Chapter 3

Using Bluetooth

Chapter 3
Using Bluetooth
Introduction
Bluetooth-equipped devices can communicate without wires, using frequency-hopping spread spectrum
(FHSS) radio frequency ( RF) to transmit and receive dat a in the 2.4 GHz Industry Scientific an d Medica l (ISM)
band (802.15. 1) . B lue to ot h wire l ess t ec hno l og y is spec ifica lly de sig ned fo r sho r t-r an g e (3 0 feet/10 meters)
communication and low power consumption.
EDAs with Bluetooth capabilities can exchange information (e.g., files, appointments, and tasks) with other
Bluetooth enabled devices such as phones, printers, access po ints, and other mobile computers. To use the
Bluetooth phone as a modem, create a dial-up mo dem connection between the Bluetooth mobile computer
and a Bluetooth enabled phone.
Symbol mobile comp uters with Bluetooth techno lo gy use the StoneStreet Bluetooth stack. To program
Bluetooth within the EDA refer to the Micr osoft Embedded Visual C++ help.

Adaptive Frequency Hopping

Adaptive Frequency Hopping (AFH) is a method of avoiding fixed frequency interferers, and can be used with
Bluetooth voice. All devices in the pi co net (Blue tooth ne two rk) must be AFH-capable in orde r 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 consist s of four main sections:
•
Channel Classification - A method of detecting an interference on a channel-by-channel basis, or
pre-define d ch an ne l ma sk.
•
Link Management - Coordi nates and d istributes the AFH infor mation to th e rest of the Blue tooth network.
•
Hop Sequence Modification - Avoids interference by selectively reducing the number of hopping
channels.
•
Channel Maintenan ce - A method for periodically re-evaluating the channels.
When AFH is enabled, the Bluetooth radio “hops arou nd” (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 EDA 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 definition of ranges based on power class is difficult
to obtain due to power and device differences, an d whethe r on e mea sure s open space or closed of fice space.
NOTE It is not recommended to perform Bluetooth wireless technology inquiry when high rate 802.11b operation
is required.