The needle of the speed-indicator flicked and wagged to and fro; the cinders rattled on the roof, and a whirl of dust sucked after the whirling wheels, The crew of the combination sat on their bunks, panting in their shirt- sleeves, and Cheyne found himself among them shouting old, old stories of the railroad that every trainman knows, above the ...
One of the main drawbacks to a digital TV signal or digital cable signal, for instance, is that it is an artificial reproduction of the original data, whereas an analog signal starts out as an exact copy of the original.
A sound wave's frequency is a number that tells you how many waves pass by each second. Frequency is measured in Hertz (Hz). So for example, 60 Hz, the frequency of most TVs, is 60 waves per second. Or in the case of television, this means that the picture refreshes 60 times a second.