Method and apparatus for mitigating interference from terrestrial broadcasts sharing the same channel with satellite broadcasts using an antenna with posterior sidelobes

• US 6,778,810 B1
• Filed: 01/10/2000
• Issued: 08/17/2004
• Est. Priority Date: 12/03/1999
• Status: Expired due to Term

• Current Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Original Assignee: DIRECTV, LLC (AT&T, Inc.)
• Inventors: Anderson, Paul R.
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Pan, Yuwen
• Application Number:
  US09/480,089
• Time in Patent Office: 1,681 Days
• Field of Search: 455/12.1, 455/13.3, 455/3.02, 455/283, 342/37, 342/379, 342/359, 342/360, 343/777, 343/844, 343/895, 343/840
• US Class Current: 455/12.1
• CPC Class Codes: H01Q 1/52 Means for reducing coupling between antennas; Means for reducing coupling between an antenna and another structure absorbing means H01Q17/00
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system

Abstract

An apparatus for simultaneously receiving a first signal from a non-terrestrial source and a second signal from a terrestrial source on the same or overlapping channels using a receive antenna with posteriorly-directed sidelobes is disclosed. The apparatus comprises at least one terrestrial transmitter transmitting information on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at satellite. The terrestrial transmitter includes a azimuthal gain characteristic directed substantially away from the Earth'"'"'s Equator. In an alternative embodiment, the terrestrial transmitter is disposed at a location defining a vector angularly displaced from the primary sensitive axis by an angle of less than 90 degrees. A method of transmitting information is also disclosed. In this method the information is transmitted on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at the satellite and a posterior secondary sensitive axis. The method is performed by transmitting the information from a terrestrially-based transmitter to a terrestrial receive antenna in a direction substantially away from the Equator.

Claims

1. A terrestrially-based transmission system, comprising:

at least one terrestrial transmitter transmitting information on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at the satellite; and

wherein the terrestrial transmitter is disposed at a location defining a vector angularly displaced away from the primary sensitive axis by an offset angle γ

of less than 90 degrees; and

wherein the offset angle γ

is defined such that β

<

γ

<

90°

−

δ

, wherein β

is an angular extent of an effective beamwidth of the satellite receive antenna, and δ

is an angle from due South to a vector from the satellite receive antenna to the satellite.

2. The apparatus of claim 1, wherein the satellite receive antenna further comprises at least one posterior secondary sensitive axis.

3. The apparatus of claim 1, wherein the satellite is disposed in a substantially geosynchronous orbit.

4. The apparatus of claim 1, wherein the satellite is disposed in a substantially geostationary orbit.

5. The apparatus of claim 1, wherein the offset angle γ

is definable by an elevation component γ

y_el∈

(−

(90°

, 90°

) and an azimuth component γ

_az∈

(−

90°

−

δ

), (90°

−

δ

)), and wherein |γ

_el|>

β and

−

(90°

−

δ

)<

γ

_az<

(90°

−

δ

).

6. The apparatus of claim 5, wherein γ

_el<

−

β

.

7. The apparatus of claim 1, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited to between AZ_TW and AZ_TE wherein AZ_TW is about 295°

Northwest and AZ_TE is about 65°

Northeast.

8. The apparatus of claim 1, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited an angle φ

defined by AZ_TW and AZ_TE, the angle φ

determined according to a latitude of the satellite receive antenna and a minimum elevation angle of the primary sensitive axis ε

_min.

9. The apparatus of claim 8, wherein ε

_min is about 10° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 105° and

130°

.

10. The apparatus of claim 8, wherein ε

_min is about 15° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 95° and

130°

.

11. The apparatus of claim 8, wherein ε

_min is about 5° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 100° and

130°

.

12. The apparatus of claim 1, further comprising a terrestrial receive antenna, for receiving the information transmitted from the terrestrial transmitter.

13. The apparatus of claim 1, wherein the terrestrial receive antenna is disposed proximate the satellite receive antenna.

14. A reception apparatus, comprising:

a terrestrial receive antenna for receiving a first signal from a terrestrial transmitter on a frequency usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a satellite receive antenna primary sensitive axis directed substantially at the satellite, the terrestrial receive antenna having a terrestrial receive antenna primary sensitive axis angularly displaced away from the satellite receive antenna primary sensitive axis by an offset angle γ

of less than 90 degrees; and

wherein the offset angle γ

is defined such that β

<

γ

<

90°

−

δ

, wherein β

is an angular extent of an effective beamwidth of the satellite receive antenna, and δ

is an angle from due South to a vector from the satellite receive antenna to the satellite.

15. The apparatus of claim 14, wherein the satellite receive antenna further comprises at least one posterior secondary sensitive axis.

16. The apparatus of claim 14, wherein the satellite is disposed in a substantially geosynchronous orbit.

17. The apparatus of claim 14, wherein the satellite is disposed in a substantially geostationary orbit.

18. The apparatus of claim 14, wherein the offset angle γ

is definable by an elevation component γ

_el∈

(−

90°

, 90°

) and an azimuth component γ

_az∈

(−

(90°

−

δ

), (90°

−

δ

)), and wherein |γ

_el|>

β and

−

(90°

−

δ

)<

γ

_az<

(90°

−

δ

).

19. The apparatus of claim 18, wherein γ

_el<

−

β

.

20. The apparatus of claim 14, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited to between AZ_TW and AZ_TE wherein AZ_TW is about 295°

Northwest and AZ_TE is about 65°

Northeast.

21. The apparatus of claim 14, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited an angle φ

defined by AZ_TW and AZ_TE, the angle φ

determined according to a latitude of the satellite receive antenna and a minimum elevation angle of the primary sensitive axis ε

_min.

