Radio-optical transmission system, in particular for space telecommunications

• US 4,928,317 A
• Filed: 10/14/1988
• Issued: 05/22/1990
• Est. Priority Date: 10/29/1987
• Status: Expired due to Term

• Current Assignee: Societe Anonyme DBA
• Original Assignee: Societe Anonyme DBA
• Inventors: Franchini, Elisabeth
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/257,620
• Time in Patent Office: 585 Days
• Field of Search: 455/617, 455/601, 455/600, 455/618, 455/619, 455/609
• US Class Current: 398/119
• CPC Class Codes: H04B 10/11 Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
• CPC Class Codes: H04B 10/118 specially adapted for satellite communication

Abstract

A radio-optical transmission system in particular for space telecommunications, comprising a radio-optical interface between a first modulated radio wave (15) and a light wave (18), wherein the transmitted light wave (18) is subjected to wavelength modulation.

Claims

1. A radio-optical transmission system for transmitting information, in particular for space telecommunications, said system comprising:

a first, radio-optical interface device for converting a first modulated radio wave to a light wave, said first radio-optical interface device being a microwaveoptical interface device comprising;

a microwave receiver circuit; and

an optical transmitter circuit connected to an output of said microwave receiver circuit and comprising, in succession;

a mixer receiving an oscillator signal;

a filter connected to an output of said mixer and providing a filtered output accordingly;

an amplifier receiving said filtered output to provide an amplified filtered output;

a current controlling circuit receiving said amplified filtered output and providing a current controlled output accordingly;

a laser having its injection current modulated in accordance with said current controlled output; and

a temperature control circuit connected to said laser, such that said optical transmitter circuit transmits said information without intermediate demodulation thereof;

said radio-optical transmission system further comprising a second, optical-radio interface device for converting said light wave to a second modulated radio wave, said second, optical-radio interface device being an optical-microwave interface device comprising;

an optical receiver circuit comprising, in succession;

an optical matching circuit followed by a detector diode;

a filter connected to an output of said detector diode and providing a filtered output accordingly;

at least one amplifier receiving said filtered output;

a frequency acquisition and tracking loop coupled to an output of said amplifier;

a laser;

a current controlling circuit, coupled to an output of said frequency acquisition and tracking loop, for controlling the laser;

a temperature control circuit for controlling the laser;

said laser being connected to an input of the optical matching circuit, wherein said optical receiver receives said information without intermediate demodulation thereof; and

a microwave transmitter circuit connected to an output of said optical receiver circuit.

2. A system according to claim 1, wherein the first radio optical interface device is on board a first satellite, and wherein the second optical radio interface device is on board a second satellite.

3. A system according to claim 2, wherein the first radio wave is a microwave emitted by a first ground station and received by the first satellite, and wherein the second radio wave is a microwave emitted by the second satellite and received by a second ground station.

4. A system according to claim 1, wherein the first and second modulated radio waves are microwaves.