CN112152696B

CN112152696B - Uplink interference geographic positioning method and system for high-throughput satellite

Info

Publication number: CN112152696B
Application number: CN201910581472.3A
Authority: CN
Inventors: 唐舜康; 黄俊贤; 梁彦聪; 胡海; 陈文熙; 叶吉帆
Original assignee: Asia Satellite Telecommunications Co Ltd
Current assignee: Asia Satellite Telecommunications Co Ltd
Priority date: 2019-06-29
Filing date: 2019-06-29
Publication date: 2022-10-28
Anticipated expiration: 2039-06-29
Also published as: CN112152696A

Abstract

A geolocation method and system for locating high-throughput satellite interferers. The method involves determining the relative power level difference between the interfering signal received by the victim spot beam and a co-phased neighbor spot beam on the same satellite. Using the beam pattern data, the relative power levels of the beams in a pair determine the contours of the possible locations, which correspond to the relative power difference of the signals received by the two beams in the pair. The intersection of the contours from the pairs of spot beams indicates the location of the interference source.

Description

Uplink interference geographic positioning method and system for high-throughput satellite

Technical Field

The present application relates to satellite communications, and more particularly to a method and system for geolocation of an uplink interferer for High Throughput Satellites (HTS).

Background

Conventional Fixed Service Satellite (FSS) systems use one or more large wide beams to cover a large geographic area. Sometimes, a satellite may experience interference from uplink signals in its operating frequency band. It is valuable to be able to identify the location of such signals in order to take corrective action. Prior techniques for geo-locating such signals rely on time difference of arrival and frequency difference of arrival techniques involving a satellite and a ground station and a second adjacent satellite and ground station using the same frequency spectrum. This may be difficult to achieve in practice.

Modern satellite communications are moving from FSS to High Throughput Satellite (HTS) systems, where the satellite employs a large number of narrow spot beams and relies on color multiplexing to improve the capacity of each beam. HTS is considered particularly attractive because it can achieve higher capacity for both uplink and downlink, and modern satellite communications require greater emphasis on bi-directional traffic, i.e., uplink and downlink to terminal devices, such as the satellite-based mobile internet. This means that HTS systems can expect significantly more upstream signals from endpoints, will rely more on being able to accurately receive and transmit these signals, and may be subject to greater risk of interference from unexpected or malicious upstream signals.

Therefore, it would be advantageous to have a better method and system for geo-locating an upstream interfering signal source.

Disclosure of Invention

To address the foregoing, in one aspect, the present application describes a satellite system to locate an uplink interferer. The system may include: a plurality of co-located spot beam antennas to receive uplink signals and wherein each spot beam has a respective geographic coverage area, the respective coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color multiplexing mode; a digital channelizing processor to digitally channelize the received signals from each of the co-color spot beam antennas to produce a corresponding digitized spectrum; a spectrum analysis module to identify an interfering carrier in one of the digitized spectra and determine a relative power level between the interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectra; and a geo-location module to, for each of the relative power levels, determine a geo-located contour based on the relative power level and identify a geographic location of the upstream interference source based on an intersection between two or more of the contours.

In another aspect, the present application describes a method for locating an uplink interferer using a high-throughput satellite having a plurality of co-located spot beam antennas to receive the uplink signal and where each spot beam has a corresponding geographic coverage area, the respective coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color-multiplexed pattern. The method may include digitally channelizing the received signals from each of the co-located spot beam antennas to produce a corresponding digitized spectrum; detecting an interfering carrier in one of the digitized spectra; determining a relative power level between an interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectrums; for each of the relative power levels, determining a geo-located contour based on the relative power level; and identifying a geographic location of the upstream interference source based on an intersection between two or more of the contours.

