Difference between 1000BASE-SX and 1000BASE-LX

Definition

1000BASE-SX is a fiber optic Gigabit Ethernet standard for operation over multi-mode fiber using a 770 to 860 nanometer, near infrared (NIR) light wavelength.

1000BASE-LX is a fiber optic gigabit Ethernet standard specified in IEEE 802.3 Clause 38 which uses a long wavelength laser (1,270–1,355 nm), and a maximum RMS spectral width of 4 nm. 1000BASE-LX is specified to work over a distance of up to 5 km over 10 µm single-mode fiber.

Application

1000BASE-SX

The standard specifies a distance capability between 220 metres (62.5/125 µm fiber with low modal bandwidth) and 550 metres (50/125 µm fiber with high modal bandwidth). In practice, with good quality fiber, optics, and terminations, 1000BASE-SX will usually work over significantly longer distances.

1000BASE-LX

1000BASE-LX is specified to work over a distance of up to 2 km over 9 µm single-mode fiber. In practice it will often operate correctly over a much greater distance. Many manufacturers will guarantee operation up to 10 or 20 km, provided that their equipment is used at both ends of the link. 1000BASE-LX can also run over multi-mode fiber with a maximum segment length of 550 m. For any link distance greater than 300 m, the use of a special launch conditioning patchcord may be required. This launches the laser at a precise offset from the center of the fiber which causes it to spread across the diameter of the fiber core, reducing the effect known as differential mode delay which occurs when the laser couples onto only a small number of available modes in multi-mode fiber.

1000BASE-ZX

1000BASE-ZX is an Ethernet transmission system which uses 1,550 nm wavelength to achieve distances of at least 70 kilometres (43 miles) over single-mode fiber. The distances up to 120 kilometres (75 miles) over single-mode fiber, sometimes called 1000BASE-EZX. Ranges beyond 80 km are highly dependent upon the path loss of the fiber in use, specifically the attenuation figure in dB per km, the number and quality of connectors/patch panels and splices located between transceivers.

1000BASE-TX

The device is simpler to implement and is called it 1000BASE-TX .The simplified design would have, in theory, reduced the cost of the required electronics by only using two unidirectional pairs in each direction instead of four bidirectional pairs. These have wide range of applications in the high speed data transfer applications. However, this solution has been a commercial failure due to the mandatory Category 6 cabling that is involved in the manufacturing and usage of the product and the rapidly falling cost of 1000BASE-T products.

Bottom line

Gigabit Ethernet standards are defined in the 802.3z standards of Project 802 developed by the IEEE. 1000BASE-LX technologies are in the beginning stages of being widely implemented in enterprise-level networks and are primarily used for long cable runs between pieces of equipment on a campus or within a building. When you use multimode fiber-optic cabling in 1000BASE-LX implementations, a condition called differential mode delay (DMD) can sometimes occur.

What is the difference between AT and ATX power supplies?

AT power scheme is the original power scheme that most of the older computers used. AT-style computer cases had a power button that is directly connected to the system computer power supply. Pushing the power button kills all the power instantly (whether the Operating System is ready for it or not!)

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An ATX power supply is typically controlled by an electronic switch. Instead of a hard switch at the main power input, the power button on an ATX system is a sensor input monitored by the computer. ATX systems allow the Operating System to control the final “off” signal to the power supply; this gives the OS time to save all information and complete important tasks before turning off the power supply using a dedicated output signal (PS_ON#). ATX power supplies also support lower power modes. They have an additional “Standby” power output (5VSB) that stays on to power standby devices whenever the system goes into low-power mode.

 

The ATX specification is the newer and more power efficient design. It is superior to the AT power supply scheme, and is used on almost all modern desktop and laptop computers. ADL Embedded Solutions offers PC/104 power supplies that support the ATX power scheme with 5V, 12V and 5VSB outputs only. Although the full ATX specification has additional voltages (12V, -5V and 3.3V), these extra power inputs are intended for Desktop systems; most embedded systems have no use for these extra voltage inputs and so they are omitted to save power and space.

 For power rating of each connection, please see below.

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