ADDER 2112T User Manual page 45

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 colour depth of images
by diffusing or altering the colour 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
Use the ALIF 2000 series unit with 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: The audio output of the ALIF receiver sounds like a scratched
record.
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
Protocol (STP) enabled but do not also 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. AIM cannot cross subnet boundaries.
• Manually reset 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.
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