Fiber optic communication and Ethernet cables have significant differences in the way they transmit data and their application scenarios, which leads to differences in the number of cores between them. This article will compare the transmission of optical fiber and network cable.
一, Fiber optic communication transmission
1. Single mode fiber and multimode fiber
Single mode fiber: only transmits optical signals of one mode, suitable for long-distance transmission. Single mode optical fibers typically use two cores, one for transmitting signals and the other for receiving signals.
Multimode fiber: capable of transmitting optical signals in multiple modes, suitable for short distance transmission. In general, multimode optical fibers also use two cores, one for transmitting signals and the other for receiving signals.
2. Full duplex communication
Full duplex: Fiber optic communication typically uses full duplex mode, which means simultaneous transmission and reception. Each direction requires an independent fiber core to transmit signals, therefore two fiber cores are needed.
Half duplex: Although there are also half duplex modes, in most applications, full duplex mode is more common because of its higher transmission efficiency.
3. Signal transmission method
Optical signal: Fiber optics achieve data communication by transmitting optical signals. The propagation loss of optical signals in optical fibers is very small, so even long-distance transmission can maintain high signal quality.
Bidirectional transmission: Due to the nature of optical signals, one fiber core can be dedicated to transmitting signals, while the other fiber core can be dedicated to receiving signals, thus avoiding interference between signals.
二, Ethernet transmission
1. Ethernet standard
10BASE-T: Early 10 Mbps Ethernet used two pairs of wires (4-core), one for sending and one for receiving.
100BASE-TX: 100 Mbps Ethernet uses two pairs of wires (4-core), one for sending and one for receiving.
1000BASE-T: 1000 Mbps (1 Gbps) Ethernet uses four pairs of wires (8 cores), each pair of wires is used for both transmission and reception, and adopts full duplex mode.
2. Full duplex and half duplex
Full Duplex: 1000BASE-T Ethernet adopts full duplex mode, with each pair of wires used for both transmission and reception simultaneously. This mode requires more complex signal processing techniques such as echo cancellation and signal separation.
Half duplex: Early Ethernet standards such as 10BASE-T and 100BASE-TX could adopt half duplex mode, but in 1000BASE-T, full duplex mode is standard configuration.
3. Signal transmission method
Electrical signal: Ethernet cables achieve data communication by transmitting electrical signals. The propagation loss of electrical signals in copper wires is relatively high, especially during high-speed transmission, requiring more wire pairs to ensure signal quality and transmission efficiency.
Multi pair cables: Using multiple pairs of cables can improve the transmission rate and reliability of signals. For example, 1000BASE-T uses four pairs of wires (8 cores), each pair of wires is used for both transmission and reception, and can achieve a transmission rate of 1 Gbps.
