Telecommunications Radioelectriques Et Telephoniques T.r.t.

Michel Riffiod

Jean-Pierre Tomasi

Raymond Strauch

A simulator is provided for testing a radio altimeter of the type which emits a frequency-modulated wave, the modulation being according to linear segments of slope p, and which compares the frequencies of the emitted wave and of the wave which is received after reflection to provide a distance measurement. The simulator according to the invention is connected between the transmitting antenna and the receiving antenna of the altimeter, and comprises two signal-processing chains which are arranged, in parallel, between a receiving section and an SSB mixer, the output terminal of which is connected to a transmitting section. The first chain is formed by first devices, which generate a quantity G, which is proportional to p, and second devices, which generate a signal possessing a frequency f.sub.d, the ratio of f.sub.d and G assuming a predetermined, adjustable ratio, Q. The second chain is formed by a coupler which is connected to a variable attenuator. The SSB beats substractively between the two signals which it receives.

Electronically adjustable delay-simulator for distance-measuring

A range measuring apparatus of the linear frequency modulation type is disclosed which comprises a measuring control loop for rendering the beat frequency between the transmitted and received frequencies equal to a fixed frequency. The apparatus further includes means for forming a permanent second beat signal between two signals derived from the generator supplying the frequency modulated signal, one of these signals being delayed by means of the delay line. A phase detector receives this second pulsed signal and the signal of a controlled frequency oscillator and supplies a signal which controls the slope of the frequency modulation. The error signal of the measuring control loop controls the frequency of the signal from the oscillator. This arrangement results in an increased precision in the range measurements.

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Paris, France

Michel Riffiod