10BROAD36 is an obsoletecomputer network standard in theEthernet family. It was developed during the 1980s and specified inIEEE 802.3b-1985. TheInstitute of Electrical and Electronics Engineers standards committeeIEEE 802 published the standard that was ratified in 1985 as an additional section 11 to the base Ethernet standard.[1] It was also issued asISO/IEC 8802-3 in 1989.[2]
The standard supports10 Mbit/s Ethernet signals over standard 75 ohmcable television (CATV) cable over a 3600-meter range. 10BROAD36modulates its data onto a higherfrequencycarrier signal, much as anaudio signal would modulate a carrier signal to be transmitted in aradio station. Intelecommunications engineering, this is abroadband signaling technique.[a] Broadband provides several advantages over thebaseband signal used, for instance in10BASE5. Range is greatly extended (3,600 m (11,800 ft), versus 500 m (1,600 ft) for 10BASE5), and multiple signals can be carried on the same cable. 10BROAD36 can even share a cable with standard television channels.
10BROAD36 was less successful than its contemporaries because of the high equipment complexity (and cost) associated with it. The individual stations are much more expensive due to the extraradio frequency circuitry involved; however the primary extra complexity comes from the fact that 10BROAD36 is unidirectional. Signals can only travel one direction along the line, so head-end stations must be present on the line to repeat the signals (ensuring that no packets travel through the line indefinitely) on either another, backwards direction frequency on the same line, or another line entirely. This also increases latency and prevents bidirectional signal flow.
The extra complexity outweighed the advantage of reusability of CATV technology for the intendedcampus networks andmetropolitan area networks. An installer atBoston University using theUngermann-Bass product noted that no installers understood both the digital and analog aspects of the system.[3]Inwide area networks it was quickly replaced byfiber-optic communication alternatives, such as100BASE-FX (which provided ten times the data rate). Interest incable modems was revived for residentialInternet access, through later technologies such asData Over Cable Service Interface Specification (DOCSIS) introduced in the 1990s and is still widely used today.
Broadband networks employ frequency-division multiplexing to divide coaxial cable into separate channels, each of which serves as an individual local network.
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