Question:Why do radio stations that are broadcasting in the same area need to broadcast their signals using different frequencies (of the radio waves that carry the signals)?
If the signals were all transmitted at the same frequency your radio could not distinguish one signal from another.
The range of different radio frequencies available is limited.
Also the closer together the signal frequencies are the more interference there will be between adjacent radio channels.
Because digtial radio is less affected by noise/interference, digital channels can be much closer together. This allows more radio channels in the same range of frequencies than if analogue were being used.