I'm using DF, started to use it on 4th Dec and it confirmed my OV on 8th Dec.
You have to wear a sensor the size of a £1 coin under your arm each night and it records your BBT while you sleep.
In the am you sync the info from your sensor to a reader, which then uploads to your PC and gets sent to fertility experts for review. They email you to let you know when OV occurred and they give you green days to DTD on.
It's far easier than doing BBT yourself and also takes the stress out of collecting temps. All you need to record is periods, CM, DTD and OPK results if you wish.
It comes with a price tag of £495.
Here is an example chart. The red line indicates OV.
I've only been TTC since I got DF
https://i1116.photobucket.com/albums/k568/lola201111/2912.png