Time axis in spectrogram for event relatd data

I have EEG data that is event related so the data times actually go from -500 to 1500 ms with fs=256. I would like to create a spectrogram of the epochs with the time axis labeled correctly but just can't seem to figure it out. Any help very welcome. Thanks Kim

Answer 1

[Jeremy]

Here is some lines I've used to set up a spectrogram with more control on how it is created. You should be able to use tStart to get what you need.

tStart=150; %seconds
fs=1000; %Hz
nfft=fs/binWidth; %samples
overlap = 50;%
fLimit=400; %Hz

T = 0:1/fs:2;
X = chirp(T,100,1,200,'q');
[~, f,t,P]=spectrogram(X,hann(nfft),nfft/(100/overlap),nfft,fs);
f(f>fLimit)=[];
t=t+tStart;
P=10*log10(P(1:length(f),:)');
sf=surf(f,t,P,'edgecolor','none');

view(0,90);
axis tight;

[Kim]

Jeremy Thanks so much I will try this and let you know