The ICT Lounge
 
Section 2.3:
Sensors
 
In the last section we looked at how data can be input into a computer system (both manually and directly).

In this section we will discuss how sensors can be used to automatically detect changes in the environment around and then directly feed this data into a computer for processing.



Key Concepts of this section:
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Know the definition of the term 'sensor'.
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Understand the different types of sensors and what uses they perform.
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Be able to discuss advantages and disadvantages of sensors.

Sensors (what are they?)
Key Words:
Data, Automatic, Measured, Analogue, Digital, Analogue to Digital Converter, ADC
Definition:
"A device which automatically inputs data into a computer system, where the data is constantly changing and can be measured."

Overview of Sensors:
Examples:
Thermometers are examples of temperature sensors.
 
Infrared burglar alarms are examples of light sensors.
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Used to detect data in the surrounding environment that constantly changes. For example:
  • Temperature - measuring heat in a room
  • Light - setting off a burglar alarm
  • Humidity - detecting when plants become too dry.
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This information is ‘physical’ and ‘analogue’.

Analogue data is constantly changing and it changes very smoothly.

For example: Outside temperature changes all of the time but it does so very gradually and smoothly. It doesn't suddenly jump from 10°C to 20°C.

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Computers don’t understand analogue data and therefore it needs to be converted to digital (e.g. 1’s and 0’s).

The computer can then read the data.

A special device called an Analogue to Digital Converter (ADC) is used in
order to achieve this.





Examples of Sensors
Key Words:
Temperature, Pressure, Light, Sound, Humidity, pH, Monitoring, Data Collection

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The table below shows you some examples of sensors:
Temperature
Pressure
Light
 
REMEMBER!
Sensors are used to AUTOMATICALLY get data into a computer system.
NOTE:
We will look at each sensor in greater detail further down this page.
 
Activity!

Click the above task and write-up the required information about sensors.

 

 

 
Sound
Humidity/Moisture
pH
 
 


Uses of Sensors
Examples:
Sensors in burglar alarms can
automatically detect intruders.
 
Automatic doors open when people are
detected nearby.
A variety of sensors are used on automatic greenhouses to keep plants in perfect conditions.
pH sensors are used to monitor the acidity and alkalinity level of aquariums (wrong levels can kill fish).
Malfunctioning sensors used on cars to assist in 'reverse parking' can cause crashes.

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Sensors are used in monitoring and control applications.

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When monitoring, the data is sent directly to some sort of a computer and is then processed and used.

For example:
A burglar climbs through a window and walks through an alarm’s light sensor. The computer inside the alarm will pick up on the broken light signal and use this information to sound the alarm

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Sensors can also be used for a wide range of data collection and everyday applications.

For example:
  • Taking measurements in scientific experiments
  • Measuring pollution in the atmosphere
  • Sensing the temperature in a room and using this to either turn a heating system on or off
  • Automatic doors open themselves when they detect a person nearby.

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The table below specifies the uses of different types of sensors:

Type of Sensor:
Used For:
Temperature
Automatic washing machines, Central heating systems, Automatic greenhouses, Cookers.
Pressure
Burglar alarm systems, Washing machines, Robotics, Environmental monitoring.
Light
Automatic greenhouses, Automatic doors, Burglar alarm systems, Street lighting control.
Sound
Burglar alarm systems, Voice recognition systems (like using a voice command to start a car).
Humidity/Moisture
Automatic greenhouses, Environmental monitoring, Agriculture, Factories that manufacture items that can be ruined by too much air moisture (microchips etc).
pH
Automatic greenhouses, Chemical manufacturing, Environmental monitoring, Aquariums (wrong pH can kill fish).


Advantages/Disadvantages of Sensors
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The table below highlights some of the main advantages and disadvantages of using sensors:

Advantages
Disadvantages
Readings taken using sensors are more accurate than those taken by a human.
Faulty sensors can give incorrect results.

For example: if the sensors on a car that help with reverse parking become dirty they may not identify an obstacle and cause you to crash into it.
Sensors can monitor information constantly (They don’t get tired like humans can).
Sensors can respond to information immediately (Burglar alarms goes off as soon as an intruder is detected).
No need for humans to operate the sensor. This can be useful if gathering the information is hazardous like in detecting radiation levels for example.


Some videos:
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Here are some links to videos that contain more information about topics discussed regarding sensors:

Please add your questions/comments below:
 

Links to Theory Units:
Section 4: Networks and the Effects of using them
Section 6: ICT Applications
Section 8: Safety and Security
Section 9: Audience
Section 10: Communication
 
Links to Practical Units:
Section 11: File Management
Section 12: Images
Section 13: layout
Section 14: Styles
Section 15: Proofing
Section 16: Graphs and Charts
Section 17: Document Production
Section 18: Data Manipulation
Section 19: Presentations
Section 20: Data Analysis
Section 21: Website Authoring