GB2196183A - Antenna calibration - Google Patents
Antenna calibration Download PDFInfo
- Publication number
- GB2196183A GB2196183A GB08723383A GB8723383A GB2196183A GB 2196183 A GB2196183 A GB 2196183A GB 08723383 A GB08723383 A GB 08723383A GB 8723383 A GB8723383 A GB 8723383A GB 2196183 A GB2196183 A GB 2196183A
- Authority
- GB
- United Kingdom
- Prior art keywords
- antenna
- azimuth
- values
- elevation
- orientation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/12—Supports; Mounting means
- H01Q1/125—Means for positioning
- H01Q1/1257—Means for positioning using the received signal strength
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/005—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using remotely controlled antenna positioning or scanning
Landscapes
- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
A method of automatically calibrating an antenna pointing system (12, 14, 16, 18) for receiving signals from earth-orbiting satellites with a directional antenna (10) includes using a data processor (20) and memory in combination with the pointing system to rotate the antenna about two axes in a scanning movement, storing nominal azimuth and elevation values corresponding to orientations of the antenna at which signals of a predetermined strength are picked up, generating and storing a table of actual azimuth and elevation values using the orbital positions of known satellites and the geometrical relationship defining the azimuth and elevation of points in the geostationary orbit viewed from the antenna location, and correlating the actual values and nominal values to yield an estimate for the mean azimuth and elevation errors of the pointing system. Subtracting the errors from the actual azimuth and elevation values calibrates the pointing system. The system can then be operated to point the antenna at selected satellites on the basis of their orbital positions. <IMAGE>
Description
SPECIFICATION
Reception of satellite signals
This invention relates to a method and apparatus for automatically calibrating the orientation of a directional antenna to receive radio transmissions from an earth orbiting satellite or satellites, primarily satellites in the geostationary orbit.
In the field of the reception of TV or data communications signals from earth orbiting satellites, the strength of the radiated signal at the receiving location is generally of a low level which demands the use of high-gain antennae, which are inevitably highly directional, in order to obtain a satisfactory received signal-to-noise ratio. Adjusting the orientation of such an antenna to receive a selected satellite transmission is therefore a skilled and time consuming operation. In the case of geostationary satellites, adjustment of the antenna to receive different satellite transmissions can be carried out automatically using servo-controlled motors if the positions of the wanted satellites are know and stored, but successful operation of such an automatic system depends on having an accurate positional reference for the antenna, again requiring the services of a skilled person.
It is an object of this invention to provide means for the installation of a satellite ground station by relatively unskilled personnel.
According to a first aspect of this invention, there is provided a method of automatically calibrating the orientation of a directional antenna for receiving signals from an earth-orbiting satellite, the antenna being coupled to a radio receiver and positioning means, the positioning means comprising means for indicating the nominal orientation of the antenna in relation to an internal reference orientation, an antenna drive unit for rotating the antenna about at least two axes, and data processing means, wherein the method includes::
operating the drive unit to cause the antenna to sweep about the said axes in a scanning movement;
monitoring the strength of signals received by the receiver, the processing means being caused to store positional information representing a plurality of nominal orientations of the antenna with respect to the internal reference at which signals of a predetermined strength are received;
causing the processing means to perform a correlation operation in which data representative of the stored positional information is correlated with data representative of stored reference information related to known positions of satellite signal sources with respect to an external reference to derive automatically an error value or values; and
causing the processing means to combine the error value or values with the stored reference information so as to generate calibrated orientation data for controlling the drive unit and thereby allowing the antenna to be driven automatically to a required orientation for receiving signals from a selected satellite.
This automatic calibration procedure avoids the need for accurate manual setting-up of the antenna and its pointing system as part of the installation on site. The method is particularly useful for calibrating an antenna to receive signals from satellites in the geostationary orbit, since actual azimuth and elevation angles of points in the geostationary orbit may be calculated automatically given the installed location of the antenna on the earth's surface, the geometrical relationship between the geostationary orbit and the azimuth and elevation angles at that location, and the orbital positions, i.e. the longitudes, of the points. The correlation process may then be carried out between the calculated actual azimuth and elevation angles and nominal azimuth and elevation angles resulting from the scanning step referred to above.As a result, pointing the antenna at a selected satellite may be performed automatically given the orbital position of the satellite using the corresponding calculated actual azimuth and elevation values together with azimuth and elevation error values resulting from the correlation process.
