Complex sentence: During that time he invented a hydrophone system which he licensed back from the university to become the basis of his first entrepreneurial activity, Medisonics (UK) Limited, funded by his income as a journalist.
Split into simpler sentences: During that time he invented a hydrophone system which he licensed back from the university. The hydrophone became the basis of his first entrepreneurial activity, Medisonics (UK) Limited, which was funded by his income as a journalist.