confusion between serial bit stream and baud rate

ashraf_can2 · ‎09-26-2006

Hi there!

I will be most grateful if someone can help me out with the following query:

I understand that a modem sends data a bit at a time (supports the transmission and reception of a serial bit stream). I also understand that a modem, in order to achieve higher bit rates, tends to use modulation techniques that encode more than 1 bit in the signal (ie 2 bits per baud). So, does this mean that a modem doesn't always send data serially? (ie if it's sending 4 bits per baud, is it sending 4 bits at a time?)

Thank you very much in advance for helping me out.

Kind regards,

Ashraf.

pciaccio · ‎09-27-2006

A modem can only send one piece of information at a given interval of time. It's modulation scheme allows the modem to send/reveive more data at a faster interval of time. QAM (Quadrature Amplitude Modulation)and other various forms of this is a mixture of Phase, Frequency and Amplitude modulation that allows for more data to be placed on the same signal and be transmitted faster then the older modulations techniques. At any given time the modem is still transmitting one bit of information...As for the Baud rate. Baud is an old term that defines a set of bits (similiar to Byte) but for comm purposes it is called Baud. It is a word. In old Teletype days Baud was used often to destinquish the speed of the conversation. Usually 50Baud or 75 Baud was used. It meant that you were sending 50 words per sec...Please rate...

ashraf_can2 · ‎09-27-2006

Dear Pciaccio,

Hi there!

Thank you very much for your reply and for clearing up my confusion.

I appreciate your help very much and wish you a wonderful day.

Kind regards,

Ashraf.