In an apparatus aspect, the invention provides apparatus for the automatic calibration of the orientation of a directional antenna, the antenna being coupled to a radio receiver and being rotatable about at least two axes using a drive unit associated with the antenna, wherein the apparatus comprises:
a control circuit for energising the drive unit; and
processing means for connection to the receiver and coupled to the control circuit;
wherein the control circuit is actuable to cause the drive unit to rotate the antenna in a scanning movement, the processing means being operable to monitor the strength of signals received by the receiver and to store positional information representing a plurality of nominal antenna orientations at which signals of a predetermined strength are received.
wherein the processing means is arranged also to store reference information related to known positions of satellite signal sources and to perform a correlation operation in which data representative of the stored positional information is correlated with data representative of the stored reference information to yield automatically an error value or values;
and wherein the processing means has means for receiving information identifying a selected satellite signal source and is further arranged to combine the error value or values with the stored reference information so as to generate calibrated orientation data whereby receipt of the identifying information causes a signal to be transmitted from the processing means to the control circuit to drive the antenna automatically to a required orientation for receiving signals from the selected satellite.Advantageously, the processing means includes a memory for storing information relating to positions of the antenna corresponding to the geostationary orbit. To simplify the scanning procedure, the radio receiver may have a broadband input stage and be operable to receive signals over a predetermined frequency range so that a plurality of satellite transmissions of different carrier frequencies can be received without tuning the receiver separately to detect each separate transmission.
The invention will now be described by way of example with reference to the accompanying drawing which is a diagram of a typical ground station arrangement in accordance with the invention.
Referring to the drawing, a directional antenna 10, typically with a parabolic reflector, is coupled to a drive unit comprising a first servo-controlled motor 12 controlling azimuth position, and a second servo-controlled motor 14 controlling the elevation angle of the antenna. The motors are driven from respective motor control circuits 16 and 18, which are in turn controlled by a data processor 20 via connections 1 6A and 18A. The drive unit and the control circuits- 16 and 18 together constitute a pointing system for the antenna 10.A radio receiver 22 coupled to the antenna 10 via a low-noise amplifier 24 generates a signal at an output 26 which is indicative of the received signal strength from a detector, the latter being operable over a wide frequency range so that frequency tuning is not critical to successful operation of the system.
The antenna assembly, comprising antenna 10, low noise amplifier 24, and motors 12 and 14, may be mounted by unskilled personnel on the ground or on a fixed above-ground structure such that it has approximate references to flat level on the ground and perpendicular to the ground. Operation of the system shown in the drawing begins with a search phase in which the antenna is caused to scan over at least a 360" azimuth range with the elevation being incre
mented in small steps delta e, where delta e is less than the beam width of the antenna.
Typically the elevation is incremented 1" per azimuth sweep. Scanning could normally start at approximately 20 elevation, with the elevation being increased step by step for each azimuth
revolution. Whenever the detected signal level from the receiver reaches a predetermined value
indicating that a satellite transmitting in the frequency band of the receiver has been located, the
processor 20 stores the nominal azimuth and elevation angles of the antenna axis in a memory
associated with the processor together with a value representative of the maximum signal
strength.
The scanning procedure results in a list of nominal azimuth and elevation values in the memory
which include values corresponding to known satellites in the geostationary orbit whose orbital
positions, i.e. longitudes, are also known.
The known satellite orbital positions are entered as constants in the processor memory. Table
1 below gives examples of such positions together with the relevant satellites. The figures in
brackets are longitude values to be used for calculation as will be described below.
Satellite position Satellite 27.80 (-28) INTELSAT V 50 (-5) TELECOM 1B 1 h' (-1) INTELSAT 1 W 70E (+7) EUTELSAT F2 1UOE (+10) EUTELSAT F4
130E (+13) EUTELSAT F1 TABLE 1
Since a geometrical relationship connects positions in the geostationary orbit with azimuth and
elevation angles at-any chosen location on the surface of the earth, a table of actual azimuth and
elevation values can be calculated for points on the geostationary orbit which are visible from
that location. Table 2 is an abbreviated list of orbit positions and the corresponding azimuth and
elevation values for 50 46' N latitude and 3"4'W longitude.
