Transmitting EDS Images

I’ll never forget my first message-center installation 25 years ago. The cables that transmitted the messages really blew my mind. To send the programmed message from controller to display, a single strand of wire connected to every lightbulb in the sign. The entire bundle had a 3-in. diameter and required a 4-in. conduit. Such was the state of the industry in 1978. Today, not only have the display technologies advanced, so have the media (thank God). Today’s high-resolution image files would be impossible to display without the plethora of sophisticated communication systems now available. All of today’s electronic-display technologies operate from computers or, in some cases, video processors. In any event, the display information sent to the signs is digital data. Whereas yesteryear’s lamp displays might display only 300 to 500 bits of data per second, today’s systems transmit millions of information bits in the same timeframe. Media that transmits from processor to display should be selected carefully to best facilitate the system’s intended use. The following basic primer addresses the various communications media used with modern electronic digital signage (EDS) systems. Some are extremely simple, others quite complex. I always use the simplest system that meets a customer’s needs. I have listed the media types in order, from simplest to most complex. Direct wire The simplest communication method is from computer to sign, with nothing but a wire in between. Some basic systems still operate with Belden or coaxial cable. However, for any system, the preferred, direct-wire communication system is fiberoptic. It’s thinner and less subject to interference from power sources and other conductors. It can even run in the same conduit as power lines. For a simple, shopfront sign, this is the easiest communication methodology. Wireless microwaves In certain circumstances, even when a sign is relatively proximal to the computer, a direct wire still isn’t feasible, for example, when a business and its sign are on opposite sides of the street. Assuming a direct sightline and a distance of up to one mile, you can program with a microwave system. This would operate similarly to a directly wired system. Laser communication A laser works similarly to a microwave because it requires a clear line of sight. Its advantage is that it can maintain a further operational distance between the computer and sign. With both systems, however, it’s essential that the beams be fixed between sending and receiving devices. If the connection is broken, communications cease. Wi-Fi Wireless Internet connections — also known as Wi-Fi or 802.11, which refers to a series of wireless LAN specs developed by the Institute of Electrical and Electronics Engineers — don’t require a direct, unbroken sightline, making them an effective option when a direct-wire system can’t be implemented because of impediments such as a public right-of-way or another structure between the computer and the sign. Its range is usually limited to 100 ft. or less, but can be extended with directional antennae. Wi-Fi transmits data at approximately 10MB/sec., substantially slower than direct-wire or a laser system, but still serviceable for certain applications. Modems Basic communication to a remote display entails a modem-and-telephone system, which uses landlines or mobile-phone technology. Its limiting factor is the modem’s 56K-maximum transmission speed. Therefore, the larger and more complex the image, the greater the amount of data transmitted; the greater the data load, the longer it takes to transmit. A text display has limited data-transmission requirements and is easily handled via modem. Even a moderate-resolution, color system that displays still images can easily operate via modem. However, a remote, high-resolution display, which depicts video or animation, implements huge files, which could take hours to download. Remote displays with modems, and all other communication schemes more complex than direct wire and line-of-sight media, require computers within the sign and the host computer from which the messages are programmed and/or sent. Virtually all sign-operation software provides a scheduling package. This allows the programmer to create or download messages up to one year in advance into the sign’s presentation schedule. The on-site computer stores this schedule and choreographs the length, time and sequence of each message. From the host computer, the scheduling system charts the timing of transmissions to the remote computer. This is essential for using signs with modems. When sending large files, the programmer sets the system to transmit during non-business hours, to take advantage of lower long-distance rates and not occupy the central computer, which might be an integral component of another function during business hours. The simplest modems use a landline telephone system. However, cell-phone and digital technologies are available for locations where landlines aren’t accessible. Dated analog cellular modems are being phased out, and they aren’t recommended if a digital signal is available. Digital systems, available in most markets today, are significantly more dependable. Satellites Satellite communication is a viable option for any form of data transmission, including electronic signs. Unfortunately, it’s expensive to purchase the bandwidth. However, if a client already uses satellite systems between offices, it’s possible to piggyback" onto the existing satellite signal without additional cost or interrupting the existing data stream. In the electronic-sign industry, this is rarely used. However, I would consider it for multiple-location installations where a satellite is already in use. Cable networks Just as it’s now possible to access the Internet using a cable connection, the same system can communicate messages to an electronic sign. A cable system’s benefits include speed and the ability to rapidly send files of virtually any size. Its only liability is limited availability; while cable is available in most populous areas, pockets of remote, uncovered locations remain. DSL Digital-service lines (DSLs) are nearly as fast as cable. Likewise, the system can send virtually unlimited data. Like cable, the issue is availability; some areas of the country don’t offer DSL service. Even in areas that offer service, the DSL system will only work at a limited distance from the phone company’s network. Fiber to the curb In a few areas, even where DSL isn’t available, the local phone provider may offer a new service called "fiber to the curb." In this instance, the telephone company provides fiberoptic cable from their line directly to the curbside of the sign’s location. When DSL or phone lines aren’t available, this system provides an internet link. A purpose for every option With these myriad options, you can establish communication with an electronic sign anywhere in the world. The issues, as always, are cost and complexity. However, in all circumstances, the cost is less than it was 20 years ago. It’s no longer necessary to route large, proprietary conduit from the computer to the sign. All the options listed above cost less than $100 per month. The possible exception is satellite transmission, which can range from zero to very expensive if you must purchase a separate bandwidth. In any event, study the size of files to be sent, how often the sign will be updated and your available options. I’ve found it best to do this homework on behalf of customers rather than asking them to make these determinations.