mind that your conversations are not necessarily private. It is easier for unautho-rized people to eavesdrop on wireless communications than to intercept wire or ca-ble communications.Cell phones and computersA personal computer (PC) can be hooked up to the telephone lines for use with on-line networks such as the Internet. For some people, getting on the Internet is themost important justification for buying a computer.You can connect a laptop or notebook computer to a cell phone with a portable mo-dem that converts incoming computer data from analog to digital and also converts out-going data from digital to analog. This will let you get on-line from anywhere withinrange of a cellular base station. Figure 32-2 is a block diagram of this scheme.608 Wireless and personal communications systemsMost commercial aircraft have telephones at each row of seats, complete with jacksinto which you can plug a modem. If you plan to get on-line from an aircraft, you mustuse the phones provided by the airline, not your own cell phone, because radio trans-ceivers can cause interference to flight instruments. You must also observe the airline’srestrictions concerning the operation of electronic equipment while in flight. If youaren’t sure what these regulations are, ask one of the flight attendants.Satellite systemsA satellite system is, in a certain sense, a gigantic cellular network. The repeaters,rather than being in fixed locations, are constantly moving. The zones of coveragePeripheralsCell phonetransceiverRadio signalsPortablecomputerControl signalsAnalog dataDigital dataModem32-2A cell phone can be equipped with a modem, allowingportable or mobile access to on-line computer networks.