SX1231
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
Q(t)
Real-time
Magnitude
Real-time Phase
I(t)
Figure 8. Cordic Extraction
3.5.10. FSK Demodulator
The FSK demodulator of the SX1231 is designed to demodulate FSK, GFSK, MSK and GMSK modulated signals. It is
most efficient when the modulation index of the signal is greater than 0.5 and below 10:
2 × FDEV
----------------------
0.5 ≤ β =
≤ 10
BR
The output of the FSK demodulator can be fed to the Bit Synchronizer (described in section 3.5.12), to provide the
companion processor with a synchronous data stream in Continuous mode.
3.5.11. OOK Demodulator
The OOK demodulator performs a comparison of the RSSI output and a threshold value. Three different threshold modes
are available, configured through bits OokThreshType in RegOokPeak.
The recommended mode of operation is the "Peak" threshold mode, illustrated in Figure 9:
RSSI
[dBm]
‘’Peak -6dB’’ Threshold
‘’Floor’’ threshold defined by
OokFixedThresh
Noise floor of
receiver
Time
Zoom
Zoom
Decay in dB as defined in
OokPeakThreshStep
Fixed 6dB difference
Period as defined in
OokPeakThreshDec
Figure 9. OOK Peak Demodulator Description
Rev 2 - Nov 2009
Page 27
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