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FUR
THER
INFORMA
TION
Problem: The mouse pointer of the ALIF receiver is slow or sluggish when
moved across the screen.
This issue is often related to either using dithering on the video output of one or more
transmitting computers or using VGA-to-DVI video converters.
Dithering is used to improve the perceived quality and color depth of images by diffusing
or altering the color of pixels between video frames. This practice is commonly used
on Apple Mac computers using ATI or Nvidia graphics cards. VGA-to-DVI converters
unwittingly produce a similar issue by creating high levels of pixel background noise.
ALIF units attempt to considerably reduce network traffic by transmitting only the pixels
that change between successive video frames. When dithering is enabled and/or VGA-to-
DVI converters are used, this can have the effect of changing almost every pixel between
each frame, thus forcing the ALIF transmitter to send the whole of every frame: resulting
in greatly increased network traffic and what’s perceived as sluggish performance.
Remedies:
• Linux PCs
Check the video settings on the PC. If the Dither video box option is enabled, disable it.
• Apple Mac with Nvidia graphics
Use the Adder utility for Mac’s – Contact technical support.
• Apple Mac with ATI graphics
Enable the Magic Eye dither removal feature.
• Windows PCs
If you suspect these issues with PC’s, contact technical support for assistance.
• Replace old VGA adapters on host computers with DVI video cards.
Problem: My monitor is displaying a pink screen
It is possible that the source computer and ALIF transmitter are sending a high resolution
Dual Link signal in response to a request from your Dual Link monitor. However, your
ALIF receiver is unable to correctly process the signal, causing the pink screen issue (DVI
resolutions above 1920 x 1200 are generally Dual Link).
ALIF2002T and 2112T transmitters are able to send Dual Link video when requested,
however, an ALIF2000R receiver is required to process the higher resolution signal fully
at the other end. Other receivers, such as the ALIF1000R, 1002R and 2020R units cannot
process Dual Link DVI as they are Single Link devices.
Ensure that the ALIF transmitter is set to supply a Single Link EDID to the graphics card.
When the video source is changed to a Single Link video resolution, the pink screen
should disappear and the video should be displayed normally. Alternatively, change the
monitor to a Single Link DVI monitor.
It is important not to mix Dual Link Transmitters with Single Link Receivers.
On an AIM controlled system, ensure that the Video compatibility check is enabled as this
ensures that the correct video mode is displayed for the monitor being used.
Problem: The audio output of the ALIF receiver sounds like a scratched re
-
cord.
This issue is called Audio crackle and is a symptom of the same problem that produces
blinding (see previous page). The issue is related to missing data packets.
Remedies:
As per blinding discussed previously.
Problem: AIM cannot locate working ALIF units.
There are a few possible causes:
• The ALIF units must be reset back to their zero config IP addresses for AIM discovery.
If you have a working network of ALIF’s without AIM and then add AIM to the network
AIM will not discover the ALIFs until they are reset to the zero config IP addresses.
• This could be caused by Layer 2 Cisco switches that have
portfast
enabled on the ports to which ALIF units
are connected. Without portfast enabled, ALIF units will all be assigned the same zero
config IP address at reboot and AIM will only acquire them one at a time on a random
basis.
You can easily tell whether portfast is enabled on a switch that is running STP: When
you plug the link cable from a working ALIF unit into the switch port, check how long
it takes for the port indicator to change from orange to green. If it takes roughly one
second, portfast is on; if it takes roughly thirty seconds then portfast is disabled.
Remedies:
• Ensure that the ALIF units and the AIM server are located within the same subnet
because AIM cannot cross subnet boundaries.
•
the ALIF units to their zero config IP addresses.
• Enable portfast on all switch ports that have ALIF units attached to them or try
temporarily disabling STP on the switches while AIM is attempting to locate ALIF units.