Installing Commercial Multiroom A/V Distribution without a Switcher?

California startup claims a breakthrough A/V signal distribution on large commercial systems that eliminates central switchers in favor of daisy-chain topology with inline transmitters and receivers.

Installing Commercial Multiroom A/V Distribution without a Switcher?
The smaller boxes on top are the simplified Tx and Rx without scaler; the bigger ones on the bottom are the Tx and Rx with built in scalers. The highly visible yellow RJ45 connectors are for daisy chain input and output.
Jason Knott · February 14, 2013

“Just the fact that central switching has been used for almost a century does not mean it’s the ‘right’ way or at the least the only way or the best way to form A/V systems,” says Xiaozheng Lu, CEO of Luxi Electronics Corp.

The California-based startup company claims it has invented a distributed A/V system, the Presenter, that reduces labor, allows for system expansion, cuts the amount of wire necessary, and eliminates problems with signal degradation due to long cable runs. The design is aimed at large, multi-source installations, such as a sports bar with several satellite dishes and cable TV feeds.

In a nutshell, centralized switching-based systems use a star topology/home-run wiring where every wire is run back to a central switcher. In the Presenter system, the integrator instead uses a daisy-chain topology for up to six sources with in-line transmitters (Tx) and receivers (Rx) in Cat 6 cable.

“For almost a century, the only way we knew for signal switching and distribution is to send all source signals to a central switching device (a big box), then distribute the signals from that central box to all the displays,” say Lu. “These kinds of systems work well, especially for the small system with few I/Os. Without the alternatives, we have accepted this as the de facto standard.”

Lu adds, “The system switching is achieved by controlling which Tx inserts its local signal to the chain. The system distribution is achieved by controlling which Rx extracts signal from the chain to the local display. By using multiple pieces of the same Tx and the same Rx, we can form systems of any size without any central box.

“Imagine this daisy chain system as a river flowing through all the Tx and Rx devices; each Tx is a port to load signal to a boat: each Rx is a port to unload the signal from a boat. Multiple signals are allowed to flow through the daisy chain (river) to achieve true matrix switching.”

Lu has generated a long White Paper outlining his patent-pending product line. In the White Paper, he tackles video distribution from both an A/V and an IT perspective.  Each Tx has a built-in scaler to convert VGA/audio, component video/audio, HDMI and DisplayPort signals at any resolution and refresh rate to a common digital format chosen by Luxi for flowing through the daisy chain. Each RX also has a built-in scaler to convert the digital signal back for the local display.

Why Now?
Why is this type of A/V distribution topology only being “discovered” now? According to Lu, it’s because digital technology now makes daisy chain topology possible without signal degradation.

“In an analog daisy chain system, the signal quality degradation through each box accumulates. So after three or four boxes, the signal quality is no longer usable,” he says. But with Luxi’s technology, each Presenter box re-encodes the signal to eliminate jitter or error.
It’s not a perfect solution, admits Lu, noting there is a bandwidth limitation that allows the topology to only send six different signals over a single Cat 6 cable. (This is not an issue for a single feed system where the system is simply functioning as a balun, switcher, scaler or splitter, but it is a problem in matrix systems that have more than six sources.) Lu says the company is working on a fiber solution or the addition of a Node.

For smaller systems that most integrators are designing and installing in modest homes, Luxi’s new system is not application. A traditional centralized distribution system would cost much less. But for long-run systems and those with mixed signal formats, Lu says his system is better from a cost standpoint. Also, this type of signal distribution is not applicable for systems where all the sources are in a single rack.

  About the Author

Jason has covered low-voltage electronics as an editor since 1990. He joined EH Publishing in 2000, and before that served as publisher and editor of Security Sales, a leading magazine for the security industry. He served as chairman of the Security Industry Association’s Education Committee from 2000-2004 and sat on the board of that association from 1998-2002. He is also a former board member of the Alarm Industry Research and Educational Foundation. He is currently a member of the CEDIA Education Action Team for Electronic Systems Business. Jason graduated from the University of Southern California. Have a suggestion or a topic you want to read more about? Email Jason at [email protected]

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