mrf89xa Microchip Technology Inc., mrf89xa Datasheet - Page 71

• Manufacturer Part Number: mrf89xa
• Description: Ultra-low Power, Integrated Ism Band Sub-ghz Transceiver
• Manufacturer: Microchip Technology Inc.

3.4.10.1
The FTOVAL<7:0> bits (FLTHREG<7:0>) determine
the sensitivity of the OOK receiver, as it sets the com-
parison threshold for weak input signals (that is, those
close to the noise floor). Significant sensitivity
improvements can be generated if configured correctly.
The noise floor of the receiver at the demodulator input
depends on the following conditions:
• The noise figure of the receiver
• The gain of the receive chain from antenna to
• The matching, including SAW filter
• The bandwidth of the channel filters
FIGURE 3-12:
© 2010 Microchip Technology Inc.
base band
Optimizing the Floor Threshold
FLOOR THRESHOLD OPTIMIZATION
FTOVAL<7:0>
Increment
Yes
Preliminary
Set MRF89XA in OOK RX mode
Default OOKTHSV<2:0> setting
Adjust Bit Rate, Channel filter BW
It is therefore important to note that the setting of the
FTOVAL<7:0> bits will be application-dependant. The
procedure shown in the flow chart in Figure 3-12 is
recommended to optimize the FTOVAL<7:0> bits.
The new floor threshold value found during this test
should be the value used for OOK reception with those
receiver settings.
Note that if the output signal on DATA is a logic ‘1’, the
value due to the FTOVAL<7:0> bits is below the noise
floor of the receiver chain. Conversely, if the output sig-
nal on DATA is a logic ‘1’, the value due to the
FTOVAL<7:0> bits is several dB above the noise floor.
Monitor DATA pin (pin 20)
Optimization complete
Continuous mode
No input signal
Glitch activity
on DATA ?
No
MRF89XA
DS70622B-page 71