Computer science studies, data communication with short questions this is part 3.
What is fiber optics?
Fiber optics uses binary method of data transfer. It is made up of a thin glass fiber. It is thinner than hair. Data transfer rate of fiber optics is very fast. There is no chance of data loss.
Write two advantages and two disadvantages of fiber optics cable.
The advantages are that it provides faster data transmission and better security for signal during transmission. The disadvantage are that is difficult to install and very costly.
An important characteristic of finer optics refraction. Refraction is a characteristic of a material to pass or reflect light.
Describe the roles of core and cladding in optical fiber.
The core carried the light signal. Cladding reflects the signal back into the core with perfect internal reflection so that no light escapes form the core.
Write a short note on microwave transmission.
Microwave are radio waves that are used to provide high-speed transmission. Data is transmitted through the air form one microwave station to another similar to radio signals. Microwave used line-of-sight transmission
How does microwave system work?
Microwave uses line-of-sight transmission. It means that the signals travel in straight path and cannot bend. Microwave stations are placed within 20 to 30 each other. Each station receives signal from previous station and transfer to the nest station.
What is the disadvantage of microwave system?
A disadvantage of microwave is that it is limited to line-of- sight transmission. This means that microwave signals must be transmitted in a straight line. There can be no obstruction such as buildings or mountains, between microwave stations.
What is communication satellite?
Communication satellite is a space station. It receives microwave signals from earth station. It amplifies the signals and retransmits them back to earth. It is established in space about 22.300 miles above the earth.
Write one advantage and one disadvantage of communication via satellite.
The advantage is that a satellite can allow long distance wireless communications. The disadvantage is the high cost to put a communications satellite in orbit.
Which units are used to measure the transmission rate of modems?
The unit of measure is bits per second (bps).
Define demodulation. Why is it necessary?
The process of converting digital signal into analog signal is called modulation. It is converted from digital to analog from.
Define demodulation. Why is it necessary?
The process of converting analog signal into digital signal is called demodulation the modem on receiving computer receiver data in analog form. The incoming analog data is converted back into digital format to be used by the computer.
How does a modem allow computers to communicate over telephone lines?
Modem translates computer data into signals compatible with the telephone system.
Baseband is a communications technique in which digital signals are placed on the transmission line without change in modulation. It transmits up to a couple of miles. It does not require complex modems. Digital signals are commonly called baseband signals.
Broadband is a technique to transmit large amounts of data over log distance. It can send data by modulating each signal onto a different frequency. It transmits several streams of data simultaneously using FDM (Frequency Division Multiplexing) technique.
Compare broadband and In broadband transmission
data is carried on high-frequency carrier waves. Several channels may be transmitted over a signal cable. It allows one medium to be used to a variety of transmission needs. Baseband transmission does not use a carrier wave. It sends data along channel by voltage fluctuations. It cannot transmit multiple channels on one cable but it is less expensive than broadband as it can use less expensive cable and connectors.
FDM stands for Frequency Division Multiplexing. It divides the bandwidth of a communication line into smaller frequency bandwidths. Each part of the communication line can be used for transmitting data separately.
Explain external modem.
External modem is attached to the system unit as an external device through telephone line. This modem is connected to computer using serial cable to COM1 or COM2 port. It requires external power supply. It is easy to setup.
Explain internal modem.
Internal modem is a circuit board that is inserted into an expansion slot on the motherboard. It cannot be moved from one computer to another easily. It is difficult to setup than other types of modem.
What do you know about wireless modem?
Wireless modem transmits the data signals through air instead of cable. It is also known as radio-frequency modem. It is designed to work with cellular technology and wireless local area networks.
What is start signal? Write its different states.
Asynchronous transmission uses a special start signal. It is transmitted at the start of each message. It is sent when the character is about to be transmitted. A start bit has a value of 0. It is called space state. It the start bit has the value1; it indicates that the line is idle.