BrettE wrote:
> Well I figured it out. Apparently the BCM3510 won't lock onto an
> Annex A 64QAM or 256QAM if it is stuffed with MPEG null packets. I
> modified my mpeg block to send a 0x47 sync byte, followed by 187 bytes
> of PRBS15 sequence and now the BCM3510 demodulator is locked and
> happy.
>
> To me this seems like a bug in the demodulator, why should it care
> what is inside the mpeg packets? The next step in the modulator is a
> randomizer, so there was already plenty of randomization in the bit
> stream being fed into the interleaver - byte to symbol mapper -
> etc. . . Plus the BCM3510 was happy locking onto Annex A 16QAM,
> 32QAM, and 128QAM with MPEG null packets.
>
> Anybody ever hear of anything like this?

Before it finds the beginning of the packet, it doesn't know what's
inside and what's start/end overhead. If it could know to ignore the
packet's payload, it would have already synced.

Jerry
--
Engineering is the art of making what you want from things you can get.
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