NXP Semiconductors MKW01Z128, Reference Manual

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Sub 1 GHz Transceiver Architecture Description
MKW01xxRM Reference Manual, Rev. 3, 04/2016
5-18 Freescale Semiconductor, Inc.
Figure 5-7. OOK Peak Demodulator Description
In peak threshold mode the comparison threshold level is the peak value of the RSSI, reduced by 6dB. In
the absence of an input signal, or during the reception of a logical "0", the acquired peak value is
decremented by one
OokPeakThreshStep every OokPeakThreshDec period.
When the RSSI output is null for a long time (for instance after a long string of "0" received, or if no
transmitter is present), the peak threshold level will continue falling until it reaches the "Floor Threshold",
programmed in
OokFixedThresh .
The default settings of the OOK demodulator lead to the performance stated in the electrical specification.
However, in applications in which sudden signal drops are awaited during a reception, the three parameters
should be optimized accordingly.
5.7.11.1 Optimizing the Floor Threshold
OokFixedThresh determines the sensitivity of the OOK receiver, as it sets the comparison threshold for
weak input signals (i.e., those close to the noise floor). Significant sensitivity improvements can be
generated if configured correctly.
Note that the noise floor of the receiver at the demodulator input depends on:
• The noise figure of the receiver.
• The gain of the receive chain from antenna to base band.
• The matching - including SAW filter if any.
• The bandwidth of the channel filters.