RFM69HCW Datasheet, PDF (28/79 Pages) List of Unclassifed Manufacturers – ISM TRANSCEIVER MODULE

RFM69HCW
Note
- RssiValue can only be read when it exceeds RssiThreshold
- The receiver is capable of automatic gain calibration, in order to improve the precision of its RSSI measurements.
This function injects a known RF signal at the LNA input, and calibrates the receiver gain accordingly. This
calibration is automatically performed during the PLL start-up, making it a transparent process to the end-user
- RSSI accuracy depends on all components located between the antenna port and pin RFIO, and is therefore
limited to a few dB. Board-level calibration is advised to further improve accuracy
RSSI Chart - With AGC
0.0
-20.0
-40.0
-60.0
-80.0
-100.0
-120.0
-120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0
Pin [dBm]
Figure 8. RSSI Dynamic Curve
3.4.10. Cordic
The Cordic task is to extract the phase and the amplitude of the modulation vector (I+j.Q). This information, still in the
digital domain is used:
‹ _{Phase output: used by the FSK demodulator and the AFC blocks.}
‹ Amplitude output: used by the RSSI block, for FSK demodulation, AGC and automatic gain calibration purposes.
Real-time
Magnitude
Q(t)
Real-time Phase
I(t)
Figure 9. Cordic Extraction
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