TDA5230 Datasheet, PDF (86/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
Functional Description
Do 500 (50) readings of ASKNP with no RF input signal applied (=noise only). Calculate
average and Standard Deviation (automatically done by TDA523x Explorer). Signal
Detector Threshold is average plus 2 times the standard deviation. Of course this value
has to be rounded and converted to hexadecimals. For a final application the Signal
Detector Threshold should be varied to optimize the false alarm rate and the sensitivity.
Verification if Squelch only is possible
Apply a bit pattern (e.g.PRBS9) with correct data rate at about -80 dBm input signal
power and minimum FSK deviation to the RF input. Do 500 (50) readings of ASKNP
calculate average minus three times the Standard Deviation. This value should be higher
than the calculated Signal Detector Threshold calculated above. If this is not the case,
Signal Detector AND Noise Detector must be used.
Noise Detector Threshold
Do 500 (50) readings of FSKNP with no RF input signal applied (=noise only). Calculate
average and Standard Deviation. Noise Detector Threshold is average minus the
standard deviation. Round this value and convert it to hexadecimals. For a final
application, the Noise Detector Threshold should be varied to optimize false alarm rate
and sensitivity.
Signal Detector Low Threshold:
The Signal Detector Low Threshold is always required in combination with the Noise
Detector.
Set register bit SDLORE to 1. Apply a bit pattern (e.g.PRBS9) at correct data rate at
about -80 dBm input signal power and minimum FSK deviation to the RF input. Do 500
(50) readings of ASKNP calculate average. Change SDSELLO till average is smaller
than 50d (0x32). SIGDETLO = 0.8 * (average - 3 * standard deviation). Set register
SDLORE back to 0. The last setting of SDSELLO has also to be used for configuration!
Verification
Threshold settings should be verified by testing receiver sensitivity over the input
frequency range, with a steps size of 100Hz, at minimum FSK deviation with all
combinations of minimum and maximum data rate and duty cycle.
A detailed description of the suggested procedure to determine the signal and noise
detector thresholds for user specific applications can be found in the application notes
“How to choose an Application specific Signal Detection Threshold for TDA523x based
ASK Mode Applications” and “How to Choose an Application Specific Signal- and Noise-
Detection Threshold for TDA523x based FSK Mode Applications”.
Data Sheet
82
Version 4.0, 2007-06-01