CS485 Sylabus

### The bandwidth of a transmission medium

• Acceptable level of power loss

• Acceptable loss threshold (set by electrocal engineers):

 ``` power(output signal) ----------------------- ≥ ln 2 ~= 0.7 power(input signal) ```

This value is known as the half-power point: click here

• Range of acceptable frequencies of a transmission media

• Definitions:

• Let f0 = the low end frequency such that:

 ``` power(output signal) ----------------------- = ln 2 = 0.7 power(input signal) ```

• Let f1 = the high end frequency such that:

 ``` power(output signal) ----------------------- = ln 2 = 0.7 power(input signal) ```

• Graphically: the frequencies f0 and f1 are defined as follows:

• Fact:

 Electrical signals (= alternating current)) that have a frequency between f0 and f1 will pass through the transmission medium with relatively little loss of energy

• Bandwidth of a communication medium

• Definition: bandwidth of a communication medium:

• Bandwidth of a communication medium (a.k.a., transmission channel) = f1 − f0

Graphically:

Fact:

• There is a direct relationship between

 Bandwidth of a communication channel                   and        Maximum transmission rate of the communication channel (= how fast you can transmit communication channel)

This relationship is called the Shannon formula and will be discussed next