picks up television waves of many different frequencies and converts them into electrical signals
what does the tuner of a television receiver do?
selects one particular frequency from the many received by the aerial
what does the audio decoder of a television receiver do?
selects extracts the audio signal from the transmitted television signal
what does the audio amplifier of a television receiver do?
increases the strength of the electrical audio signal
what does the loudspeaker of a television receiver do?
converts the electrical signal into sound
what does the vision decoder of a television receiver do?
extracts the vision signal from the transmitted television signal
what does the vision amplifier of a television receiver do?
increases the strength of the electrical vision signal
what does the picture tube of a television receiver do?
converts the electrical signal into light
why is there a power supply in a television receiver?
to supply extra energy to the amplifiers
what does the picture consist of? what does it do?
consists of an electron gun situated inside an evacuted glass tube, which is painted with a special phosphor coatingthe electron gun fires a beam of electrons at the phosphor paint on the screen where the kinetic energy of the electrons is turned into a spot of light
how is a picture built up on the TV screen?
by moving the electron beam across the screen in a series of lines
as the beam moves across the screen the brightness of the spot is altered by changing the number of electrons hitting each part of the screen
a new picture is produced 25 times each seconds and because our eyes retain the image on the retina of the eye, each picture merges into the next
since each picture is only slightly different from the previous one the picture appears to move
what is the difference in the way television signals are transmitted compared with radio signals?
the carrier wave is modulated to carry two synchronised signals, each signal is then extracted by a seperate decoder
describe a colour television.
A colour television has three different coloured phosphor dots at each point on the screen.
One electron gun fires at each colour and by altering the number of electrons fired at each dot they are lit up with varying brightness.
This allows all the colours to be produced by colour mixing.