RF69 Datasheet, PDF (32/81 Pages) List of Unclassifed Manufacturers – Low Power Integrated UHF Transceiver with On-Chip +20dBm PA

RF69
signed result is loaded in FeiValue in RegFei, in 2‟ s complement format. The time required for an FEI evaluation is 4 times
the bit period.
To ensure a proper behavior of the FEI:
 The operation must be done during the reception of preamble
 The sum of the frequency offset and the 20 dB signal bandwidth must be lower than the base band filter bandwidth
The 20 dB bandwidth of the signal can be evaluated as follows (double-side bandwidth):

= 


The frequency error, in Hz, can be calculated with the following formula:
SRXF162939in Rx mode
Preamble-modulated input signal
Signal level > Sensitivity
Set FeiStart
=1
F eiD one
No
=1
Yes
R ead
F eiValue
Figure 14. FEI Process
3.4.15. Automatic Frequency Correction
The AFC is based on the FEI block, and therefore the same input signal and receiver setting conditions apply. W hen the
AFC procedure is done, AfcValue is directly subtracted to the register that defines the frequency of operation of the chip,
F_RF. The AFC can be launched:
 Each time the receiver is enabled, if AfcAutoOn = 1
 Upon user request, by setting bit AfcStart in RegAfcFei, if AfcAutoOn = 0
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