# [FieldTrip] Beamforming analysis in frequency band

Noa Hertz noahertz6 at gmail.com
Sun Apr 19 12:57:46 CEST 2015

```Thank you Tzvetan!

This raised two more question regarding the source analysis:

1. What is the difference between defining the frequency range under
cfg.foi (such as cfg.foi=[30 48]) and defining if under the cfg.tapsmofrq
(such as cfg.foi=[39 39] cfg.tapsmofrq=9)?
2. the cfg.tapsmofrq option only exist in the ft_freqanalysis function, and
not in the ft_sourceanalysis function. in  ft_sourceanalysis the only
option is cfg.frequency which, as I mention, has to be a scalar. My
question is whether defining the cfg.tapsmofrq in the ft_freqanalysis is
also causing the source analysis to use the range of frequencies and not
the single frequency.

*Thanks a lot,*

*Noa*

2015-04-16 14:53 GMT+03:00 Tzvetan Popov <tzvetan.popov at uni-konstanz.de>:

>
> Dear Noa,
>
> you should use frequency smoothening to achieve this. For example, a
> configuration of cfg.foilim = [20 20] ; and cfg.tapsmofrq = 10; will allow
> you to estimate sources in the 10 to 30 Hz band.
>
> Hi all,
>
> I'm doing source analysis in the frequency domain of a resting-state data.
> when doing the source analysis, I want to use several frequency bands of
> interest, such as beta (13-30 Hz) and gamma (30-48 Hz).
> My problem is about the cfg.frequency parameter, which must be a scalar
> (whereas i'm interested in a frequency band). Arbitrarily choosing a
> frequency in the middle of the range doesn't seem right.
>
> What is the common practice when doing source analysis using this function?
>
> You could evaluate this tutorial:
> http://www.fieldtriptoolbox.org/tutorial/beamformer
>
> Does the cfg.tapsmofrq parameter is supposed to enable choosing frequency
> band instead of a single peak frequency?
>
> and some detailed explanation in a pictorial form here:
>
> best
> tzvetan
>
>
> Any suggestions will be very much helpful!
>
> Thanks,
> Noa
>
>
>
>
>
>
>
>
>
>
>
>
>
> *This is the script I’m using:    cfg = [];    cfg.method ='mtmfft';
> cfg.output ='fourier';    cfg.keeptapers = 'yes';    cfg.foilim = [30
> 48];    cfg.tapsmofrq = 2;
> freqClosed=ft_freqanalysis(cfg,eyesClosed);    *
>
>     cfg            = [];
>     cfg.method='pcc';
>     cfg.frequency  = 39; % must be a scalar
>     cfg.lambda     = 0;
>     cfg.vol        = vol;
>     cfg.grid       = grid;
>     cfg.feedback   = 'textbar';
>     cfg.keepfilter='yes';
>     source1         = ft_sourceanalysis(cfg, freqClosed);
>
>
> --
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>
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