Speed
Currently, there are 3 speed modes defined by the latest USB 3.0 specification. They are Super-Speed, Hi-Speed and Full-Speed. The new
SuperSpeed mode has a transfer rate of 4.8Gbps. While the specification retains Hi-Speed, and Full-Speed USB mode, commonly known
as USB 2.0 and 1.1 respectively, the slower modes still operate at 480Mbps and 12Mbps respectively and are kept to maintain backward
compatibility.
USB 3.0 achieves the much higher performance by the technical changes below:
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An additional physical bus that is added in parallel with the existing USB 2.0 bus (refer to the picture below).
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USB 2.0 previously had four wires (power, ground, and a pair for differential data); USB 3.0 adds four more for two pairs of differential
signals (receive and transmit) for a combined total of eight connections in the connectors and cabling.
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USB 3.0 utilizes the bidirectional data interface, rather than USB 2.0's half-duplex arrangement. This gives a 10-fold increase in
theoretical bandwidth.
With today's ever increasing demands placed on data transfers with high-definition video content, terabyte storage devices, high
megapixel count digital cameras etc., USB 2.0 may not be fast enough. Furthermore, no USB 2.0 connection could ever come close to the
480Mbps theoretical maximum throughput, making data transfer at around 320Mbps (40MB/s) — the actual real-world maximum.
Similarly, USB 3.0 connections will never achieve 4.8Gbps. We will likely see a real-world maximum rate of 400MB/s with overheads. At
this speed, USB 3.0 is a 10x improvement over USB 2.0.
Applications
USB 3.0 opens up the laneways and provides more headroom for devices to deliver a better overall experience. Where USB video was
barely tolerable previously (both from a maximum resolution, latency, and video compression perspective), it's easy to imagine that with
5-10 times the bandwidth available, USB video solutions should work that much better. Single-link DVI requires almost 2Gbps throughput.
Where 480Mbps was limiting, 5Gbps is more than promising. With its promised 4.8Gbps speed, the standard will find its way into some
products that previously weren't USB territory, like external RAID storage systems.
Listed below are some of the available SuperSpeed USB 3.0 products:
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External Desktop USB 3.0 Hard Drives
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Portable USB 3.0 Hard Drives
Technology and components
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