Bluetooth interview questions

1. what is BR and EDR? what is the difference? Ans: BR is basic rate - 1 Mbps EDR is:Enhanced DataRate-2-3 Mbps 2. Sequence of operations for HFP profile Ans:HF sends AT+BRSF? to indicate supported features AG sends +BRSF and OK AG can support more indications. So HF sends AT+CIND? to query supported indicators by AG AG sends +CIND and OK Finally it queries for Call Handling and multi party features by sending AT+CHLD? AG sends +CIND and OK if supports or sends OK if not supported. 3. bluetooth layer hierarchy from bottom: Baseband LMP/L2CAP RFCOMM/SDP OBEX/profile(PBAP) application 4. how many devices can be in piconet? Ans:7 active slaves and 255 parked slaves.Any of 255 slaves can be activated. Only one master and all slaves synchronize to clock of Master. 5. what are the codecs used in A2DP? Ans: SBC is Mandatory MPEG-1.2 Audio is optional. There are 2 more optional codecs. 6.what is the frequency modulation method? Ans:OFDM,adaptive frequencymodulation for interoprability with other wifi networks in ISM band, Frequency hopping spread spectrum. 7.what is AVDTP Signalling sequence? IDLE state CONFIGURED state OPEN state STREAMING state CLOSING state Endpoint discovery to Stream Release procedure 1.Stream Endpoint Discovery 2.Get capabilities 3.Stream configuration 4.Stream establishment 5. Stream start 6.Stream suspend 7.Stream reconfigure 8. Stream Release 8.what are HCI commands? 1.HCI_CreateConnection 2.HCI_Disconnect 3.HCI_CreateConnectionCancel 4.HCI_AcceptConnection 5.HCI_CreatePhysicalLink 6.HCI_AcceptPhysicalLink. 9.What are bluetooth frequencies? A. 2400-2480 f=2402+k k=0..75 2 Mhz lower guard frequency 3 Mhz upper guard frequency