How to synchronize two datasets with different AND varying sampling rate?

I have the data sets, Data1 and Data2 like below:

 Data1.t % vector with timestamps e.g. [0.1, 0.4 2 2.3 4 4.5 4.7 etc...]
 Data1.data % The voltage measured of a 0.1 Hz triangle function at the times specified above.

and:

 Data2.data % the same 0.1 Hz triangle function but measured at different times than in Data1.t

The problem is that I want to figure out the time at which Data2 was sampled, i.e. Data2.t (there is at least 10 samples per period)

I was thinking of using something like

 Data2.t=interp(Data1.data(start_index_n:stop_index_n),...
                Data1.t,...
                Data2.data(start_index_n:stop_index_n))

If I'm lucky I can find the

 start_index_n

for each period "n" in both Data1.data and Data2.data with some peakfinder-function… and then cycle through all the recorded periods.

(I started writing this as a question but as I was writing I realised how I could approach the problem. So this post is mainly to help others)