In another aspect, the present application provides a method for locating an upstream interferer using a high-throughput satellite having a plurality of co-located spot beam antennas to receive the upstream signals and where each spot beam has a corresponding geographic coverage area, the respective coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color multiplexing pattern, the high-throughput satellite receiving and digitally channelizing the signals from each of the co-located spot beam antennas to produce a corresponding digitized spectrum to detect interfering carriers in one of the digitized spectra. The method may include receiving data regarding power levels of interfering carriers in three or more digitized spectra from a high throughput satellite at a terrestrial network operations center over a communication link; determining, from the data regarding power levels, a relative power level between the interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectra; for each of the relative power levels, determining a geo-located contour based on the relative power level; and identifying a geographic location of the upstream interference source based on an intersection between two or more of the contours.

Drawings

Reference will now be made, by way of example, to the accompanying drawings which illustrate exemplary embodiments of the present disclosure, and in which:

fig. 1 illustrates in block diagram form one example of an HTS payload;

fig. 2 illustrates an exemplary coverage area for an HTS system in a four-color multiplexing mode;

FIG. 3 shows a one-dimensional beam pattern cut plane showing the pattern of the overlap of three co-colored beams;

FIG. 4 illustrates an uplink portion of an exemplary satellite system;

FIG. 5 shows a one-dimensional beam pattern slice with relative gain shown thereon;

fig. 6 illustrates, in flow chart form, an exemplary method of locating a source of an interfering signal;

FIG. 7 shows, in an example, contours corresponding to relative gains determined for a beam pair;

figure 8 shows contours corresponding to the relative gains determined for two beam pairs;

figure 9 shows contours corresponding to the relative gains determined for three beam pairs;

FIG. 10 shows contours corresponding to the relative gains determined for six beam pairs;

FIG. 11 shows contours corresponding to relative gains based on two nearby beam pairs and one more distant beam pair; and

fig. 12 illustrates an exemplary method for locating an uplink interferer.

Like reference numerals are used in the figures to denote like elements and features.

Detailed Description

Other exemplary embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, when read in conjunction with the accompanying drawings.

Any feature described in relation to one aspect or embodiment of the invention may also be used in one or more other aspects/embodiments. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described herein.

In this application, the term "and/or" is intended to cover all possible combinations and subcombinations of the listed elements, including any one, any subcombination, or all elements listed individually, without necessarily excluding other elements.

In this application, the phrase "at least one of" is intended to encompass any one or more of the listed elements, including any one of, any subcombination of, or all of the elements listed individually, without necessarily excluding any other elements, and without necessarily requiring all elements.

Overview of satellites

Satellites are devices located in orbital space that are used for various purposes. In one exemplary embodiment, the satellite is a communications satellite. That is, they are located in the orbital space for the purpose of providing communication. For example, communication satellites are designed to relay communication signals between two endpoints (which may be fixed or mobile) to provide communication services such as telephony, television, radio, and/or internet services.

Satellites may use various orbital paths around the earth. For example, the satellites may be located in geostationary orbit, mo Erni sub-orbit, elliptical orbit, polar and non-polar earth orbits, and the like. Communication satellites are typically located in geostationary orbit. That is, the satellite has a circular orbit above the equator of the earth and follows the direction of the earth's rotation. The orbital period of a satellite in such an orbit is equal to the rotation period of the earth and may therefore occur in a fixed position in the sky seen by the ground station.

The communication satellites are typically spaced apart along a stationary orbit of the earth. That is, the satellite is located in an orbital position. Satellite operators coordinate their use of orbit positions according to international treaties of the International Telecommunication Union (ITU), and the spacing between orbit positions depends on the coverage and operating frequency of the satellite. For example, in at least some example embodiments, the spacing between satellites may be between 2-3 degrees of orbital longitude. In at least some example embodiments, the separation between satellites may be less than 2 degrees. Separating the satellites in this manner allows reuse of the operating frequencies of the uplink and downlink. For example, by separating adjacent satellites by a distance greater than the width of the beam used for uplink ground station antenna transmission (i.e., an angle measured in a horizontal plane between directions in which the power of the beam is at least half its maximum), the same communication signal frequency may be employed up to adjacent satellites, which may cause interference that meets or is below the coordination requirements. Similarly, if the separation distance between adjacent satellites is greater than the antenna receive beamwidth for the downlink ground station, the same communication signal frequency may be used to downlink from the adjacent satellites, which may cause interference that meets or is less than the coordination requirements.

