I&C SCI 11 Lecture Notes - Lecture 1: Strowger Switch, Patch Cable, Telephone Call
Document Summary
Alexander graham bell device that could transmit voice signals (telephone: modern telephone network provide telephone service. Two-way, real-time transmission of voice signals across network. Telegraph vs. telephone: telegraph required expert operator. Knowledge of morse code: telephone terminal simple. No expertise required: telephone more targeted. Analog transmission system: connectivity to original telephone system, task was to deliver a signal replica of original voice sound. Cost: n(n-1)/2 transmission lines required if lines are deployed between everyone n users. Ex: 1000 people = 495,000 lines: telephones switches interconnect telephone users on demand. Telephone switch: consists of patch cord panel and human operator, telephone call has three phases. User picks up phone and activates signal that connects it to telephone office. Check to see if available, and then operator connects the two lines. Then various lines involved are made available for other. Strowger switch connections: automated electromechanical switches, organized switching offices. In turn connected to tandem offices and so forth: telephone numbering system.