Here is a weekly chart of the GBPUSD pair. As you can see, the double stochastic is doing a nice job pin pointing the weekly cycles.
(red line is the full cycle, dashed blue is the half cycle)
Thats very nifty, What are the numbers you used for that? And have you dont any non-over-obtimised backtesting 
Hopfully I’ve spelt the important things correctly, but I probibly have not.