Cryogenic supersonic aircraft fuel tank - is surrounded by fuel pipe harness to permit heating or cooling

摘要

A spatial monitor has a frequency and phase selective evaluator (13, 27, 29, 30, 32) with a coupled first receiver electrode (5) associated with two transmit electrodes (3, 4). These transmit electrodes are fed, via two operating amplifiers (14, 15) with counter-phase a.c. A fourth electrode (6) is associated with the first receive electrode, and the two electrodes are couplable alternately to the evaluator via a first changeover switch. The latter is assigned a second synchronously operated change-over switch (11) via which the voltage of the first and electrode (3) is switchable between two predetermined voltage levels in such a fashion that the input signal of the evaluator device (13, 27, 29, 30, 32) for noise from outside remains constant. The transmit electrodes are pref. asymmetric composed to the first receive and the fourth electrodes.