FXTH870xD
Sensors
Freescale Semiconductor, Inc.
97
Figure 70. Impact of Duty-Cycle on SYNC Pattern
12.12
Input Signal Envelope
The combination of the external LF antenna and any external components as shown in
should not significantly filter
the envelope of the LF carrier as shown in
. Excessive filtering will cause the received message error rate (MER) to
increase.
Figure 71. Antenna Q-factor Equivalent Model for the LF Envelope
Figure 72. LF Envelope Filtering
LFA
LFB
SUZUKA
Antenna model
C
R
• Antenna Q-factor acts as a 1
st
order
low pass filter on the LF envelop
• Filter time constant :
t
= R.C
Recommended
< 15.3
sec
Recommended
< 15.3
sec
Содержание FXTH870 D Series
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