ACCELERATED SATELLITE ACQUISITION SCHEME
A user terminal includes a reconfigurable phased array antenna having a plurality of antenna elements. The user terminal is operable for: broadening a field of regard of the reconfigurable phased array antenna; receiving signals from a plurality of satellites within the field of regard using the reconfigurable phased array antenna; determining one or more attributes of the received signals for each of the satellites; and selecting one of the plurality of satellites for communication based on the attributes of the received signals. After the satellite has been selected, the user terminal is configured for: switching to a directional mode for the reconfigurable phased array antenna; establishing the communication with the selected satellite using the reconfigurable phased array antenna; and tracking the selected satellite. Ephemeris data broadcast by the satellites is used by the user terminal to track the satellites and to perform handovers between satellites.
1 . A method of establishing communication with a satellite, comprising:
providing a user terminal ( 104 ) including a reconfigurable phased array antenna ( 214 ) having a plurality of antenna elements ( 300 ), wherein the user terminal ( 104 ) is operable for:
broadening ( 604 ) a field of regard of the reconfigurable phased array antenna ( 214 );
receiving ( 606 ) signals from a plurality of satellites ( 102 ) within the field of regard using the reconfigurable phased array antenna ( 214 );
determining ( 608 ) one or more attributes of the received signals for each of the satellites ( 102 ); and
selecting ( 608 ) one of the plurality of satellites ( 102 ) for communication based on the attributes of the received signals.
2 . The method of claim 1 , wherein the attributes comprise signal strength, signal quality, or proximity to other signals.
3 . The method of claim 1 , wherein broadening ( 604 ) the field of regard includes at least one of:
using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
using ( 604 ) a spoiled beam by changing at least one of a phase and amplitude for one or more of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ) to spread a beam width.
4 . The method of claim 3 , wherein using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) further comprises one of:
selecting ( 604 ) one antenna element ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
selecting ( 604 ) a sub-array of two or more antenna elements ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ).
5 . The method of claim 3 , wherein the spoiled beam is generated by introducing a phase difference that alters a coherence of the received signals at the reconfigurable phased array antenna ( 214 ).
6 . The method of claim 1 , wherein, after the satellite ( 102 ) has been selected, the user terminal ( 104 ) is operable for:
switching ( 612 ) to a directional mode for the reconfigurable phased array antenna ( 214 );
establishing ( 612 ) the communication with the selected satellite ( 102 ) using the reconfigurable phased array antenna ( 214 ); and
tracking ( 614 ) the selected satellite ( 102 ).
7 . The method of claim 6 , wherein tracking ( 614 ) the selected satellite ( 102 ) comprises determining ( 614 ) an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the reconfigurable phased array antenna ( 214 ) based on ephemeris data for the satellites ( 102 ) relative to a current terrestrial or airborne location of the user terminal ( 104 ).
8 . The method of claim 1 , wherein the reconfigurable phased array antenna ( 214 ) is stationary prior to selecting the field of regard.
9 . The method of claim 1 , wherein the reconfigurable phased array antenna ( 214 ) is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the field of regard, but the reconfigurable phased array antenna ( 214 ) is not slewed once the field of regard is selected.
10 . An apparatus for establishing communication with a satellite ( 102 ), comprising:
a user terminal ( 104 ) including a reconfigurable phased array antenna ( 214 ) having a plurality of antenna elements ( 300 ), wherein the user terminal ( 104 ) is operable for:
broadening ( 604 ) a field of regard of the reconfigurable phased array antenna ( 214 );
receiving ( 606 ) signals from a plurality of satellites ( 102 ) within the field of regard using the reconfigurable phased array antenna ( 214 );
determining ( 608 ) one or more attributes of the received signals for each of the satellites ( 102 ); and
selecting ( 608 ) one of the plurality of satellites ( 102 ) for communication based on the determined attributes of the received signals.
