CIRCUIT FOR COIN TELEPHONE SET IN MOBILE RADIO TELEPHONE SYSTEM

• US 3,576,402 A
• Filed: 03/13/1968
• Issued: 04/27/1971
• Est. Priority Date: 03/13/1968
• Status: Expired due to Term

• Current Assignee: Edington, John E., Gerald P. Baker, Ralston H. Robertson Jr
• Original Assignee: Edington, John E., Gerald P. Baker, Ralston H. Robertson Jr
• Inventors: Baker, Gerald P., Edington, John E., Robertson, Ralston H. Jr.
• Application Number:
  US04/712,701
• Time in Patent Office: 1,140 Days
• US Class Current: 455/550.1
• CPC Class Codes: H04M 17/023 Circuit arrangements
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

In a coin telephone set adapted for use in a mobile radio telephone system that provides phone service on trains, for example, signaling reliability is enhanced by the employment of means including a timing circuit for ensuring the transmission of multifrequency dial signals of limited duration irrespective of the duration of the manual actuation of the dial.

Claims

1. A mobile telephone set comprising, in combination, multifrequency dial signal generating means including pushbuttons, means for applying voice current from said set and signals from said dial to a radio transmitter, and means for limiting the duration of signals from said dial to a period equal to the duration of the operation of one of said pushbuttons or to a preselected duration, whichever is shorter, whereby spurious signaling resulting from gaps and fading in unduly long signals is avoided, said signal generating means including a multifrequency oscillator having frequency determining elements and an active element and said limiting means including a monostable multivibrator and a transistor switch connected in tandem between said frequency determining elements and said active element.