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'Single-ended signalling' is the simplest method of transmitting electrical signals over wires. One wire carries a varying voltage that represents the signal, while the other wire is connected to a reference voltage, usually ground. The alternative to single-ended signalling is called ''differential signalling''. This technique is less expensive to implement, but its limitations are that the signal cannot be transmitted over long distances or quickly. SE is the SCSI standard, and viable cable lengths range from 1.5 meters to 3 meters.
The main advantage of single-ended over differential signalling is that fewer wires are needed to transmit multiple signals. If there are ''n'' signals, then there are ''n''+1 wires - one for each signal, plus one for ground. (Differential signalling uses at least 2''n'' wires.) The main disadvantage of single-ended signalling is that the return currents for all the signals share the same wire, and can sometimes cause interference ("crosstalk") between the signals. This limits the bandwidth of single-ended signalling systems.

Contents

Standards

Standards

Single-ended signalling is a widely used technique, and can be seen in a number of common transmission standards, including:

★ RS-232 serial communications

★ PS/2 mouse and keyboard connectors

★ I²C serial bus

★ TTL circuits

★ CMOS logic circuits

★ ECL circuits

★ Most parallel computer buses, such as:

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★ VMEbus

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★ PCI

★ VGA video connectors

★ SCSI hard disk interfaces

★ RCA jacks for audio signals