Wk2 Transmission Concepts
-
Upload
abaigail-rose-artagame -
Category
Documents
-
view
229 -
download
0
Transcript of Wk2 Transmission Concepts
-
8/10/2019 Wk2 Transmission Concepts
1/13
Data and Information
Dataany representation, such as a figure or a letter, to
which meaning can be ascribed.
InformationAny organized signal
-
8/10/2019 Wk2 Transmission Concepts
2/13
Data Transmission
Defined as the movement of information over some physicalmedium, using some physical representation appropriate
to the medium.
-
8/10/2019 Wk2 Transmission Concepts
3/13
Data Communications
Controlling, checking and handling of the movement ofinformation in a communications-based computer system.
-
8/10/2019 Wk2 Transmission Concepts
4/13
Compression
The encoding of data so that it requires less disk space forstorage and transmission.
-
8/10/2019 Wk2 Transmission Concepts
5/13
Encryption
The science of converting computer data and messages tosomething incomprehensible by means of a key, so that it
can be reconverted only by an authorized recipient holding
the matching key.
-
8/10/2019 Wk2 Transmission Concepts
6/13
Data Transmission:
1. Serial TransmissionBits are transmitted one afteranother. (serial-by-bit)
2. Parallel TransmissionBits are transmitted all at once.
(parallel-by-bit/serial-by-character)
-
8/10/2019 Wk2 Transmission Concepts
7/13
Modes of Transmission:
1. Simplex
2. Half-Duplex
3. Full-Duplex
4. Point-to-point
5. Multi-drop
I. Bus
II. Ring
III. Hub
IV. Wireless
-
8/10/2019 Wk2 Transmission Concepts
8/13
Data Communications Circuit:
1. DTE (Data Terminal Equipment)a computer
transmit and receive equipment.2. DCE (Data Communication Equipment)an
equipment that interfaces the DTE to the network.
-
8/10/2019 Wk2 Transmission Concepts
9/13
Transmission Methods:
1. Asynchronousa character-framed transmission
2. Synchronousa message-framed transmission
3. Isochronousa synchronous data transmitted without aclocking source
4. Pleisiochronousa synchronous transmission of varying
levels of bandwidth
-
8/10/2019 Wk2 Transmission Concepts
10/13
Synchronization:
1. Network Synchronizationrequired so that station sharing a
network can transmit and receive in an orderly fashion
2. Frame Synchronizationrequired to keep track of the individual
channels in a TDM system
3. Codeword and node synchronizationrequired to keep tracks of
block of bits in a bit stream.4. Symbol Synchronizationrequired in order that symbols, which
may be hidden in a noisy waveform, are sampled at the optimum time
5. Carrier Synchronizationrequired in order to demodulate a carrier
modulated wave in the most efficient manner.
-
8/10/2019 Wk2 Transmission Concepts
11/13
Transmission Codes:1. Binary Digit (bit)defined as the amount of information
derived from the knowledge of two equiprobables and can be
represented mathematically by a 1 or 0 or electrically by two
deferring conditions +v orv, on or off.2. Alpha numeric characters are being coded into binary notations.
BCD (Binary Coded Decimal)a 4-bit code used to
represent decimal numbers in terms of binary notation. To
represent alpha information an additional 2 bits is being
added. (6 bits represents BCD with alphanumeric
characters)EBCDIC (Extended Binary Coded Decimal Interchange
Code)an extension of BCD code that uses 8 bits instead
of six.
International Alphabet No. 5 (ASCII)a 7-bit code
developed by ANSI, CCITT and ISO.
Telegraph Codes (IA 2)the International Alphabet No. 2is a 5-bit code used in telegraphy. Also known as the
Baudot Code
UNICODE (Universal Code)An attempt to standardize
longer and more complex coding scemes used to
accommodate more complex languages such as Japanese
and Chinese. Supports 65,536 (216) characters.
-
8/10/2019 Wk2 Transmission Concepts
12/13
Efficiency of CodesThe efficiency of a two-condition code can be expressed by
the formula:
Log2N
E = --------------------
M
Where: E = the efficiency of the code
N = the number of characters or symbols required
M = the number of bits in the code
-
8/10/2019 Wk2 Transmission Concepts
13/13
Data Transmission Rates
1. Modulation RateRate at which changes in the condition
of the circuit can be made in a given time
2. Data Signaling RateRate at which information can be
transmitted3. Data (Information) Transfer RateRate at which actual
data arrives after transmission