The difference between Bit and Baud rate is complicated and intertwining. Both are dependent and inter-related. But the simplest explanation is that a Bit Rate is how many data bits are transmitted per second. A baud Rate is the number of times per second a signal in a communications channel changes.
Bit rates measure the number of data bits (that is 0′s and 1′s) transmitted in one second in a communication channel. A figure of 2400 bits per second means 2400 zeros or ones can be transmitted in one second, hence the abbreviation “bps.” Individual characters (for example letters or numbers) that are also referred to as bytes are composed of several bits.
A baud rate is the number of times a signal in a communications channel changes state or varies. For example, a 2400 baud rate means that the channel can change states up to 2400 times per second. The term “change state” means that it can change from 0 to 1 or from 1 to 0 up to X (in this case, 2400) times per second. It also refers to the actual state of the connection, such as voltage, frequency, or phase level).
The main difference between the two is that one change of state can transmit one bit, or slightly more or less than one bit, that depends on the modulation technique used. So the bit rate (bps) and baud rate (baud per second) have this connection:
bps = baud per second x the number of bit per baud
The modulation technique determines the number of bit per baud. Here are two examples:
When FSK (Frequency Shift Keying, a transmission technique) is used, each baud transmits one bit. Only one change in state is required to send a bit. Thus, the modem’s bps rate is equal to the baud rate. When a baud rate of 2400 is used, a modulation technique called phase modulation that transmits four bits per baud is used. So:
2400 baud x 4 bits per baud = 9600 bps
Such modems are capable of 9600 bps operation.
crystal clear explanation//…..thnx man….
thanks lots. its been of much help.
woh,i now understood actual difference b/w both..
Thank you. very good explanation.
but I have same question as suresh if all 1′s or all 0′s transmitted per sec then what will be the baud rate? and how do you define number of bits require to represent in one symbol/state?
please clear my doubt.
If baud rate=zero means all bits are same (no transition) and bitrate=8bit/sec
so,considering bps = baud per second x the number of bit per baud
we will not get above desired bit rate with formulae.Then wats the exact relation between them?
It can be understood like this:
In the article, Baud rate is defined as the number of times a signal in a communications channel changes state or varies. But if defined properly the statement should read “Baud rate is defined as the number of times a signal in a communications channel can change state or vary”.
So a 1 bit signal defined at 8 Baud can change at max. 8 times in one seconds. But if it changes lesser than that doesn’t mean that the Baud rate cannot be 8.
So if there is no transition, that doesn’t mean that it is 0 Baud. If the bits transmitted during that second are N then Baud rate can be anywhere between 1 to N depending on symbol size for that signal transmission.
@Swati: If bitrate = 8bps and no transition is there, do not assume that baud rate is zero. In this case baud rate can be anywhere between 1 to 8 depending on symbol size used for signal transmission. Suppose if symbol size is 4 then baud rate is 2. The only thing is that the symbol didnt change during that one sec but may change the next or some other sec and the hardware is programmed to look for those many changes every seconds. If the signal will change more times than baud rate then only hardware will see a wrong communication.
Bit rate = No. of bits / sec
Baud rate = No. of symbols /sec
It can be agreed,
Bit rate is nothing which the no. of 1′s and 0′s we are transmitting over a channel per second.
Baud rate is no. of symbols we are transmitting over the channel per second, ie; a SYMBOL is made up of group of bits, may be of 1, 2,3, 4….etc according to the requirement.
eg; If I have a data which can have only 16 states, then I will select the symbol size as 4,, this means 16 various symbols can be represented using a 4 bit cmbinations from 0000 to 1111.
Here and if I have a channel which can transmit 400Bits/sec, the baudrate the we can achieve will be 400/4 = 100 Bauds/sec, simply means 100 Symbols/sec.
Baudrate( symbols/sec) = Bitrate (bits/sec) / bits per Baud
ie ; bds/sec = (bts/sec ) * (bds/bts)
here bts in nr and bts in dr get cancells, yields bds/sec
bts –> bits
bds –> Bauds (Symbols)
One more thing for all, I cannot understand/agree on the above detentions for the baudrate which makes it very complex to understand,
“A baud rate, by definition, means the number of times a signal in a communications channel changes state or varies. For example, a 2400 baud rate means that the channel can change states up to 2400 times per second. The term “change state”, means that it can change from 0 to 1 or from 1 to 0 up to X (in this case, 2400) times per second. It also refers to the actual state of the connection, such as voltage, frequency or phase level).”
To Whoever concerned,
Please clarify this with a real example.!!!!
If we have bitrate=8bps and baud rate=zero(means no transition).
Then putting this baud rate in above formulae we will get zero bps bitrate and thats wrong as it is 8bps.
Any solution???
Crystal clear indeed
Sorry to be late, but I think you might be able to answer this question:
When you see a serial datagram with a scope and want to calculate baud rate, do you have to ignore start & stop bit ? ( only measure the data length and divide by time)
thanks in advance.
While calculating Baud, we should consider the number of bit signals per second transmitted. If in the network 8 bits /second is transmitted, the Baud will be 8Bd. To know about Baud, please follow the link: http://www.tech-faq.com/baud-rate.html
To understand BAUD RATE consider u have an instrument which tell u only two directions north and south .It internally has a pointer which takes 1 second to move from N to S and 1 more second two move from S to N (you can’t see its motion as it is totally covered). There is a problem with u that you u know binary number (1 & 0) & not aware of decimal system (1,2,….9). Your instrument have a little opening in which digits can be represented , let 1 represent N and ’0′ represent S . Now your instrument represent N and S alternatively after each second , thus your symbol changes once per second . So your baud rate is 1 and the same will be bit rate as u r seeing one bit at a time.
Now consider u have a little advance instrument which can tell you all the four directions ie N ,E, W, S with the slight change that now its pointer move from N to E, E to S , S to W ,W to N and each move requires 1 sec ( it takes 1 sec to move from N to E ,similarly others). You have 4 symbols ( N,E,S,W) and to percieve it with binary digit it requires 4 different combinations using bits 0 and 1. These 4 combinations requires at least 2 bits per symbol and we have the combination as 00,01,10,11 .
N 00
E 01
S 10
W 11
Now on your instrument u r seeing 2 bits at a time which is changing (actually symbol is changing) in every second . Thus BAUD RATE is 1 but BIT RATE is 2 (two bits is transmitted from the screen of yr instrument to you)
Very good explanation……….. Thanx….
Hey Swati…?
Got your answer?
Really very very good explanation.
10 out of 10.
Thanks man.
Thnx dude…A very clear explanation..
thanks to all and specailay bravim kumar maurya
it is really a good explanation..
best explanation ever read. thanx
excellent article, better than wikipedia.
good conceptual knowledge.
5 out of 5
crystal clear…. awesome explanation…
exelent explanation……………………………….
hi there..hope you can help em with this one…
if i’m not mistaken, the higher the baud rate, the better. Is this correct?
but what if, i have an HMI connected to my PLC at a baud rate of 19200, what would happen if i change this to 9600 or 4800 baud rate?
Excellent Bravin…no one should have any doubt.