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9.4 Information systems 5. Information can be transmitted in the form of electrical impulses
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Syllabus reference (October 2002 version) | ||
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| 5. Information can be transmitted in the form of electrical impulses |
Students learn to:
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Students: |
Extract from Senior Science Stage 6 Syllabus (Amended October 2002). Board of Studies, NSW.
[Edit: 28 Aug08]
Prior learning: Science Stages 4-5, Outcome 4.12 (content 4.12b: technology), Outcome 5.12 (content 4.12c: technology).
gather, process, analyse and present information from secondary
sources to identify energy
transfers involved in coding and decoding information by digital
technologies.
- Gather information by researching a range of
different digital devices such as fax machines, digital video cameras,
MIDI (musical instrument device interface). Look at a variety of sources such
as magazines, encyclopaedias and internet sites.
- Process the information to select and evaluate
the relevant information in these sites.
- Analyse the data to identify the energy that is
supplied to the device and the energy that it is converted
into.
- Select an appropriate format to present what you have found. A table may be suitable or a series of labelled diagrams.
identify communication technologies that transform one type of energy into electrical energy
- Some examples of communication technologies that transform different types of energy into electrical energy are identified in the following table.
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Communication technology |
Type of energy transformed into electrical energy |
| microphone | sound |
| TV camera | light |
| scanner | light |
| electric keyboard | kinetic (movement) |
| receiving antenna | electromagnetic radiation in the radio frequency |
| photoelectric cell | light |
describe the transmission of images using digital technologies in terms of scanning of the input image along very thin lines
| Background
Electronic devices, such as fax machines, can communicate via the telephone network, which includes landline, wireless communication or via satellites. These machines can send and receive an exact copy of any sort of document, a page at a time. |
- The essential parts of scanning digital technologies
are:
- a transmitting device, which translates the visual matter (text and graphics) of the copy into electrical impulses according to a set pattern
- a synchronised receiving device, which translates these impulses and prints an exact copy.
- In a typical system, the scanner consists of a source projecting a narrow beam of light and a photoelectric cell. The copy to be transmitted is scanned by the light beam, which moves along the device, scanning it in a series of thin lines. The output of the photoelectric cell is suitably amplified in a coupling device and used to modulate a carrier radio signal, or is transmitted directly over the telephone cables.
explain how the coding of the image into a series of zeros and ones allows its transmission and ultimate decoding
- Electronic digital devices work by digitising an image, i.e. dividing it into a grid of dots. Each dot is either on or off, depending on whether it is black or white. Electronically, each dot is represented by a bit that has a value of either 0 (off), or 1 (on). In this way, the device translates a picture into a series of zeros and ones (called a bit map) that can be transmitted like normal computer data. On the receiving side, a device reads the incoming data, translates the zeros and ones back into dots, and reprints the image.
Bitmaps 
Webopedia, the online encyclopedia dedicated to computer
technology.
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