Hardware Reference
In-Depth Information
Although RF overcomes line-of-sight issues that can cripple an IR mouse, early versions
of RF products had a high potential for interference from other devices and from other
devices in use in the same room because of a limited range of channels. For example,
some early wireless products required the user to manually select the channel used by the
transceiver and mouse. If more than six users in a small room had wireless devices, inter-
ference was practically inevitable.
Fortunately, improvements in frequency bands used and automatic tuning have enabled
all users of a particular type of device to avoid interference with other electronic devices
or with each other. For example, the 27MHz frequency pioneered by Logitech's Palomar
line of peripherals has become a de facto standard for most recent wireless input devices.
(Microsoft and IBM have also used it for their wireless products.) Logitech allows users
to enable a digital security feature that uses one of more than 4,000 unique codes to pre-
vent accidentally activating another computer with a wireless device or signal snooping
byanother user.Mostvendorsusesimilar technology,butsome might useamuch smaller
number of codes. Many recent wireless products use FastRF technology, which provides
2.5 times the transmission rate of conventional 27MHz devices. The responsiveness of a
FastRF connection is all but indistinguishable from a corded mouse or keyboard.
Finally, there's Bluetooth. Although most wireless products use proprietary radio trans-
ceivers, Microsoft, Logitech, and some others have developed wireless mouse and key-
board products using the Bluetooth wireless standard. Bluetooth-enabled devices have an
effective range of up to 30 feet and might be compatible with other brands of devices that
are also Bluetooth enabled. The only drawback I've seen with Bluetooth-based devices is
that they usually consume more power, resulting in shorter battery life, and the configura-
tion or pairing of the device and transciever can be more difficult than those using propri-
etary wireless technology.
For more information about Bluetooth,
see
Chapter 17
,
“
Local Area Networking
,
”
p.
Power Management Features of Wireless Input Devices
A wireless mouse is useless if its batteries fail, so several vendors of wireless products
have developed sophisticated power-management features to help preserve battery
life—especially with optical mice, which use power-eating LEDs to illuminate the mous-
ingsurface.Forexample,LogitechCordlessmicehavefouroperatingmodes,asshownin
Table 15.3 Logitech Cordless Mouse Optical Power Management
