Method and system for detecting broadcast signals transmitted by terrestrial sources and received by a satellite

Patent metadata

Field	Value
Publication number	US-9331775-B2
Application number	US-201314060776-A
Country	US
Kind code	B2
Filing date	Oct 23, 2013
Priority date	Oct 23, 2012
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method ( 50 ) for detecting broadcast signals, transmitted by terrestrial sources ( 40 ) and received by a satellite ( 20 ), in individual signals obtained respectively from different individual antennas ( 24 ) of an antenna array ( 22 ) of the satellite, includes a first detection iteration ( 51 a ) and a second detection iteration ( 51 b ), each of the first and second detection iterations including a step ( 52 ) of forming, from the individual signals, virtual beams of different respective main radiation directions, and a step of searching for the presence of broadcast signals in the virtual beams. Furthermore, for at least one broadcast signal detected during the first detection iteration, the respective contributions of the at least one detected broadcast signal to the different individual signals are attenuated, relative to the first detection iteration, for all or part of the virtual beams formed during the second detection iteration. A system ( 10 ) for detecting broadcast signals is also described.

First claim

The invention claimed is:

1. A method for detecting broadcast signals, transmitted by terrestrial sources and received by a satellite, in individual signals respectively from different individual antennas of an antenna array of the satellite, wherein:
said method comprises a first detection iteration and a second detection iteration, each of said first and second detection iterations comprising a step of forming, from the individual signals, virtual beams of different respective main radiation directions, and a step of searching for the presence of broadcast signals in the virtual beams,
for at least one broadcast signal detected during the first detection iteration, the respective contributions of said at least one detected broadcast signal to the different individual signals are attenuated, relative to said first detection iteration, for all or part of the virtual beams formed during the second detection iteration.

2. The method as claimed in claim 1 , wherein the first detection iteration comprises, for each broadcast signal detected in the virtual beams, steps of:
estimating the respective contributions of said detected broadcast signal to the different individual signals,
suppressing the respective contributions of said detected broadcast signal in the different individual signals,
and wherein, during the second detection iteration, at least one virtual beam is formed from the individual signals obtained after suppression of the contributions of the broadcast signals detected during the first detection iteration.

3. The method as claimed in claim 2 , wherein the step of estimating the respective contributions of a detected broadcast signal to the different individual signals comprises steps of:
estimating a demodulated signal from said detected broadcast signal,
estimating a direction of arrival and an amplitude of arrival, on the antenna array, of said detected broadcast signal,
computing the respective contributions of said detected broadcast signal to the different individual signals, as a function of the demodulated signal, of the direction of arrival and of the amplitude of arrival of said detected broadcast signal.

4. The method as claimed in claim 3 , comprising, for each detected broadcast signal, the estimation also of the linear polarization of arrival of said detected broadcast signal on the antenna array, the respective contributions of said detected broadcast signal to the different individual signals being also computed as a function of said linear polarization of arrival.

5. The method as claimed in claim 3 , wherein, when a broadcast signal has been detected, a virtual beam is formed in the direction of arrival and/or the linear polarization of arrival of said detected broadcast signal to estimate the demodulated signal.

6. The method as claimed in claim 3 , comprising, for each detected broadcast signal, the estimation also of a frequency of arrival and/or of an instant of arrival of said detected broadcast signal on the antenna array, the respective contributions of said detected broadcast signal to the different individual signals being also computed as a function of the frequency of arrival and/or of the instant of arrival.

7. The method as claimed in claim 1 , wherein, during the second detection iteration, the virtual beams formed are predefined virtual beams of main radiation directions and/or of linear polarizations different from the main radiation directions and/or linear polarizations of the virtual beams formed during the first detection iteration.

8. The method as claimed in claim 1 , wherein the virtual beams formed during the second detection iteration are adaptive virtual beams determined as a function of the broadcast signals detected during the first detection iteration.

9. The method as claimed in claim 8 , wherein the adaptive virtual beams formed during the second detection iteration are orthogonal to the respective main radiation directions and/or to the respective linear polarizations of at least a part of the virtual beams, formed during the first detection iteration, in which broadcast signals have been detected.

10. The method as claimed in claim 8 , wherein the first detection iteration comprises, for each broadcast signal detected in the virtual beams, a step of estimating a direction of arrival and/or of a linear polarization of arrival, on the antenna array, of said detected broadcast signal, and wherein the adaptive virtual beams formed during the section detection iteration are orthogonal to the respective directions of arrival and/or orthogonal to the respective linear polarizations of arrival of at least a part of the broadcast signals detected during the first detection iteration.

11. The method as claimed in claim 1 , wherein the broadcast signals are AIS signals transmitted by ships and/or ADS-B signals transmitted by aircraft.

12. The method as claimed in claim 11 , wherein the direction of arrival of a detected broadcast signal is estimated as a function of information, included in said broadcast signal, relating to the position of the terrestrial source having transmitted said detected broadcast signal.

13. A processor and an electronic memory comprising a stored set of program code instructions which, when the program code instructions are executed by the processor, implement a detection method for detecting broadcast signals, transmitted by terrestrial sources and received by a satellite, in individual signals respectively from different individual antennas of an antenna array of the satellite, said method comprising i) a first detection iteration and a second detection iteration, each of said first and second detection iterations comprising a step of forming, from the individual signals, virtual beams of different respective main radiation directions, and a step of searching for the presence of broadcast signals in the virtual beams, and ii) for at least one broadcast signal detected during the first detection iteration, the respective contributions of said at least one detected broadcast signal to the different individual signals are attenuated, relative to said first detection iteration, for all or part of the virtual beams formed during the second detection iteration.

14. A processing device comprising means configured to detect broadcast signals in individual signals, obtained respectively from different individual antennas of an antenna array of a satellite, in accordance with a method as claimed in claim 1 .

15. A system for detecting broadcast signals transmitted by terrestrial sources, comprising at least one satellite in earth orbit and at least one terrestrial processing device as claimed in claim 14 , said satellite comprising:
an antenna array comprising a plurality of individual antennas,
means adapted to transmit all or part of the individual signals, obtained respectively from the different individual antennas, to the processing device,
the processing device comprising means adapted to receive said individual signals transmitted by the satellite.

Assignees

• Astrium Sas
• Airbus Defence & Space Sas

Inventors

• Picard Mathieu
• Mege Alexandre

Classifications

• H04B7/18517

  Transmission equipment in earth stations · CPC title

• H04B7/18523 Primary

  Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service (arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20) · CPC title