Có 13+ tài liệu thuộc chủ đề "tín hiệu vô tuyến"
dlib.hust.edu.vn Xem trực tuyến Tải xuống
luận văn thạc sĩ khoa học Phân tích, giải điều chế tín hiệu vô tuyến dải sóng ngắn hf ngành : điện tử viễn thông m∙ số Nguyễn văn thăng Ng−ời h−ớng dẫn khoa học : TS. Nguyễn viết nguyên Hà Nội 01/2008 Bản cam đoan Tôi xin cam đoan toàn bộ nội dung đề cập trong luận văn “phân...
tailieu.vn Xem trực tuyến Tải xuống
You spoke into a microphone or special handset, and the voice from the other end of the connection usually came through a loudspeaker. Because of the nature of the equipment, you and the party you were speaking with had to take turns talking, pushing a button before you spoke. The concept of mobile phones as status symbols is illustrated by...
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CELLULAR PHONE EQUIPMENT. There are three parts to a cellular phone system: the cellular telephone, or cellphone. the cell site, which receives and transmits radio signals from and to your phone. THE CELLULAR TELEPHONE. The small portables available are marvels of engineering, and may have a standard, rectangular shape, or the popular flip-phone styling, which covers the keypad when not...
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THE BUSINESS OF CELLULAR PHONES. The business of cellular phones is a big one. Although cellular phone companies must make a large initial investment, the potential for an enormous return makes it certain that there will be no shortage of firms to service the cellular user.. WHERE CAN YOU GET CELLULAR SERVICE?. Cellular service was deployed beginning in 1983in order...
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GETTING CELLULAR SERVICE. Cellular phone equipment must meet stringent standards and pass a number of stiff tests, so you are assured of getting a quality product no matter where you buy it. The real deciding factor on where to buy your cellular phone is the human one — the standards, know-how, and customer service capabilities of the dealer.. Advertising for...
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Fixed costs, though, account for only a part of what it costs to operate a cellular phone. These one-time expenses are outlined in the following text.. If you suspend service and then request that it be resumed, you may have to pay this fee again. If you ask that your service be switched from one phone to another using the...
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Because convenience and safety are two prime factors in the design of a cellular phone, as many of its controls as possible — sometimes all of them — are grouped together on the handset of the vehicle-installed phone as well as on the portable.. The actual keys, key sequences, and indicators on any particular phone may be very different from...
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Using your cellular phone when you’re away from your home cellular service area, traveling in another, is called roaming. Virtually all cellular carriers have made arrangements under which you can simply arrive in a service area other than your own and automati- cally start to use that carrier’s service.. HOW TO TELL WHEN YOU’RE ROAMING. The boundaries that mark the...
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To be able to place and receive telephone calls for various wireless applications — a telephone for the construction site, or on a boat, for example — you may want to consider a transportable phone. Vehicle- installed phones used to be the primary type of cellular phone, and are still important for many users.. A typical cellular phone installation for...
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OPTIONS AND ACCESSORIES. Note that some types of chargers require that the battery is installed in the phone while it is charged. This means that you can’t use the phone while it is charging.. Most also charge the phone’s battery at the same time.. HANDS-FREE OPERATION. 88 OPTIONS AND ACCESSORIES. The hands-free arrangement consists of a speaker, which may be...
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This chapter will help you to understand some of the difficulties you may encounter in using your cellular phone, and, when possible, will show you what you can do about them.. Disconnects occur because of signal dropouts —either your phone loses the signal from the cell site or the cell loses the signal from your phone. That is, when you...
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This chapter concerns safety and security — safety in the sense of maintaining your usual standard of driving while using a cellular phone, how cellular improves safety, and in safeguarding your phone equipment. and security in the sense of guarding the privacy of your conversations.. Using a phone at the same time you’re trying to concentrate on the road and...
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INTO THE FUTURE. DIGITAL CELLULAR. There are two competing standards for digital cellular. 114 INTO THE FUTURE. 116 INTO THE FUTURE. 118 INTO THE FUTURE. a mix of mobile and fixed operation can be accommodated with no change to the design of the system.. 120 INTO THE FUTURE