LH Surge Level

I had a Park Fertility Smiley face on Day 10 of my cycle, which means I would ovulate in the next 24-36 hours. However, thats not quite true when I do blood tests and ultrasound scans. Usually, day 10 my follicles are still growing and too early to ovulate, progesterone and all else still rising including the LH level. So the question is, how does the test work? Does it detect the first surge and considered that as Peak fertility even though our LH continue to rise? What level is considered LH Surged by the test? How does the test determine that surge equal to ovulation in the next 24-36 hours? What is the accuracy level of the test?

Thank you!