Many countries began converting audio and video broadcasts, or sound and pictures, from analog to digital signal technology in the late twentieth century. Traditional analog broadcasts, which have been used for radio and television since the early twentieth century, used a continuous signal that looked like waves passing over water. Sampling, a technology that converts signal waves into a series of numbers, made analog to digital signal processing possible.
Taking many repeated snapshots of an analog signal and converting each snapshot to a digital signal using a series of zeros and ones, known as binary numbers, is what sampling an analog signal entails. The resulting numbers were broadcast as a broadcast, and the TV or radio converted them back to analog signals. It was possible to send digital programming over an analog signal in the late twentieth century, and some countries did so. The amount of information that could be sent over a much smaller frequency range, or bandwidth, was an advantage of using a fully compressed binary number signal. x000D_
A typical digital compression system took each frame, or a single snapshot of a broadcast, and converted it from an analog to digital signal using a variety of technologies. The system examined the following frame and compared it to the one before it. Only the moving parts of the image, such as a moving object or a changing color, were transmitted. This process was repeated indefinitely, requiring far less data because only the changes in a picture were transmitted.
To successfully convert an analog to digital signal, adequate sampling and error correction, a technique for removing digital values that did not fit the signal, were both required. Random signal noise could cause errors during transmission, so software was developed to check the signal, a technique also used in compact disc (CD) devices to remove signal errors caused by scratches or age. For a variety of reasons, digital broadcast signals were advantageous to programming companies. Radio and television signal bandwidths, or frequencies available for broadcasting, were limited in many countries; broadcasts had to compete with emergency services, wireless telephone and radio signals, and a variety of other uses. Broadcasters were able to send more information and better video over the same frequencies by converting from analog to digital signal broadcasts and using data compression.
High-definition (HD) television became popular in the late twentieth century as a way to improve broadcast picture quality. Broadcasters could send more data over a digital signal than they could over an analog signal, resulting in HD improvements at the same time. Signal compression improved signal quality even more with existing bandwidths by allowing a higher-density signal to be sent.
Because the signals could be easily sent to viewers over existing high-speed connections, the growth of Internet-based communications became a growth market for digital broadcasting. In the early twenty-first century, on-demand movies, Internet radio, and other markets grew as a result of digital signals, benefiting broadcasters and giving consumers more options. Customers in rural areas benefited from digital programming because analog TV signals weakened as the receiving antenna moved further away from the transmission tower. As long as the signal is received, a digital TV will convert the values back to a high-quality picture. Because distance does not degrade the picture, remote customers can see the same picture on a TV as a local customer.