Is there some limits that the sample rate can't set higher than 8Mhz when using QAM encoder of AD9789?
Thanks in advance
By my calculations, your input data rate of 8 MHz is too high. Based on the 1884.16 MHz DACCLK and 16x + 4*2x interpolation, your data rate should be 7.36 MHz. Please try that and see if you still lose data, or increase your DACCLK to 2.048 MHz.
When i use QAM encoder, the sample rate(code rate) can't set higher than 8MHz, it will lead to bad output, but the datasheet said the sample rate can be fDAC/48, so I don't know if I mad a mistake or the QAM encoder has some limits。Thanks a lot!
You'll need to check that you have the correct interpolator rates and clock rates chosen. Can you give some more details of the exact configuration you have and what you are trying to do?
Thanks for your reply,And I want to use AD9789 to finish QPSK in DVB 16-QAM mode,When I set the sample rate higher than 8MHz,I found it began to lose some data.My configuration is as the list:fDAC=1884.16MHz,sample rate=8MHz(I have tested with oscilloscope).I bypass the SRRC and one of Half-Band Interpolation Filters,then I have tried many delay value,but the problem didn't solve.
I wonder that there is some limits in QAM encoder,becouse I see some standard the QAM encode rate is always lower than 8MHz,
does AD9789's QAM encoder have the same limits?
Thanks a lot. I read the datasheet that "when use Channelizer Mode,The maximum baud rate supported in channelizer mode is fDAC/48",so why don't I set the baud rate to higher than 8MHz?
Thanks very much.
That refers to the maximum bandwidth of the 16x interpolator's filter stop band. In your case, you need to calculate your data rate max by dividing your DACCLK by the 16x interpolator plus the other 4 interpolators you have enabled, for a total divide of 256.
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