Có một bí ẩn nào đó xung quanh chuyển vùng, và rất nhiều câu hỏi phát sinh trên những gì chuyển vùng và làm thế nào nó hoạt động. Chương này được thiết kế để trả lời những câu hỏi. LÀM THẾ NÀO ĐỂ GIỚI THIỆU khi bạn đang di chuyển trong | The Cellular Connection A Guide to Cellular Telephones Fourth Edition. Robert A. Steuernagel Copyright 2000 John Wiley Sons Inc. ISBNs 0-471-31652-0 Paper 0-471-20340-8 Electronic 8 MOBILE AND TRANSPORTABLE PHONES 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. CAR CELLULAR TELEPHONE COMPONENTS A typical cellular phone installation for an automobile consists of four basic components the power source the control head the transceiver logic unit and the antenna see Figure . Most problems with installed car phones are a result of poor or improper installation resulting from the need to connect several components on many different vehicle models. These components are incorporated into a single unit in the transportable and portable cellphone but should be considered logical parts of any cellular phone. Many vehicle-installed phones have some of these components incorporated into a single multi-functional component. Power Source In most cellular phone installations the phone receives its power from an automobile battery. If it is part of a permanent installation the 75 76 MOBILE AND TRANSPORTABLE PHONES Figure A TYPICAL INSTALLATION A typical cellular phone installation consists of four basic components 1 power source 2 control head 3 transceiver logic unit and 4 antenna. phone may be permanently connected or hardwired to the vehicle s electrical system. In a portable system or one that is intended to be removed periodically for security reasons or for use away from the car a quick-disconnect plug or an adapter that lets the phone take its power from the car s cigarette lighter may be used. Control Head The part of a mobile cellular phone called the control head consists of the receiver and cradle with .
