89d4184393
This commits introduces a significant redesign of the AX.25 decoding block. Due to the poor AX.25 sync flag, the decoders exhibited too many false alarms. To deal with this problem, we introduced the quadrature demod filter block, that tried to measure the SNR based on the running variance of the signal. The problem with that was that the user should have to fine tune two parameters, the one related with the amplitude of the incoming signal and the second one related with the window that the calculations should take place. This solution worked until now, but we can always increase the performance. The new AX.25 decoder stores the bitstream in a queue and always tries to exlpoit possible valid frames in the queue. If now sync flags have been encountered, the queue is flushed. After a valid frame extraction, bits corresponding to this frame are also deleted from the queue. This technique requires more memory and CPU, but it increases a lot the decoding performance. |
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