Synchronous analog outputs coded in Python show DELAY

[Alessandro]

Good morning,
I'm new in this forum. I'm writing because I'm working on a project related to the generation of two encoded signals. As you can see from the uploaded code, the encoded signal (encoded[]) is made of a fixed base (encoding[]) that is multiplied by each element in the array data[].
Therefore the encoded signal is a bit stream of 0 and 1 that I created using funcCustom.

The main constraint of this projects is that the two signals must be SYNCHRONOUS.

The PROBLEM is that in reality they're not as you can see from the oscilloscope image. Sometimes it happens that there is a small delay of 4µs and sometimes there isn't at all. Why does it happen? This is crucial for my application. 
In the code I used this kind of synchronization:

dwf.FDwfAnalogOutMasterSet(hdwf, c_int(1), c_int(0))
dwf.FDwfAnalogOutConfigure(hdwf, c_int(-1), c_bool(True))

Thank you,
Alessandro

CDMA_customFunc.py

[attila]

Hi @Alessandro

For such digital signals it would be better to use the digital-out function.

I've made some changes to your script to generate without jitter: CDMA_customFunc.py

With analog-out use the funcCustomPattern option to have fixed sample rate. With funcCustom it aims for the specified frequency using fraction sample step which results varying sample lengths.
With AD2 the given pattern is fit to the buffer size, so power of two number of samples should be provided to have equal sample rate.
The latest software fixes a possible 20ns phase problem:
https://forum.digilentinc.com/topic/8908-waveforms-beta-download/

 

[Alessandro]

Hi,
assume that I want to change my code with two synchronized digital outputs. Is there a way to set the digital output voltage level in AnalogDiscovery2?

Thank you

[attila]

Hi @Alessandro

See the following post: