10BROAD36
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10Broad36 is an obsolete standard for carrying 10 Mbit/s Ethernet signals over standard 75 ohm CATV cable over a 3600 meter range. Unlike most Ethernet standards, like 10BASE-T, which use a baseband type encoding, where the signal is simply encoded directly on the wire without any sort of carrier wave, 10Broad36 modulated its data onto an RF baseband, much as an audio signal would be encoded onto a carrier wave to be transmitted in a radio station. This provides several advantages over the more traditional baseband signal. Range is greatly extended, (3600 meters, versus 100 meters for 10BASE-T) and multiple signals can be carried on the same line. 10Broad36 could even share a wire with standard CATV signals.
10Broad36 was less successful than its contemporaries because of the high-equipment complexity (and cost) associated with it. The individual stations were much more expensive due to the extra RF circuitry involved, however the primary extra complexity came from the fact that 10Broad36 was unidirectional. Signals could 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 wire for long-haul Ethernet, and as such was quickly replaced by fiber alternatives, such as 10BASE-FX.
External links
- Details of various ethernet standards (http://www.techfest.com/networking/lan/ethernet4.htm)