hello i am using ad9858 dds . and i want to generate chirp having freq range from 10 khz to 1 Mhz. how can i set start freq and stop freq
Once the AD9858 starts the frequency sweep, it's not setup to automatically stop on a output frequency. The user must program the part (step rate or step size to zero) during the sweep while externally tracking the sweep and then issue an FUD to stop the sweep at the desired output frequency.
There's other DDSs that can do this automatically. If interested, I would recommend looking at the AD9910. That part has the most flexiability.
thanks for giving anser but when i start the sweeping at 10 Khz , it goes to about 250 Mhz and then back to 0Hz or very low frequency.
so it always sweep in whole span rather it shas to stop at 10 Khz in downside.
i set start freq from one of four profle. Is it right way?
if it is right then i have to calculate time required for frequency sweep i.e. T given in data sheet. but where i have to put in the VB code?
or can u provide me VB code that can be used to set the start freq and stop freq?
See later post for further discussion
i did not understand your answer .
which post should i refer?
rt - it looked to me like your later post was further discussion on this same topic, is this still an open question?
yes this question is still open because i could not generate chirp with specific frequency range.
Per my other posts, if setting the frequency step word to zero does not stop the frequency sweep then the DDS may be damaged because it should stop the sweep.
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