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Digital Signage Common Sense: Digital versus Analog Signal Extension
Posted on Friday, September 28, 2012

Most people, professionals and nonprofessionals alike, assume that the digital signage all around us is made up of digitally powered screens.  In reality, digital signage can operate in a number of ways.  We are faced with the following question: Is using digital signals necessary in deploying digital signage networks? This has turned into a relevant argument in the digital signage industry with many vocal supporters and criticizers.  

The first and only notable benefit of a digital signal is that the quality and depth of the picture color is maintained whereas that of an analog signal is inconsistent.  An organization is recognized through its brand & thus a digital signage network needs to reliable in displaying the brand colors.  For instance, with digital signals, the Coke red on screen A will be exactly the same as the Coke red on screen B.   

On the other hand, we do see an advantage using analog signals versus digital signals in some dimensions.  Category 2 HDMI cables can be effective to distances of about 50 feet. HDMI extenders range from 100 ft-800ft, depending on whether they are using single or dual CATX cable and up to 1000 ft. using fiber.  At HD resolutions (1920 X 1080), DVI cables max out at about 15 feet and DisplayPort cables at about 40 feet.  Both DisplayPort and DVI Extenders max out at 330 ft at HD (1080P) resolutions.  HD analog signals, by several manufacturers, can support distances of up to 2000 feet over copper and several miles over fiber.  Hence, distance has the advantage using Analog systems.  Another example of analogs’ positive influence in distance is in environments where multiple screens are showing the same content due to the cost savings on players and licensing fees by having fewer players to cover the equivalent distance. 

Another major advantage of analog over distance is the resistance to interference while many DVI and HDMI extenders have issues with RF and other radio frequencies. 

Analog devices from digital signage players and from VGA, DVIi and DisplayPort can all support up to 1080p resolution, thus resolution can be removed from the equation for our analysis.

Finally cost is the final metric to compare.  Creating content in 1080p resolution versus 720p or lower has a higher cost due to the cost of equipment as well as the process of extending the signals from the players to the screens. The following chart displays the average of on-line prices at maximum cable lengths for Digital versus Analog resolutions.

Based on the above analysis, it is safe for me to conclude thatdigital output to Digital Signs has a place in current and future deployments, especially as network streaming based and HDBaseT based systems become more prevalent. However, network owners and operators should still consider an analog system if they are concerned about lowering both capital expenditures as well as operating costs over the life of their networks.  I would love to collect the thoughts of the audience on the subject.  Does the rest of the industry feel the same way?