Inside the boat there may be a trained operator, plus a couple of guards.

Until fairly recently, an experienced trained operator identified signals, but now computers may do this.

This method is relatively slow and requires a trained operator, but does not damage the lock or door.

The 80 emergency exchanges would be slashed to just three with the loss of 8,000 trained operators.

It is reassuring to know that a trained operator is standing by to help.

The center operates 24/7 throughout the year, with trained operators on duty to monitor the systems and correct any problems.

After months of practice, a trained operator could produce recognizable speech.

In fact, the signals could be understood directly by trained operators.

Lack of an established market, high cost, and the need for trained operators slowed its adoption.

They say that trained operators still make too many mistakes.