Bt Unit Description - Panasonic KX-TH1211B Service Manual

KX-TH1211B/KX-TH1212B/KX-TGA930T
4.3.

BT Unit Description

4.3.1. Frequency
The frequency range of 2,402 MHz - 2,480 MHz is used. Refer to Frequency Table (P.56).
4.3.2. Bluetooth Technology
This communication system uses the Chipset of Bluetooth technology. Bluetooth Technology make this system possible to use
multiple Voice and Data link simultaneously. Bluetooth technology uses the Frequency Hopping Spread Spectrum (FHSS)
scheme, and the Time Division Multiple Access/Time Division Duplex (TDMA/TDD) scheme.
4.3.2.1. Frequency Hopping Spread Spectrum (FHSS)
FHSS is one of the schemes of Spread Spectrum technology. The advantage of Spread spectrum is lower average power
density, better tolerance to interference and better security. FHSS transmitter makes its spectrum spread by changing the
transmitting frequency very fast.
Bluetooth system changes its channel on every chance of transmitting, based on its own Hopping table. The maximum hopping
rate is 1600 hops/second, and the number of hopping channels is 79.
4.3.2.2. Time Division Multiple Access/ Time Division Duplex (TDMA/TDD)
TDMA/TDD is time-sharing scheme for simultaneous multiple communication. TDMA/TDD structure of Bluetooth is more flexible
and complicate than other FHSS cordless telephone systems.
The length of a Bluetooth communication slot is 625 µs. On Base Unit, RX slot is always just after the TX slot to receive response
from Terminal Unit. Below figure is an example of Slot condition on Base Unit.
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