Well sort of worked. I didn't think of using the timer, at the time, and
restricted to about metre in front of lens and not being able to move the
R/C fast enough. Tasteful purple streaks. The one I used I'd previously
DSO'd and the first 6 .278mS bits of two 1s were clear , ie 100100 but the
remaining 90 bits blurred into 1 over about 1/25 of the frame width ,
partially because out of bad focus and perhaps overloading of the sensor.
Just for interest I will try again using timer mode and suspending the
camera so it will rotate about 4 revs per sec and hold the R/C about 3m away
and repeatedly pressing the button should catch enough part traces if not
one across the whole frame, raising and lowering the R/c also.
For timing and not just code sequence for anyone without a DSO perhaps feed
1KHz to another Tx LED mounted above the R/C in question. Whether a
smartphone camera would have short enough response time for a static use and
so a simple app is moot.