The CRC16 of the AX.25 seems that is too weak for the new
decoding approach and we get many false positives.
Now the AX.25 decoder, makes waits for at least two
occurances of the AX.25 SYNC flag.
In case of scrambling the self synchronizing scrambler ensures
that enough repetitions of the AX.25 flag have been received.
However, this does not hold for the case of non scrambled
transmissions. In this case, we wait for at least two consecutive
AX.25 flags to reduce the false alarms. Experiments have shown
that due to the poor CRC there were many false positive frames.
It is expected however, to miss some transmissions that use only one
AX.25 flag.
The decoders produce a PMT message containing several information about
the decoded frame. While this is very convenient for handling data
inside the flowgraph, it is not for third party applications. The JSON
converter block is responsible to serialize all the information
contained in a PMT originating from a decoded frame.
For simple demonstration some metadata were added on the AX.25 decoder.
These metadata are still a WIP and they subjected to changes.
Manolis Surligas