LA1RMA:
A straight key is very difficult to implement,- because the elements in a sign will be of uneven timing. Thats why the site only supports a iambic key or a normal keyboard.
Proposal:
Make a running average of element duration, marks and spaces.
When the new element is shorter than the running averaage classify it as 1 (dot or elemeny space), when longer than thh running average as a dash durattion. In case of space classify with decision levels 2 and 6.
This is the decoding process. The quotient of decoded character element length and running average is of tat element is a fist indicator