How to Decimate or Resample Channel Data in DIAdem

Updated Jul 6, 2018

Reported In

Software

  • DIAdem

Issue Details

We oversample acquired data, but we only need to see every Nth sample. How do I use DIAdem to decimate or resample channel data?
 

Solution

The DIAdem ANALYSIS Resampling channel function creates a new waveform channel at a new given sample rate. The input isn't explicitly a decimation factor to get every 10th or 100th sample, but you can create the same effect with a bit of math.
  1. In DIAdem ANALYSIS panel, open Channel Functions function group and select Resampling function as displayed below: 
  1. Select your X-Channel and as many Y-channels as desired. You should see a preview on the right side of the window if you are only resampling a single Y-Channel.
  2. DIAdem gives you the input channel's sample rate at the bottom of the window.
  1. Divide your Input Channel Sampling Rate [Hz] by your given decimation factor (10 for every 10th sample) to get Sampling rate of the interpolation Channel [Hz]. Here, every 10th sample at 17.1 Hz is decimated to sampling at 1.71 Hz.
  1. Click OK or Calculate to create a new waveform channel in your default channel group (here renamed Decimated_x10 and Decimated_x100).
  1. Below is a VIEW 2D Axis System with 10x decimation in purple (sampling at 1.71 Hz) and 100x decimation in blue (sampling at 0.171 Hz) verified by the channel length.
    • Note: The decimated length may be different from the original length because length is an integer value.

Additional Information

Resampling function can be also automated in a DIAdem script by calling ChnResampleFreqBased function.
You can also refer to Resampling shipping example.

A similar functionality can be also achieved by loading the channel to the Data Portal using Data Reduction Navigator functionality:
  1. In DIAdem Navigator, right-click the channel you need to decimate
  2. select Data Reduction...
  3. check option Data Reduction and set Interval Width or No. of Intervals to the desired value
  4. check option 1st value to obtain a output channel with the first value of each interval of the original channel
Data Reduction can be automated in a DIAdem script by calling DataFileLoadRed command.
 

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