ADRV9009-ZU11EG pyadi-iio

Hi,

In the system for the ADRV9009-ZU11EG, does anyone understand the mapping between the two ADRV9009, two channels per ADRV9009, two DDS tones per channel, two numbers for complex data into the sdr.dds_frequencies[...] vector?   I understand why it is 16 elements long, because 2*2*2*2=2^4 =16, based on the accounting from the sentence above.  Here is the code that references the dds_frequencies ... 

https://github.com/analogdevicesinc/pyadi-iio/blob/master/examples/adrv9009_som.py

https://github.com/analogdevicesinc/pyadi-iio/blob/master/adi/dds.py

The example shows, sdr.dds_frequeincies = [20e6, 0, 20e6, 0,0,..., 0] and sdr.dds_phases=[0,0,90000,0,0,0,90000,0,0,...,0]

I can see on the freq. domain plots that, that gives a single spike at -20MHz and none or very small amount at 20MHz.  

I can get the frequency to go to positive frequencies by changing the phase to 90 degrees associated with the 1st frequency. 

sdr.dds_frequeincies = [20e6, 0, 20e6, 0,0,..., 0] and sdr.dds_phases=[90000,0,0,0,0,0,90000,0,0,...,0]

Is this the correct way to sweep between positive and negative frequencies and only get a single frequency (and not the positive and negative)? 

I tried putting in negative frequencies but that did not work. 

Nathan

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