Communications: directive radio wave systems and devices (e.g. – Directive – Including antenna orientation
Reexamination Certificate
2001-09-25
2002-11-05
Phan, Dao (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including antenna orientation
Reexamination Certificate
active
06476764
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a method for monitoring a non-tracking satellite terminal antenna, after initial installation, wherein the terminal operates within a geo-synchronous satellite communications network. More particularly, the present invention relates to detecting mis-pointing of a non-tracking satellite terminal antenna due to antenna mis-pointing upon initial installation, and a long-term event, such as building settlement, as well as a short-term event such as any weather related phenomena, for example earthquakes and wind storms.
BACKGROUND OF THE INVENTION
DETAILED DESCRIPTION OF THE RELATED ART
As shown in
FIG. 1
, a satellite communications network
100
employs a plurality of satellite terminals
130
comprising antennas
140
to communicate with a satellite
110
as well as a network control center
120
. There are various conventional means of installing and pointing the ST
130
which are time-consuming and tedious, as detailed below. Nonetheless, post-installation monitoring of an ST
130
is important to insure proper reception of signals at the ST
130
, as well as to reduce the number of costly site revisits by an installer if the initial installation is not successful, or due to short term and long term events that degrade link margin performance between the satellite
110
and the ST
130
.
A conventional means of installing a satellite terminal (ST) antenna
130
in a geo-synchronous satellite system
100
can be time-consuming and tedious. The installation requires knowledge of the desired satellite
110
location on the geo-synchronous orbital arc and its elevation and azimuth angles relative to the antenna location. The installer performs an initial search by pointing the antenna toward the direction of the target satellite until sufficient satellite signal power is received to declare successful acquisition of the target satellite. Once the target satellite is acquired, the installer optimizes antenna pointing by peaking the strength of the received signal. The idea is to align the antenna bore-sight directly towards the target satellite. The installer can also employ the method described in a related patent application of Russell J. Fang, entitled “System and Method for Pointing the Bore Sight of a Terminal Antenna towards the Center of a Satellite Station-Keeping Box In the Geo-Synchronous Orbit”, filed September 25, 2001, to align the boresight of the antenna to the center of a satellite station keeping box. In any event, the non-tracking antenna is left untouched for operational use, after its installation by any method. Accordingly, a need exists for a post-installation monitoring method that can measure how well the bore sight of the antenna of a ST
130
is aligned relative to the center of the satellite station keeping box, which is the ideal satellite position.
Also, significant antenna mis-pointing can result if the installer attempts to install the antenna under rainy or cloudy conditions or if the installer does not follow the recommended procedure for ST
130
installation as detailed above. In addition, despite an antenna being perfectly pointed, certain events can cause antenna mis-pointing as well. For example, short-term events such as earthquakes, hurricanes, tornados, micro bursts, and other natural events can cause antenna mis-pointing. Also, long term events such as building settlement can cause gradual antenna mis-pointing, and eventually resulting in gross antenna mis-pointing.
A mis-pointed terminal antenna not only causes degradation to the transmission link performance between the satellite
110
and the ST
130
, but also can cause undesirable interference to users in an adjacent satellite system. Many times, costly site revisits are necessary, along with customer complaints as a consequence of a mis-pointed antenna. Accordingly, a need exists for a means to monitor the antenna mis-pointing either due to improper installation or due to some special short term or long term events as cited above. A need exists for quickly detecting these mis-pointed antennas and informing the network operations and control center for necessary corrective measures.
SUMMARY OF THE INVENTION
The above described disadvantages are overcome and advantages realized by a method for determining the pointing of a non-tracking satellite terminal antenna as a result of improper installation, or a long term event, such as building settlement, or a short term event such as weather related phenomena. The satellite terminal antenna is adapted to receive a signal from at least one satellite within a communications network. The satellite terminal then identifies a satellite station keeping box in which the satellite is expected to be present, and divides the satellite station keeping box into a plurality of regions. The method comprises determining a plurality of first measurement values, each representing a magnitude of a signal received from the satellite by the satellite terminal antenna when the satellite terminal antenna is pointing towards a first location, corresponding to a substantially central area of the satellite station keeping box. The next step involves determining at least one second measurement value corresponding to a respective one of the satellite position regions and representing a magnitude of a second signal received by the satellite terminal antenna from the satellite. The satellite terminal antenna then compares at least one of the second measurement values to the first measurement value corresponding to the region of the satellite station keeping box to which the second measurement value corresponds. Finally, the ST issues an alarm signal when a result of the comparison indicates that at least one second measurement value differs from the first measurement value by mote than a pre-determined amount.
REFERENCES:
patent: 4030099 (1977-06-01), Valenti et al.
patent: 5561433 (1996-10-01), Chaney et al.
patent: 5592176 (1997-01-01), Vickers et al.
patent: 5923288 (1999-07-01), Pedlow
Hughes Electronics Corporation
Phan Dao
Sales Michael W.
Whelan John T.
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