In order to perform communication functions, satellites are equipped with various required elements. For example, a satellite may include a communications payload (which may further include a transponder, one or more antennas, and a switching system), a thruster (to push the satellite into a desired orbit), a tracking and stabilization system (for satellite attitude keeping and satellite orbital keeping), a power subsystem (to power the satellite), and a command and control subsystem (to maintain communication with a ground control station).

The transponder of the satellite forms a communication channel between the two endpoints to allow communication between the two endpoints. The transponder also determines the capacity of the satellite communication.

The antenna of the satellite transmits and receives communication signals. More specifically, an antenna is an electronic component that can convert an electrical signal (which may be generated by a transmitter) into a Radio Frequency (RF) signal that can propagate in space, and convert a received RF signal into an electrical signal. In at least some example embodiments, the antenna may be connected to an amplifier, which may amplify the power of the RF signal to be transmitted or received.

The communication signal may be a microwave signal. Microwave signals are RF signals with wavelengths ranging from as long as one meter to as short as one millimeter. Likewise, the frequency of the RF signal may be in the range of 300MHz to 300 GHz. More specifically, certain bands of microwave signals are better suited for satellite communications. For example, in at least some example embodiments, the satellite may operate within frequencies of the C-band defined by the ITU. The C-band is a portion of the electromagnetic spectrum, ranging from about 4GHz to 8GHz. That is, communication signals are transmitted and received by the satellite in this frequency range. In some cases, the satellite may operate at frequencies above 8GHz. For example, a satellite may operate within the Ku band of frequencies. The Ku band is a portion of the electromagnetic spectrum, ranging from about 10GHz to 18GHz. In at least some example embodiments, the satellite may operate in other high frequency bands above the Ku band. For example, a satellite may operate within the Ka band. The Ka band is a portion of the electromagnetic spectrum ranging from approximately 26.5GHz to 40GHz (currently, fixed Satellite Service (FSS) defines frequency bands at 27-31GHz for the uplink and 17.7-21.2GHz for the downlink). In some examples, a satellite may be designed to operate in more than one band. In one example, a satellite may be designed to receive and transmit signals within the C-band, ku-band, and Ka-band. It should be understood that the satellite may operate in other microwave frequency bands. For example, a satellite may operate in any one of the defined microwave frequency bands ranging from about 1GHz to 170 GHz. Examples of other microwave bands may include the X-band, Q-band, V-band, and so forth.

High throughput satellite system

As described above, in a conventional satellite fixed service (FSS) system, one or several large beams (e.g., a global beam for C-band (semi-global beam) and some regional beams for Ku-band) are generally used to cover a desired region.

In high-throughput satellite (HTS) systems, the satellite uses multiple narrow spot beams (e.g., 0.6 degree Ka or Ku band beams). The spot beams are arranged in a pattern to cover a desired area. HTS systems typically rely on "color multiplexing. Different portions of the spectrum used by different spot beams, or the same portion but using different polarizations, are referred to as different "colors". That is, each color represents a segment of the spectrum having a certain bandwidth and a certain polarization that can be used by end users within the coverage area of the spot beam. The spatial separation of the beams allows each color to be multiplexed by multiple beams to increase system capacity. In many embodiments, HTS systems attempt to minimize inter-beam interference of downlink and uplink signals by ensuring that adjacent beams use different colors. Generally, using fewer colors will result in higher inter-beam interference, especially at the edge of coverage (EOC), however, as more bandwidth is allocated per coverage area, the overall capacity of the system may also become higher. Conventional HTS network designs may use a 4-color multiplexing scheme, but some systems may have 2, 6, 8, or more colors. It will be appreciated that a 2-color multiplexing mode will result in some adjacent beams using the same color.

