How to Choose the Right KVM Extender?

how to choose a kvm extender

About KVM Extender

A KVM extender is useful wherever you need to control a computer from a distance. By transporting KVM signals anywhere from 15 feet to several miles away from the computer system, a KVM extender effectively overcomes the distance limitation of HDMI, DisplayPort and USB cables. It can be widely used in various applications to enable remote PC access, like industrial control center, broadcast, education, healthcare, etc. Here are the key elements to take into consideration when buying a KVM extender.

KVM Extender Key Considerations

Assess Video Connectivity and Resolution

First and foremost, you need to assess video connectivity and resolution. Resolution is the number of horizontal and vertical pixels which can be displayed on a monitor. The higher the resolution, the clearer and sharper the image displayed. You can check if the KVM extender supports the resolutions that your displays and source system support, like 4K@60 or 1080P@60.

Another aspect you need to consider is the video interface of the KVM extender, like the most common HDMI and DisplayPort interface. Their specifications establish the maximum supported resolution per revision, the required bandwidth, as well as the corresponding high-bandwidth digital content protection (HDCP) revision. For instance, to extend a 4K UHD display running at 60Hz, you need a KVM extender which supports a video connector compliant with DisplayPort 1.2 (or higher), or with HDMI 2.0 (or higher). However, for a lower resolution like 2560×1600, a KVM extender compatible with DisplayPort 1.1 or HDMI 1.2 will work as well.

AV Access_Blog_ 4K, 1080P

Verify Support for USB Devices and Other Peripherals

KVM extenders can extend various kinds of USB devices. While keyboard and mouse are the primary USB devices, USB flash drives and USB audio devices can also be extended. USB devices can be divided into three categories: USB HID devices, USB 2.0 devices and USB 3.0 devices. The latter two can further be categorized based on the type of transfer they support. KVM extenders may support some or all types of USB devices. Before purchasing a KVM extender, please ensure it can handle all the required types of USB and other peripheral signals for the installation.

AV Access_Blog_USB Cable Image (1)

Ensure Support for Audio Devices

Most KVM extenders have a combination of connectors which can support both analog and digital audio devices. For example, line-in connectors can be used to connect an amplified analog audio source like an audio mixer, whereas 3.5 mm jacks are used for un-amplified audio signals such as a microphone or headphone. For USB ports with isochronous data transfer, they can also connect digital audio devices or USB headsets. Both DisplayPort and HDMI video connectors can carry digital embedded audio from the system to the display.

Ascertain Transmission Medium: Distance and Bandwidth

KVM extenders transport signals over CATx or fiber optic cables. The cable type used determines the bandwidth of the link and the distance covered.

CATx cables are often used in Gigabit Ethernet local area networks (LANs). Typically, CAT5e cables support a maximum distance of 100m/328ft in point-to-point connection. KVM over IP installations benefit from longer distances over CATx cable by going through multiple routers and switches. (KVM extenders vs. KVM over IP?) In contrast, fiber optic cables provide much longer transmission distance compared to CATx in point-to-point connection. For example, fiber optic SFP+ cabling can cover up to 10 kilometers/6.21 miles.

Transmission mediums have bandwidth limitations and higher resolution video signals invariably demand higher bandwidth. Although CAT5e cables offer the necessary bandwidth support in extending uncompressed 1080p60 video, resolutions higher than 1080P@60 will not be possible as they require more bandwidth than what these cables can support. For instance, uncompressed 4K UHD resolution video (2160P60) requires upwards of 12 Gbps of bandwidth, whereas the maximum bandwidth supported by CATx cables is only 10 Gbps. In this case, you can employ those KVM extenders that use some level of compression to reduce the data size, to enable it to fit the available bandwidth. And other alternatives include running multiple cables, or going with KVM extenders with higher transmission bandwidth.

The above are the key elements you need to consider before you buy a KVM extender. Knowing your requirements on video, USB, audio, transmission distance, bandwidth and other unique needs can help you save money in the long run, because you’ll know exactly what you need and won’t end up buying unnecessary equipment. We hope this article will be helpful to you on choosing the right KVM extender.

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