User's Guide

Using Bluetooth 3-3
Introduction
Bluetooth-equipped devices can communicate without wires, using frequency-hopping spread spectrum (FHSS) RF to transmit and
receive data in the 2.4 GHz Industry Scientific and Medical (ISM) band (802.15.1). Bluetooth wireless technology is specifically
designed for short-range (30 feet/10 meters) communications and low power consumption.
Mobile computers with Bluetooth capabilities can exchange information (e.g., files, appointments and tasks) with other Bluetooth
enabled devices such as phones, printers, access points and other mobile computers. In addition, a dial-up modem connection can be
created between the Bluetooth mobile computer and a Bluetooth enabled phone. The Bluetooth phone can then be used as a modem.
Symbol mobile computers with Bluetooth technology use the StoneStreet Bluetooth stack. To program Bluetooth within the mobile
computer refer to the Microsoft Embedded Visual C++ help.
Adaptive Frequency Hopping
Adaptive Frequency Hopping (AFH) is a method of avoiding fixed frequency interferers. AFH can be used with Bluetooth voice. All
devices in the piconet (Bluetooth network) must be AFH-capable in order for AFH to work. There is no AFH when connecting and
discovering devices. Avoid making Bluetooth connections and discoveries during critical 802.11b communications. AFH for Bluetooth
can be broken-down into four main sections:
• Channel Classification - A method of detecting an interference on a channel-by-channel basis, or pre-defined channel mask.
• Link Management - Coordinates and distributes the AFH information to the rest of the Bluetooth network.
• Hop Sequence Modification - Avoids the interference by selectively reducing the number of hopping channels.
• Channel Maintenance - A method for periodically re-evaluating the channels.
When AFH is enabled, the Bluetooth radio “hops-around” (instead of through) the 802.11b high-rate channels. AFH coexistence
allows Symbol mobile computers to operate in any infrastructure.
The Bluetooth radio in this mobile computer operates as a Class 2 device power class. The maximum output power is 2.5mW and the
expected range is 32.8 feet (10 meters). A definitive definition of ranges based on power class is difficult to obtain due to power and
device differences, and whether one measures open space or closed office space.
It is not recommended to perform Bluetooth wireless technology inquiry when high rate 802.11b operation is
required.
Turning the Bluetooth Radio Mode On and Off
Turn off the Bluetooth radio to save power or if entering an area with radio restrictions (e.g., an airplane). When the radio is off, the
mobile computer can not be seen or connected to by other Bluetooth devices. Turn on the Bluetooth radio to exchange information
with other Bluetooth devices (within range). Communicate only with Bluetooth radios in close proximity.
To achieve the best battery life in mobile computers with multiple radios, turn off the radios that are not being
used.