22. The apparatus of claim 21, wherein ε

_min is about 10° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 105° and

130°

.

23. The apparatus of claim 21, wherein ε

_min is about 15° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 95° and

130°

.

24. The apparatus of claim 21, wherein ε

_min is about 5° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 100° and

130°

.

25. The apparatus of claim 14, further comprising a terrestrial receive antenna, for receiving the information transmitted from the terrestrial transmitter.

26. The apparatus of claim 14, wherein the terrestrial receive antenna is disposed proximate the satellite receive antenna.

27. A method of transmitting information on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at the satellite and a posterior secondary sensitive axis, comprising the step of:

transmitting information from a terrestrially-based transmitter to a terrestrial receive antenna from a location defining a vector angularly displaced away from the primary sensitive axis by an offset angle γ

of less than 90 degrees; and

wherein the offset angle γ

is defined such that β

<

γ

<

(90°

−

δ

), wherein β

is an angular extent of an effective beamwidth of the satellite receive antenna, and δ

is an angle from due South to a vector from the satellite receive antenna to the satellite.

28. The method of claim 27, wherein the offset angle γ

is definable by an elevation component γ

_el∈

(−

90°

, 90°

) and an azimuth component γ

_az∈

(−

(90°

−

δ

), (90°

−

δ

)), and wherein |γ

_el|>

β and

−

(90°

−

δ

)<

|γ

_el<

(90°

−

δ

).

29. The method of claim 27, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited to between AZ_TW and AZ_TE wherein AZ_TW is about 295°

Northwest and AZ_TE is about 65°

Northeast.

30. The method of claim 27, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited an angle φ

defined by AZ_TW and AZ_TE, the angle φ

determined according to a latitude of the satellite receive antenna and a minimum elevation angle of the primary sensitive axis ε

_min.

31. The method of claim 30, wherein ε

_min is about 10° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 105° and

130°

.

32. The method of claim 30, wherein ε

_min is about 15° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 95° and

130°

.

33. The method of claim 30, wherein ε

_min is about 5° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 100° and

130°

.

34. A method of receiving information on at least one frequency simultaneously usable by at least one satellite transmitting to a satellite receive antenna having a sensitivity characterizable by a primary sensitive axis directed substantially at the satellite and a posterior secondary sensitive axis, comprising the step of:

receiving information from a terrestrial-based transmitter to a terrestrial receive antenna from a location defining a vector angularly displaced away due South from the primary sensitive axis by an offset angle γ

of less than 90 degrees; and

wherein the offset angle γ

is defined such that β

<

γ

<

(90°

−

δ

), wherein β

is an angular extent of an effective beamwidth of the satellite receive antenna, and δ

is an angle from due South to a vector from the satellite receive antenna to the satellite.

35. The method of claim 34, above, wherein the offset angle γ

is definable by an elevation component γ

_el ∈

(−

90°

, 90°

) and an azimuth component γ

_az ∈

(−

(90°

−

δ

), (90°

−

δ

)), and wherein |γ

_el|>

β and

−

(90°

−

δ

)<

γ

_el<

(90°

−

δ

).

36. The method of claim 34, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited to between AZ_TW and AZ_TE wherein AZ_TW is about 295°

Northwest and AZ_TE is about 65°

Northeast.

37. The method of claim 34, wherein the transmitter is characterizable by an azimuthal gain characteristic substantially limited an angle φ

defined by AZ_TW and AZ_TE, the angle φ

determined according to a latitude of the satellite receive antenna and a minimum elevation angle of the primary sensitive axis ε

_min.

38. The method of claim 37, wherein ε

_min is about 10° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 105° and

130°

.

39. The method of claim 37, wherein ε

_min is about 15° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 95° and

130°

.

40. The method of claim 37, wherein ε

_min is about 5° and

the latitude is between about 24°

North and about 48°

North, and the angle φ

is between about 100° and

130°

.

41. The method of claim 34, further comprising the steps of:

aligning an azimuth and elevation angle of the satellite receive antenna to direct the primary sensitive axis substantially at the satellite; and

aligning an azimuth angle of the terrestrial receive antenna to direct a terrestrial receive antenna primary sensitive axis substantially at the terrestrial transmitter and substantially in the direction of the Equator.

42. A transmission network capable of simultaneously transmitting a first signal and a second signal to a location on a single transmission channel, comprising:

a satellite transmitter, for transmitting the first signal to the location substantially along a first axis;

a terrestrial transmitter, for transmitting the second signal to the location along a second axis within an offset angle γ

of at most 90 degrees of the first axis, wherein the offset angle γ

is defined such that β

<

γ

<

(90°

−

δ

), wherein β

is an angular extent of an effective beamwidth of the satellite receive antenna, and δ

is an angle from due South to a vector from the satellite receive antenna to the satellite;

a first antenna comprising a sensitive characteristic having a plurality of lobes and nulls therebetween, the plurality of lobes including a main lobe substantially aligned with the first axis, and a null substantially aligned with the second axis, and at least one sidelobe substantially aligned with a side lobe axis disposed at least 90 degrees away from the main lobe; and

a second antenna having a main lobe substantially aligned with the second axis.

43. The apparatus of claim 42, wherein the second antenna further comprises at least one null substantially aligned with the first axis.

44. The apparatus of claim 42, wherein the offset angle is between approximately 10 and 90 degrees.

45. The apparatus of claim 42, wherein the offset angle comprises an azimuth component between about −

90 and 90 degrees and an elevation component between about 10 and 90 degrees.

46. The apparatus of claim 42, wherein the side lobe axis is disposed between approximately 96 and 132 degrees away from the first axis.