CXA1994AM/BM
Description of Operation
M-ary (M = 2- or 4-level) FSK emodulation system
Polarity discrimination output and MSB comparator output are used to demodulate the 4-level waveform shown
below.
4-level FSK demodulating waveform
+4.8kHz
+1.6kHz
–1.6kHz
01 00 10 11 01 10 00
–4.8kHz
Polarity discrimination output
POS
NEG
0 011 010
MSB comparator output
1.6kHz
4.8kHz
10 011 00
The 4-level FSK demodulating data is divided into a polarity discrimination output and a MSB comparator
output shown above. Here, the polarity discrimination output corresponds to a conventional NRZ comparator
output. The MSB comparator output is made comparing to the optional level setting between MSB and LSB
levels as reference.
For the 2-level FSK demodulation, it corresponds to a conventional NRZ comparator output.
Take care that the polarity of NRZ output is inverted in CXA1484A.
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