Thread Subject: spectrogram of time series in base MATLAB (wavelets?)

Hi all,

I've got a 1-D time series of data at 1000Hz for 2.X hours (about 1e7 points).

I'd like to make a frequency vs time plot for this data, like specgram in the SPT - but I only have access to base MATLAB. Do you know of any user-developed functions that I could download to do this? I took a look at the file exchange, but I didn't find any files that appeared to be of good quality or easy to use.

I also understand that this type of analysis is often done with wavelets, and I'd be open to trying that if someone has a function that I could use. As far as I know, this wouldn't give frequency as a function of time but 'scale' instead - I'd be OK with that because I'm more looking for the presence of variations in the data rather than their absolute frequency.

Thanks for your help!