RSSI register count accuracy

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    Question: What kind of accuracy can be expected on the RSSI register count value?

     

    Answer:

    RSSI values from the datasheet:

       
    •    Typical Receiver Sensitivity of -90 dBm
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    •    Typical RSSI value for PWRin > -40 dBm is 28 - 31
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    •    Typical RSSI value for PWRin < -95 dBm is 0 -10

     

    Our in-house testing has revealed roughly +/-7.5dBm part variance. RSSI register count vs. input power level is relatively linear over a given power level range.

    General note: With a single reading, the RSSI value it is meant to be used for a crude relative signal level measurements between channels and to decide if a signal or interferer is near the noise floor or is plenty strong. Averaging several samples on a channel improves the relative accuracy significantly especially for signals near the noise floor where signal-plus-noise will cause more uncertainty in the RSSI value. The absolute accuracy of the RSSI varies from part to part but is stable over the entire temperature range (+/-1 count) and supply voltage range (+/- 0.5 count). Absolute accuracy would require a careful calibration step in a well controlled final test environment.