Referring to fig. 1, one example of an HTS payload 100 is shown in block diagram form. HTS payload 100 in this example includes N spot beam antennas 102. A signal received in one spot beam antenna 102 is amplified by a Low Noise Amplifier (LNA) 104, down-converted in a mixer 106, and input to a Digital Channelizing Processor (DCP) 108. The DCP 108 digitizes the downconverted spectrum to produce a digitized spectrum for fast analysis and switching operations, including channel switching or reallocation. The digitized channels are output by the DCP 108 for up-conversion, amplification (typically by a traveling wave tube 110), and transmission via the antenna 102.

Geolocation of interference sources

Satellites sometimes experience uplink interference where the satellite's receiving antenna detects unwanted signals within its operating bandwidth. Uplink interference may cause problems with the use of one or more channels. Uplink interference may be malicious or unintentional. In either case it is valuable to be able to identify the source of the uplink interference. However, one of the challenges is that the coverage area of a beam (even a spot beam) is a large geographic area. Identifying the geographical location of the interfering signal sources is very valuable, but also challenging.

In FSS systems, geolocation of uplink interference is possible, but active participation by neighboring satellites is required. This technique generally relies on the computation of time difference of arrival (TDOA) and frequency difference of arrival (FDOA) of the signals between the primary satellite/ground station and between the reference satellites/ground stations. In other words, at least two geosynchronous satellites and two ground stations are required to identify the location of the interference source. The reference satellite must be adjacent to the victim satellite and must share the same spectrum and coverage, which makes geolocation very difficult to actually operate.

Uplink interference can be a greater potential problem in HTS systems, since HTS is more involved in bi-directional data communication, i.e., simultaneous upload and download, for both the home and the mobile user.

More advanced, in one aspect, the present application provides a method and system for geolocation of HTS system uplink interference that is not dependent on neighboring satellites or TDOAs or FDOA. In some embodiments, the geolocation method utilizes a layout of color multiplexed spot beams and a digital channelization technique.

Fig. 2 shows an example of a portion of a coverage area 200 of an HTS system. The coverage area 200 is formed by a series of individual spot beam coverage areas. Color multiplexing is employed to minimize interference by ensuring that adjacent beams (i.e., adjacent coverage areas) do not use the same color. To illustrate this concept, the example shown in fig. 2 labels the respective coverage areas as red, blue (b), green (g), or orange (o). The co-colored "red" coverage areas are shown with thicker line widths and are labeled as

beams

0,1,2,3,4,5,6 and 11, respectively. It should be understood that although the coverage areas are represented as isolated circles, the beam gain patterns extend beyond the indicated circles. For example, the illustrated circles may indicate-3 dB points.

Fig. 3 shows an example of a one-dimensional pattern slice for three co-colored beams:

beams

0,1 and 4. Note that the gain pattern for beam 4 is still visible in the beam pattern for the range of beam 0, although the gain is significantly diminished, for example. Thus, any interfering uplink carriers transmitted from a location within the coverage area of one beam, although of lower power, may still be detected in the surrounding co-colored beam. In practice, the power that can be picked up by an adjacent spot beam antenna depends on the level of isolation between the two antenna patterns and the receiver sensitivity of the adjacent beam.

The uplink spectrum for each user beam may be digitized and processed by the on-board DCP and then transmitted to the downlink beams. Many advanced digital spectrum analysis functions can be implemented on the payload using advanced analog-to-digital conversion IC chips and DSP processors. For example, DCP can be used to measure the power of a particular carrier within the digitized spectrum. In accordance with one aspect of the present application, when the satellite receives the uplink interfering carrier, the power levels received by all of the co-colored beams can be measured and used to geo-locate the source of the uplink interfering signal. Geolocation can be done on satellite or power measurements (absolute or relative) are sent to a ground Network Operations Center (NOC) via a DCP high speed telemetry link where geolocation is done.

When an uplink interfering carrier is detected in one beam (the "victim" beam), the satellite may measure any corresponding uplink carrier located in the closest co-color beam, i.e., beams 1 through 6. The beams in the next layer of the co-color beam "loop", e.g., beam 11, may still be introduced in the positioning process if desired, as described further below, as long as the received carrier power level of the further away beam is still within the dynamic range of the beam input receiver.

Referring now to fig. 4, an uplink portion of an exemplary satellite system 400 is shown including a series of spot beam coverage areas 402 using a 4-color multiplexing mode, victim beam 0, and nearby co-located spot beam i. The system 400 includes receive antennas 404 for the two spot beams, a DCP 406, and in this example a terrestrial NOC 408, which receives data from a satellite via a high speed telemetry link (HSL TLM). DCP 406 includes a spectrum analysis module 410 configured to measure the power level of interfering carriers within the digitized spectrum.

In the two spot beams 0 and i, there are various losses/gains in the path that the signal under test travels. The uplink Equivalent Isotropic Radiated Power (EIRP) of the interfering station is set as E _U . Free space loss from station to satellite antenna is L _fs . The receiving antenna gains of the spot beam 0 and the beam i pointing to the interference station are respectively G ₀ And G _i . The repeater path loss (or gain) from the antenna output to the DCP input and from the DCP input to the spectrum analysis module is denoted gr for beam 0 and beam i, respectively ₀ 、gd ₀ And gr _i 、gd _i . Due to the nature of the geolocation problem, parameter E _U And L _fs Is unknown. And path loss g _r Are known and adequately measured during payload ground testing. The gain gd is known and can be changed by the HTS operator to adjust the input power level of the spectral analysis module. The parameter gd can be adjusted at sub-channel accuracy (e.g., BW =1 MHz) without affecting traffic in the remaining spectrum. Given these quantities, the measured carrier power level L ₀ And L _i Can be expressed as:

L ₀ ＝E _U ·L _fs ·G ₀ ·gr ₀ ·gd ₀ (1)

L _i ＝E _U ·L _fs ·G _i ·gr _i ·gd _i (2)

then, L ₀ And L _i Relative gain g between _0,i Namely:

wherein the unknown parameter E _U And L _fs Are eliminated. Since gr and gd are already known, equation (3) can be further simplified to

Where c is a constant normalized by the gr and gd parameters of the two repeater paths.

For the common color beams 1 to 6, the satellite may then find g accordingly _0,1 、g _0,2 ... And g _0,6 。

Referring now also to fig. 5, the one-dimensional pattern slice of fig. 3 is shown with the relative gains of

beams

0 and 1 and

beams

0 and 4 indicated, i.e., g _0,1 And g _0,4 . It will be appreciated that once the relative gain between a pair of beams is known, one or more points in a one-dimensional pattern slice corresponding to the relative difference in the pattern can be identified. It should also be understood that fig. 5 is a one-dimensional pattern slice. In two dimensions, the relative gain between a pair of beam patterns corresponds to a contour plot. The point at which two or more relative gain contours intersect is a likely location of an interferer.

A gain pattern for each beam may be obtained during the HTS payload testing phase. The HTS payload test phase may include measuring the gain pattern of each individual antenna in the X-Y (or U-V) slice during assembly, before the antenna is integrated into the satellite. The measured data may be compared to simulation data to verify design parameters. These gain patterns may be stored in beam direction map database 412. In some cases, beam direction database 412 may store a 2D beam pattern or gain contour map of beam pairs for a range of relative gains. Regardless of which data map is stored, the uplink interference geolocation module 414 uses the relative gains between beam pairs measured by the spectrum analysis module 410 to find a corresponding contour map based on the gain or relative gain data stored in the beam direction map database 412 and to find the point at which the contours of each beam pair intersect that is closest to the victim beam. The analysis may be performed automatically and the resulting cross-location data output to identify possible geographical locations of interfering upstream signal sources.

