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PN 9 Sequence for AD9467

Question asked by simon32 on Aug 6, 2012
Latest reply on Aug 9, 2012 by David.Buchanan

Dear Forum,

 

I am testing an FPGA interface to the DDR output from an AD9467 ADC. One of the test modes for the AD9467 is to generate a PN 9 sequence. The first three numbers I read from the ADC are similar to three listed in the data sheet, i.e. 0x87BE, 0xAE64, 0x929D, with the exception of the MSB.

 

I am using two's complement data format. I have a couple of questions :

 

1) Does the data format used affect the output from the PN 9 sequence?

 

2) Is it possible to post the whole sequence to the forum, I'm assuming there are only 511/16 ~= 32 x 16 bit words? It would be useful to have the expected sequence for each data format, i.e. offset binary, twos complement and Gray coding.

 

3) Is example (say) C code available for generating the sequence used in the AD9467 including the initial seed? I have implemented the x9 + x5 + x0 polynomial and it seems to give different results.

 

Thanks in advance,

 

Simon

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