Hi Bob
  this thread reminds me -  
   
  I had a Fortran fft program that I picked up years ago. I converted it to Quick Basic with success. I tried to convert it to assembly language to run faster but I had problems with the rounding off of numbers. I wrote a triggering program with the fft routine to do short term /long term averaging with frequency rather than amplitude. You could choose the frequency zones for monitoring (avoiding known noisy frequencies). It also worked well . (written in Quick basic) I wanted the program to be able to learn the difference between a near and teleseismic event but never got there. When the recording of the "fft amplitude/area under the curve" fell below the running long term average the recording of the event stopped. I could look at my computer screen after coming home from work an could instantly see blips on the screen from possible events. I fell in to the easy mode now by recording continuously and then looking on the internet every couple of days for events that I
 think may have been recorded by my sensors. I am thinking of "blowing the dust off and starting again with the investigation.
  regards
  Barry
  PS  back when computers were slow the was a frequency transform called a Walsh transform which used square waves rather than sine waves. It ran quite fast but I guess became useless when processors stepped up.


Hi Bob
  
this thread reminds me -  
  
 
  
I had a Fortran fft program that I picked up years ago. I converted it to Quick Basic with success. I tried to convert it to assembly language to run faster but I had problems with the rounding off of numbers. I wrote a triggering program with the fft routine to do short term /long term averaging with frequency rather than amplitude. You could choose the frequency zones for monitoring (avoiding known noisy frequencies). It also worked well . (written in Quick basic) I wanted the program to be able to learn the difference between a near and teleseismic event but never got there. When the recording of the "fft amplitude/area under the curve" fell below the running long term average the recording of the event stopped. I could look at my computer screen after coming home from work an could instantly see blips on the screen from possible events. I fell in to the easy mode