One possible reason is the strides of the optimazer is too large, which couldn't cover the dip at zero time delay.
After set it to 1 the accuracy improves.
It's also because the data generated has a g2(0) close to the ground truth 0.5, which makes it harder for the classifier
CarlatBuffalo
commented
3 years ago 
One possible reason is the strides of the optimazer is too large, which couldn't cover the dip at zero time delay. After set it to 1 the accuracy improves. It's also because the data generated has a g2(0) close to the ground truth 0.5, which makes it harder for the classifier