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Peer Review-Logical Solutions VIS-3

The Logical Solutions VIS-3 DVI Extender consists of a transmitter and receiver unit ? each of which contains a single ST-type fiber connector and a DVI-D female connector.

Product:Logical Solutions VIS-3 DVI extender

Price: $2,695 for the pair (transmitter and receiver)

Company website:www.thinklogical.com

Plus: Single-strand, multi-mode fiber solution; no need for external power at transmitter; default resolution if DDC information isn't present

Minus: External power required at receiving end; no HDCP support

Design

The Logical Solutions VIS-3 DVI Extender consists of a transmitter and receiver unit — each of which contains a single ST-type fiber connector and a DVI-D female connector. As such, DVI-I cables won't work with the VIS-3, which can only transmit digital signals. Each unit measures 4.5 by 5.5 by 1.25 inches and has two mounting brackets integrated into the unit's design.

Some DVI-over-fiber products take a multi-strand approach, using four individual strands of multimode fiber to send the red, green, blue, and DDC information. This approach is similar to the DVI-over-copper approach, which uses individual conductors or pairs in a Cat5/6 cable to transmit RGB and DDC (control) information. However, the Logical Solutions VIS-3 takes a different approach, transmitting all video and DDC information via a single strand of multi-mode fiber. To accomplish this, the VIS-3 uses multiple lasers at different wavelengths across one fiber: three high-speed lasers split red, green, and blue into separate bands of light while a fourth, lower-speed laser inserts DDC information.

The VIS-3's transmitter and receiver each comes with an external power supply. Unlike DVI-over-copper solutions, which use power insertion at the transmitter to power the receiver, the VIS-3 requires power at the receiver. This limits usefulness somewhat, especially for wall-mounted plasma/LCD or ceiling-mounted projector locations with limited additional power receptacles. However, the transmitter can be powered from the DVI port on most graphics cards and laptops, which provides additional flexibility if the VIS-3 is mounted at a conference table, lectern, or other location without power receptacles.

Performance

The simple connectivity of the VIS-3 allows for easy setup. My testing consisted of connecting the fiber optic cable's ST connectors from the transmitter to the receiver, then connecting the DVI output from the receiver to a monitor. After powering up the monitor, I applied power to the DVI receiver and transmitter before connecting a laptop's DVI-D output to the transmitter's DVI-D input.

The laptop I used immediately recognized the monitor across my 200-foot, multi-mode test cable, automatically using the DDC information to configure the monitor to the laptop's optimal resolution. My testing was with single-link DVI signals (up to 1920x1080 at 60 Hz or 1280x1024 at 85 Hz), and all tests performed flawlessly. To verify other resolutions, Logical Solutions provides an optical budget, which shows typical optimal and maximum distances a particular resolution can be driven on optical cable types (www.thinklogical.com/pdf/thinklogical_vis3_man_C.pdf).

The VIS-3's lack of High-Bandwidth Digital Content Protection (HDCP) transmission may also limit its utility in instances where the DVI output device attempts to send HDCP-protected content. Depending on the device/display combination, HDCP-protected content will either be displayed as snow or 480p resolutions. Logical Solutions noted this limitation during testing and has a subsequent product in the works that will address both dual-link and HDCP deficiencies — albeit with multiple fiber strands.

I was unable to test two features in my lab that bear mention: transmission up to 3,280 feet (1,000 meters) maximum distance and default resolution. The former is approximately twice the distance of other products on the market and will probably be extended in the near future due to the introduction of new lower-power, high-speed lasers. The latter default resolution is worth mentioning because the receiver will automatically set the monitor or other external display devices to an 800x600 resolution if DDC information doesn't reach the receiver unit.

My units passed DDC information and could change the resolution on the monitor without difficulty. But the decision to provide a lower-resolution display signal in the absence of DDC information is a smart move on Logical Solutions' part because many DVI-equipped displays won't display a DVI signal if DDC information is lacking. However, my recommendation would be to default to1024x768 because many DVI-equipped displays and computers use 1024x768 as their optimal resolution.

Value

The VIS-3's multiplexed transmission design allows its DVI signal (minus HDCP) to run on a single strand of multi-mode fiber. The single-strand approach is beneficial for use of DVI transmitters in existing locations with limited additional available strands.

Yet, the value proposition for other locations must be weighed on a case-by-case basis. Copper-based DVI transmission solutions can carry a full DVI signal (including HDCP) up to 150 feet at a much lower cost than a fiber solution. Beyond 150 feet, fiber is currently the only viable alternative. Other fiber-based DVI extenders that use multiple fiber strands have a lower transmitter/receiver base cost, but increase in aggregate cost when the price of multiple fiber strands are factored in. Taking these issues into account — along with current fiber optic cable market prices — the Logical Solutions' single-strand VIS-3 product appears to be a good value for transmissions beyond 800 feet where the VIS-3's higher transmitter/receiver base cost is offset by the savings derived from the cost of using a single fiber strand.

Tim Siglin is an industry analyst and cofounder of Transitions Inc., a business and technology development firm serving startups and Fortune 10 clients in the United States, Europe, and the Pacific Rim. He can be reached atmmayfield@hanleywood.com

 


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