Matra Nortel Communications

Eads Defence and Security Networks

G&eacute;rard Marque-Pucheu

Albert Roseiro

The successive symbols of a digital stream are converted into phase increments which are accumulated. A modulating phase is obtained by filtering the accumulated phase. A complex signal is produced whose argument represents the modulating phase. Two quadrature radio waveforms are respectively modulated on the basis of that complex signal, and a radio signal resulting from a combination of the two modulated waveforms is transmitted. The complex signal may be filtered digitally. Its real and imaginary components are converted into analog form, and are subjected to anti-aliasing analog filtering and then mixed with the two radio waveforms. Appropriate sizing of the digital filters provides efficient modulation with small envelope variations, causing little adjacent channel interference and a low error rate.

Digital modulation process and modulator implementing the process

The station includes a coded speech signal source having a given digital rate, a modulator for producing a radio signal from the coded speech signal provided by the source, and a redundancy encoder having a coding rate of the form K/N, where K and N are integers such that 0<K<N. An operating mode of the station is selected from at least a first operating mode where the modulator directly receives the coded speech signal and converts it into a radio signal occupying a determined fraction of time on a carrier frequency, and a second operating mode where the redundancy encoder receives the coded speech signal, and the modulator receives the output signal from the redundancy encoder and converts it into a radio signal occupying N/K times the determined fraction of time on a carrier frequency.

Growing community of inventors

Paris, France

Gérard Marque-Pucheu

Growing community of inventors

Paris, France

G&eacute;rard Marque-Pucheu

Gérard Marque-Pucheu