SATELLITE POSITION AZIMUTH ELEVATION
-72 -78.3 0.3
-71 -78.0 0.9
-70 -77.2 1.6
-69 -76.4 2.2
-68 -75.6 2.8
-67 -74.8 3.4
-3 -8.6 31.7
-2 -7.3 31.7
-1 -6.0 31.8
0 -4.7 31.9
1 -3.4 31.9
2 -2.1 32.0
3 -0.8 32.0
4 0.4 32.0
5 1.7 32.0
6 3.0 32.0
7 4.3 31.9
8 5.6 31.9
9 6.8 31.8
10 8.1 31.7
74 74.5 3.6
75 75.3 3.0
76 76.1 2.4
77 76.9 1.8
78 77.7 1.1
79 78.5 0.5
TABLE 2
These values can be calculated from a mathematical relationship stored as part of the processor program, or they may be stored as a look-up table in the memory, the values having been read into the memory prior to installation.
By windowing Table 2 with Table 1 to the known satellite positions, Table 3 below can be produced in the processor memory.
SATELLITE POSITION AZIMUTH ELEVATION
-28 -38.6 24.4
-5 -11.1 31.4 -1 -6.0 31.9
7 4.3 32.0
10 8.2 31.7
13 12 31.4
TABLE 3
The only difference between the values produced by the scanning operation referred to above, and corresponding values in Table 3 will be a potentially large azimuth error and a relatively small elevation error due to the almost inevitable inaccuracy of installation, plus a component due to the difference between the actual geographical location of the antenna and the nominal location for which the apparatus was pre-programmed prior to or during installation.
The nominal values produced from scanning together with the values of Table 3 enable the processor to determine azimuth and elevation errors of the antenna pointing system. Firstly, the a priori standard deviations and mean probabilities for the azimuth and elevation errors are entered as constants, and then the nominal azimuth and elevation values are correlated in known manner by the processor with the values of Table 3 to yield most likely (i.e. maximum likelihood) estimates for the mean of the azimuth and elevation errors.
These errors are next subtracted from the azimuth and elevation values of Table 2 so that the system now contains calibrated or corrected azimuth and elevation reference values for driving the antenna directly to the required orientation for receiving signals from a selected satellite simply on the basis of the orbital position of the satellite.
Since satellites in the geostationary orbit do not in general remain exactly fixed in position with respect to the receiving location, small adjustments in the antenna orientation will usually be required from time to time, particularly if the antenna is relatively large and consequently has a very narrow beamwidth. Such adjustments may be carried out on a continuous basis using conventional antenna tracking techniques based on monitoring the received signal strength. Such techniques include step track or conical scan procedures.
CLAIMS
1. A method of automatically calibrating the orientation of a directional antenna for receiving signals from an earth orbiting satellite, the antenna being coupled to a radio receiver and positioning means, the positioning means comprising means for indicating the nominal orientation of the antenna in relation to an internal reference orientation, an antenna drive unit for rotating the antenna about at least two axes, and data processing means, wherein the method includes::
operating the drive unit to cause the antenna to sweep about the said axes in a scanning movement;
monitoring the strength of signals received by the receiver, the processing means being caused to store positional information representing a plurality of nominal orientations of the antenna with respect to the internal reference at which signals of a predetermined strength are received;
causing the processing means to perform a correlation operation in which data representative of the stored positional information is correlated with data representative of stored reference informaton related to known positions of satellite signal sources with respect to an external reference to derive automatically an error value or values; and
causing the processing means to combine the error value or values with the stored reference information so as to generate calibrated orientation data for controlling the drive unit and thereby allowing the antenna to be driven automatically to a required orientation for receiving signals from a selected satellite.
2. A method according to claim 1, wherein the stored reference information comprises a plurality of actual antenna orientation values based on the external reference and corresponding to the direction of points on the geostationary orbit when viewed from the location of the antenna on the surface of the earth.
3. A method according to claim 2, including a preliminary step of feeding the location of the antenna on the surface of the earth into the processing means, and causing the processing
SATELLITE POSITION AZIMUTH ELEVATION
-72 -78.3 0.3
-71 -78.0 0.9
-70 -77.2 1.6
-69 -76.4 2.2
-68 -75.6 2.8
-67 -74.8 3.4
-3 -8.6 31.7
-2 -7.3 31.7
-1 -6.0 31.8
0 -4.7 31.9
1 -3.4 31.9
2 -2.1 32.0
3 -0.8 32.0
4 0.4 32.0
5 1.7 32.0
6 3.0 32.0
7 4.3 31.9
8 5.6 31.9
9 6.8 31.8
10 8.1 31.7
74 74.5 3.6
75 75.3 3.0
76 76.1 2.4
77 76.9 1.8
78 77.7 1.1
79 78.5 0.5
TABLE 2
These values can be calculated from a mathematical relationship stored as part of the processor program, or they may be stored as a look-up table in the memory, the values having been read into the memory prior to installation.
