Multi-taper derivative of the time-frequency spectrum - continuous process
Usage:
[dS,t,f]=mtdspecgramc(data,movingwin,phi,params)
Input:
Note that all times can be in arbitrary units. But the units have to be
consistent. So, if E is in secs, win, t have to be in secs, and Fs has to
be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike
times, the units have to be consistent with the units of data as well.
data (in form samples x channels/trials or a single vector) -- required
movingwin (in the form [window winstep] i.e length of moving
window and step size.
Note that units here have
to be consistent with
units of Fs - required
phi (angle for evaluation of derivative) -- required
e.g. phi=[0,pi/2] giving the time and frequency
derivatives
params: structure with fields tapers, pad, Fs, fpass, trialave
-optional
tapers : precalculated tapers from dpss or in the one of the following
forms:
(1) A numeric vector [TW K] where TW is the
time-bandwidth product and K is the number of
tapers to be used (less than or equal to
2TW-1).
(2) A numeric vector [W T p] where W is the
bandwidth, T is the duration of the data and p
is an integer such that 2TW-p tapers are used. In
this form there is no default i.e. to specify
the bandwidth, you have to specify T and p as
well. Note that the units of W and T have to be
consistent: if W is in Hz, T must be in seconds
and vice versa. Note that these units must also
be consistent with the units of params.Fs: W can
be in Hz if and only if params.Fs is in Hz.
The default is to use form 1 with TW=3 and K=5
Note that T has to be equal to movingwin(1).
pad (padding factor for the FFT) - optional (can take values -1,0,1,2...).
-1 corresponds to no padding, 0 corresponds to padding
to the next highest power of 2 etc.
e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT
to 512 points, if pad=1, we pad to 1024 points etc.
Defaults to 0.
Fs (sampling frequency) - optional. Default 1.
fpass (frequency band to be used in the calculation in the form
[fmin fmax])- optional.
Default all frequencies between 0 and Fs/2
trialave - (average over trials/channels when 1, don't average when 0) - optional. Default 0
Output:
dS (spectral derivative in form phi x time x frequency x channels/trials if trialave=0;
in form phi x time x frequency if trialave=1)
t (times)
f (frequencies)0001 function [dS,t,f]=mtdspecgramc(data,movingwin,phi,params) 0002 % Multi-taper derivative of the time-frequency spectrum - continuous process 0003 % 0004 % Usage: 0005 % 0006 % [dS,t,f]=mtdspecgramc(data,movingwin,phi,params) 0007 % Input: 0008 % Note that all times can be in arbitrary units. But the units have to be 0009 % consistent. So, if E is in secs, win, t have to be in secs, and Fs has to 0010 % be Hz. If E is in samples, so are win and t, and Fs=1. In case of spike 0011 % times, the units have to be consistent with the units of data as well. 0012 % 0013 % data (in form samples x channels/trials or a single vector) -- required 0014 % movingwin (in the form [window winstep] i.e length of moving 0015 % window and step size. 0016 % Note that units here have 0017 % to be consistent with 0018 % units of Fs - required 0019 % phi (angle for evaluation of derivative) -- required 0020 % e.g. phi=[0,pi/2] giving the time and frequency 0021 % derivatives 0022 % params: structure with fields tapers, pad, Fs, fpass, trialave 0023 % -optional 0024 % tapers : precalculated tapers from dpss or in the one of the following 0025 % forms: 0026 % (1) A numeric vector [TW K] where TW is the 0027 % time-bandwidth product and K is the number of 0028 % tapers to be used (less than or equal to 0029 % 2TW-1). 0030 % (2) A numeric vector [W T p] where W is the 0031 % bandwidth, T is the duration of the data and p 0032 % is an integer such that 2TW-p tapers are used. In 0033 % this form there is no default i.e. to specify 0034 % the bandwidth, you have to specify T and p as 0035 % well. Note that the units of W and T have to be 0036 % consistent: if W is in Hz, T must be in seconds 0037 % and vice versa. Note that these units must also 0038 % be consistent with the units of params.Fs: W can 0039 % be in Hz if and only if params.Fs is in Hz. 0040 % The default is to use form 1 with TW=3 and K=5 0041 % Note that T has to be equal to movingwin(1). 0042 % 0043 % pad (padding factor for the FFT) - optional (can take values -1,0,1,2...). 0044 % -1 corresponds to no padding, 0 corresponds to padding 0045 % to the next highest power of 2 etc. 0046 % e.g. For N = 500, if PAD = -1, we do not pad; if PAD = 0, we pad the FFT 0047 % to 512 points, if pad=1, we pad to 1024 points etc. 0048 % Defaults to 0. 0049 % Fs (sampling frequency) - optional. Default 1. 0050 % fpass (frequency band to be used in the calculation in the form 0051 % [fmin fmax])- optional. 0052 % Default all frequencies between 0 and Fs/2 0053 % trialave - (average over trials/channels when 1, don't average when 0) - optional. Default 0 0054 % Output: 0055 % dS (spectral derivative in form phi x time x frequency x channels/trials if trialave=0; 0056 % in form phi x time x frequency if trialave=1) 0057 % t (times) 0058 % f (frequencies) 0059 0060 if nargin < 3; error('Need data, window parameters and angle'); end; 0061 if nargin < 4; params=[]; end; 0062 0063 if length(params.tapers)==3 & movingwin(1)~=params.tapers(2); 0064 error('Duration of data in params.tapers is inconsistent with movingwin(1), modify params.tapers(2) to proceed') 0065 end 0066 0067 [tapers,pad,Fs,fpass,err,trialave,params]=getparams(params); 0068 clear err 0069 data=change_row_to_column(data); 0070 [N,C]=size(data); 0071 Nwin=round(Fs*movingwin(1)); % number of samples in window 0072 Nstep=round(movingwin(2)*Fs); % number of samples to step through 0073 nfft=max(2^(nextpow2(Nwin)+pad),Nwin); 0074 f=getfgrid(Fs,nfft,fpass); Nf=length(f); 0075 params.tapers=dpsschk(tapers,Nwin,Fs); % check tapers 0076 params.tapers=tapers; 0077 winstart=1:Nstep:N-Nwin+1; 0078 nw=length(winstart); 0079 if trialave==0; dS=zeros(length(phi),nw,Nf,C); else dS=zeros(length(phi),nw,Nf); end; 0080 for n=1:nw; 0081 indx=winstart(n):winstart(n)+Nwin-1; 0082 datawin=data(indx,:); 0083 [ds,f]=mtdspectrumc(datawin,phi,params); 0084 dS(:,n,:,:)=ds; 0085 end; 0086 dS=squeeze(dS); 0087 sz=size(dS); 0088 % if length(sz)==3; 0089 % dS=permute(dS,[2 1 3 4]); 0090 % elseif length(phi)>1 0091 % dS=permute(dS,[2 1 3]); 0092 % end; 0093 winmid=winstart+round(Nwin/2); 0094 t=winmid/Fs;