chapter 2

Question 1

what is Data Logging?

Answer 1

Involves collecting data automatically using sensors in scientific experiments or while monitoring a system.

Question 2

what are Sensors

Answer 2

A sensor is a type of detector or device that receives a signal and responds to it in a distinctive manner which is read by an observer or instrument.

Question 3

Advantages and Disadvantages of Sensors?

Answer 3

1. Readings that are taken by sensors are much more accurate than human readings.
2. The readings are taken at constant intervals, allowing the microprocessor to take immediate action.
3. Sensors are able to do all the calculations or automatic processes while humans perform other tasks.

Question 4

Types of sensors

Answer 4

Temperature Sensor:
Used in controlling central heating systems and also to monitor temperatures in chemical processes.

Moisture Sensor:
Used to monitor greenhouse environment.

Oxygen Sensor:
Used in environmental factors such as measuring percentage of oxygen in a river to check for pollution.

Light Sensor:
Controls growth in greenhouse.
Used to detect presence of vehicle near traffic lights.
Also used to detect presence of a person near automatic doors.

Infra Red Sensor:
Used in detecting an intruder who breaks infrared beam.
Pressure Sensor
Used to detect intruders in a burglar alarm system and some use it to count vehicles on the road.

Acoustic Sensor:
Used to pick up sounds in a burglar alarm system.

Motion Sensor:
Used to detect speeds for vehicles. (E.g. radar guns measuring vehicle speed)

pH Sensor:
Used to measure acidity in rivers.
Also used to measure soil acidity in greenhouse.

Question 5

Other devices used in data logging

Answer 5

Barcode Readers:
Machines that take data from printed barcodes and allow automatic stock control.

Radio Frequency Identification (RFID):

Here small electronic devices containing microchip and antenna are used to read from a distance of 5 meters.
Used in livestock, library books etc.

Biometrics:
Involves obtaining data and identifying characteristics automatically in security systems. (E.g. use of finger prints, palm prints and facial prints)

Magnetic stripes:
Contain information stored on magnetic material often on back of credit/debit cards and information is retrieved using card reader.

Optical Character Recognition (OCR):
Information on paper is read by a scanner and is processed by OCR software and stored in electronic format.

Voice Recognition:
Recognizes spoken words. For example disabled people who cannot use keyboard ad where spoken commands are used to communicate.

Optical Mark Recognition:
Scans a printed document and reads pre-defined positions and the system records where marks have been entered and it detects the responses automatically.