Details:

Personal Author:
Means, James R., Jr. ; Bowser, George
Means, James R., Jr. ; Bowser, George Less -
Corporate Authors:
Pittsburgh Research Center (U.S.)
Conference Authors:
WVU Conference on Coal Mine Electrotechnology (6th : 1982 July 28-30 : Morgantown, West Virginia)
Description:
A new phone system was developed that provides eight full duplex communications channels over a single twisted shielded phone line, with no central switching station or line amplifiers. This system greatly simplifies installation and maintenance over that required with conventional switching systems. The system is based on microprocessor technology and digital frequency synthesis. Frequency division multiplexing is used over a bandwidth of approximately 300 kHz, and a baseband voice channel (compatible with conventional pager phones) is provided as a backup to assure communication if the multiplex features fail. Multiplex operations are controlled over a 30-kHz digital channel. The system is designed to operate with up to 16 km (10 miles) of cable plant and a maximum phone separation of 8 km (5 miles). The digital techniques permit a limited amount of monitoring and control capability to each phone. This consists of two pair of contact inputs or outputs, to be used as desired. These "flags" may be read or controlled by a dispatcher's phone.
Subject:
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Mining

Source:
Proceedings of the Sixth WVU Conference on Coal Mine Electrotechnology, Morgantown, West Virginia, July 28-30, 1982. Cooley WL, ed., Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, Contract J0123017, 1982 Nov; :116-123
Document Type:
Book Chapter
Funding:
U.S. Bureau of Mines contract J0123017
Genre:
Conference Publications
Collection(s):
National Institute for Occupational Safety and Health
Main Document Checksum:
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urn:sha256:6dd0e53bb09375a8c00e561cb893207952c086753a6974f9bab58bbef4be67e1
File Type:

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