KVM: Instant feedback

KVM systems allow source computers to be located away from end points, essential in medical applications for hygiene and security

KVM system manufacturers argue that their extenders and switchers may be the answer to many AV signal distribution and management needs in a range of applications.

We  regularly  hear about  AV and IT convergence in the AV industry. Services that were once the domain of AV specialists: like audio and video distribution, voice and video conferencing and in-room equipment control are migrating to IP networks and coming under the domain of the IT department.

While  posing  a  threat  to  the  established and traditional AV industry and forcing  many integrators to become expert in IT technology, this situation brings with it  considerable opportunity to establish exciting new offerings to  customers. We can  now take advantage  of devices  and  techniques  developed  for,  and widely used in, the professional IT sector; many of which were, in turn, originally developed for the consumer market; like touchscreens, voice control and device positioning.  

A technology that is extremely well established in the IT world, but is under-used and under-valued in the AV world is that of keyboard, video and mouse (KVM) extension and switching.  Distributing  video  signals  over  anything but  the  shortest  distance  has  always  posed  a problem.    Direct  connection  between  displays and  the  computer  systems  and  media  players that  feed  them  is  limited  to  a  few  metres using  conventional  methods.  Greater  distances require  AV  extenders  that  convert  the  video data  into  some  intermediate  form  for  long-distance transmission, commonly HDBaseT over a  CatX  cable  or  fibre. 

However  the  basic  and most  common  video  extenders  are  capable  of just  sending  the  video  signal  in  one  (forward) direction, from a computer to a remote screen, although the latest incarnation of HDBaseT now includes  USB  transfer.  They  are  incapable  of receiving commands from the user to manage the operation of the source device and provide an  interactive  experience.  KVM  extenders  add that return path; allowing mice, touchscreens, sensors, cameras and other interactive devices to be included.

Growing use of interactivity in AV installations is increasing the need for KVM extenders.  “KVM solutions are  needed  in  a  growing  number  of applications,”  observes  AJ  Shelat,  VP  of  sales, Hall Research. “Traditional KVM applications are used for video, keyboard and mouse, however the growth comes out of integrating the increasing number  of  USB  devices  that  are  used  with PCs. There are many USB peripheral devices, like large  format  touch  screen  displays,  document cameras, VTC cameras, microphones, that require integration  into  today’s  pro  AV  installs.    The applications can range from education, huddle and conference rooms, medical, command and control  centres, museums, video  conferencing, collaboration and digital signage.”

control room

Development of KVM systems has focused on delivering  equipment  that  does  not  introduce perceivable  latency,  visual  artefacts  or  delay in user  response. In  the  IT  sector,  their  role  is to  separate  computers  from  user  workstations, either by direct connection or over a network.  

“KVM  solutions  are  designed  for  real-time interaction and introduce zero or micro-seconds of  latency,”  points  out  Jamie  Adkin,  VP  of sales  for  Adder  Technology.  “That  real-time nature  makes  the  user  feel  connected  to  the technology: a touchscreen responds instantly, a pen feels connected to a graphics tablet and a cursor is synchronised to the mouse movement.”

KVM  extenders  are  deployed  in  critical installations  in  which  reliability  and  continued operation is essential.  They have been developed to  provide  highly  robust  operation  and  are capable  of  delivering  ongoing  performance in  more  hostile  and  difficult  situations  than commercial AV-grade technology; although this does come at a cost.  They can, therefore, solve problems  in  AV  installations.   

Nicola  Jagger, project manager at D J Willrich cites an example: “During a recent museum installation we came up  against  some  long  cable  runs  of  over  100 metres  that  were  interrupted  by  several  patch panels. Standard DVI extenders were unable to reliably drive signals over those lengths, but we found that the KVM extenders, using a different transmission methodology worked perfectly.”

In addition to providing direct point-to-point extension, KVM signals can also be distributed through switches and over networks so that any display  device  or  user  workstation  can  access any source device. This is an extremely practical way  of  installing flexible systems  of unlimited size and  layout  that  can  be configured  and switched to suit current and  future  end user requirements.  There are two distinct  types of KVM switching systems: direct KVM and KVM-over-IP. Direct KVM requires a dedicated point-to-point connection from the switch to each end point, whilst KVM-over-IP operates over an established, or dedicated, IP network.

Each  has  particular  advantages  and disadvantages, as Shelat explains: “Direct KVM delivers the easiest installation with little to no network  configuration  required  and  the  signal will  have  no  impact  on  the  building’s  data network.  However  ease  of  installation  comes with  the  loss  of  scalability  and  flexibility  of installation. The integrator may need to pull a dedicated cable and not be able to use existing network  infrastructure.  KVM-over-IP  solutions give  the  integrator  the  ability to leverage the existing  network  infrastructure,  possibly  add more  locations  or  route  signals  through  a virtual matrix switch. The downside is that this type  of  deployment  will  require  some  level  of networking  knowledge,  possible  signal  delays or latency issues from increased network traffic, and may require additional network equipment.”   

