M carrier
M Carrier is a type of carrier equipment standardized by AT&T for transmission over power lines.
Appearing as early as 1925, carrier equipment for power lines was designed to communicate with technicians operating high voltage electrical equipment, which was often located hundreds of miles away from existing telephone infrastructure.[1] Instead of running new dedicated telephone wires to remote locations, carrier equipment could be used to transmit phone signals over high voltage wires built to handle anything from 120 volts to 220,000 volts. High voltage carrier equipment was installed by electricians and low voltage carrier equipment was installed by phone technicians.[2]
M1 Carrier
M1 carrier equipment was designed for use with rural 7,200 volt power lines and could be installed without disrupting power to the grid. By 1953 the Bell System had almost 10,000 M1 carrier stations in service.[3]
References
- ↑ Wolfe, W. (January 1925). "Carrier Telephony on High Voltage Power Lines". Bell System Technical Journal. 4 (1): 152–177. Retrieved 19 June 2025.
- ↑ Dunham, J. (January 1948). "Power Line Treatment for the M1 Carrier Telephone System" (PDF). Bell Labs Record. 26 (1): 2–5. Retrieved 19 June 2025.
- ↑ Geils, J. (January 1953). "Test Set for the Ml Carrier System" (PDF). Bell Labs Record. 31 (1): 10–13. Retrieved 19 June 2025.
See also
- Power-line communication (section: history)