information between networks. It can select the best path to route a message, as well as translate information from one network to another. It can connect a LAN to a WAN. |
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What is a repeater? |
This is used in a network to strengthen a signal as it is passed along the network cable. A signal degrades over distance so a repeater can boost the signal and extend the maximum cable length. |
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What is a bridge? |
A bridge connects and passes packets between two network segments that use the same communications protocol. This allows data to be broadcast in one direction rather than broadcast in many. |
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What are the different types of server? |
- File server: stores documents and resources and allows access to those by computer and user. - Proxy server: verifies and routes requests and bans those that are not permitted. - Applications server: stores and distributes programs to users, keeps quotas of instances of applications running to ensure licence agreements are not broken. - Email server: routes email as well as holds email and email accounts. - Print server: controls printing, including quotas. - Backup server: stores copies of user information and files, security permissions, emails and even programs. |
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Optical communication: What is fibre optic communication? |
A glass fibre that carries light. The fibres can be wrapped in bundles, and the cables are capable of conducting modulated light transmission. |
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What are the advantages of fibre optic communication? |
- High bit rate - handles both speech and data - Better quality service as it is less susceptible to interference - Unaffected by electro magnetic disturbance (voltages, clicks, atmosphere) - Difficult to tap into them - so they are secure - Large distances covered |
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What are the disadvantages of fibre optic communication? |
- More expensive than other networking media - Only economical when the bandwidth is fully utilised or likely to be in the near future - High cost of installation compared to copper wires |
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What is Light Amplification by Stimulated Emmision of Radiation (LASER) communication? |
A laser outputs a focused electromagnetic energy field in which all waves are at the same frequency and aligned in phase. |
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What are the advantages of LASER communication? |
- Data transferred at high speeds - Used in locations where laying cable is not an option |
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What are the disadvantages of LASER communication? |
- Line of sight is required (signal can be bounced) - Can be blocked by fog/mist |
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What is infrared as communication? |
Infrared is a focused ray of light in the infrared frequency spectrum. It is measured in terahertz, or trillions of hertz, modulated with information and sent from a transmitter to a receiver over a relatively short distance. |
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What are the advantages of infrared? |
- Speed up to 4Mb/s - No cabling - Unlicensed |
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What are the disadvantages of infrared? |
- Distance between the two terminals has to be low - A line of sight is always needed - Susceptible to interference from other light sources |
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What are the uses of optical communication? |
- Used in high voltage installations Infrared: mice and keyboards, car locks, printers, headphones, home security and home control systems Fibre optics: long distance communications, lighting, signage and aircraft communications Lasers: mapping the ocean floor, data transmission |
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What is bandwidth? |
The maximum amount of data that can travel over a given data transmission channel in a given amount of time. |
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What is bluetooth? |
A protocol for connecting headset to phone or connecting computer to mobile Personal Data Assistant (PDA). Has a range of approx 10m. |
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Wireless technology: What are the advantages of bluetooth? |
- Communication between the two devices can be made secure with a key - It can work without a line of sight between the devices - Any portable devices with bluetooth can connect as its a standard, and many devices now make use of this |
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Wireless technology: What are the disadvantages of bluetooth? |
- There is a limit on both the data transfer rate and the distance between the devices - It allows connectivity to only one device at a time |
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Wireless technology: What are the advantages of radio technology? |
- Does not require physical connection between devices - this allows for no line of sight and physical obstructions between devices - A worldwide standard exists allowing many devices to connect |
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Wireless technology: What are the disadvantages of radio technology? |
- Signal strength can be reduced by distance and obstacles - Can have security vulnerabilities (if not correctly set up) - Bandwidth linked to number of connected devices |
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Types of communication applications |
- Fax - Internet Relay Chat (IRC) - Bulletin boards - Tele/videoconferencing |
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What are the advantages of fax? |
- If the sending and receiving equipment is compatible then faxes can be sent and received in colour - A fax machine gives a receipt of delivery to the number you entered - Modern fax machines have the ability to hold address books and to send faxes to groups of people |
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What are the disadvantages of fax? |
- The received document cannot be directly edited - There is no guarantee of where you are sending the fax to and who may see it - The quality is variable - it depends on the quality of sending and receiving machines and the original |
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What are the features of email communication? |
- Allows you to send messages to many people at the same time - using lists and sending carbon copies - Can add a digital signature on the message and encrypt the message to increase security - Email client can send back confirmation of delivery and of opening - some software means you can cancel this - Pictures and text can be sent - A single point of contact (email address) can be picked up anywhere in the world - An email can sit on a server until the recipient is ready to read it, improving security - Facilities also include distribution lists and address books |
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What are the features of Bulletin Board communication? |
- A website where users can post and read messages from other users - Can be accessed through the internet and can be used to give information or contain links to downloadable documents - Accessible anywhere in the world and can have many recipients - Parts can be password protected - Parts of a bulletin board an be set aside for selected groups of users - Can set up threads of conversations and ensure that all posts are kept together: users can be notified by email of new postings - Can have posts moderated before they are made accessible to users |
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What is tele/videoconferencing? |
Enables communication to take place between groups of people who are geographically remote. Teleconferencing enables participants to talk and videoconferencing includes video as well as sound. |
