RE: FFT and waveform

[Mark Rivers <rivers@cars.uchicago.edu>]

Hi Kaz,

 

This is from the areaDetector/ADCore release notes for the upcoming R2-5 release.  These items are available now in the master branch on github.

 

****************************************

### NDPluginFFT

* New plugin to compute 1-D or 2-D Fast Fourier transforms.  It exports 1-D or 2-D

  NDArrays containing the absolute value of the FFT.  It creates 1-D waveform

  records of the input, and the real, imaginary, and absolute values of the first row of the FFT.

  It also creates 1-D waveform records of the time and frequency axes, which are useful if the 1-D

  input represents a time-series. The waveform records are convenient for plotting in OPI screens.

* The FFT algorithm requires that the input array dimensions be a power of 2, but the plugin

  will pad the array to the next larger power of 2 if the input array does not meet this

  requirement. 

*  The simDetector test application in

  [areaDetector/ADExample](https://github.com/areaDetector/ADExample)

  has a new simulation mode that generates images based on the sums and/or products of 4 sine waves.

  This application is useful for testing and demonstrating the NDPluginFFT plugin.

****************************************

 

 

This is from the areaDetector/ADExample notes for the upcoming R2-2 release.  These items are available now in the master branch on github.

 

****************************************

* Created a new driver in ADExample/exampleApp/ADCSimDetectorSrc.

  This driver generates times-series data for 8 signals as a 2-D array [8, NumTimePoints].

  The signals are common waveforms (sine, cosine, square wave, sawtooth, random noise, etc.)

 

  The driver was written in part to test the new NDPluginTimeSeries and NDPluginFFT plugins

  in ADCore R2-5. But it can also serve as a starting point for writing drivers that are used

  to collect time-series data like ADCs, waveform digitizers, etc. 

 

  There is a new iocs/iocADCSimDetector directory that creates an application for testing

  the driver.

* Added a new sine-wave simulation mode to simDetector.  This simulation mode constructs images

  as the sum or products of two sine waves in the X and Y directions.  It was designed in part

  to test the new NDPluginFFT plugin in ADCore R2-5.

****************************************

 

Mark

 

 

From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Gofron, Kazimierz
Sent: Sunday, March 27, 2016 11:24 AM
To: 'tech-talk@aps.anl.gov'
Subject: FFT and waveform

 

Hi all,

 

My waveform (1024 current reading in [A], @1s) needs to be processed for frequencies using FFT method. The current values are in range between pA and mA ranges.

 

There is an existing tech-talk exchange on FFT from about 5 years ago that discuss FFT3, fftw, and waveProc.  

 

FFT3 based:

http://www.aps.anl.gov/epics/tech-talk/2011/msg01143.php

http://www.fftw.org/fftw3_doc/Complex-DFTs.html#Complex-DFTs

The github fftw development:

https://github.com/FFTW/fftw3

 

The waveProc is bit dated (2004?)

http://www.aps.anl.gov/epics/download/modules/index.php

 

Any newer solutions and suggestions?

 

Kazimierz Gofron

NSLS-II Controls Group

Brookhaven National Laboratory

(p) +1 (631) 344 5283

(f) +1 (631) 344 8085

(e) kgofron@bnl.gov

(w) www.bnl.gov/nsls2