In some embodiments, the beam direction database 412 and UL interference geolocation module 414 may be implemented on-board the satellite rather than at the terrestrial NOC 408.

Referring now to FIG. 6, an exemplary process 600 for geolocation of an interfering carrier source for a high-throughput satellite is shown in flow chart form. Process 600 includes receiving an upstream signal at an HTS payload, as indicated by operation 602. The upstream signal is within the operating spectrum used by the HTS. As described above, each spot beam will receive signals within its assigned spectral "color", i.e., the portion of the operating spectrum assigned to them and having the correct polarization.

In operation 604, the received spectrum is digitized by the DCP on the HTS. In the normal course, the DCP will also continue to channelize the spectrum from each spot beam and transmit the uplink channel to the correct downlink channel. In this case, the DCP identifies the interfering carriers after digitizing the spectrum, as indicated by operation 606.

The DCP can identify interfering carriers based in part on the frequency plan of the spot beam. For example, the frequency plan may include a particular frequency range. Carriers outside this frequency range but within the operating range of the spot beam may be interfering carriers. In another example, the carrier may be within a frequency plan of the spot beam. In this case, the frequency plan may have a series of associated spectral specification lines set to indicate the expected normal range of variation for legitimate uplink carriers. If the carrier breaks the normal line (e.g., is exceeded in most continuous wave interference scenarios), it may be considered an interfering carrier. Even if the interfering carrier does not disrupt the normative line (i.e., it operates within the spectral normative line), it can be detected because of the degradation caused to the Es/No (energy per symbol versus noise power spectral density) value of the legally modulated wave.

If the DCP identifies an interfering carrier in operation 606, the DCP measures the relative gain between the pairs of co-chromatic beams, where the victim beam is one of the beams in each pair. As described above, the surrounding six beams in a four color multiplexing mode may be used in some embodiments. At the edge of coverage (EOC), there may be less than six available co-color beams. The location analysis may rely on less than six co-color beams, or may introduce additional more distant co-color beams, but provided those more distant co-color beams can detect carriers in the digitized received spectrum.

The relative gains between the victim beam and its co-colored neighboring beams are then used in operation 610 to determine contours indicative of the locations of possible interfering sources corresponding to each relative gain value. Geographic line segments or curves drawn by the relative gain values of a pair of beams may mark those locations where the relative gain between the two antenna beam patterns matches the measured relative gain. In operation 612, the uplink interference geolocation module identifies locations where all of the at least one contours from each beam intersect. This position marks the possible positions of the interfering carrier sources.

For illustration, consider the case where an uplink interfering carrier is detected in beam 0. Reference may be made back to fig. 2, which shows the directional patterns of the co-colored "red" beams 0 to 6. At the DCP on the satellite, it has been determined that beam 0 is receiving an interfering carrier, which the DCP also finds in the spectrum of the co-colored beams 1-6. The interfering carriers have the same shape and frequency but are lower in power. For this example, the following table gives the carrier power measured in dBm and the relative gain between beam 0 and each of the other beams:

HTS beam	Beam	0	Beam 1	Beam 2	Beam 3	Beam 4	Beam 5	Beam 6
									DCP Carrier Power (dBm)	-7.0	-49.2	-28.0	-45.3	-32.2	-37.4	-31.5
Beam relative gain g _0,i (dB)	0.0	42.2	21.0	38.3	25.2	30.4	24.5

Fig. 7 shows a geographic map of the contour between beam 0 and beam 1, which corresponds to a relative gain value of 42.2 dB. Fig. 8 shows a geographical diagram of the contour line added between beam 0 and beam 2, which corresponds to a relative gain value of 21 dB. It should be noted that the contour lines intersect at multiple locations. In this example, there are two strong candidate locations, as indicated in the figure. Other contours added with other beam pairs may help identify the best candidate location. Figure 9 shows the contour added between beam 0 and beam 3 and figure 10 shows a geographic map of the contours from all six beam pairs. Note that using all six pairs of beams will result in some contour from all six pairs of beams intersecting at the same point within the beam 0 footprint.

