Overview:
Bluetooth radios operate in the unlicensed ISM band at 2.4 GHz. A frequency hop transceiver is applied to combat interference and fading. A shaped, binary FM modulation is applied to minimize transceiver complexity. The gross data rate is 1Mb/s. A Time-Division Duplex scheme is used for full-duplex transmission.

The Bluetooth baseband protocol is a combination of circuit and packet switching. Slots can be reserved for synchronous packets. Each packet is transmitted in a different hop frequency. A packet nominally covers a single slot, but can be extended to cover up to five slots. Bluetooth can support an asynchronous data channel, up to three simultaneous synchronous voice channels, or a channel which simultaneously supports asynchronous data and synchronous voice. Each voice channel supports 64 kb/s synchronous (voice) link. The asynchronous channel can support an asymmetric link of maximally 721 kb/s in either direction while permitting 57.6 kb/s in the return direction, or a 432.6 kb/s symmetric link.

Radio
The Bluetooth air interface is based on a nominal antenna power of 0dBm. The air interface complies with the FCC rules for the ISM band at power levels up to 0dBm. Spectrum spreading has been added to facilitate optional operation at power levels up to 100 mW worldwide. Spectrum spreading is accomplished by frequency hopping in 79 hops displaced by 1 MHz, starting at 2.402 GHz and stopping at 2.480 GHz. Due to local regulations the bandwidth is reduced in Japan, France and Spain. This is handled by an internal software switch. The maximum frequency hopping rate is 1600 hops/s. The nominal link range is 10 centimeters to 10 meters, but can be extended to more than 100 meters by increasing the transmit power.

Radio specification

Receiver

RX sensitivity: -70dBm

IP3: -16dBm

CP1dB: -26dBm

Double-sided IF bandwidth: 1.0MHz

C/Ico-channel (0.1% BER): 11dB

C/I1MHz (0.1% BER): -8dB

C/I 2MHz (0.1% BER): -40dB

C/IAWGN (0.1% BER): 18dB

In-band image rejection: 20dB

Antenna diversity: not required

Transmitter

TX power:

nominal: 0dBm

optional range:-30 - +20dBm

Modulation index (no ISI): 0.28-0.35

TX carrier offset: <75kHz

TX carrier drift in slot: TBD

Adjacent channel power (1MHz): -20dBm

Out of band spuriousness: 50dB

Power control requirements:

optional range: -30 - +20dB

Frequency Sources

Reference timer accuracy: 20ppm

L500kHz: -89dBc/Hz

L 2MHz: -121dBc/Hz

Channel-switching time: 220us

TX/RX turnaround time: 220us

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