Key areas of pervasive computing

• is a system composed of multiple wireless sensors
• it is more or less a stratergy than key area
• difficult to implement 

• location
• temperature
• gases
• position
• sound
• pressure
• light

Sensors

• Sensors gather data

Interface

• it helps to visualise the state of the data

Micro-controller board

• this is the main connection between the sensors and the interfaces
• can be embedded due to their size

Buses

• A bus is a physical connection , which can be shared by multiple hardware componets , in order to communicate with one another.
• another purpose of buses is to reduce the number of pathways needed for communication between the componets by carrying out all communications over a single data channel. 

A sensor is a converter that measures a physical quantity and converts into signal which is by a instrument

• Stands for Global Positioning system 
• works by using a triangulation of satelite signals 
• genrally limited to outside due to the need for satelite connection

Electromagnetic Radiation

used for old phones , night vision 

• uses soundwaves
• much like sonar and radar
• needs an emitter to fully work

• uses radio waves 
• can get interupted easily 
• enables wireless communication between devices

it is used to calculate the temperature of a surface or an area

there are to types of tempreture sensors , these are :

• contact
• non-contact

Contact

• Thermocouples
• Thermoresistor

Non-contact

• Thermal radiation

used for measuring pressure of fluids

example types of pressure sesnors consist of vaccum and guage .

Vaccum

measures pressure below ambient pressure 

Guage

measures atmospheric pressure 

It is able to clalculate change in force 

used to detect movement

Connections

there are many different connection and componets 

the device must match the format of the device connecting to

Serial

is a method of sending data between devices 

data is transfered one bit at a time 

There are two forms of serial data transfer

It is normally bit - bit

Used in networks as well as long distance communication

Serial cable are easier and therefore cheaper

less cables

data is sent yo each clock tick 

and example of this is a USB

A bus is used to transfer data inside a device  between key componets

data travels at 1 bit at a time

Analouge input

it is a continious wave which is varied by a thrid party parameter .

change in voltage depicts the alteration of a third party parameter.

Examples

• potentiometer
• accelerometer 
• temperature sensor

Digital input

Continiuous bit-stream with a data range 0 and 1

constantly sends a value to the input

RFID

• wireless
• non-contact

It uses Radio frequnecy magnetic fields to transfer data

there are two typed of RFID tags they are :

• Powered
• Non-powered

they are also made of two componets which are :

• Reciever and tag 

• doesnt have a local powere source
• the magnetic fields of the reader powers the device and transfer data
• data is usually a single string or integer

• Contains a bttery which allows the device to transmit at a longer range
• Means the overall device is large and heavier

• RFID are execellent ways to track items or objects with  implemented RFID tags
• used for identifcation 

• IT is based of RFID technology 
• fundamentals are the same
• two way communication is needed

PROS

• can detect users through unqiue tag codes
• passive tags do not require a portable power source

CONS

• hackers can scan tags and get data
• it cant pass large volumes of data
• needs a larger scanning system 

• It is used to complete the circuit 
• the thread in a ground pin is not insulated
• the thread in a ground pin is connected to a end pin , it must not touch any thread connected to a different pin