SX1231-31SKB868-EVAL Semtech, SX1231-31SKB868-EVAL Datasheet - Page 30

• Manufacturer Part Number: SX1231-31SKB868-EVAL
• Description: development tool usb kit for sx1231 transceiver...
• Manufacturer: Semtech

3.5.12.1. 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:
It is therefore important to note that the setting of OokFixedThresh will be application dependant. The following procedure
is recommended to optimize OokFixedThresh.
The new floor threshold value found during this test should be used for OOK reception with those receiver settings.
3.5.12.2. Optimizing OOK Demodulator for Fast Fading Signals
A sudden drop in signal strength can cause the bit error rate to increase. For applications where the expected signal drop
can be estimated, the following OOK demodulator parameters OokPeakThreshStep and OokPeakThreshDec can be
optimized as described below for a given number of threshold decrements per bit. Refer to RegOokPeak to access those
settings.
3.5.12.3. Alternative OOK Demodulator Threshold Modes
In addition to the Peak OOK threshold mode, the user can alternatively select two other types of threshold detectors:
Rev 4 - Nov 2010
ADVANCED COMMUNICATIONS & SENSING
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.
Fixed Threshold: The value is selected through OokFixedThresh
Average Threshold: Data supplied by the RSSI block is averaged, and this operation mode should only be used with
DC-free encoded data.
Figure 10. Floor Threshold Optimization
OokFixedThresh
Increment
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Adjust Bit Rate, Channel filter BW
Default OokFixedThresh setting
Set SX1231 in OOK Rx mode
Monitor DIO2/DATA pin
Optimization complete
Continuous Mode
No input signal
Glitch activity
on DATA ?
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