[R] three related time series with different resolutions

[William Simpson]

 I wasn't clear: x and z are pulse *trains* with irregular gaps between pulses.
>
> x is a rectangular pulse 4 sec long. Its onset and offset are known
> with sub-millisecond precision. The onset varies irregularly -- it
> doesn't fall on neat 1/2 sec or sec boundaries for example.
>
> y is a sampled continuous waveform. It is highly noisy, and it is
> actually well represented by samples 1/2 sec apart or so.
>
> z is a very short pulse -- perhaps 5 ms long -- occurring at irregular times.