5203 Arbitrary Generator

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5203 Arbitrary Generator

Post by Guest » Fri Jun 25, 2010 11:11 am


I am trying to set up the arbitrary generator on the 5203 and found some unclear points in the documentation.

The manual says: "The arbitrary waveform generator uses direct digital synthesis (DDS). It maintains a 32-bit phase counter that indicates the present location in the waveform. The top 11 bits of the counter are used as an index into a buffer containing the arbitrary waveform."

11 bits would mean 2^11=2048 samples, while the data sheet states that the 5203 has a 8k memory - what is wrong here?

The sample code ps5000con.c has a passage:
" * - allows for custom waveform (values 0..4192) of up to 8192 samples long", but the data sheet says the DAC has a resolution of 12 bit, so range would be 0..4095 - which one is correct?

The API call ps5000SetSigGenArbitrary has a parameter "arbitraryWaveformSize, the size of the arbitrary waveform buffer", how is this used? It does not make sense for continuous signals to upload only a partial (less than 8192 samples) waveform unless
- you want to have gaps in the generated waveforms (which means the remaining samples would need to be interpreted as 0)
- the DDS phase accumulator is changed to wrap not at 8191 samples, but at a lower sample number (which would be possible, but rather uncommon for a DDS). How does this work?

- Martin

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Re: 5203 Arbitrary Generator

Post by Robin » Mon Jun 28, 2010 1:37 pm

Hi Martin

The comment in the console example is incorrect. The signal range should be 0 to 4095 (I have changed this in the example).

When you call ps5000SetSigGenArbitrary, the waveform buffer can be between




The phase counter is changed to wrap at the size of the buffer.

Regarding the phase counter, the manual is incorrect, it should say "the top 13 bits". I will make sure this is corrected.

Thanks for bringing this to our attention.



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