The pinnacle of gravity wave propulsion, the Federation guards the secret (and the deployment) of this device with a jealous fervor. Although little more than a 'simple' augmentation of an existing system no-one can argue with the results. The Enhanced IPD uses a modified field generator to produce three overlapping bubbles with 120° of phase separation. Although this does not allow a ship to travel any faster, it does allow a much finer degree of control enabling even large vessels to perform intricate defensive manoeuvres with comparable ease. Construction