Convert spectrogram time to UTC

I have produced a spectrogram of a signal, starting at 18:33:01 UTC on 6th July 2013. I need the time to be in UTC rather than time instants; does anybody know how to convert this?

Any help would be appreciated.

[dpb]

Can you more fully explain what you mean by "rather than time instants"?

[Harry Bell]

I have defined my spectrogram as

[s,f,t,p] = spectrogram(bz,win,overlap,nfft,sample_freq);

where bz is the signal I am investigating. This returns "t" as a vector of time in seconds from the start of the dataset. I would like to plot UTC time rather than t.

Answer 1

[Walter Roberson]

starttime = datetime('18:33:01 UTC 6th July 2013', 'InputFormat', 'HH:mm:ss ''UTC'' dd''th'' MMMM yyyy', 'TimeZone', 'UTC');

event_times = starttime + seconds(t);
plot(event_times, ...)

One hopes that in reality you have your starting time in a format that is easier to parse: the above is a bit weak for the possibility of "1st" or "2nd" or "21st" or "22nd" or "23rd".

[Harry Bell]

Hi Walter, thank you very much!