 method is always used inquiry access code (GIAC) formed from a reserved in the packet header, and for the payload in one type of address for this purpose. Dedicated inquiry access codes SCO packet. It simply repeats each bit three times, (DIAC) can also be used when the initiator is looking allowing the receiver to decide on the basis of majority only for certain types of devices. Now a potential slave rule what data bit to assign to each group of incoming bits. can lock on to the master, provided it is receiving during The other FEC method, applied in certain type ACL the master's transmission time and on the transmission and SCO packets, uses what's called a (15,10) shortened frequency. To facilitate this match-up, the inquiry pro- Hamming code. For every ten data bits, five parity bits cedure uses a special frequency hop routine and timing. are generated. Since out of every 15 transmitted bits only Only 32 frequency channels are used and the initiator ten are retrieved, the data rate is only two-thirds what transmits two burst hops per standard time slot instead it would be without coding. This code can correct all of one. On the slot following the transmission inquiry single errors and detect all double errors in each 15-bit bursts, the initiator listens for a response from a potential code word. slave on two consecutive receive channels whose fre- Wireless communication is susceptible to eavesdrop- quencies are dependent on the previously transmitted ping SO Bluetooth incorporates optional security mea- frequencies. sures for authentication and encryption. Authentication When a device is making itself available for an in- is a procedure for verifying that received messages are quiring master, it remains tuned to a single frequency for actually from the party we expect them to be and not a period of 1.28 seconds and at a defined interval and from an outsider who is inserting false messages. En- duration scans the channel for a transmission. At the end cryption prevents an eavesdropper from understanding of t