11 . The apparatus of claim 10 , wherein the attributes comprise signal strength, signal quality, or proximity to other signals.
12 . The apparatus of claim 10 , wherein broadening ( 604 ) the field of regard includes at least one of:
using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
using ( 604 ) a spoiled beam by changing at least one of a phase and amplitude for one or more of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ) to spread a beam width.
13 . The apparatus of claim 12 , wherein using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) further comprises one of:
selecting ( 604 ) one antenna element ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
selecting ( 604 ) a sub-array of two or more antenna elements ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ).
14 . The apparatus of claim 12 , wherein the spoiled beam is generated by introducing a phase difference that alters a coherence of the received signals at the reconfigurable phased array antenna ( 214 ).
15 . The apparatus of claim 10 , wherein, after the satellite ( 102 ) has been selected, the user terminal ( 104 ) is operable for:
switching ( 612 ) to a directional mode for the reconfigurable phased array antenna ( 214 );
establishing ( 612 ) the communication with the selected satellite ( 102 ) using the reconfigurable phased array antenna ( 214 ); and
tracking ( 612 ) the selected satellite ( 102 ).
16 . The apparatus of claim 15 , wherein tracking the selected satellite ( 102 ) comprises determining an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the reconfigurable phased array antenna ( 214 ) based on ephemeris data for the satellites ( 102 ) relative to a current terrestrial or airborne location of the user terminal ( 104 ).
17 . The apparatus of claim 10 , wherein the reconfigurable phased array antenna ( 214 ) is stationary prior to selecting the field of regard.
18 . The apparatus of claim 10 , wherein the reconfigurable phased array antenna ( 214 ) is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the field of regard, but the reconfigurable phased array antenna ( 214 ) is not slewed once the field of regard is selected.
19 . An apparatus for establishing communication with a signal source ( 102 ), comprising:
a reconfigurable phased array antenna ( 214 ) having a plurality of antenna elements ( 300 ), wherein:
a field of regard of the reconfigurable phased array antenna ( 214 ) is broadened ( 604 ) prior to receiving ( 606 ) signals from the signal source ( 102 );
the reconfigurable phased array antenna ( 214 ) is switched ( 612 ) to a directional mode when establishing ( 612 ) communications with the signal source ( 102 ) and tracking ( 612 ) the signal source ( 102 ).
20 . The apparatus of claim 19 , wherein the field of regard is broadened ( 604 ) by at least one of:
using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
using ( 604 ) a spoiled beam by changing at least one of a phase and amplitude for one or more of the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ) to spread a beam width.
21 . The apparatus of claim 20 , wherein using ( 604 ) a lesser number than a total number of the plurality of antenna elements ( 300 ) further comprises one of:
selecting ( 604 ) one antenna element ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ); and
selecting ( 604 ) a sub-array of two or more antenna elements ( 300 ) from the plurality of antenna elements ( 300 ) of the reconfigurable phased array antenna ( 214 ).
22 . The apparatus of claim 20 , wherein the spoiled beam is generated by introducing a phase difference that alters a coherence of the received signals at the reconfigurable phased array antenna ( 214 ).
23 . The apparatus of claim 19 , wherein tracking the signal source ( 102 ) comprises determining an initial pointing vector comprised of an azimuth and elevation and an initial tracking vector comprised of a flight path for the reconfigurable phased array antenna ( 214 ) based on ephemeris data for the signal source ( 102 ) relative to a current terrestrial or airborne location of a user terminal ( 104 ).
24 . The apparatus of claim 19 , wherein the reconfigurable phased array antenna ( 214 ) is stationary prior to selecting the field of regard.
25 . The apparatus of claim 19 , wherein the reconfigurable phased array antenna ( 214 ) is slewed to establish an initial pointing vector comprised of an azimuth and elevation prior to selecting the field of regard, but the reconfigurable phased array antenna ( 214 ) is not slewed once the field of regard is selected.