Difference between Synchronous and Asynchronous Transmission

Details: Last Updated: 21 January 2021

What is Transmission?

Transmission is the action of transferring or moving something from one position or person to another. It is a mechanism of transferring data between two devices connected using a network. It is also called communication Mode.

In computer networking there are two types of Transmission:

Synchronous
Asynchronous transmissions

What is Synchronous Transmission?

Synchronous data transmission is a data transfer method in which is a continuous stream of data signals accompanied by timing signals. It helps to ensure that the transmitter and the receiver are synchronized with each other.

This communication methods is mostly used when large amounts of data needs to be transferred from one location to the other.

What is Asynchronous Transmission?

Asynchronous Transmission is also known as start/stop transmission, sends data from the sender to the receiver using the flow control method. It does not use a clock to synchronize data between the source and destination.

This transmission method sends one character or 8 bits at a time. In this method, before the transmission process begins, each character sends the start bit. After sending the character, it also sends the stop bit. With the character bits and start and stop bits, the total number of bits is 10 bits.

KEY DIFFERENCES:

Synchronous is a data transfer method in which a continuous stream of data signals is accompanied by timing signals whereas Asynchronous data transmission is a data transfer method in which the sender and the receiver use the flow control method.
In, synchronous transmission method users need to wait until it sending finishes before getting a response from the server. On the contrary, Asynchronous transmission method users do not have to wait until sending completes before receiving a response from the server.
Synchronous Transmission sends data in the form of blocks or frames while Asynchronous Transmission send data in the form of character or byte.
Synchronous Transmission is fast. On the other hand, Asynchronous transmission method is slow.
Synchronous Transmission is costly whereas Asynchronous Transmission is economical.

How Synchronous Transmission works?

Separate clocking lines used when the distance between the data terminal equipment (DTE) and data communications equipment (DCE) is short.
This method uses a clocking electrical system at both transmitting and receiving stations. This ensures that the communication process is synchronized.
Devices that communicate with each other Synchronously use either separate clocking channels.

How Asynchronous Transmission works?

Asynchronous communication is eased by two bits, which is known as start bit as '0' and stop bit as '1.'
You need to send '0' bit to start the communication & '1' bit to stop the Transmission.
There is a time delay between the communication of two bytes.
The transmitter and receiver may be function at different clock frequencies.

Synchronous Transmission vs Asynchronous Transmission

Here is the main difference between Synchronous vs. ASynchronous Transmission:

Synchronous	Asynchronous
Synchronous data transmission is a data transfer method in which a continuous stream of data signals is accompanied by timing signals.	Asynchronous data transmission is a data transfer method in which the sender and the receiver use the flow control method.
Synchronous handler do not return until it finishes processing the HTTP request for which it is called.	Asynchronous handler helps you to run a process independently of sending a response to the user.
Users need to wait until it sending finishes before getting a response from the server.	Users do not have to wait until sending completes before receiving a response from the server.
In this transmission method, blocks of characters are transmitted at high- speed on the transmission line.	In asynchronous transmission, the information should be transmitted character by character.
It sends data in the form of blocks or frames.	Data is sent in the form of character or byte.
Synchronous Transmission is fast.	Asynchronous transmission method is slow.
Synchronous Transmission is costly.	Asynchronous Transmission is economical.
The time interval of transmission is constant.	The time interval of transmission is random.
Synchronous Transmission does not have a gap between data.	In asynchronous transmission, there is a gap between data.
Synchronous postback renders the entire page of any postback.	Asynchronous postback renders only needed part of the page.
It does not need any local storage at the terminal end. ‭ ‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬	It requires local buffer storages at the two ends of the line to assemble blocks.
Synchronous replication should be performed when reliable and long-term storage is required.	Asynchronous replication an ideal for projects that span across long distances and have a very minimal budget.
This method does not need any synchronized clocks.	This method requires accurately synchronized clocks at both ends. ‭ ‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬
You can use it in the low-speed communication like the connection of a terminal to a computer.	You can use it in high-speed applications like the Transmission of data from one computer to another.
The voice-band and broad-band channels are mostly used in the Synchronous Transmission.	The voice-band channels that have a narrow type in the used asynchronous transfer.

Advantages of Synchronous Transmission

Here are the benefits/pros of Synchronous Transmission:

It helps you to transfer a large amount of data.
It offers real-time communication between connected devices.
Each byte is transmitted without a gap between the next byte.
It also reduces time timing errors.

Advantages of Asynchronous Transmission

Here are pros/benefits of Asynchronous Transmission:

This is a highly flexible method of data transmission.
Synchronization between the receiver and transmitter is unnecessary.
It helps you to transmit signals from the sources which have different bit rates.
The Transmission can resume as soon as the data byte transmission is available.
This mode of Transmission is easy for implementation.

Disadvantages of ASynchronous Transmission

Here are cons/drawbacks of Asynchronous Transmission

In Asynchronous Transmission, additional bits called start and stop bits are required to be used.
The timing error may take place as it is difficult to determine synchronicity.
It has a slower transmission rate.
May create false recognition of these bits because of noise on the channel.

Disadvantages of Synchronous Transmission

Here are the cons/drawbacks of Synchronous Transmission.

The accuracy of the received data depends on the receiver's ability to count the received bits accurately.
The transmitter and receiver need to operate simultaneously with the same clock frequency.