- 16th February 2011, 12:55 #1

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## Difference between Baud Rate and Bit Rate

Hi,

I would like to know the difference between baud rate and bit rate. And is there any formula relating to both variables that I can use to convert from baud rate to bit rate and vice versa? If for example my project needs a 1200 bps, what is the baud rate I need for my transmitter?

Thanks.

Regards.

- 16th February 2011, 12:55

- 16th February 2011, 13:08 #2

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## Re: Difference between Baud Rate and Bit Rate

There is not 1200 ???

No sure if there exists difference.

+++

- 16th February 2011, 13:13 #3

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## Re: Difference between Baud Rate and Bit Rate

Bit rate is a measure of the number of data bits (that's 0's and 1's) transmitted in one second. A figure of 2400 bits per second means 2400 zeros or ones can be transmitted in one second, hence the abbreviation 'bps'.

Baud rate by definition means the number of times a signal in a communications channel changes state. For example, a 2400 baud rate means that the channel can change states up to 2400 times per second. When I say 'change state' I mean that it can change from 0 to 1 up to 2400 times per second.

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- 16th February 2011, 13:23 #4

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## Re: Difference between Baud Rate and Bit Rate

when u said for baud rate it changes from 0 to 1, it does not include counting for 1 to 0 transition? so ur 2400 times per second is all from 0 to 1?

- 16th February 2011, 13:23

- 16th February 2011, 13:27 #5

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## Re: Difference between Baud Rate and Bit Rate

bit rate : no of bits transmitted per sec like 1200 bits transmitted in 1 sec

baud rate: no of frames(1 or multiple bits ) transmitted per sec

if u transmit 1 bit at a time then bit rate = baud rate

if u transmit 2 bit at a time then bit rate = 2x baud rate and so on

- 16th February 2011, 13:35 #6

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## Re: Difference between Baud Rate and Bit Rate

bit rate will be equal or more than baud rate.... baud rate can never be more than bit rate...

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- 16th February 2011, 13:37 #7

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- 16th February 2011, 13:37

- 16th February 2011, 13:45 #8

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## Re: Difference between Baud Rate and Bit Rate

okay, I am a little confused. cause in my situation now I am suppose to get a 1200 bps signal but the computer program which i am going to use to generate the signal only allows me to key in baud rate. so i planning to transmit a periodic signal of 4 binary '1' bits followed by 4 binary '0' bits and so on. And this periodic signal includes a start and stop bit in the packet.

- 16th February 2011, 15:54 #9

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## Re: Difference between Baud Rate and Bit Rate

Hi,

baud rate can be seen as number of symbols per second. I.e say you have 8 symbols . In binary you need 3 bits to represent 8 symbols. 000 to 111. Now, if a system can transmit 8 symbols in one second you say baud rate is 8 and equivalent bit rate is 24 bit/sec (8X3).

- 16th February 2011, 19:23 #10

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## Re: Difference between Baud Rate and Bit Rate

i think he means that when bit rate is 1000 then boud rate will be 1000/2=500 , he just wrote it the wrong way.

500 frames (baud rate) , each 2 bit, =1000 bps (bitrate)

Actually what he wrote is correct, bitrate will be twice the baudrate for 2 bit transition

AlexLast edited by alexan_e; 16th February 2011 at 20:01.

- 16th February 2011, 20:12 #11

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## Re: Difference between Baud Rate and Bit Rate

Hi,

Bit Rate: Number of bits transmitted per second(as stated above).

Baud rate: It is measurement of the number of times per second a signal in a communication channel chages it state. e.g, 2400 baud rate means that signal in a channel can change states upto 2400 times per second.

Relation between Bit rate and baud rate: bps(bits per second)= Baud per second * Number of bits per baud(It ll be determined by the modulation technique used)

Use this relation and do not forget to take care of modulation technique used(bpsk,qpsk and so on) and you ll always go back and forth from bit rate to baudrate successfully. Examples given above holds true according to the relation mentioned.

In your specific case:

you need 1200bps and you r transmitting 4bits(1,s or o,s) per baud so your baud rate ll be

1200/4= 300 baud rate

Hope it helps.

/SC

- 16th February 2011, 23:08 #12

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## Re: Difference between Baud Rate and Bit Rate

It's relate to modulation scheme.

Say:

For QPSK, spectrum effiency is 2bit/s/Hz, so Baud rate is bps/2.

For 16QQAM, spectrum effiency is 4bit/s/Hz, so Baud rate is bps/4.

For 128QQAM, spectrum effiency is 7bit/s/Hz, so Baud rate is bps/7.

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- 17th February 2011, 00:30 #13

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- 17th February 2011, 23:16 #14

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## Re: Difference between Baud Rate and Bit Rate

For AFSK, spectrum effiency is 1bit/s/Hz, so Baud rate = bps.

For 4FSK, spectrum effiency is 2bit/s/Hz, so Baud rate is bps/2.

- 22nd May 2013, 07:51 #15

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