Alcatel Espace

Alcatel Telspace

Gerard Leclerc

Michel Comte

Didier Lemaitre

Denis Blavette

The invention relates to apparatus for detecting the presence or the absence of a signal carrier wave received by a receiver. The carrier wave is modulated by a digital signal at a symbol clock frequency. According to the invention, the apparatus includes:

Apparatus for detecting the presence or the absence of a digitally

A demodulator stage for direct demodulation of a phase quadrature modulated signal provides two baseband signals and comprises a matched 900.degree. coupler to which the modulated signal is fed and supplying two phase quadrature modulated signals. Two low-noise amplifiers with identical specifications each receive one of the phase quadrature modulated signals and supply an amplified signal. Two mixers each receive one of the amplified signals and a common local oscillator signal and supply the baseband signals. The 90.degree. coupler, the low-noise amplifiers and the two mixers can be integrated into the same MMIC. One application is to a receiver for frequency evasive phase quadrature modulated signals.

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Osny, France

Gerard Leclerc