By windowing Table 2 with Table 1 to the known satellite positions, Table 3 below can be produced in the processor memory.
SATELLITE POSITION AZIMUTH ELEVATION
-28 -38.6 24.4
-5 -11.1 31.4
-1 -6.0 31.9
7 4.3 32.0
10 8.2 31.7
13 12 31.4
TABLE 3
The only difference between the values produced by the scanning operation referred to above, and corresponding values in Table 3 will be a potentially large azimuth error and a relatively small elevation error due to the almost inevitable inaccuracy of installation, plus a component due to the difference between the actual geographical location of the antenna and the nominal location for which the apparatus was pre-programmed prior to or during installation.
The nominal values produced from scanning together with the values of Table 3 enable the processor to determine azimuth and elevation errors of the antenna pointing system. Firstly, the a priori standard deviations and mean probabilities for the azimuth and elevation errors are entered as constants, and then the nominal azimuth and elevation values are correlated in known manner by the processor with the values of Table 3 to yield most likely (i.e. maximum likelihood) estimates for the mean of the azimuth and elevation errors.
These errors are next subtracted from the azimuth and elevation values of Table 2 so that the system now contains calibrated or corrected azimuth and elevation reference values for driving the antenna directly to the required orientation for receiving signals from a selected satellite simply on the basis of the orbital position of the satellite.
Since satellites in the geostationary orbit do not in general remain exactly fixed in position with respect to the receiving location, small adjustments in the antenna orientation will usually be required from time to time, particularly if the antenna is relatively large and consequently has a very narrow beamwidth. Such adjustments may be carried out on a continuous basis using conventional antenna tracking techniques based on monitoring the received signal strength. Such techniques include step track or conical scan procedures.
Claims (14)
1. A method of automatically calibrating the orientation of a directional antenna for receiving signals from an earth orbiting satellite, the antenna being coupled to a radio receiver and positioning means, the positioning means comprising means for indicating the nominal orientation of the antenna in relation to an internal reference orientation, an antenna drive unit for rotating the antenna about at least two axes, and data processing means, wherein the method includes::
operating the drive unit to cause the antenna to sweep about the said axes in a scanning movement;
monitoring the strength of signals received by the receiver, the processing means being caused to store positional information representing a plurality of nominal orientations of the antenna with respect to the internal reference at which signals of a predetermined strength are received;
causing the processing means to perform a correlation operation in which data representative of the stored positional information is correlated with data representative of stored reference informaton related to known positions of satellite signal sources with respect to an external reference to derive automatically an error value or values; and
causing the processing means to combine the error value or values with the stored reference information so as to generate calibrated orientation data for controlling the drive unit and thereby allowing the antenna to be driven automatically to a required orientation for receiving signals from a selected satellite.
2. A method according to claim 1, wherein the stored reference information comprises a plurality of actual antenna orientation values based on the external reference and corresponding to the direction of points on the geostationary orbit when viewed from the location of the antenna on the surface of the earth.
3. A method according to claim 2, including a preliminary step of feeding the location of the antenna on the surface of the earth into the processing means, and causing the processing means to generate the actual orientation values using a geometrical relationship and the known position of the geostationary orbit.
4. A method according to claim 2, wherein the actual orientation values correspond to known positions of satellite signal sources in the geostationary orbit.
5. A method according to claim 1, wherein the stored positional information is a plurality of nominal azimuth and elevation values and the stored reference information is a plurality of actual azimuth and elevation values corresponding to points on the geostationary orbit viewed from the installed location of the antenna.
6. A method according to claim 5, wherein the correlation operation uses a prior deviation and mean probability constants for azimuth and elevation errors.
7. A method according to claim 3, wherein the antenna is driven to the required orientation for receiving signals from a selected satellite in the geostationary orbit by automatically generating the required azimuth and elevation values.
