Editor :
KS.Kim
Document name
Project code
Version:
1.0
Nov. 28. 2013
ECO / DF No.
Identification No. : Document No.
File:
Page 4 / 6
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Technical aspects of 125 kHz
– magnetic field:
virtually no reflections,
cubical decrease of field strength
allows good range control,
released frequency band (ISM),
high penetration,
low quiescent current demand due to 125 kHz input stage (SMART KEY FOB),
less sensitive for detuning compared to higher frequency.
For the down-link from the SMART KEY FOB to the vehicle, the standard radio frequency
(RF) is used (similar to the classic remote control functions) with FSK modulation.
1.3
System Overview / Block Diagram
Figure 1: Principle of Communication
ECU sends LF challenge via exterior antenna
ID tag sends identification code to RF receiver
Doors are unlocked automatically
User pulls open the door
L
F
R
F
