LVD

Abbreviation for Low Voltage Differential, a technology used in some modern SCSI equipment. Traditionally SCSI had been a “single-ended” technology, which basically meant that data was transferred by sending a series of digital ones and zeros down parallel wires. The voltage spikes and valleys at the other end were interpreted as “1s” and “0s”, respectively. As speeds and distances increased, the tolerances for signal noise and other anomalies decreased, and so did reliability. LVD signaling was developed to address the need for greater speed and SCSI cable lengths. It involves generating two inverse voltage signals simultaneously, and measuring the “differential” or difference between the primary and inverse voltages at the other end of the wires. The advantage of this approach is that the differential signals are much easier to discern and less susceptible to degradation over distance. The concept is analogous to balanced wiring in audio setups, and gives the same type of advantages.