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Communication and Data Transmission Networking


Q.1 What is Data Transmission?
Sol: Data transmission refers to the process of transferring data between two or more digital devices. Data is transmitted from one device to another in analog or digital format. Basically, data transmission enables devices or components within devices to speak to each other.
Q.2 How does data transmission work between digital devices?
Data is transferred in the form of bits between two or more digital devices. There are two methods used to transmit data between digital devices: serial transmission and parallel transmission. Serial data transmission sends data bits one after another over a single channel. Parallel data transmission sends multiple data bits at the same time over multiple channels.
Types of Data Transmission
Q.3 What is serial Transmission ?
Sol: When data is sent or received using serial data transmission, the data bits are organized in a specific order, since they can only be sent one after another. The order of the data bits is important as it dictates how the transmission is organized when it is received. It is viewed as a reliable data transmission method because a data bit is only sent if the previous data bit has already been received.

Serial transmission has two classifications: asynchronous and synchronous.
Asynchronous Serial Transmission: Data bits can be sent at any point in time. Stop bits and start bits are used between data bytes to synchronize the transmitter and receiver and to ensure that the data is transmitted correctly. The time between sending and receiving data bits is not constant, so gaps are used to provide time between transmissions.
The advantage of using the asynchronous method is that no synchronization is required between the transmitter and receiver devices. It is also a more cost effective method. A disadvantage is that data transmission can be slower, but this is not always the case.
Synchronous Serial Transmission: Data bits are transmitted as a continuous stream in time with a master clock. The data transmitter and receiver both operate using a synchronized clock frequency; therefore, start bits, stop bits, and gaps are not used. This means that data moves faster and timing errors are less frequent because the transmitter and receiver time is synced. However, data accuracy is highly dependent on timing being synced correctly between devices. In comparison with asynchronous serial transmission, this method is usually more expensive.
Q.4 When is serial transmission used to send data?

Serial transmission is normally used for long-distance data transfer. It is also used in cases where the amount of data being sent is relatively small. It ensures that data integrity is maintained as it transmits the data bits in a specific order, one after another. In this way, data bits are received in-sync with one another.
Q.5 What is parallel transmission?
When data is sent using parallel data transmission, multiple data bits are transmitted over multiple channels at the same time. This means that data can be sent much faster than using serial transmission methods. In parallel data transmission, multiple bits are sent simultaneously down different wires (channels) within the same cable.
Q.6 When is parallel transmission used to send data?
Sol: Parallel transmission is used when:   (i) a large amount of data is being sent; (ii) the data being sent is time-sensitive (iii) and the data needs to be sent quickly.
Q.7 Data Transmission Modes?
The term Transmission Mode defines the direction of the flow of information between two communication devices i.e. it tells the direction of signal flow between the two devices.
There are three ways or modes of data transmission: 
(i) Simplex, (ii) Half duplex (HDX), (iii) Full duplex (FDX)

Simplex Simplex transmission is one-way transmission. It is also called unidirectional because the signal travels in onlyone direction. For example, Radio or TV broadcasting system, which are always in one direction from Radio/TV station to our radio or TV sets.
Half-Duplex: In half-duplex transmission data transmission can be take place in both directions, but not at the same time. This means that only one side can transmit at a time. For example, walky-talky devices used by security agencies are half-duplex as only one person can talk at one time.

Full-Duplex: Full-duplex (also known as Duplex) transmission can take place in both directions at the same time. For example, telephone or mobile conversation is an example of full-duplex communication, where both sender and receiver can hear each other at the same time.
Q.8 Difference between analog and digital communication?





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