Telecommunications Fundamentals: Network Infrastructure & Transmission
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Early Telephone Technology & Specifications
Alexander Graham Bell invented the telephone in 1876. Early telephony involved transistor technology. Key specifications included a central voltage of -48V, impedance ranging from 400-1750 ohms, and a 440 Hz tone. The busy tone marking was typically 350-current, with frequencies between 480-620 Hz. DTMF (Dual-Tone Multi-Frequency) technology became standard. Common cable specifications included a diameter of 0.4 mm, an impedance of 280 ohms/km, and a transmitting frequency range of 300-3400 Hz.
Subscriber & Urban Cabling
The cable inside the rosette connects old and new subscriber equipment to the Network Termination Point (NTP/PTR). Urban distribution cables, such as those used by Laredo for... Continue reading "Telecommunications Fundamentals: Network Infrastructure & Transmission" »