Hardware Reference
In-Depth Information
Many manufacturers, including Microsoft, Logitech, and second-tier vendors, offer
bundled kits that include a wireless keyboard and mouse that share a transceiver. Because
many of these keyboards and mice have the latest features, including programmable keys,
multimedia and Internet-access keys, and optical sensors, these wireless combos are often
the top-of-the-line products from a given vendor and are often less expensive than buying
the keyboard and mouse separately.
The three major technologies used by wireless input devices are as follows:
• IR
• Proprietary radio frequency
• Bluetooth
All three technologies normally use a transceiver connected to the USB or PS/2 ports on
the computer. Because many wireless transceivers are designed for use with a mouse and
keyboard, PS/2-compatible versions have twocables—one forthe mouse portandonefor
thekeyboardport.AUSB-compatibletransceiverneedsonlyoneUSBporttohandleboth
devicesifthesystemsupportsUSBLegacy(keyboard)functions.Thetransceiverattached
to the computer draws its power from the port.
The transceiver receives signals from the transceiver built into the mouse or keyboard.
These devices require batteries to function; therefore, a common cause of wireless device
failure is battery rundown. Early generations of wireless devices used unusual battery
types, but most recent products use off-the-shelf AA or AAA batteries, including re-
chargeables.Somehaveinternallithium-ionorNiMHrechargeablebatteries,inwhichthe
transceiver connected to the PC also doubles as a charger. Some are rechargeable via spe-
cial docks or USB cable connections.
Although all three technologies rely on battery power, the similarities end there. IR
deviceshavearelativelyshortrange(12ft.maximum),andaclearline-of-sightmustexist
between the input device and transceiver. Anything from a Mountain Dew can to a sheet
of paper can block the IR signal from reaching the transceiver, assuming you're aiming
thetransmitter builtintoyourinputdevicecorrectly inthefirstplace.Somelate-model IR
devices have transceivers that can receive signals through a relatively wide 120° range,
but this technology is much more temperamental than the others and has been abandoned
by most vendors.
BecauseoftheproblemswithIRdevices,almostallvendorsofwirelessinputdevicesnow
useradiofrequency(RF)signalsfortransmissionbetweenthedeviceandtransceiver.RF-
based wireless devices have no line-of-sight problems, but they can vary in the maximum
distances they will allow from the transmitter.
