SIA HANDOUT 1 REVIEWER

COMMUNICATION:

-            act of transmitting and exchanging information between people, people and objects, and objects and objects through various media and actions.

-            Delivering an information from source to receiver with giving meaning to Understanding the information from source.

-            LATIN word: Communicare

INTERNET:

-             is the largest computer network in the world. Its predecessor, Advanced Research Projects Agency Network (ARPAnet), was born in 1969.

NETWORK COMMUNICATON:

-            refers to communication between terminal devices through a computer network.

SIGNAL:

-            MEANS OF COMMUNICATION: refers to a sign or indication that conveys information about something or that tells someone to do something.

-            COMMUNICATED INFORMATION: refers to an event or act, which shows that something exists or that gives information about something.

-            ELECTRONICS TRANSMITTED INFORMATION: This refers to a detectable physical quantity or impulse by which messages or information can be transmitted via telegraphy, telephony, radio, radar, or television.

EXAMPLES OF SIGNALS:

• Electrical signals (voltages and currents in a circuit)

• Acoustic signals (audio or speech signals)

• Video signals (intensity variations in an image)

• Biological signals (sequence of bases in a gene)

• Noise (interference – unwanted and undesired form of signal)

The main purpose of the signal is to ensure that the synchronization between the sender and receiver over a physical medium is maintained.

WAVES:

-            refer to disturbances in that energy to travel through a medium from one location to another.

WAVELENGTH:

-            the horizontal distance of a wave from a point to the corresponding point on the next wave.

AMPLITUDE:

-            vertical distance from a given point on the wave from the horizontal axis.

PHASE:

-            describes the position of the waveform relative to time zero.

FREQUENCY:

-            The number of waves made per second or as cycles per second.

-            reciprocal of the period to complete one (1) wave cycle. The unit for frequency is in Hertz (Hz)

-            1 Hz means 1 cycle per second (cps).

PERIOD:

-            This refers to the amount of time (expressed in seconds) required to complete one (1) full cycle.

GENERAL CATEGORIES OF WAVES

ANALOG WAVE:

-            is a wave in which both the amplitude and time continuously vary over their respective intervals

-            Results in a wavy characteristic.

-            Examples: the human voice and music.

DIGITAL WAVE:

-            It is a wave with several discrete (jumpy) states such as high or low, and on or off.

-            It has a fixed amplitude, but its pulse width and frequency can be changed.

-            Example: the data stored in the memory of a computer in the form of 0s and 1s.

NETWORK MEDIA:

-            Computers facilitate information exchange and resource sharing from one location to another

-            through some sort of wiring/cabling or waves that act as a physical path, which carries electrical or electromagnetic signals between a transmitter and a receiver.

WIRED or BOUNDED MEDIA:

-            Networking media use cables and are limited by physical geography.

WIRELESS or UNBOUNDED MEDIA:

-            Networking media do not use any cables in transmitting data and is not bounded by physical geography.

TRANSMISSION MODE:

-            SIMPLEX MODE: Connection wherein data flows in one (1) direction only (unidirectional). This type is either transmit-only or receive-only

-            HALF-DUPLEX MODE: Connection wherein data can flow in both directions, but not simultaneously (both at the same time) over a shared physical medium.

-            FULL-DUPLEX MODE: Connection wherein data simultaneously flows in both directions

TRANSMISSION TYPE:

-            SERIAL TRANSMISSION: which data with each bit lining up in a series as the bits are sent over a single wire at a time. (one at a time)

-            PARALLEL TRANSMISSION: wherein a group of bits is sent simultaneously, but each uses a different channel.

WIRED OR BOUNDED MEDIA

SERIAL CABLE:

-            The most widely used standard for serial data communications is intended to operate over distances of up to 50 feet and has a communication speed that is equal to or less than 20Kbps.

COAXIAL CABLE:

-            refers to two (2) conductors enclosed by an insulating protective coating.

TYPES:

THIN(THINNET) CABLE:

-            flexible coaxial cable about 0.25 inches thick.

-            It uses British Naval Connector (BNC)-T cable connector attached to LAN Card (NIC).

THICK(THICKNET CABLE):

-            relatively rigid coaxial cable about 0.5 inches in diameter.

-            It uses vampire tap or piercing tap as connectors.

TWISTED PAIR CABLE:

-            consists of two insulated strands of copper wire that are arranged in a regular spiral pattern.

UNSHIELDED TWISTED-PAIR(UTP) CABLE:

-            refers to a twisted pair cable that contains no shielding.

-            It has eight (8) individual copper wires, in which pairs of them are twisted around each other

-            to form a four-pair color-coded wire

-            Attenuation refers to signal loss due to impedance.

-            Crosstalk refers to the twisted-wire pairs producing a magnetic field cancellation effect

SHIELDED TWISTED-PAIR(STP) CABLE:

-            refers to a twisted pair cable that combines the techniques of twisting wires, cancellation, and shielding.

-            Each pair of eight (8) individual copper wires is twisted and then wrapped in a metallic foil.

FIBER OPTIC CABLE:

-             A bundle of extremely thin and cylindrically shaped glass fibers surrounded by a concentric layer of glass coating that can conduct modulated light transmissions.

PARTS:

-            CORE: the innermost section that consists of one (1) or more very thin strands or fibers made of glass or plastic.

-            CLADDING: an outer optical glass or plastic coating that surrounds and traps the light in the core by the principle of total internal reflection.

-            COATING: is made from plastic that helps to shield the core and cladding from damage.

-            STRENGTHENING FIBERS: stand as protection for the core against compressive forces or crushing and tension or excessive pulling.

-            CABLE JACKET(SHEATH): outermost layer that protects a buffer or a bundle of buffer-coated fibers against moisture, abrasion, crushing, and other environmental dangers.

FIBER OPTIC MODES

-            SINGLE-MODE FIBER OPTIC CABLE:

-            MULTIMODE FIBER OPTIC CABLE:

WIRELES OR UNBOUDED MEDIA

RADIO WAVE:

-            A wireless medium that is used for multicast communications and paging systems over long distances.

ANTENNA:

-            which is also known as aerial

-            refers to a metallic structure that acts as a transducer that converts electrical energy to electromagnetic energy (upon transmission of signal) and vice-versa.

TYPES OF WAVE PROPAGATION:

-            LINE OF SIGHT: method by which radio waves travel from the transmitting antenna to the receiving antenna.

-            GROUND WAVE(SURFACE): method by which radio waves are radiated directly towards the earth’s surface.

-            SKYWAVE(IONOSPHERIC): method by which radio waves radiate upwards from the transmitting antenna of the earth into a direction towards the ionosphere.

-            SPACE WAVE: method by which radio waves radiation exceeds 30 MHz up to 300 GHz.

OTHER WIRELESS MEDIUM TECHNOLOGIES:

INFRARED: a wireless medium that is used for short-range communication in a closed area using line-of-sight propagation.

MICROEAVE: a wireless medium that is used for unicast communication

BLUETOOTH: short-range wireless communication technology that allows devices to transmit data or voice wirelessly over a short distance.