One-Dimensional Convolutional Neural Network
is it fixed 1-D filter within a specific time interval?


Yes. The same as filters in 2D. Adjacent filters may even have no overlap with each other.

1D CNN is almost the same as 2D CNN both mathematically and visually by setting the second dimension (either the horizontal or vertical one in visualizations) to 1. This way, 1D filters are placed (possibly with some overlap) in one dimension instead of 2D filters being spread in two dimensions. 

The below image shows a filter set with shared parameter $W$ covering the overlapping regions of the input.



By shared parameter we mean $f_i=\mbox{ReLU}(\mbox{sum}(W \odot  \mbox{region}_i))$, where $\odot$ is a point-wise product between a region of input and $W$.