As described above, in some cases near the EOC, there may not be six surrounding co-color beams. Thus, more distant co-color beams can be introduced into the localization analysis. Referring again to fig. 2, in the case where interference is found in beam 0 but only beams 1 and 6 are adjacent co-colored beams, the location analysis may consider using a beam in the "second tier co-color ring" that is further away from beam 0, such as beam 11. It can be appreciated that the power level of the interfering carrier may be very low in beam 11; however, if desired, the DCP gain gd can be adjusted in order to obtain reasonably accurate measurements. The relative gain values for this example may be:

HTS beam	Beam	0	Beam 1	Beam 6	Beam 11
						DCP Carrier Power (dBm)	-7.0	-49.2	-31.5	-46.8
Beam relative gain g _0,i (dB)	0.0	42.2	24.5	39.8

Fig. 11 shows the relative gain contours from

beams

1,6 and 11, and the possible interference source locations identified at the intersection of those contours within the coverage area of beam 0.

Although the foregoing description may describe the drawing of a contour, it is not necessarily meant to generate a map or other image with drawn lines. For the visual illustration of the concept of localization, a drawing of the contour and a visual identification of the intersection can be easily envisaged; however, it should be understood that in many embodiments, the graph is described in mathematical or numerical terms, and the identification of the intersection point may be determined using various numerical methods or algorithms to find the intersection location of the two curves.

The beam direction map database may store beam patterns determined during the HTS test phase, which may be stored in a matrix form, or in any other suitable data structure. For example, the matrix form may reflect a two-dimensional pattern of gain values for each point in the grid that encompasses a particular geographic area. The resolution of the pattern test may be selected based on a balance of test sensitivity and possible errors, desired geographic resolution of location services, and memory storage limitations.

Fig. 12 illustrates, in flow diagram form, an exemplary method 700 for geo-locating an upstream interferer. In the example method 700, certain operations are indicated as being performed by the HTS, and certain operations are indicated as being performed by the terrestrial NOC. It should be understood that in some cases, some or all of the operations described as being performed by the terrestrial NOC may be performed by a processing unit at the HTS.

In this example method 700, HTS first detects uplink interference in operation 702 and then identifies a victim beam in operation 704. In operation 706, the DCP measures the power levels of the interfering carriers in the victim beam and in the surrounding co-color beams. The number of surrounding beams that need to be measured may depend on whether the victim beam is close to the coverage edge and the color multiplexing mode of the HTS.

In operation 708, the DCP considers path loss differences between the beams. This is used to determine the constant c between the beam pairs. Recall that the constant c is the ratio of gr and gd for the two repeater paths. In some embodiments, the constant c may be predetermined and stored in memory for various co-colored spot beam pairs. In this case, operation 708 involves retrieving the required constants from memory.

In operation 710, the DCP determines the relative gains of the beam pairs and then, in operation 712 of this example, relays those relative gain values to the ground NOC.

At the terrestrial NOC, in this example, certain HTS errors or uncertainties are optionally accounted for in a manner described further below, as shown by operation 714.

In operation 716, the relative gains are used to generate contour maps from the stored beam pattern data for the pairs of spot beams. In this example, the NOC first determines the contours of the first beam pair (beam 0 and beam i). The NOC then identifies the intersection in operation 718. For the first beam pair, there is naturally no crossover, so the NOC cannot locate the interferer. The NOC evaluates whether the source of the interference source has been identified with sufficient confidence, as shown in operation 720. In operation 722, it is determined whether additional beam relative gain data is available and, if so, as shown in operation 724, a return is made to add the next beam pair contour and identify the intersection point.

