Question
How to change the start frequency (Fstart) of the AD5930 on the fly withoutoutput interruption?
Answer
Please note that AD5930 was designed to generate a frequency sweep.I would recommend you to use AD9837 or AD9833 if you would like to use singlefrequency and update manually.
http://www.analog.com/en/products/rf-microwave/direct-digital-synthesis-modulators/ad9833.html
http://www.analog.com/en/products/rf-microwave/direct-digital-synthesis-modulators/ad9837.html