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AD9789 and Rate Converter

Question asked by sda7 on Apr 10, 2013
Latest reply on May 24, 2013 by e.gatti@electrosys.it

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Hello all,

Improperly working Sample Rate Converter, the output signal has the unwanted images. If my calculations are correct? I may be something to consider? Please help solve my problem.

 

Channelizer Mode;

Fdac = 1800MHz;

Fbaud = 6,75MHz;

SRRC – enable;

Mapper – enable;

Interpolation factor N = 4;

Total interpolation ratio of the SRRC filter and the five half-band interpolation filters I = 2 * 2^4 = 32;

 

P/Q = Fdac / (Fbaud * 16 * I) = 100/192;

P = 0x640000;

Q = 0xC00000;

 

DCO divide factor N = 4;

Fdco = Fdac / (16 * N) = 28,125MHz;

 

When N = 2 no improvement occurs.

 

P.S. If we apply the P / Q = 0.5, all works very well, just not as Fbaud what is necessary.

Best regards!

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