Data and Signal's- Intro
Information can be sent over long distance this is called transmission.
Different types of electromagnetic wave are carried for transmission, including radiowaves , microwaves , infrared and visible light.
Information can be set in the form of analouge or digital sounds.
Information in the form of speech or music can be transmitted as an analouge or digital signal. an analouge signal will resemble the original speech or music by having the frequency or amplitude of the wave go up and down in the same way as the sound in speech or music goes up down.
Analogue means simillar or corresponding information in the form of an analogue signal can be added to another eelctromagnetic wave which is used for tranmission.
this wave carries the analouge signals and is called the carrier w
Information can be transmitted in the form of a digital signal
unlike an analaouge signal , the digital signal uses a code with two states which are called ON and OFF
the ON state is a small pulse of the electromagetic wave.
The Off state is the gap between the pulses where there is no electromagnetic wave.
Digital signals are series of pulses consisiting of just two states, ON(1) or OFF(0), there are value
Digital signal- Advantages
Digital signals carry more information per second than analouge signals. This is the same whether opticals fibres , cables or radio waves are used.
Digital signals maintain their quality over long distance better than analogue signals. you will notice less noise and crackling from DAB radio program, than in an ordinary FM or AM.
Digital signal- disadvantages
Digital signals need more bandwithd to the same information .
the transmitter and reciver have to sychronise very careful so that the information makes sense. if you start counting halfway through or a digital number you 1011001 where as you should hce recieved 11101100011.
Digitals signal have more bandwidth to carry the same information as a analogue signal. Bamdwitdth is the amount of space on the carrier wave- the range of frequencies ou need to accomadate the carrier wave and the information it is carrying.
However it is possible to compress a digital signal so that it's fits into smaller bandwidth. This is done by only sending the new information, if the image remains the same , no more information is sent, this then saves bandwidth.
Noise gets amplified in analogue signals. In digital the shape of the pulse changed but not the pattern.