I'd like to experiment with some motion in my keyboard chords in a way that approximates what this song sounds like:
http://www.youtube.com/watch?v=k0BWlvnBmIE
 
The next post under this message has a link to a version without the vocals, so the keyboard motion I'm looking for is even more prominent via the link in the next post below.

You can hear what I'm referring to in the immediate opening of the song, and then it continues in parts throughout.

There are a bunch of experienced hands here on the forum, so I'm looking for some thoughts on how they did it.

I have Dimension Pro, Rapture, just about all of the DSF expansion packs for those, and Kontakt with plenty of libraries in there. I also have the arpeggiator in Sonar X2.

I'm wondering whether they used LFOs or an arpeggiator or what. And however they did it, how might the tempo of the motion be controlled?

I'm thinking of trying to swap out a guitar strum with this keyboard in motion type of thing on a song I'm presently working on.

Any specific ideas would be appreciated.

It's normally best to provide a link to the song rather than assuming that everyone is familiar with it. Anyway I found one that's backing track only:
http://www.youtube.com/watch?v=S3BiFaMLGWI

Seems like a good candidate for using several instances of Rapture and messing with its LFOs and step sequencers.

Kev999 - hey, that link is great!  It really highlights exactly what I'm asking about.
 
I'm trying to experiment to get anything like that, hoping someone has some tips to try or specific suggestions.

Well, it's a synth patch with is carefully messed with throughout the song (simple filter eq - strong lowpass early on which opens up more high end as the chorus builds). I'm guessing it's a tremolo on the patch with a square shaped response pattern (rather than sinusoidal). Well, most likely a blend between the two, but slightly more squarish in shape I think. It 'could' be a delay that is triggered internally in the synth and cuts when the keys are released, but I think it sounds more like a tremolo.

Hmm, on a second listen, the attack seems to be on each 'pulse' which suggests it might actually be a delay. Really not sure.

As for actually creating the patch, I don't know much about making synth sounds, but it does sound pretty standard and simple just tuned well for the song. I guess it's made up of a few layers though. It could be more complex than it initially sounds. In fact, a second brighter patch definitely comes in later in the song playing the same notes. I won't go into more detail because I can't. Jeff Evans tends to be pretty good with this stuff. I'd suggest you shoot him a PM if he doesn't chime in. I'm sure he can dissect it well.

I see my name mentioned so I had better chime in! I think it sounds like there is a fair bit of delay in terms of the amount of feedback. So the first chord is probably the one that is making the sound. The rest are subsequent echoes I think.
 
It is the volume envelope of the sound that is important. It is a short, piano percussive like ADSR. There is a filter closed down on it a bit with it's own ADSR as well and this ADSR is faster than the volume ADSR giving the sound a little percussive transient at the start. It may be dual oscillator but they are not detuned much if it is. A single osc sound would do it too. The depth of that filter ADSR is only just enough to open up the sound briefly at the start.

It is not difficult with the right synth. Hit once, repeat in eighth notes the rest, and real-time control movement for the rest. An arpeggiator will do that and a synth that has real-time controls that can be moved while only one hand is doing the chord in the song.
 
Nothing to it with a little bit of practice.
I think my synth - Juno Stage could do it. Set the tempo of the patch to the tempo of the song and set the arpeggiator for the rest of the measure and move controls that alter whatever is altered back and forth.
 
 

Al is also talking about the riff or rhythmical value of the part which is important and integral to what the part is saying. I am talking about the shape of that very first sound. That volume ADSR envelope and the filter ADSR envelope shape and depth are very important factors in that in that sound too. I tend to think of it as a synth sound with a piano shape. The PPG wave had some very nice sounds like this but many synths can do it too. (real and virtual) It is a fairly simple sound to get right.
 
 

 
Back when Jerry Lee Lewis did it they just called it 16th notes.

When I think about Katy Perry? There's only one thing I'd like to see open wide? And it has nothing to do with "awake..." And I'd like to experiment with some motion on it as well... (I'm talking of course about her openness to new types of music?)

We can all agree that there are many ways to achieve the same result here.  I like to use combinations of the techniques mentioned when more emphasis is needed.  For example, sawtooth LFOs sync'ed to a step sequencer for added attack, 'doubled up' parameters in a Mod Matrix for depth, or one-shot LFOs as an additional envelope with an arpeggiator. 

Since the OP mentioned Rapture, there's another useful technique to explore in the Step Generator now:  Retrigger Steps.  As a start, bring the odd-numbered steps up, the even-numbered steps down, and alt-click on each of the odd-numbered steps (those steps are now highlighted). 

Whatever is in the Envelope Generator will be retriggered on the alt-steps. Works best with an AD envelope without a sustain point (press S over the node with the vertical red-orange line).  Or create your own with two node-clicks in the EG.  By gradually reducing the step heights over the length of the sequence, you can superimpose an envelope shape over the entire phrase.