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AD9239 - data shift between channels

Question asked by david77 on Jan 25, 2011
Latest reply on Jan 26, 2011 by david77

Hi,

 

I'm using a AD9239-250 connected with a Xilinx virtex 5 (rocket IO GTX).

It works not so bad but i still have a problem that i don't understand.

 

When i put the PMGs inputs to 0, i get the user pattern that is in my case "CCAADDBB11224455". so i have on each channels :

Chan1 => 1122 4455 CCAA DDBB 1122 4455 CCAA DDBB

Chan2 => CCAA DDBB 1122 4455 CCAA DDBB 1122 4455

Chan3 => DDBB 1122 4455 CCAA DDBB 1122 4455 CCAA

Chan4 => CCAA DDBB 1122 4455 CCAA DDBB 1122 4455

Then if i synchronized on the "CC" comma i ll have my 4 channels synchronized. That is ok.

 

Then when i put PMGs inputs to 1 (i have the same signal splited in 4 on the Analog inputs), i get on my 4 channels :

Chan1 => DDBB   1122     4455      CC3B     6370     A8DC    335F      CCC2     0BA3

Chan2 => 1122     4455     CC40     E3BF     372A     8251     CCC3     EC20     BA99

Chan3 => 4455     CC52    8404      3B43      6213     CCA7    3C3B     C18B     A47D

Chan4 => 4455     CCAA   DDBB    1122      4455     CC3B     537B     A8AC     3051

 

As you can see after the last user patter packet (4455) i get "CC" then the first 12 bits data.

They should all be similar (red), but actually only the channel 1 and 4 are similar. But if we shift a bit the data on others channels (blue), we can see similar value. So in reallity aftter the "CC" we should get these blue values for channel 2 and channel 3.

 

Since the way these data are shifted is really random i cannot find a way to synchronized my 4 channels.

 

Please help me to found a way out.

Thank you

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