Data Transmission Modes:
There are 3 ways to
transmit data from one point to the other.
1. Simplex: Communication can be
in one direction in this mode, receivers receive single from transmitting
device. In this way the flow of information is unidirectional, it is used very
little for data communication.
2. Half-duplex: In this mode the communication channel is used in both directions, but
data transfer can be done in only one direction at a time. Hence the
half-duplex line can alternately send and receive data.
3. Full duplex: In this mode, communication channels are used in both directions at one
time. Using the full duplex line increases the capability because the required
line turnaround time in the half-duplex system is overcome. The example is a
telephone line.
Digital and Analog Transmission:
Data transmits from 1
point to electrical signals, which are digital or analog. Therefore, it is
necessary to know the difference between analog and digital. An analog signal changes
in the continuous range between power, sound, light and radio waves. On the
other hand, digital signal accepts only discreditable set of values in the
given range. Examples are computer and computer related tools. Analog signal is
measured in volts and its frequency is in hertz. Digital signal is the order of
the voltage displayed in the binary form. When digital data is sent to analog
medium, then the digital signal is converted to analog. The technique to
convert digital signals into analog is called modulation.
Conversely,
conversion to analog to digital is called demodulation. The device that is
analog and digital to the digital is called modem.
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