Technical Descriptions; Fhss Description - Panasonic KX-TG3411BXH Service Manual

4 Technical Descriptions

4.1.

FHSS Description

4.1.1. Frequency
The frequency range of 2.4 GHz-2.48 GHz is used. Transmitting and receiving channel between base unit and handset is same
frequency.
4.1.2. FHSS (Frequency Hopping Spread Spectrum)
This telephone is using an IC chip which has similar specification to WDCT (World Digital Cordless Telephone) and is the
telephone system that can use multiple portable unit simultaneously. The explanation of this system is mentioned below. This
system uses a Time Division Multiple Access/Time Division Duplex (TDMA/TDD) scheme:
transmitting and receiving frequencies of the base unit and handset are shared in the same frequency. The construction of RX/
TX frequency data is shown below. It consists of 6 slots from the base unit to the handset, and 6 slots from the handset to the
base unit, total 12 slots in 10 ms. By this slot system, simultaneous air link and communication between 6 handsets and the
base unit can be realized. One communication between handset and the base unit is done by one slot from the base unit to
handset, and another slot from handset to the base unit.
DSS makes spectrum spread by multiplying carrier signal by PN code. The purpose to make spectrum spread is to reduce
power density per time and per band. On the other hand, FHSS makes spectrum spread by changing channel every 10 ms
according to Hopping table. Also the purpose to make spectrum spread is to reduce power density per time and per band.
Handset - > Base Unit
RX1 RX2
FHSS
Current
system
DSS
Other
system
RX3 RX4 RX5
Frequency
Hopping
5 3
10 ms
Base Unit - > Handset
RX6 TX1 TX2
1 4 2
Frequency
Frequency
7
KX-TG3411BX/KX-TG3412BX/KX-TG3419BX/KX-TGA341BX
TX3 TX4 TX5 TX6