Improve Convolutional Autoencoder
After taking a look at your code, it seems that you've not employed any kind of regularization. You may want to use dropout. Moreover, in convolutional autoencoders, in the decoder part, there is a well-known artifact called checkerboard. I don't know how this can be a problem for your task since you're using one-dimensional convolution in the decoder. By the way, I guess using dropout will suffice. Try to use both in decoder and encoder.