MOBILE TELEPHONES

[Music] mmm here comes a trailer truck out on the open highway miles from the nearest town let's say important for someone to get in touch with the drivers of this outfit how can it be done watch zl4 3592 this is joe hello joe this is bill where are you boys now on route 30 headed for centerville about 25 miles out that's fine we got a special can you pick up some stuff for the ajax company it's at the charleston depot think you can handle it sure can bill we've got enough room for it fine joe take care of it right bill see you later bye better make a right turn onto 117. the boss wants us to make a pickup at the charleston depot all right there you have it a practical example of modern communication [Music] here's a job of road construction on the outskirts of a big city the center of such activity is constantly shifting and is seldom near a regular telephone yet there is often need for one okay i'll call george this is wj 6 it's 9233 give me adams 2 6 6 3 5. lee construction company martin speaking hello george this is my say they're having plenty of trouble out here with the engine on the grader yeah what's the matter with it well nobody seems to know for sure johnny says he thinks it's a fuel pump might be at that tell you what i'll do i'll send stevens out to check it over before we have real trouble anything else oh that's all okay so long this is mobile telephone service in this service conversations travel part way by radio partway by telephone lines in order to reach vehicles traveling the highways between cities a number of transmitting and receiving stations connected to telephone lines are spaced at intervals along the highway so that one will always be in range of the moving vehicle the antennas are placed preferably on high ground because the high frequency waves are limited in distance to the line of sight to understand how mobile telephone service works let's go back and see how it was used to pick up that load at charleston bill knew that one of his trucks should be in the vicinity of centerville rolling along little more than half full if he could get in touch with the truck he would be okay this seemingly unusual assignment was simpler than you might think all bill had to do was to call the truck on the mobile telephone service with which all his transports were equipped using his regular business telephone he dialed long distance long distance this is adam's 26635 i want to get in touch with a mobile unit will you try to reach zl4 3592 at centerville thank you the call from bill's office to the telephone building then went out over regular telephone lines passed several towns to the telephone building in centerville the mobile service operator at that point handled the call so that it went out on the air from an antenna located near centerville the truck was in the vicinity and responded with its own transmitting equipment in the radio part of calls between vehicles and mobile service stations frequency modulation fm is utilized to ensure high quality transmission except for the radio part of the conversation the calls travel back and forth over telephone lines another type of mobile telephone service was used when our friend mac called from his mobile telephone this service is designed to provide a means of communication for those who travel in city areas as well as those who travel along inter-city highways any place having regular telephone service or any vehicle having mobile equipment can originate or receive a call in the case of a call from a vehicle it is transmitted from the car to the nearest of the several station receiving antennas these are connected by telephone lines to the base station by having several receiving antennas it is ensured that the reception from mobile units having relatively low powered transmitters and antennas close to the ground will not be blocked by high buildings after the call reaches the receiving station antenna it is handled like a regular telephone call the return message that is the base station end of the call goes out over a telephone line to a transmitter which is powerful enough to cover the entire city from a single high centrally located antenna when mobile telephone equipment is used the push to talk button on the handset is pushed down when a person talks and released when he listens thus the mobile telephone equipment in the car transmits when the handset button is down and receives when the button is up now let's see the equipment that makes mobile telephone service work here in an automobile a transmitter unit and a receiver unit are being compactly and neatly installed sometimes a larger battery and generator are needed for additional power the flexible antenna is mounted on top of the vehicle or in the case of trucks on the side toward the rear the control unit is simple to operate a signal lamp on the right of the unit will remain lighted when the apparatus is switched on and ready for service the operator calls by ringing a bell at the same time a signal lamp on the left of the unit lights up removal of the receiver switches off the call light and the bell let's watch this action again should the subscriber be away from his car at the time the call comes in the lamp will remain lighted until the subscriber returns and calls the mobile service operator companion to the mobile equipment of course is the necessary base station equipment mobile calls are received on antennas like this then they are carried to the receiver from the receiver they go by telephone wires to the control terminal then to the central office switchboard and thereafter being handled as ordinary calls the return part of the call goes back to the central office then back through the control terminal where it is automatically switched to the transmitter then it goes out through the transmitting antenna and the call is on the air again throughout the country mobile telephone stations are being expanded to become links in a nationwide network the mobile telephone greatly expands the scope of voice communication it provides added telephone service in our principal cities allows for more efficient operation at railway terminals furnishes easy contact between land and vessels on our waterways and at the same time adds to the convenience of travel it provides an easy way of keeping in touch with vehicles on the major highways it is one more step toward telephone service for anyone anytime anywhere you