Alcatel Espace

Alcatel

Emile Tonello

Rodolphe Nasta

Christian Herbere

Jean-Luc Foucher

Pascal Triaud

Rémi Challamel

Dominique Rousselet

Marc Atge

The invention relates to a telemetry, control, and ranging link of a satellite; it proposes using spread spectrum transmission for the up link, i.e. for commanding the satellite and for the ranging up signal. It proposes using subcarrier modulation for the down link, i.e. for telemetry and for the ranging down signal. This makes it possible for the up link to withstand interference and to provide co-localization; on the down link, the use of subcarrier modulation makes it possible to continue using existing equipment and known solutions.

Telemetry tracking and command satellite link

The invention relates to the command link of a satellite, also referred to as the telemetry, tracking and control link. Depending on the bit rate needed for the link, the invention proposes using either direct modulation of a carrier to transmit at high bit rates or subcarrier modulation of the carrier to transmit at low bit rates. The invention also proposes a receiver and a transmitter for receiving and transmitting on the command link.

Method of high and low bit rate transmission on the command link of a satellite

A receiver for receiving frequency modulated signals and having a controlled acquisition band, the receiver including: a phase-locked loop (PLL) demodulator (40); a frequency translation circuit (30) including an intermediate frequency filter (36); a recentering loop (44) for recentering the signal received in the filter (36) when closed, and a decision circuit for closing the recentering circuit when a frequency to which the PLL is locked is sufficiently close to a desired frequency.

Receiver for receiving frequency modulated signals and having a

A phase-locked loop demodulator comprises a mixer and a loop filter between an input and an output. A voltage-controlled oscillator is connected between its output and an input of the mixer. The demodulator further comprises a lock-on detector circuit whose output signal is adapted to increase the static loop gain after lock-on by modifying the characteristics of the filter.

Phase-locked loop demodulator having loop filter controlled by lock

A satellite transponder has the local oscillator in the receiver slaved to a quartz crystal oscillator by a narrowband phase-locked loop during a standby period or in the absence of received signal and by a wideband phase-locked loop immediately the signal is received, at which time the narrowband phase-locked loop is switched out automatically.

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Toulouse, France

Emile Tonello