log all data points from oscilloscope

[datalogging]

Hello,

My oscilloscope is connected to the computer via USB and reading in a signal. I am using SignalExpress LE. 

A pulse is occuring 10 times per second (10 Hz) with a much shorter pulse width.  Under Step Setup> Measurements, I choose Peak-to-Peak. I want to record the height of the pulse.

I click "Record" and I see the file pop up in Log after clicking "Stop".  Exporting to ASCII, I look at the file and find that the data points are being recorded every second (dt = 1.00000seconds).

Is there an option so that I may log every data point that has occurred (10x per second)?

Thank you for your help.

[Joe Steak]

Hey datalogging,

How are you creating the pulse that you are reading in? And what are you using to actually write it out to a file? Are you sure that the original pulse is outputting at a rate of 10x per second? When you export to the ASCII file it should export all of the data that it has collected.

What is the oscilloscope and other hardware you are using?

Hopefully we can figure something out soon!

Joe S

Applications Engineer

National Instruments

[datalogging]

Hi Joe,

Thank you for your response.  I am using a pulse generator (Interstate Electronics Corp P25) to create the signal and Tektronix TDS 2024B oscilloscope. Ive attached a screenshot to show the signal.  The pulse width is approximately 250 microseconds.  The horizontal distance is 25 ms per division... equal to approximately 10 Hz frequency.

I click on "Record", and unclick the same button to stop.   A log appears in the bottom left box.  I open to view the data fields that I have chosen, right-click, then choose "export to ascii".  When I open the .txt file, I see "dt = 1.0000s" and the number of data points agrees with this sampling rate.  My signal is 10 Hz, and I would like to collect all data points from this sampling. Currently I only collect data from each full second.

My intended application will be to use the oscilloscope to read output from a Photomultiplier Tube.  The pulse is expected to be very short (femto to picoseconds long) and the frequency will range from 1 to 10 Hz.

Is it possible to collect all data points using signalExpress LE?

Thank you for your help.

[DFGray]

What version of SignalExpress are you using?  Could you please attach your current project for us to look at?  Your screenshot does not include such information as your sample rate, number of points taken, etc.

[datalogging]

It is such information that I would like to adjust. I do not know where to adjust the sample speed and would like to know how to do this according to my signal. Is this possible? Thank you.

[DFGray]

You can change how much data you acquire at each scan on the Horizontal tab of the step setup.  Set the values to get the amount of data you want to acquire.  I would recommend setting the number of points to the minimum which will still get the information you need from each pulse.  This will minimize the amount of communication over the USB port and increase your repetition rate.

Note that this will not guarantee you will get every data point, but it will guarantee one pulse per data set.  What percentage of the points you get will depend on how fast the scope you are using can set up after a data acquisition and how fast the USB port can get that information to SignalExpress.