Black Box ACS251A - Manual (Page 12)

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CHAPTER 2: Introduction
2. Introduction
2.1 Overview
There are many KVM extenders available, but until now many of them have used
analog image transmission, which inherently degrades image quality (especially
over long distances and at high video resolutions).
The ServSwitch™ Brand Fiber KVM Extender II and II-SM is a digital image-
transmission system. Video output from a local computer CPU is automatically
digitized by the Extender’s Local Unit and transmitted serially to the Remote Unit
on a single fiber at data rates up to 1.5 Gbps. The Remote Unit converts the digital
signal back into the original analog signal. Up to the maximum specified cable
lengths, image quality is independent of cable length.
The Extender uses its second fiber to send remote mouse and keyboard
information back to the local CPU. The Extender needs only these two fibers for
full operation. Compared with some analog KVM extenders that require as many
as five fibers, the Fiber KVM Extender II and II-SM can save you significant
amounts of money, especially if you’ll need to run fiber cable across long distances.
There are two models of the Extender:
• The Fiber KVM Extender II (ACS250A) is the multimode model. It transmits
digital video up to 220 m (720 ft.) across 62.5/125-µm multimode fiber or up
to 400 m (1310 ft.) across multimode fiber.
• The Fiber KVM Extender II-SM (ACS251A) is the single-mode model. It
transmits digital video up to 10 km (6.2 mi.) across 9/125-µm single-mode fiber.
In addition to the keyboard, video, and mouse information, the Local Unit can
also digitize optional sound information from a local CPU or other audio device
and encode it into the digital information sent to the Remote Unit on the video
fiber. The sound quality won’t approach high fidelity (it will be converted to
monaural if it’s stereo), but will be roughly equivalent to that of sound transmitted
over the telephone, which is sufficient for error messages and so forth.
You can also connect an optional local user station (keyboard, monitor, and
mouse only) to the Local Unit. The Local Unit will pass video through to the local
monitor and will switch the keyboard and mouse. (This means that the local user
contends with the remote user for keyboard and mouse control of the CPU: Once
the active user station is idle for 2 seconds, the first user to type at the keyboard or
move the mouse will be granted control.)