Bit duration and bit rate

[rameshrai]

Hi,

I have a question on bit duration and bit rate. What is the bit duration used in various communication system such as ADSL, GSM, CDMA etc? For eg, computer is connected to a modem....what is the bit duration used here in modem? Is there any standard specification for bit duration and bit rate or it is the choice of designer?

Any link for read would be helpful

With thanks,
Ramesh

 

[gavin23]

Bit Duration depends on the electrical protocol being used, which depends on the communications protocol being used (eg ADSL or Ethernet). Once you decide or know what protocol is being used you can then go to the standard to see how protocol is implemented, which will give you more information about the bit rate/bit duration.

If you're the designer, then its up to you what bit rate you use.

-Gavin

 

[rameshrai]

thanks Gavin,

i got nearer to the answer to my question but at the same I wish somebody could tell me more details on this with links to read on the matter

 

[gavin23]

Maybe if you could be more specific as to what exactly you're trying to do and what you're looking for.

-Gavin

 

[BradtheRad]

We might think baud rate is the same as bits transferred per second, but it can be different depending on the protocol.

I have transferred data directly from one computer to another. It required some troubleshooting. I set the baud rate to 300 and watched the oscilloscope. It went slow enough that I could observe the squarish waves and see 8 or 9 or 10 bits go by to transfer one byte of data.

I remember that a bit was either high or low (as we might expect). I did not specifically measure a bit duration, but I had the impression it was 1/300 second.

 

[rameshrai]

what is the bit duration of data inside the computer? at what rate is it transferred to the modem?