| Each letter in the word is represented by | | | | signaling speed in a channel in which the |
| different signal amplitude using thirty two | | | | noise is purely random. This theorem may be |
| scale order. If we do so information flow | | | | used as a very good approximation for the |
| speed gets greatly increased as per Hartley | | | | ultimate channel capacity of most of the |
| law. Since now each letter is represented by | | | | transmission channels in spite of the fact |
| one symbol instead of five. But in such a | | | | that the noise present in most channels is |
| case noise will cause numerous error making | | | | never perfectly random. It is found that the |
| the system useless extremely large | | | | limiting channel speed for a typical |
| transmitting power is used. This fact may be | | | | telephone channel is about thirty three kilo |
| established on comparing the power | | | | bits per second. How ever speeds used in |
| requirements for the binary coding system and | | | | practice over such channels do not normally |
| any N-level system under the same noise | | | | exceed eleven kilo bits per second. Doubling |
| conditions. For a given transmission and | | | | the speed the bandwidth of a noise limited |
| coding system there results are threshold | | | | channel will double its capacity would amount |
| noise levels below which practically no | | | | to misinterpretation. Actually the capacity |
| errors occur due to noise. Using binary code | | | | gets increased by only eighty percent |
| noise has to compete with the full power of | | | | depending upon signal to noise ratio. Thus we |
| the transmitter to cause any serious error. | | | | see that there exists possibility of trading |
| It is found that in a practical channel, | | | | bandwidth for signal to noise ratio. It may |
| signal to noise ratio of thirty decibel | | | | also be noted that a low channel capacity |
| ensures almost error free reception. This | | | | does not mean that the desired amount of |
| thirty decibel ratio implies that noise power | | | | information can not be seen over a given |
| be one by thousand of signal power or root | | | | channel. It simply means sending this amount |
| mean square noise voltage be one by thirty | | | | of information takes longer time. Lastly it |
| one of root mean square signal voltage. | | | | may be seen that the Shannon-Hartley theorem |
| | | | represents a fundamental limitation. Any |
| The transmitted power is required to rise | | | | attempt to exceed the Shannon limit would |
| tremendously if a desired high signal to | | | | result in unacceptable error rate. In good |
| noise power ratio is to be maintained on | | | | quality transmission system maximum |
| increasing signaling speed that is on | | | | acceptable error ratio is one in 1000000. All |
| increasing the number of coding levels. | | | | the messages sent though the noise limited |
| Shannon-Hartley theorem gives the maximum | | | | channel are unpredictable or random. |