mrf89xa Microchip Technology Inc., mrf89xa Datasheet - Page 72

• Manufacturer Part Number: mrf89xa
• Description: Ultra-low Power, Integrated Ism Band Sub-ghz Transceiver
• Manufacturer: Microchip Technology Inc.

3.4.10.2
A sudden drop in signal strength can cause the bit error
rate to increase. For applications, where the expected
signal drop can be estimated, the OOK demodulator
parameters set by the OOKTHSV<2:0> and OOK-
THPV<2:0>
OOKCREG<4:2>) can be optimized.
For a given number of threshold decrements per bit,
specified by OOKTHPV<2:0>:
• 000
• 001
• 010
• 011
• 100
• 101
• 110
• 111
For each decrement of value from OOKTHSV<2:0>
bits:
• 000
• 001
• 010
• 011
• 100
• 101
• 110
• 111
DS70622B-page 72
MRF89XA
once in each chip period (default)
once in 2 chip periods
once in 4 chip periods
once in 8 chip periods
twice in each chip period
4 times in each chip period
8 times in each chip period
16 times in each chip period
0.5 dB (default)
1.0 dB
1.5 dB
2.0 dB
3.0 dB
4.0 dB
5.0 dB
6.0 dB
Optimizing OOK Demodulator
Response for Fast Fading Signals
bits
(OOKCREG<7:5>
and
Preliminary
3.4.10.3
In addition to the Peak OOK threshold mode, the user
can alternatively select other two types of threshold
detectors:
• Fixed threshold: The value is selected through the
• Average threshold: Data supplied by the RSSI
In Equation 3-14, the higher cut-off frequency enables
a sequence of up to eight consecutive ‘0’s or ‘1’s to be
supported, while the lower cut-off frequency presented
in Equation 3-15 allows for the correct reception of up
to 32 consecutive ‘0’s or ‘1’s.
EQUATION 3-14:
EQUATION 3-15:
OOKCREG register (for more information, refer to
Section 3.4.10.1 “Optimizing the Floor Thresh-
old”).
block is averaged with the cut-off frequency.
OOKATHC<1:0>
OOKATHC<1:0>
Alternative OOK Demodulator
Threshold Modes
=
=
00
© 2010 Microchip Technology Inc.
11
⇒
⇒
f
cutoff
f
cutoff
=
=
BRVAL<6:0>
--------------------------------- -
BRVAL<6:0>
--------------------------------- -
8 π
32 π
•
•