Digital signage distribution technology: What lies beneath

When considering a digital signage project, users usually focus on display types and content management software. For the integrator, however, there is an important component that the user rarely considers-the distribution technology and platform. This infrastructure transmits the digital video and audio from the server to the appropriate displays, and is a key contributor to actual digital signage performance. In addition, as the connecting component for all displays, the distribution technology can be a significant part of the project budget. That's why choosing the correct distribution technology is vital in ensuring a successful digital signage installation.

Options for digital signage distribution

There are three main options for digital signage distribution - data network, fiber-optic cable, and CAT5 cable. In this article, these options will be presented together with the core considerations in choosing a distribution technology which is essentially cost, performance, and existing infrastructure.

Digital signage distribution options: Platforms and combinations

Each platform has its own benefits and drawbacks. When harnessing more than one platform there are a number of interesting combinations as discussed below.

Data Network Platform: A data network platform uses a computer network infrastructure in order to transmit content in the form of compressed multimedia files (such as MPEG files) from the management station to the central server and from there to the computer connected to the display device. The central server handles distribution to multiple displays, and the display-end computer decompresses the file for display on the display device. This solution requires a dedicated CPU in every single display device deployed.

Benefits and drawbacks

The advisability of data networks depends largely on existing infrastructure. If there is an existing computer network infrastructure in place, using a data network platform for digital signage can save costs significantly. However, if no computer network already exists, the need to implement such an infrastructure will increase costs considerably. This solution is also slower as a network infrastructure cannot deliver content in real time.

An additional cost, related to data networks, is caused by the need for display devices to be connected to local computers or a equipped with embedded CPUs, resulting in extra investment in hardware, an important factor for the project cost as a whole. Since the CPUs are located in remote locations, this complicates maintenance and servicing of each screen. The multiple CPUs require more memory, increasing pressure on the network, and increasing the buffers further slowing down and complicating the solution.

In addition, a data network platform limits the user to the compression technologies available on the market today. Technologies that significantly downgrade the quality of the multimedia content and the displays' dependence on the network, is another major consideration for 24—7 locales that cannot tolerate display downtime.

Fiber optic extenders

Fiber optic cable is a transmission medium favored for applications that need high bandwidth, long distances, and complete immunity to electrical interference. That makes it ideal for digital signages, which require high resolution and transmission over long distances. Unlike network platforms, fiber optic cable does not require CPUs or special software at the display end. All that is required is a transmitter and receiving unit for each display.

There are mainly two options for fiber-optic cable - single mode or multi-mode. Single-mode fiber provides a higher transmission rate and up to fifty times more distance than multi-mode, but it also costs more. In general, the decision between different types of fiber should be the result of a simple cost-benefit evaluation: the distance and level of resolution or performance required versus the acceptable investment in distribution technology.

Benefits and drawbacks

Fiber optic cable is optimal for transmitting high-resolution multimedia over long distances, a feature which makes it particularly appropriate for digital signage. Fiber optic cable provides network-independent performance without downtime or transmission lags. It can transfer media over 40 kilometers or more. In addition, it requires no special infrastructure, software, or display-side CPUs.

However, fiber optic is mainly point-to-point technology, in other words, a pure fiber optic cable solution will not allow multiple displays to receive output from a single video source. This can prove to be a significant obstacle for multiple-display digital signage installations such as malls and airports.

In addition, fiber optic cable has a high price compared to other technologies. Fiber optic cable's expense can prove prohibitive when planning a large digital signage project. A possible solution, discussed below, is the combination of fiber optic cable with other, less expensive solutions, allowing the user to benefit from fiber optic cable's advantages while reducing the total cost of the project.

CAT5 distribution systems

CAT5 cable is also a transmission medium favored for local installations that need high bandwidth and high resolution without any existing network infrastructure. CAT5 cable technology provides these advantages at a considerably lower cost than fiber optic cable. CAT5 technology supports real-time multimedia transfer through inexpensive, low density, and twisted pair cabling.

Benefits and drawbacks

In certain ways, CAT5 technology as a distribution platform combines the best aspects of fiber-optic and network technologies. Like fiber optic technology, CAT5 requires no special software or display-side CPUs and is completely hardware-based and network independent. Only transmitter and receiving units are required. While CAT5 covers shorter distances than fiber optic cable (typically 100-300 m/300-1000 ft), CAT5 cable costs considerably less than fiber optic cable, making it a leading option for combination solutions which overcome CAT5 cable's distance limitations.

In addition, CAT5 technology can be used in point-to-multi-point applications, allowing the broadcast of media content from one central source to hundreds of display stations. As a result, CAT5 technology alone or combined with fiber optic cable is an ideal solution for multiple-display digital signage installations.

Due to its network independence, CAT5 cable allows high performance and real-time transmission of high-resolution multimedia without slowdowns or downtime. If CAT5 technology is combined with a BIOS-level hardware solution for remote access over IP (such as a KVM IP extender), it can even allow remote maintenance and troubleshooting for the content server that manages the content to be displayed, minimizing downtime and loss of investment.

CAT5 cable's low expense, ease of installation, and flexibility makes it a good choice for a primary distribution technology as well as a leading ‘last mile' option for combination platforms.

Combination technologies

Because of the advantages and drawbacks of each of the technologies listed, it is frequently advisable to use a combination of technologies for optimal performance at the lowest possible cost.

Fiber optic and CAT5 cable

When dealing with high-resolution media over large distances that must be broadcast to a group of displays, a combination of fiber optic and CAT5 cable is the optimal solution. In this case, fiber optic cable is used for distance broadcasting together with a local CAT5 video broadcaster for ‘splitting' the broadcast to various displays. This is a simple solution to install, since all that is needed is to connect the fiber optic receiver with the CAT5 video broadcaster. And the use of CAT5 cable for the last 50-150 meters/150-500 feet of cabling instead of fiber optic cable can provide significant savings.

Conclusion: With the CAT5 compatible equipment you were able to save over 50 percent of the costs. Additional savings are accrued from the CAT5 cabling itself which costs less than fiber.

Data network and CAT5 cable

When managing multiple groups of digital signage displays from a remote location, a combination of data networking and local CAT5 cabling can give the user the best of both worlds-remote management over IP combined with low-cost and network-independent infrastructure. The ‘last mile' use of CAT5 in place of data networks at the display end saves the cost of a computer (or CPU) for every display. All that is needed is a local central server, which is remotely managed through the data network. The local server is connected to multiple displays through CAT5 technology, freeing the local installation from network dependence. The digital signage of each location is network-independent, and each installation is far less expensive to implement. Bandwidth issues are also surmounted by transmitting media to the local computer ahead of time for scheduling on-the-fly. At the time of broadcast, media is transmitted locally over CAT5 cabling, which is network independent and not limited by bandwidth.

Conclusion

Distribution infrastructure is an important part of digital signage, and choosing the correct distribution technology is a crucial element of any digital signage project. While each distribution technology has its advantages and drawbacks, the correct combination of technologies can achieve low cost and high performance, no matter what the project size or complexity.