What does vertical range really mean?And the gain factor?

[sxs707]

The NI PXI-5102 Digitizer: what does vertical range really mean, does it the voltage range of the signal to be measured or of the signal at the input terminal of the ADC??

How to control the gain of the digitizer? And what factors may affect the gain?

[DFGray · Accepted solution]

The vertical range is the valid input range of the digitizer on that channel.  If you set the range to an invalid value, it will be coerced to the next highest value.  This is how you control the gain of the digitizer.  It is easiest to set the vertical range to the expected maximum range of your input signal and allow the NI-SCOPE driver to coerce the range to the next highest value.  This allows you to use your code efficiently with more than one type of digitizer (e.g. 5102 and 5112).  For example, you know your input signal has a range of 3V (+/- 1.5V).  Set the vertical range to 3.  NI-SCOPE will coerce this to 10V, the next highest valid range for the 5102.  You can find the valid vertical ranges for your device in the NI-SCOPE Documentation folder in your start menu or online.

The attenuation on your scope probe will effect the vertical range of your device.  If you have a 10X scope probe and have set the vertical range to 10, the actual vertical range will be 1.  You can have NI-SCOPE figure this out for you by setting the probe attenuation with Configure Vertical.

Further information about input ranges and gains is available in the NI-SCOPE help at topic Using Configure Vertical.

[sxs707]

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DFGray 写:

The vertical range is the valid input range of the digitizer on that channel.  If you set the range to an invalid value, it will be coerced to the next highest value.  This is how you control the gain of the digitizer.  It is easiest to set the vertical range to the expected maximum range of your input signal and allow the NI-SCOPE driver to coerce the range to the next highest value.  This allows you to use your code efficiently with more than one type of digitizer (e.g. 5102 and 5112).  For example, you know your input signal has a range of 3V (+/- 1.5V).  Set the vertical range to 3.  NI-SCOPE will coerce this to 10V, the next highest valid range for the 5102.  You can find the valid vertical ranges for your device in the NI-SCOPE Documentation folder in your start menu or online.

The attenuation on your scope probe will effect the vertical range of your device.  If you have a 10X scope probe and have set the vertical range to 10, the actual vertical range will be 1.  You can have NI-SCOPE figure this out for you by setting the probe attenuation with Configure Vertical.

Further information about input ranges and gains is available in the NI-SCOPE help at topic Using Configure Vertical.

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Morning DFGray ,

             Thank you very much for your help, I konw what is the vertical range now. I'm really sorry but i still have the other question: about the gain parameters in the returned wfmInfo structure when you use fetch or read functions. Dose it be determined by the Digitizer automatically(internal) when you set the vertical range and probe attenuation? How does it be determined?

              Thank you.

[DFGray]

The gain parameters in wfmInfo are determined by your probe attenuation, actual vertical range, and the internal calibration constants of the device.  You have control over the first two.  The internal calibration constants are set when you do a self calibration (programmatically or with the NI-SCOPE Soft Front Panel).  The exact algorithm used to find them depends on the device, but generally they are determined by factory set constants and the temperature of the device.