User guide

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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.
VGAto-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cong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Spanning Tree
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.