Multiple monitor audio/video configurations are becoming commonplace in modern day digital signage applications. Digital signage applications distribute an audio/video signal to two monitors or to hundreds of monitors. Some desktop configurations call for two monitors that will display different images, i.e. extended desktop. Displaying different images on the monitors allows an employee to increase productivity by providing the ability to view two applications simultaneously. The equipment used to effectively split an audio/video signal will differ depending on whether that signal is digital or analog and the desired configuration.
Splitting an analog signal can be as simple as using a Y-cable. This type of cable will have a single male connector that will connect to the source device and two female connectors that will be connected to separate cables which connect to the monitors. The conductors from the pins of both of the female connectors will be wired to the pins on the male connector. The splitting of the analog signal in this type of connection is uncontrolled. The construction of Ycables will have two conductors soldered to each pin of the male connector. Y-cables do not contain any circuitry or chipsets that determine which path the video signal must take. This means that the electrical video signal passing through a Y-cable will take the path of least resistance. This is especially problematic when long cables are used with a Y-cable and the result may be poor video quality. The image displayed may be ghosted (duplicate overlapping images), blurry, or no video image may be displayed. Y-cables should only be used for applications where cables lengths will be six feet and shorter. The vast majority of Y-cables will only allow for the monitors to duplicate the video image, or display the exact same image on both monitors. Some specialized cables allow for extended desktop, or the ability to display different images on the monitors. This type of cable is typically used with a specialized video card. Using a Y-cable to split a digital signal is not recommended. Splitting a digital signal with a Y-cable introduces enough loss into the signal that there result will like be no image displayed on the monitor.
For longer cable lengths an active signal splitter is recommended. Active signal splitters are available for either digital or analog signals. This type of device will have a single input that will receive a signal from the source, replicate that signal, and then output the signal to all connected monitors. Active signal splitters will typically transmit an identical image to all monitors and, therefore, are incapable of displaying different content. Active signal splitters include devices that use standard A/V cabling as well as devices that use category cable, such as Cat5e and Cat6. Devices using standard cabling will typically support applications up to 200ft for analog signals and up to 50ft for digital signals. Devices using category cable will support applications up to 3000ft for analog signals and up to 200ft for digital signals.
Applications that require extended desktop, or the ability to display different images on the monitors, typically require specialized equipment. Certain models of video cards will support two monitors through a single port, such as an LFH-59/DMS-59 port. If the video card does not offer this type of support, then the best solution may be to replace the video card with a model that supports the desired functionality. If replacing the video card is not possible, then a USB solution may be used to add this functionality. External USB video cards connect to an available USB port on the computer and provide a second monitor port to display content. This extra port can be used to support either extended desktop or duplicating the video image on the monitors.
|Active Splitter||Passive Splitter (Y-Cable)||USB Video Card|
|Duplicate Images |
Short Cable Lengths
|Duplicate Images |
Long Cable Lengths
|Extend Desktop |
Short Cable Lengths
* Maximum cable length supported by a USB Video Card will vary by manufacturer
** Requires proper equipment and specialized cabling
This white paper is for informational purposes only and is subject to change without notice. C2G makes no guarantees, either expressed or implied, concerning the accuracy, completeness or reliability of the information found in this document.