tailieunhanh - Bài tập tiếng Anh chuyên nghành Điện tử viễn thông - Ths. Nguyễn Quỳnh Giao & Ths. Nguyễn Hồng Nga (Học viện Bưu chính viễn thông)

Đây là tài liệu về tiếng Anh dành cho các bạn học chuyên nghành Điện tử viễn thông. Xin mời các bạn tham khảo. | HỌC VIỆN CÔNG NGHỆ BƯU CHÍNH VIỄN THÔNG CHƯƠNG TRÌNH PTIT ĐÀO TẠO ĐẠI HỌC TỪ X A BÀI TẬP TIENG ANH CHUYÊN NGANH ĐTVT Dùng cho sinh viên hệ đào tạo đại học từ xa Lưu hành nội bộ HÀ NỘI - 2006 BÀI TẬP TIENG ANH CHUYÊN NGANH ĐTVT Biên soạn THS. NGUYỄN QUỲNH GIAO THS. NGUYỄN HÒNG NGA UNIT 1 Exercise 1. Read the following passage then answer the questions. ANALOGUE AND DIGITAL NETWORKS Digital technology in the telephone network is nothing new. Take all the relays in older exchanges as an example. Relays are either off or on and there is no state in between these. Suitable combinations of relays could build up and remember numbers - perhaps a far-fetched example but in was digital so it will serve What is new is the transfer of speech digitally. In other words the sound we make when we speak is converted to digits and sent out on to the network. In order for the person called to understand what we are saying these numbers must be converted back to audible sound again. The audibility of speech transmitted in analogue form over long distances can be very bad. Due to for instance noise it may be difficult to understand or recognize what the other person is saying. But with a number things are different. It would need very bad handwriting indeed to distort a one beyond recognition So even if the one is distorted when it arrives it can still be interpreted and recreated to give undistorted sound in the receiver. In analogue lines the sound is amplified at regular intervals. The corresponding stage in digital lines is regeneration . the distorted number is interpreted and recreated. Herein lies an important difference between the characteristics of the two methods of transmission. In the analogue system the noise is also amplified. Every amplifying stage along the line leads to an accumulation of noise. In the digital system the information is created anew at every regeneration stage and can be sent on unaffected by the noise. A. Write .