8. Apparatus for the automatic calibration of the orientation of a directional antenna, the antenna being coupled to a radio receiver and being rotatable about at least two axes using a drive unit associated with the antenna, wherein the apparatus comprises:
a control circuit for energising the drive unit; and
processing means for connection to the receiver and coupled to the control circuit;
wherein the control circuit is actuable to cause the drive unit to rotate the antenna in a scanning movement, the processing means being operable to monitor the strength of signals received by the receiver and to store positional information representing a plurality of nominal antenna orientations at which signals of a predetermined strength are received.
wherein the processing means is arranged also to store reference information related to known positions of satellite signal sources and to perform a correlation operation in which data representative of the stored positional information is correlated with data representative of the stored reference information to yield automatically an error value or values;
and wherein the processing means has means for receiving information identifying a selected satellite signal source and is further arranged to combine the error value or values with the stored reference information so as to generate calibrated orientation data whereby receipt of the identifying information causes a signal to be transmitted from the processing means to the control circuit to drive the antenna automatically to a required orientation for receiving signals from the selected satellite.
9. Apparatus according to claim 8, wherein the processing means is arranged to store a lookup table relating positions of satellites in the geostationary orbit to azimuth and elevation values for a preselected antenna location on the surface of the earth.
10. Apparatus according to claim 8, wherein the control circuit has azimuth and elevation outputs for connection to first and second drive motors in the drive unit, the first and second motors being operable to adjust the azimuth and elevation respectively of the antenna axis.
11. A method of adjusting the orientation of a directional antenna for receiving signals from an earth-orbiting satellite, the antenna being coupled to an antenna pointing system including a drive unit for rotating the antenna in azimuth and elevation, and to a radio receiver for receiving signals within a predetermined frequency range, the radio receiver and the drive unit being connected to data processing and control means for monitoring signals received by the receiver and for controlling the drive unit, wherein the method comprises::
(i) causing the antenna to execute a scanning movement under the control of the data processing and control means and simultaneously monitoring the strength of signals received by the receiver;
(ii) storing nominal azimuth and elevation values representing the orientations of the antenna at the times where signals of a predetermined strength are received;
(iii) storing data representing the orbital positions of known transmitting satellites in the geostationary orbit;
(iv) generating a table of actual azimuth and elevation values corresponding to the orbital positions for the installed location of the antenna using a geometrical relationship;
(v) correlating the nominal and actual azimuth values to produce estimates of the mean azimuth and elevation errors in the nominal values; and
(vi) combining the estimated errors with the actual azimuth and elevation values to calibrate the antenna pointing system.
12. A method according to claim 11, wherein pointing the antenna at a selected satellite in the geostationary orbit-comprises causing the data processing and control means to actuate the drive unit so as to rotate the antenna to an orientation corresponding to the sum of or difference between on the one hand stored actual azimuth and elevation values corresponding to the orbit position of the selected satellite and on the other hand the said azimuth and elevation errors.
13. A method according to claim 12, further comprising an optimisation phase of automatically monitoring the strength of the signal received from the selected satellite and periodically adjust ing the azimuth and elevation of the antenna axis incrementally to maximise the received signal strength.
14. Apparatus for receiving signals from an earth orbiting satellite, comprising:
a directional antenna rotatable about at least two axes;
a drive unit attached to the antenna for rotating the antenna about the said axes;
a control circuit coupled to the drive unit for energising the drive unit;
a radio receiver connected to the antenna for receiving signals picked up by the antenna;
and data processing means coupled to the receiver and the control circuit and operable via the control circuit to cause the drive means to rotate the antenna automatically in a scanning movement while simultaneously monitoring the strength of signals received by the receiver and storing nominal antenna orientations corresponding to received signals having a predetermined characteristic; ;
