fm - cw radarabstandsmeßgerät

摘要

P & this apparatus, in particular a radio altimeter, comprises, in a servo-control loop, a generator of a microwave signal, a mixer which delivers a signal of the beating between the transmitted wave and the wave received, a frequency discriminator, an integrator - anamorphosing and a modulator, which delivers a sawtooth voltage to control the generator. The duration t of the saw teeth is in a linear relation to the distance to be measured. According to the invention, in order to improve the linearity of the transmission signal, a digital loop connected between the discriminator and the modulator comprises, in cascade, a device with thresholds, an adder, a memory and a digital-to-analog converter. A cutting member connects the modulator to the memory. The non - linearity of the signal emitted is reduced, three quarters, it is possible to introduce a bandpass filter - at the output of the mixer, which improves the precision on t and therefore on the distance to be measured. / p & & p & application: improvement of the precision of the radio altimeters - frequency modulation. / p