ADC08D1520: WaveVision - How to increase bounds of X-Axis

Mitchell

Part Number: ADC08D1520

Hi Team,

My customer is evaluating the ADC08D1520 EVM and is having some trouble reading out their signal using the WaveVision tool. We have a couple questions:

1. Is there any way to increase the bounds of the x-axis in the FFT window? We wanted to sample at least a 2Ghz signal but the bounds seem to max out at 800Mhz with no option to expand.

For reference, they are actually sending the ADC a 1Ghz signal and the readout is shown in the figure attached. We are not able to see the 1Ghz signal, just it’s harmonic at 500Mhz. You can see on the x-axis that the highest measurable frequency seems to be 800Mhz. When we export that data it gives us the dataset which also ends at 750Mhz. We were hoping to send at least a 2Ghz signal.

X-axis scaling allows us to zoom in and out on the axis but doesn’t increase/decrease the bounds.

2. Is there a way to export the time domain data points into a .csv file?

When exporting in the time domain we get a single buffer (8k – 32k data points) but was hoping there may be a way to get more than that in an export?

Thanks,

Mitchell

over 6 years ago

0 jim s over 6 years ago

TI__Guru* 91947 points

Mitchell,

We are looking into this.

Regards,

Jim

0 Mitchell over 6 years ago in reply to jim s

TI__Expert 4915 points

Hi Jim,

Thanks. Do you have any updates on this?

Thanks,
Mitchell

0 Rob Reeder over 6 years ago in reply to Mitchell

TI__Mastermind 40460 points

Hi Mitchell,

I apologize for the delay.

1) Wavevision will only display first Nyquist. Therefore, you are seeing the correct signal, which is the 1GHz signal folded back. This is not a harmonic, not the 500MHz signal anyway. The harmonics will be folded back as well and will move back and forth across the Nyquist display.

Here is some reading material which describes this effect.

https://training.ti.com/bandwidth-vs-frequency-subsampling-concepts

2) to export the time domain data to csv file. This is described on page 9 of the Wavevision user guide. Here is a link to the user guide.

https://www.ti.com/lit/ug/snau003/snau003.pdf

First save it as an ASCII file, then bring this into Excel and save off as a csv file. There doesn't look like there is a direct way to save this off as a csv unfortunately.

3) Lastly, the FIFO capture of the FFT is can only be up to 32k deep. Unfortunately custom FPGA code would need to be written and possibly a new FPGA used to get a deeper capture and therefore more samples.

I hope this helps.

Regards,

Rob

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ADC08D1520: WaveVision - How to increase bounds of X-Axis