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What are the advantages of tele/video conferencing? |
- The equipment required can be very simple and cheap - Videoconferencing can be done via a direct line or across the internet - The conference can be recorded for playback at a later date |
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What are the disadvantages of tele/videoconferencing? |
- The equipment can be complex and therefore very expensive - Individuals involved in the conference need to be present at the same time and there can be a slight time delay that makes conversation difficult - Image size is usually small and the quality may be poor, especially when simple equipment is used |
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What are the different types of broadband? |
- Asymmetric digital subscriber line (ADSL) - Cable - Wireless - Leased Line - Satellite |
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What is ADSL? |
It runs on copper cables and the frequencies that are not used for voice telephone calls. It is always on and allow the telephone to be used for speech and for data traffic at the same time. - It is used for short distances, typically 4km. - Asymmetric = data flow is different on one direction to the other: Download bandwidth is higher than the upload bandwidth. |
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What are the advantages of ADSL? |
- High speed connection - Use of the phone line while connected - No extra wiring; ADSL uses the existing phone line |
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What are the disadvantages of ADSL? |
- Service not available everywhere - Distance from exchange limited - Bandwidth is not guaranteed - Faster download than upload - Typical contention ratio of 50:1 (50 users sharing bandwidth) |
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What is cable broadband? |
This is the use of fibre optic cables, usually provided by television companies, to deliver an internet connection. This service is similar to ADSL as it is asymmetric, giving higher download bandwidth. Bandwidth up to 50mb is available. |
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What are the advantages of using cable broadband? |
- High speed connection - Telephone, television and internet in a single service - Single point of contact for all problems - Based on fibre-optics - more reliable, consistent and secure |
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What are the disadvantages of using cable broadband? |
- Physical cable needs to be installed - Speeds advertised are not guaranteed - Limited competition - Contention ratio issue where users share link |
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What is wireless broadband? |
The use of 2G/3G/4G technology on mobile telephone networks to allow internet access. The mobile phone or wireless device can be tethered to a laptop to use the wireless connection. Bandwidth is limited by the contract. There are also limits of data usage. |
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What are the advantages of wireless broadband? |
- Connection is not limited to home location - Can connect phone or computer - Technology constantly improving |
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What are the disadvantages of wireless broadband? |
- Coverage depends on location - Limited bandwidth and possible data usage limits - Expensive for the service |
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What is leased line broadband? |
This is a symmetric line connecting two locations. It is a direct connection that can have a high bandwidth. |
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What are the advantages of leased line broadband? |
- Bandwidth is guaranteed - No contention - Symmetric |
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What are the disadvantages of leased line broadband? |
- Requires line to be installed - Cost of the line is high |
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What is satellite broadband? |
One way: This uses a satellite for downloading and a telephone line for uploading. Two way: Uses a satellite for both uploading and downloading. Satellite broadband is often used by news companies to transmit stories for TV. |
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What are the advantages of satellite broadband? |
- No need for fixed lines - Can be mobile |
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What are the disadvantages of satellite broadband? |
- Latency delay - Cost of technology - Limited bandwidth |
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Mobile phones: What are the advantages of cellular networks? |
- Coverage is almost complete and phones can be used anywhere - People reassured as rarely out of contact - The use of the data network means pictures and text messages can be sent and web access is available - Smart phones are mini computers which can connect anywhere and any time |
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Mobile phones: What are the disadvantages of cellular networks? |
- Loss of signal, batter and credit - Phone can be tracked - Use of phones in public places can be annoying - Phones can also distract, e.g. when driving |
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Mobile phones: What are the advantages of satellite networks? |
- Can be used anywhere on the surface of the planet where there is sight of a satellite - When the normal phone system is down the satellite phone will still work - Phones are getting smaller and more portable - There is greater security as it is harder to monitor calls |
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Mobile phones: What are the disadvantages of satellite networks? |
- There needs to be line of site with a satellite - Solar flares and buildings can reduce the quality of connection - Bandwidth is low and cost is high compared with cellular |
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What are the uses of satellites? |
- Global Positioning System (GPS) - Weather - Data transfer systems - TV |
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What are the advantages of using GPS satellites? |
- High degree of accuracy - Can be linked to many different applications, e.g. satnav, google maps, etc |
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What are the disadvantages of using GPS satellites? |
- Need line of sight to satellite - Quality dependent on the software installed, not the GPS - Dependent on technology/batteries |
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What are the advantages of using weather satellites? |
- The impact of natural and man made disasters can be viewed - With geostationary satellites, the same view can be taken repeatedly - Weather predictions can be made and storm warnings given |
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What are the disadvantages of using weather satellites? |
- The images taken need to be interpreted - Only a certain number of photos per day can be received with a polar orbit - A polar orbit shows a small area in detail - A geostationary orbit shows a large area but in less detail |
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What are the advantages of using satellites for data transfer? |
- Secure connection - Does not need complex infrastructure to support communication |
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What are the disadvantages of using satellites for data transfer? |
- Very high initial set up costs - Reliant on technology working - Requires relay satellites to cover vast distances |
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What are the advantages of Satellite TV? |
- Contains more channels than broadcast radio waves - Remote areas that have problems receiving radio waves can receive satellite - Free and encrypted channels can be broadcast enabling companies to charge for services |
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What are the disadvantages of satellite tv? |
- High initial set up cost - Reliant on equipment working - Can be affected by weather conditions |
