[AstroPy] ffa in python

[R Schumacher]

I've only a cursory knowledge of FFA, but FFT 
assumes sinusoidal data (or sums of) and so may 
not best represent periodic pulses in, say, 
single ended data acquisition, or swept signals etc

FFA is supposed to look for regularity in pulses
http://en.wikipedia.org/wiki/Talk%3AFast_folding_algorithm
Being an amateur astronomer I searched your use case
https://books.google.com/books?id=OZ8tdN6qJcsC&pg=PA151&lpg=PA151&dq=fast+folding+algorithm&source=bl&ots=mwe0QvaHU5&sig=Xg1Kwad46yC_BMxyKu_GR37LaFA&hl=en&sa=X&ei=EhF3VYudBojiUeiogvAH&ved=0CDAQ6AEwBg


- Ray


At 08:33 AM 6/9/2015, you wrote:
>Good ! Thanks !
>Any comment about the comparison between ffa and fft?
>Hang
>
>On Tue, Jun 9, 2015 at 11:18 PM, R Schumacher 
><<mailto:rays at blue-cove.com>rays at blue-cove.com> wrote:
><https://github.com/petigura/FFA/blob/master/FFA.py>https://github.com/petigura/FFA/blob/master/FFA.py
>
>
>
>At 07:49 AM 6/9/2015, Anne Archibald wrote:
>>I don't think there's a general FFA algorithm 
>>anywhere, though Vlad Kondratiev wrote a tool 
>>for applying the FFA to radio data, and I have 
>>some python code lying around somewhere. If 
>>you're searching for periodicities, the 
>>standard procedure is to search an FFT with 
>>incoherent harmonic summing; there are some 
>>pulsar searching tools that will do it (PRESTO, 
>>for example) quickly and efficiently. If you 
>>only have a handful of photons, or a modest 
>>number of periods to search, there are direct 
>>approaches that are more sensitive. If you have 
>>really a long time series, there is a trick 
>>where you do an FFT on the pairwise differences of photon arrival times.Â
>>
>>In short, there are a whole range of procedures 
>>for searching for periodicity in data. Can you 
>>be a little more specific about the problem you are trying to solve?
>>
>>Anne
>>
>>On Tue, Jun 9, 2015 at 4:44 PM gonghang.naoc 
>><<mailto:ghang.naoc at gmail.com>ghang.naoc at gmail.com> wrote:
>>Hi all,
>>Is there any python resource about fast folding 
>>algorithm?  I have a series of arrival times 
>>for a lot of photons. I need to do some 
>>periodical test, but do not know how to start.
>>Thank you.
>>best
>>Hang
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