Pushbutton dial mobile radiotelephone an advanced concept in common carrier mobile service

Abstract

A real need has developed for common-carrier mobile radiotelephone service which can be connected directly into dial telephone exchanges. Many exchanges are now unattended and the mobile subscriber must be able to dial his calls and receive calls in the same manner as with his office or home dial telephone. The transmission of the dialing information from a moving vehicle into the exchange, with the accuracy required to meet telephone standards, has presented an interesting challenge in view of various radio propagation characteristics often experienced, particularly from weak signal or fringe areas. The pushbutton type of dialing described in this paper provides a digital signalling system employing tones of sufficient duration to ride over the numerous signal drop-outs sometimes lasting more than 100 milliseconds. Extensive field experience has proven this approach to be highly reliable and consistent in dialing from a mobile unit. A unique application of counter tubes and transistor switching circuits is employed in the conversion of the tones into dial pulses at the base station terminal. The use of pushbuttons has been found to be very convenient for mobile service. A number of the various features incorporated in mobile dial systems are described in this paper.