DT9816-S External A/D Sample Clock -

[pmohan]

Using 1KHz, 2usec ttl clock to pin 39 for external A/D clock. Using 'software trigger' to get any data sampling to show on the display. Under the "Acquisition info " it shows a different sample rate that is not my external rate but the default internal A/D clock freq set in the sample freq window box.  The A/D appears to be not picking up the external clock. The manual says the clock frequency is always equal to the frequency of the external A/D sample clock input that you connect to the module. I do not see any place to select "external clock" within QuickDAQ acquisition tab . Is there some other place I need to go to recognize my external clock ? Do I need to also apply an external trigger as well ?   I've tried various pulse widths and frequencies for the external clock with no change in result.    Thanks.

[JRys]

Hello,

The DT9816-S does not have a frequency counter built into external clock input to measure the external signal. If you know the rate, a simple fix is to set the internal rate to match it. 

Best regards,

John

 

[pmohan]

Thanks John,

It certainly is easy to match the desired sample frequency to my external data source PRF as you suggest. However, its the phase that is critical. I have a low duty cycle input waveform (constant PRF) that needs to be sampled precisely within a 250 to 500ns interval after a mode-based delay from PRF start. I purchased the 9816 based on the data sheet items 1) external ADC clock capable 2) Data logging app included. Unfortunately, the data sheet does not inform us " QuickDaq does not support external ADC clocking."  This is a key point a user should know.

How do customers use the 9816 external ADC clocking and log data ? This seems like a topic of interest that should be covered in a document somewhere . Are there other software add-ons that can support external clocking (and log data) for the 9816?

If I can't sync the 9816 to my external timing, I could try to sync my external system to the 9816 . Can I output a synchronized copy of the  9816 ADC clock to one of the digital outputs? I could then use that to sync my external pulse generator .

Regards, Paul

[JRys]

Hi Paul,

I'm sorry, I mistakenly thought QuickDAQ supported external clocking. You could look into using the DASYLab software because it supports both external clock and trigger. https://www.mccdaq.com/products/dasylab.aspx. Keep in mind that even with DASYLab the sample rate will be unknown because the hardware is unaware of the external clock frequency. 

Best regards,

John

[pmohan]

So I will need to buy the DASYLAB license for $1300 to use the 9816 in external ADC clock mode ?

 

Can you please answer my question above about using the 9816 to generate a copy of the internal ADC clock and provide that as an output . Is that possible ?

 

Thanks.

[Fausto]

Hello @pmohan.

The DT9816 Series modules do not have an option to output its internal ADC clock.  In order to sync the DT9816-S with an external signal, an external clock must be connected to the DT9816-S and an alternative software option (i.e. DASYLab, LabVIEW, software development using Data Translation's Open Layers .NET API) should be used.  QuickDAQ does not support an external clock input.

Regards,

Fausto