Earth voltage recording.

[E Probe]

Hi

I’m looking for a way to record fluctuations in earth voltage. We currently are using laptop soundcards, but it suffers from a lot of noise. Thinking of going to a USB type device for recording to a laptop.

Data is recorded for 1second after triggering at a sampling interval of 50ms. The sampling frequency is therefore 20kHz. Typical signal measurements are on the order of 1mV to 0.001mV. Any sample code available for signal recording, stacking and filtering?

Regards

[Joji]

Yes. There are many examples online for triggered finite acquisition. Would you be using LabVIEW, Signal Express, VI Logger, or a text based programming language? For Signal Express and VI logger there is no programming involved since they are interactive programs and very easy to set up.

Also, depending on what hardware you are using will determine what kind of example since some of the boards use different drivers and therefore different APIs to program them.

For example, if you were to a low cost USB device such as <a href="https://www.ni.com/en-us/support/model.daqpad-6015.html"><NI DAQPad-6015</a>, you could use one of the many shipping examples for the driver DAQmx  

For signal recording, there are many File I/O techniques in LabVIEW.  Signal Express and VI logger also offer data storage. 

I am not sure what you mean by stacking. But there are many methods in LabVIEW of displaying data on graphs.

For filtering, there are many examples in LabVIEW. Signal Express also offers filtering functions.

[preston_johnson]

For very sensative measurements, such as the ones you describe, you may want to consider high resolution data acquisition inputs with anti-alaising filters that will remove any signal noise outside your frequency of interest.  One excellent USB device is the USB-9233. 

http://sine.ni.com/nips/cds/view/p/lang/en/nid/202110