PN 9 Sequence for AD9467

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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  • 0
    •  Analog Employees 
    on Aug 9, 2012 5:52 PM over 8 years ago

    Hi,

    Yes, the data formatter is downstream from both the ADC core and the test pattern generator, and the selected data format is applied in all conditions.  The pattern is 511 16 bit words, and follows the ITU-T 0.150 (05/96) standard, and the seed value for the AD9567 is 0XFFFF. Attached please find the pn9 sequence in both offset binary and 2's complement formats.  Unfortunately we don't have any C code for generating the sequence.  I hope this helps.

    Regards,

    David

     

     

    AD9467pn9Sequence.xls
Reply
  • 0
    •  Analog Employees 
    on Aug 9, 2012 5:52 PM over 8 years ago

    Hi,

    Yes, the data formatter is downstream from both the ADC core and the test pattern generator, and the selected data format is applied in all conditions.  The pattern is 511 16 bit words, and follows the ITU-T 0.150 (05/96) standard, and the seed value for the AD9567 is 0XFFFF. Attached please find the pn9 sequence in both offset binary and 2's complement formats.  Unfortunately we don't have any C code for generating the sequence.  I hope this helps.

    Regards,

    David

     

     

    AD9467pn9Sequence.xls
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