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Transmitted PRBS sequence will be received at the Receiver end but how do we synchronize this sequence to the PRBS sequence generated at the receiver end and show that the BER is zero
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There's two ways:
1) You can receive a block of received bits, eg., 16-bits of the PRBS sequence, and use that as the seed to a local PRBS generator. The output of that local generator can then be XORed with the incoming stream.
Basically, you use the incoming PRBS stream to 'seed' your local generator, and then use your local generator to 'predict' what the next received pattern should be. The XOR of those patterns should be zero if they match.
You need a small control FSM to determine when to load the seed versus when to check the patterns and increment the BER counters.
This is how the Altera pattern generators/checkers work.
2) You can use the receiver pattern matching/alignment features.
I need to align multiple PRBS lanes. To do that, I use the pattern alignment features of the receiver, I use FIFOs to cross from the multiple receiver clock domains, and I use a local PRBS to track synchronization.
I can explain this second option in more detail if you need it.
Cheers,
Dave
Honored Contributor
