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AD9959 doing 2 different frequency sweeps and AM on 2 channels at once.

Question asked by Chris2017 on Dec 19, 2017
Latest reply on Jan 2, 2018 by Chris2017

Hello all,

I'm just asking to see if what I have in mind is feasible.

What I have done so far is get an Arduino Due to control the AD9959 for frequency sweeps and AM on one channel. The AM is NOT the inbuilt ramping of the DDS, I made my own for loop/etc in the arduino to continuously update the ACR register to get a nice linear sweep.

My ultimate end goal is to have 3 outputs, all of which are independent to each other. Two of the outputs would have different AM and frequency sweeps while the 3rd is just a constant amplitude/frequency output.

 

My questions are:

Is it feasible to get 2 channels outputting at the same time with different frequency sweeps on either channel?

The data sheet suggests a protocol for getting all 4 channels going at different frequencies - my issue being that there is only 1 LSR and RDW/FDW register (and also one ACR register).

So would this mean that the best I could do is start and stop each channel at different frequencies (using the CW registers 1-18), but their ramp rate/step size would all be identical?

Following this, I would not be able to doing different amplitude ramps either due to the way I have done my AM (continuously updating it in a for loop)?

In fact I believe because of how I've done the AM, bypassing the profile pins, I could not even have a separate channel set to be constant amp/freq?

(Note: the datasheet does say that there are apparently 4 CFR registers, but how do you address each individually?)

 

The only thing I could think of is if you can use the CW1-18 as substitutes for the ACR/etc registers, allowing me to have multiple different functions going at once. However I get the feeling that my best option for getting my desired outputs may be to get 2 AD9958 (only 2 channel) boards and wire them up to and arduino each.

 

Cheers,

Chris

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