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ADF7020 continuous spurious output in rx mode, even when no carrier is present

Question asked by JohnH on Aug 8, 2011
Latest reply on Aug 9, 2011 by enash



I am working with the ADF7020, and notice that while in RX mode, the chip seems to output a continuous stream of spurious random bits, even in the complete absence of any carrier. Further, using the synch word helps a little, but there is enough randomness in this spurious data that it very frequently matches a synch word, so even using a synch word does not mitigate this. This occurs with both the linear FSK domodulator setting as well as with the correlator setting.


I was hoping to find some configuration setting that allows me to specify something like a minimum RSSI level below which it would not try to demodulate the input, but there does not seem to be anything like this.


What I would have hoped for would be that when there is no input there should be no output. I am using FSK. I'd have expected only to see a mark when the frequency corresponding to a mark is present, and a space only when the corresponding frequency is present.


Is it the expected behaviour to output a continuous stream of output when there is no carrier present?



If so, does anyone have any suggestions on how to deal with this? Again, even using a synch word does not address this because there are spurious occurrances of the synch word within the output stream.


Thanks much