Direct  KVM  solutions  need  physical  point-to-point connections between the devices and through  the  switch.  This,  points  out  Owen Haigh,  head  of  global  product  management for  Lindy,  “provides  real  time,  uncompressed, platform-independent  connection.  KVM-over-IP  solutions  remove  the  physical  connection between  devices  and  deliver  the  freedom  to reach  across  the  whole  IP  network.  They  do,
however, add cost in terms of signal delay and bandwidth restriction. In many cases it is better to create a separate physical network to access users  without  touching  the  existing  in-house network and reducing its performance.”

Adkin is an advocate of KVM-over-IP systems, pointing  out  how  they  have  evolved  as  a technology  to  the  highly  capable  solutions  of today: “KVM-over-IP has long been used as a term to describe remote access technologies that use  low-bandwidth,  unreliable  WAN  networks. For eight years, we’ve been providing customers with IP-based KVM  systems using standard 1Gb/s network technology that outperform the proprietary solutions from flexibility, scalability and cost perspectives.”

The advantages of direct KVM systems make them  particularly applicable  to installations that  require instant switching of sources, total reliability and  absolute  image  quality. “Dedicated  cabling  allows a lower level of compression to be used,  resulting  in  higher quality images with less signal latency,” explains Mark Hempel, head of product management at  IHSE. “This  is  particularly  important  in high-end, near-broadcast, applications such as those found in entertainment installations and sports stadiums and in mission-critical systems like  control  rooms  and  command  centres.    An emerging technology, and one that is expanding very rapidly, is that of immersive display using virtual  reality  headsets  and  large  close-pitch videowalls.  It allows architects and car designers for example, to interact with their designs in a virtualised world and collaborate in real time.

“Virtual  reality  systems  are  also  used  in museums and retail applications to create virtual experiences  to  visitors  and  customers.  KVM systems  allow  expensive  source  computers  to be located well away from the end points and shared  as  required,  whilst  still  being  accessed from  anywhere  on-site.  This  brings  security, flexibility  and  worthwhile  cost  savings  to customers.  However  running  an  immersive display or headset requires very fast interaction between  the  headset  or  pointing  devices  and the computers that generate the visual images. A  delay  in  the  round  trip  path  of  more  than 20ms can cause motion sickness in the viewer. Our extenders introduce minimal delay and can handle these types of application well.”

An  IT  heritage  has  led  to  the  inclusion  of advanced  capabilities  and  features  in  KVM technology  that  bring  new  possibilities  and flexibility  to  the  AV  world.  Single  point-to-point extenders can handle almost all forms of analogue and digital audio and video signals as well  as  managing  single,  dual  and quad head computer  setups  and  can  readily  transport  4K video  and  higher  resolutions.  In  addition  to USB HID, bidirectional high speed USB2.0 andUSB3.0 can be transmitted,  allowing  special devices like hard disks and video cameras to be accommodated  so  that  they  can  be  accessed wherever they are located and displayed wherever they need to be seen.

A  significant  difference  between  KVM  and standard  AV  extenders  lies  in  the  selection of  codecs  used  to  reduce  signal  bandwidth. Those  used  for  video  extension  in  AV  systems are generally tailored to moving images.  KVM codecs are more than capable of handling video images without corrupting  the image in any way. However they are also tuned to manage the short straight lines and curves of text displayed on  computer  screens,  in  a  manner  that  video extenders are unable to do so well.  Interactive sessions often display on-screen text and data material and this differentiation could be quite important in user applications and a point that should be borne in mind when selecting which type of extender to use.

Nicolas Jaud, product marketing manager for Aten, points to another inherent feature: “KVM solutions  incorporate  security  procedures  that are not mandatory in traditional digital signage applications.  More  frequently  nowadays, administrators want to decide who can access or share resources. KVM solutions already include user permission rights and credentials to control access to the system.”

It  is  also  easily  possible  to  replicate  audio and  video  signals,  allowing  single  sources to  be  displayed  simultaneously  on  multiple screens, useful for digital signage applications. The crucial benefit that KVM solutions provide over  other  forms  of  video  distribution  lies  in the  capability  to  incorporate  user  interaction, even in situations in which a single interactive application  is  shared  between  several  users.
The system can be configured to prioritise and manage interactive responses in multi-users set ups in a variety of ways.

A  wealth  of  other  features  and  control capability is already incorporated into currently available KVM technology, making it eminently suited to many AV applications.  This will develop further as the market evolves, as Adkin sums up: “The experience we all get from devices in our pocket is so high that we expect the same  of the professional AV equipment we deploy in our facilities. Customers are always searching  for tighter integrations, greater flexibility and robust security because they  save  time,  money  and deliver  results.  KVM  provides  viable and  cost-effective solutions and the market continues to grow rapidly because of it.”