【正文】 FM. The Inter The Inter is a worldwide work of puters and puter works that can municate with each other using the Inter Protocol. Any puter on the Inter has a unique IP address that can be used by other puters to route information to it. Hence, any puter on the Inter can send a message to any other puter using its IP address. These messages carry with them the originating puter39。s voice is not delayed in parts or cutoff pletely. There are petitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future. 外文 翻譯（原 文） 4 Radio and television In a broadcast system, a central highpowered broadcast tower transmits a highfrequency electromagic wave to numerous lowpowered receivers. The highfrequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the highfrequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values). The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of plaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [ ] and received with signal amplitudes [ ] it would still decode to the binary message 1011 — a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to inprehensible output and hence a breakdown of the transmission. In digital television broadcasting, there are three peting standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards。s optic fibre cables are able to carry 25 times as many telephone calls as TAT8. This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than peting technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre. Assisting munication across many modern optic fibre works is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the sidebyside data transmission mentioned in the second paragraph. It is suitable for public telephone works because it establishes a pathway for data through the work and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the work about how the work is to handle the data。s voice directly determines the signal39。s handset. This electrical signal is then sent through the work to the user at the