Rf01 – Rainbow Electronics RF01 User Manual
Page 14
RF01
Bit 4-5 (rl0, rl1) range limit: Limits the value of the frequency offset register to the following values:
rl1
rl0
Max dev [f
res
]
0
0
No restriction
0
1
+15/-16
1
0
+7/-8
1
1
+3/-4
f
res
:
315, 433MHz bands:2.5kHz
868MHz band: 5kHz
915MHz band: 7.5kHz
Bit 6-7 (a0, a1) Automatic operation mode selector:
a1
a0
0
0
Auto mode off (Strobe is controlled by microcontroller)
0
1
Runs only once after each power-up
1
0
Keep the offset only during receiving (VDI=high)
1
1
Keep the offset value independently from the state of the VDI signa
In automatic operation mode (no strobe signal is needed from the microcontroller to update the
output offset register), the AFC circuit is automatically enabled when VDI indicates a potential incoming
signal during the whole measurement cycle and the circuit measures the same result in two subsequent
cycles.
There are three operation modes, example from the possible application:
1
, (a1=0, a0=1) The circuit measures the frequency offset only once after power up. This way, the
extended TX/RX maximum distance can be achieved.
Possible application:
In the final application when the user is inserted the battery the circuit measures and compensate
the frequency offset caused by the crystal tolerances. This method enables to use cheaper quartz in the
application and provide quite good protection against locking in an interferer.
2a
, (a1=1, a0=0) The circuit measures automatically the frequency offset during an initial low data
rate pattern –easier to receive- (i.e.: 00110011) of the package and change the receiving frequency
according that. The further part of the package can be received by the corrected frequency settings.
2b
, (a1=1, a0=0) The transmitter must transmit the first part of the packet with a step higher
deviation and later there is a possibility to reduce it.
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