Difference buad rate and bit rate?

I today discuss about diference between two definition(idiom). We know that serial communication is very basic for start digital comunication data.So we when select linecode for channel communication we should examine it with rate of data transmition.

We suppose that our basband line code is set NRZ that volgate 3 volt is set for binary level "1" and 0 volt is for binary level"0".So we want to now define buad rate and bit rate (data rate).

Bit Rate:

Bit rate is speed of data rate is expressed in Bit Per Second (bps). Data Rate is showed with R, that is defined function of bit time, Tb:

In Other defintion protocol data is collection of bits, that data unit is called playload. So more info we should see this  great link :

For example, an Ethernet frame can have as many as 1542 bytes or octets, depending on the data payload. Payload can range from 42 to 1500 octets. With a maximum payload, the overhead is only 42/1542 = 0.027, or about 2.7%. It would be even greater if the payload was anything smaller. This relationship is usually expressed as a percentage of the payload size to the maximum frame size, otherwise known as the protocol efficiency:

Protocol efficiency = payload/frame size = 1500/1542 = 0.9727 or 97.3%

Typically, the actual line rate is stepped up by a factor influenced by the overhead to achieve an actual target net data rate. In One Gigabit Ethernet, the actual line rate is 1.25 Gbits/s to achieve a net payload throughput of 1 Gbit/s. In a 10-Gbit/s Ethernet system, gross data rate equals 10.3125 Gbits/s to achieve a true data rate of 10 Gbits/s. The net data rate also is referred to as the throughput, or payload rate, of effective data rate.

Buad Rate:

Buad Rate is number of signal pr symbels change persecond. It is more general definition for Data Rate.

We define symbols in QAM based protocols.So If the baud rate is 4800 and there are two bits per symbol, the number of symbols is 22 = 4. The bit rate is:

R = 4800 x 3.32 log(4) = 4800 x 2 = 9600 bits/s

we concluded that data rate and buad rate  can be relation together, but first we should Modulation,they can be same or not-same based modulation that we used for sending, we can talk that bit rate is related to bit time period, buad rate is related signal period time.


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