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.
Any kind of wave (mechanical or electromagnetic) has a certain energy. Mechanical waves can be produced only in media which possess elasticity and inertia. A mechanical wave requires an initial energy input. Once this initial energy is added, the wave travels through the medium until all its energy is transferred.