Article
Digital signage connectivity
Cables, Wi-Fi and cellular offer unique ways of linking screens.
July 13, 2008
Rolling out a new digital signage network or system can be similar to playing a high-tech, high-stakes game of connect the dots. With content ready and a good idea of what displays to use, the primary question then becomes: How do you connect them?
With a wide variety of possibilities encompassing a range of cabled, wireless or cellular options for transmitting video from player to display, the answer may well be that it largely depends on what the deployer is looking for in their digital signage network.
Common connectivity solutions |
Wireless (Wi-Fi) Content is sent to the site and then sent to screens through transmitters similar to routers. Cable Hard-wired networks can vary in content quality based on the type of cable being used. Cellular Content is sent to screens remotely through existing cell phone networks. |
"You're going to want to use whatever is applicable to your display, whatever connection you have on your display and also to whatever your source is as well," said Dave Gebhart, a technical sales representative with Cables to Go, a Dayton, Ohio-based company offering a variety of solutions within the cabled set.
"In the simplest sense, you basically have to have some sort of content that's created on some sort of player that's ready to output," said Matt Nelson, director of marketing at Avocent, a provider of wireless digital signage products. "That's the first step, and then beyond that you need to figure out how many displays you want to have, whether it is a one-to-one or a one-to-many."
Going wireless
For transmitting content over wireless connections, Avocent's concentration increasingly involves having a set of centralized players shooting out signals to dispersed transmitters at the location of the screens, which then relay the content to receivers on the screens themselves, which makes handling content easier, Nelson said.
The two major advantages to Avocent's wireless system that resellers or signage installers would likely be interested in are its speed of deployment and ease of manageability, Nelson said.
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With what he called "a land rush" ongoing in trying to quickly deploy digital signage networks everywhere from malls to groceries to airports to doctors' offices, speed of deployment can be a critical concern.
"With a wireless system you can deploy a wireless digital signage system with multiple displays in a matter of hours, versus days or weeks if you were to wire it," he said. "You basically can pre-stage a media player and all your displays with a wireless system in your office and then walk out and plop into a person's store."
That means minimal disruption to the business where the signage is going in, he said, and it also means that operators can set up multiple networks per week as opposed to maybe one a week.
"When you're trying to roll out 1,500 displays across 30 metropolitan areas, wireless is really the way to go," Nelson said.
Avocent's wireless systems also increase the manageability of the system, not just of the transmitters and receivers but also the devices attached, he said. Avocent's transmitters and receivers are IP addressable, meaning there's a Web page operators can get onto to get into the system and work on it, from changing the radio frequency it's running on to rebooting a single display, from just about anywhere.
"I can even change brightness and contrast on an individual display from sitting at my desk," Nelson said.
The benefit to that is preventing truck rolls for service calls, "which saves a huge amount of cost," he said. "If someone calls up with a problem with the display on a pump at a filling station, and you can pull up the status and reset the display, nine times out of 10 that can prevent having to make a service call. Enterprise management is built into the system."
Wireless systems will work with VGA, DVI, or HDMI, Nelson said, because it automatically detects what is going into the transmitter and auto detects the receivers, supporting up to eight receivers per transmitter with little or no configuration. Multiple transmitters and receivers do call for more configuration work.
Differentiating between cable types
For cable applications, there are again a number of possible routes for signage operators, including HDMI (High-Definition Multimedia Interface), component, and composite video cables, Gebhart said.
HDMI cable carries audio and video, with purely digital picture and 1080p and 1080i resolution, he said.
While it runs an analog signal, component video cable is also capable of hi-def quality picture, according to Gebhart. Component video cable carries video consisting of three signals, one controlling luminance, or brightness; and two color difference signals that dictate the amount of color relative to luminance.
Composite video cable, Gebhart said, is basically the same kind of cable you'd find on the back of your DVD player or VCR, hooking it into your television. Composite video cable carries a composite video signal that is those three signals compressed into one signal. The composite signal then needs to be decompressed and restored to three-signal format inside the receiver, resulting in lost picture information and therefore reduced picture crispness and color richness.
"Figure out what it is that you want to show; figure out how many displays you want to connect to," Gebhart said. "Then determine your source and select the appropriate cables for the application."
Digital signage on cell phone networks Keith Kelsen, CEO of Silicon Valley-based The MediaTile Company, says you have to look at the total cost of ownership involved in operating a digital signage network, even when thinking about connectivity. To him, that means picking cellular, using a pre-existing network maintained by someone else, and not bothering your IT department too much.
"Our position is: why burden the IT department when you already have a network available. On our networks worldwide we have probably 45,000 people working on our network every day," he said.
That's because those networks are already extant cellular networks run by companies like Verizon, Vodaphone, AT&T and Sprint, he said.
"Basically when you look at cellular digital signage, and you look at connectivity, you already have an existing network that is very robust and very reliable, and it already exists - everywhere," he said.
It is a little more complicated than that, since MediaTile equipment does other things to make certain the connection is made, like amplification of signal, but it really is just about as simple as plug it in and play, Kelsen said.
There is also a safety factor to consider, he said, since using cellular digital signage means operating on a completely different network than the one that may carry mission critical data, thus not compromising the transfer of either information.
The benefits of cellular digital signage can be seen in lowered costs of the overall cost of the network, Kelsen said. There's no infrastructure work or maintenance costs involved; there's little to no need to learn a new technology, because that's been made a non-factor before you start, he says; and it lets business operators get back to the business of business.
"If I'm a retailer I'm really in the business of selling things. I don't want to get all tied up in the technology side of it. What happens is it basically becomes a big burden," Kelsen said.
And the most obvious way they do that, he says, is by making its plug-and-play system truly plug-and-play.
"With cellular digital signage it's as easy as plugging into the wall. I literally plug it in and it's ready to go," Kelsen said.
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