Electronique Marcel Dassault

Thierry Baudard

Max Schumperli

Alain Pouzet

A system for measuring the distance between an interrogating station and a transponder station comprises, at the latter station, a receiver for a phase-modulated UHF wave emitted by the interrogating station and a transmitter for sending back an outgoing main carrier modulated in phase by a locally generated subcarrier. A first oscillator generates a wave whose frequency is a subharmonic of the frequencies of both the incoming and the outgoing main carrier and from which there are derived, besides this outgoing carrier, a heterodyning oscillation and a reference oscillation which are both amplitude-modulated by the output of a second oscillator whose frequency matches that of the incoming subcarrier and which also serves as a source of the locally generated outgoing subcarrier. The amplitude-modulated heterodyning oscillation is mixed with the incoming carrier wave to produce an i-f oscillation with a central frequency matching that of the reference oscillation and with two pairs of sidebands respectively due to the phase modulation of the incoming carrier and to the amplitude modulation of the heterodyning oscillation. The first oscillator is provided with a phase-locking loop including a phase comparator which receives the i-f oscillation and the amplitude-modulated reference oscillation; the same i-f oscillation, freed from its sidebands, is compared with the unmodulated reference oscillation to yield a corrective signal for adjusting the frequency and phase of the second oscillator.

Growing community of inventors

Paris, France

Thierry Baudard