3.4) Other Information3.4) Other Information
•Different devices can be used for collecting
communication data including:
• ATM terminals for banking
• EFTPOS terminals in stores
• telephones for voice mail
• keyboards for email/IM/SMS
• video cameras & microphones for
• smart phones for file access
•After data is collected it must be converted
into a suitable form for transmission.
•This processing involves encoding and
•Encoding involves converting data from its
original form into some other form.
•Decoding is the reverse process.
•It converts data back from the form used for
transmission back into its original form.
• A telephone encodes the sound waves of
your voice into electrical signals for
transmission and then they are decoded
back into sound waves at the other end.
• Analog data is continuously variable and
represented in waves.
• Digital data is represented in a series of
jumps, or steps.
• Digital signals in information systems are
represented as a series of 1’s and 0’s.
• There are four possible encoding and decoding
possibilities in transmission.
• They are:
• analog to analog (e.g. telephone)
• digital to digital (transmission across a LAN)
• analog to digital – real world data encoded for
computers (scanners, recording sounds to
computer, digital cameras)
• digital to analog (modem converting
computer data to telephone signals)
• When a modem converts a digital signal to an
audible signal this is called modulation.
• At the other end this audio signal is converted
back to a digital signal; this is known as
• Attachments for emails also need to be encoded.
• Many email programs use the Multipurpose
Internet Mail Extension (MIME) to transmit
• Client-server architecture describes the software
relationship between the client and the server.
• A client sends a request and the server responds.
• E.g. an online newspaper delivering content to
be read offline.
• Client-server architecture provides a convenient
way of connecting programs that are distributed
across a network.
•Text, audio and images can all be displayed
through various devices.
•These include, but are not limited to:
• EFTPOS terminal
• data projectors