[AstroPy] ffa in python

[gonghang.naoc]

Thank you.  A pulsar guy recommends ffa to me. I need to find short period
signal.
The photon counts are poor in fact, but I hope I can find 10*P or 100*P at
least if I can not find P.  Another problem is even there is a short period
signal, it may not necessarily be the strongest signal. It is also a
problem?
So do you think FFT is better?  When is ffa better?
Hang

On Tue, Jun 9, 2015 at 10:49 PM, Anne Archibald <archibald at astron.nl> 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.
>
> 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 <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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