Theory of Operation
: Bluetooth
3-57
3.5
Bluetooth
The Bluetooth feature allows the radio the ability to connect wirelessly to a Bluetooth accessory or
data terminal. This feature is implemented using a combination Bluetooth/GPS integrated circuit (IC,
U1301) located on the Main Board, a low-frequency receiver (NFC, U2403), and a host controller
(U2415) with external 16 MB SDRAM (U2413) located on the keypad board. The Bluetooth IC sends
data to the host controller processor over an HCI USART link. The host controller processor
communicates to the OMAP processor on the RF board through a dedicated USB port.
Each APX accessory that is capable of Bluetooth communication will have its own unique Bluetooth
address. An external audio accessory headset can establish a digital connection using a low-data
rate GFSK modulated signal hopping on 79 x 1 MHz wide Bluetooth channels from 2402 MHz to
2480 MHz in the ISM band. Bluetooth uses a frequency hopping spread spectrum (FHSS) technique
to spread the RF power across the spectrum to reduce the interference and spectral power density.
The frequency hopping allows the channel to change up to 1600 times a second (625 us time slot)
based on a pseudo random sequence. If a packet is not received on one channel, the packet will be
retransmitted on another channel.
The Bluetooth feature is accompanied by a Low-Frequency (LF) detection circuit. Once a radio has
the Bluetooth feature enabled, a user can tap their LF enabled Bluetooth audio accessory with the
radio at the pairing spot to establish a secure Bluetooth connection. The LF circuit provides the
ability of a secure pairing connection with a Bluetooth accessory by sending secure messages
including the BT address of the external accessory during pairing. The LF circuit uses a 125 kHz
signal to communicate the secure pairing information over a dedicated SPI bus between the
Bluetooth accessory and the AVR32 processor.
Low-frequency transmission is done by the host controller itself using a NOR gate. The LF antenna
is located on the radio’s front-housing (speaker assembly) and connected to the LF receiver IC on
the keypad board via flex. The Bluetooth antenna is a stamped metal folded monopole antenna
mounted on the speaker assembly at the radio’s front housing:
Figure 3-42. Relation of Bluetooth & LF Antenna Assembly to Main & Keypad Boards
= Flex
= Spring Contact
KEY
Keypad
Board
(BT & LF)
Main Board
(NL5500)
Speaker Assembly
BT
Antenna
LF Antenna, Speaker
&
Mic
Summary of Contents for APX 2000
Page 1: ...APXTM TWO WAY RADIOS APX 1000 APX 2000 APX 4000 APX 4000Li DETAILED SERVICE MANUAL ...
Page 4: ......
Page 6: ...iv Document History Notes ...
Page 8: ...Notes vi Commercial Warranty ...
Page 10: ...Notes ...
Page 22: ...xiv List of Figures Notes ...
Page 226: ...6 64 Troubleshooting Waveforms LF CW on Spectrum Analyzer Notes ...
Page 688: ...Index 4 Index Notes ...
Page 690: ...ii Notes ...
Page 700: ...xvi List of Figures Notes ...
Page 806: ...5 50 Troubleshooting Charts PA Failure Notes ...
Page 1008: ...8 178 Schematics Boards Overlays and Parts Lists Transceiver RF Boards UHF2 84012621001 Notes ...
Page 1062: ...8 234 Schematics Boards Overlays and Parts Lists Keypad Board M2 and M3 PC000261A01 Notes ...
Page 1064: ...ii Notes ...
Page 1068: ...Notes A 4 EMEA Warranty Service and Technical Support Further Assistance From Motorola ...
Page 1090: ...Glossary 10 Glossary Notes ...
Page 1094: ...Index 4 Index Notes ...
Page 1095: ......