USB Extension Options: Breaking the 16 foot barrier
Written by Preston Wily
For the past ten years USB and FireWire have struggled to dominate the desktop interface market. Until five years ago, because of the relatively fast 400 Mbps offered by FireWire, USB, jokingly referred to as Ultra Slow Bandwidth, was relegated to low-bandwidth applications such as keyboards and mice. At the end of 2001, however, USB dealt a fatal blow to FireWire with the release of the new USB 2.0 standard offering a maximum speed of 480 Mbps, faster than the theoretical limit of FireWire (though, in practice, usually slower).
It seems that USB has essentially won the standards battle with FireWire because of its relative low-cost and high availability. The limitation of USB (both the 1.1 and 2.0 standards popular today) is the 16 foot limit. When you have more than 16 feet between your computer and your USB device you will see significant degradation in the signal that can cause problems ranging from slower transmission speeds to an entirely dropped connection. This causes problems for people who want to run a USB cable to a printer located in another room, to a presentation keyboard/mouse combo or any other USB device that may be in a remote location.
The cheapest (and arguably easiest) way to extend the distance to your USB device is by using a USB Active Extension Cable. These cables have built-in USB repeaters that actually boost the USB signal, allowing you to go further than the 16 foot maximum distance. The most common length for these cables is 16 feet and you can chain up to four of these together with no loss in signal. Assuming you are using the longest USB device cable available (also 16 feet), USB Active Extension Cables allow for a maximum distance of 80 feet between your computer and USB device. They are available in USB 1.1 (12 Mbps) and USB 2.0 (480 Mbps).
For most USB extensions 80 feet is long enough, but what if you need to go further? Super USB Extenders allow you to extend the distance to your USB devices up to 150 feet with no loss in signal. The Super USB Extender uses similar technology for the male and female interfaces, but rather than have a regular USB cable in the middle, it uses a Cat 5 cable (also known as a networking cable). The advantage of Super USB Extenders, other than the increased maximum distance, is the ability to create a custom length. If you need to go 63 feet, for example, you can simply use a Super USB Extender with a 63 foot Cat 5 Cable between the booster and receiver. Super USB Extenders are also available in USB 1.1 and 2.0 interfaces.
If you are looking for a connection beyond 150 feet, many manufacturers offer a special Super USB Extender capable of USB transfer with no signal loss at 330 feet, though this is limited to USB 1.1. Black Box has created a USB 1.1 extender capable of transmission up to 1000 feet without signal loss, perfect for connecting your computer to a security camera or webcam hundreds of feet away from your computer.
Another exciting innovation for USB extension technology is the pending release of Wireless USB. Wireless USB hubs and devices are anticipated to show up in early 2006 with maximum distances over 100 feet. Keep in mind that this is the first release and as the technology matures this distance limitation will inevitably be lifted in favor of much further distances.