the data processing means being programmed to perform a correlation operation correlating the nominal antenna orientations with the actual known orientations of satellite signal sources for the particular location of the antenna on the earth's surface, whereby orientation error values are generated, the processing means being further programmed to combine the error values with the said known orientations to yield a set of calibrated antenna orientation values for controlling the rotation of the antenna when it is required to receive signals from a selected satellite.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868624187A GB8624187D0 (en) | 1986-10-08 | 1986-10-08 | Reception of satellite signals |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8723383D0 GB8723383D0 (en) | 1987-11-11 |
| GB2196183A true GB2196183A (en) | 1988-04-20 |
Family
ID=10605455
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868624187A Pending GB8624187D0 (en) | 1986-10-08 | 1986-10-08 | Reception of satellite signals |
| GB08723383A Withdrawn GB2196183A (en) | 1986-10-08 | 1987-10-06 | Antenna calibration |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868624187A Pending GB8624187D0 (en) | 1986-10-08 | 1986-10-08 | Reception of satellite signals |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8624187D0 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0361885A2 (en) * | 1988-09-28 | 1990-04-04 | Gi Corporation | Satellite antenna alignment system |
| DE3930856A1 (en) * | 1989-09-15 | 1991-04-04 | Grundig Emv | Automatic equaliser for polariser control in satellite receiver - has coarse, manual adjuster for polarising direction and additional fine adjuster |
| DE4237994A1 (en) * | 1992-04-13 | 1993-10-14 | Crystop Display Ges Fuer Anzei | Rapid positioning of mobile satellite TV and radio receivers - controlling satellite dish using pair of motors coupled to micro-controller based unit |
| EP0731523A2 (en) * | 1995-03-10 | 1996-09-11 | Space Systems / Loral, Inc. | System and method for spacecraft antenna pointing error correction |
| GB2320153A (en) * | 1996-12-07 | 1998-06-10 | Bosch Gmbh Robert | Detecting sensor misalignment |
| WO2002039539A2 (en) * | 2000-11-08 | 2002-05-16 | Spacenet, Inc. | Automatic antennae system |
| GB2386477A (en) * | 2002-03-12 | 2003-09-17 | Andrew Corp | Satellite tracking system |
| US10215835B1 (en) * | 2015-08-26 | 2019-02-26 | L-3 Communications Services, Inc. | Estimating location of source of signal of interest |
| IT202000007138A1 (en) * | 2020-04-03 | 2021-10-03 | Cinzia Uguzzoni | ANTENNA FOR TELECOMMUNICATIONS |
-
1986
- 1986-10-08 GB GB868624187A patent/GB8624187D0/en active Pending
-
1987
- 1987-10-06 GB GB08723383A patent/GB2196183A/en not_active Withdrawn
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0361885A2 (en) * | 1988-09-28 | 1990-04-04 | Gi Corporation | Satellite antenna alignment system |
| EP0361885A3 (en) * | 1988-09-28 | 1990-08-22 | General Instrument Corporation | Satellite antenna alignment system |
| AU625680B2 (en) * | 1988-09-28 | 1992-07-16 | General Instrument Corporation | Satellite antenna alignment system |
| DE3930856A1 (en) * | 1989-09-15 | 1991-04-04 | Grundig Emv | Automatic equaliser for polariser control in satellite receiver - has coarse, manual adjuster for polarising direction and additional fine adjuster |
| DE4237994A1 (en) * | 1992-04-13 | 1993-10-14 | Crystop Display Ges Fuer Anzei | Rapid positioning of mobile satellite TV and radio receivers - controlling satellite dish using pair of motors coupled to micro-controller based unit |
| EP0731523A2 (en) * | 1995-03-10 | 1996-09-11 | Space Systems / Loral, Inc. | System and method for spacecraft antenna pointing error correction |
| EP0731523A3 (en) * | 1995-03-10 | 1997-02-26 | Loral Space Systems Inc | System and method for spacecraft antenna pointing error correction |
| GB2320153B (en) * | 1996-12-07 | 1998-10-28 | Bosch Gmbh Robert | Method and device for detecting a vertical misalignment of a gap sensor |
| GB2320153A (en) * | 1996-12-07 | 1998-06-10 | Bosch Gmbh Robert | Detecting sensor misalignment |
| US6026353A (en) * | 1996-12-07 | 2000-02-15 | Robert Bosch Gmbh | Method and apparatus for recognizing a vertical misalignment of a clearance sensor |
| WO2002039539A2 (en) * | 2000-11-08 | 2002-05-16 | Spacenet, Inc. | Automatic antennae system |
| WO2002039539A3 (en) * | 2000-11-08 | 2003-02-13 | Spacenet Inc | Automatic antennae system |
| US6563471B2 (en) | 2000-11-08 | 2003-05-13 | Gilat Satellite Networks, Ltd. | Automatic pointing antennae system |
| GB2386477A (en) * | 2002-03-12 | 2003-09-17 | Andrew Corp | Satellite tracking system |
| US6657588B2 (en) | 2002-03-12 | 2003-12-02 | Andrew Corporation | Satellite tracking system using orbital tracking techniques |
| US10215835B1 (en) * | 2015-08-26 | 2019-02-26 | L-3 Communications Services, Inc. | Estimating location of source of signal of interest |
| IT202000007138A1 (en) * | 2020-04-03 | 2021-10-03 | Cinzia Uguzzoni | ANTENNA FOR TELECOMMUNICATIONS |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8723383D0 (en) | 1987-11-11 |
| GB8624187D0 (en) | 1986-11-12 |
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