In some embodiments, the evaluation of whether an interference location has been identified at operation 720 may be based in part on a confidence measure. In some embodiments, the measurements take into account the degree of correspondence between intersecting contours. In some cases, it may also take into account the angle between the lines at the intersection, since intersection points determined from lines that are more tangential are more likely to be inaccurate. In some examples, the number of lines passing through the intersection may increase the confidence level. Confidence levels may be measured based on determinations of distances between the intersections of the various beam pairs, with lower distances corresponding to higher confidence.

As noted, the NOC (or DCP) may resolve some errors or inconsistencies at operation 714. The identified intersection of the contours may have slight errors due to imperfect beam pattern data, errors in the accuracy of the measured power levels, and errors in the measurements relative to the transponder signal path gains, among other things. Thus, in some cases, the NOC or DCP may use interval values of relative gain to give crossover areas rather than crossover points, rather than a single value.

Since the spectrum of the desired beam can be scanned quickly and sent back over a dedicated high speed link, even if the interfering carrier is moving (in the frequency or geographical location domain), its relative behavior on the beam spectrum can still be recorded and analyzed in a near real-time manner, and the proposed geolocation procedure can be performed almost immediately.

The above procedure still applies if the interfering carrier is not a single frequency/Continuous Wave (CW) type signal but a modulated wave occupying a certain bandwidth. It may be desirable to reject thermal noise below the signal carrier in the power measurement.

In some cases, the interfering carrier spectrum overlaps with the normal operating carrier spectrum in at least some of the co-colored adjacent beams. At least three methods may be considered to properly measure and geo-locate the interferer. First, the positioning process may avoid using beams that overlap with the normal operating carrier. Second, the NOC may temporarily reallocate or stop transmission of overlapping operating carriers. Third, DCP can employ a satellite-borne carrier superposition technique to directly measure the power of the interfering carriers. This technique has been used in the example of a ground-based carrier monitoring system and can be integrated into the functionality of a satellite-based DCP.

The above discussion has focused on the use of the described methods and systems to locate interfering signal sources, whether accidental or malicious. For example, the signal may be an interference signal. In one example of an unexpected interferer, the interference may come from side lobes directed to the uplinks of adjacent satellites. Geolocation may be used to identify the location of such interfering signals, where two satellites have similar coverage areas and operate in at least partially the same frequency band.

The described methods and systems may also be applied to locating other signal sources that are not "interfering". For example, in some cases it may be used to identify the location of a known user device. For example, a user device may have a GPS module that is disabled or disabled and, in an emergency, may require geolocation services from the HTS.

Exemplary embodiments of the present disclosure are not limited to any particular type of satellite or antenna.

The various embodiments presented above are merely examples and are in no way meant to limit the scope of the application. Variations of the innovations described herein will be apparent to those of ordinary skill in the art, and are within the intended scope of the present application. In addition, the subject matter described herein and in the claims is intended to encompass and encompass all suitable technical variations.

Claims

1. A satellite system for locating an uplink interferer, the system comprising:

a plurality of co-located spot beam antennas to receive an uplink signal and wherein each spot beam has a respective geographic coverage area, the respective coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color multiplexing mode;

a digital channelizing processor to digitally channelize the received signals from each of the co-color spot beam antennas to produce a corresponding digitized spectrum;

a spectrum analysis module to identify an interfering carrier in one of the digitized spectra and determine a relative power level between the interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectra; and

a geo-location module to, for each of the relative power levels, determine a geo-located contour based on the relative power level and identify a geographic location of an upstream interferer based on an intersection between two or more of the contours.

2. The system of claim 1 wherein the geolocation module includes a beam direction map database that stores beam pattern data for each of the spot beam antennas and wherein the geolocation module determines a geo-located contour by determining the contour using beam pattern data for two spot beams for which one of the relative power levels has been determined.

3. The system of claim 2, wherein the geolocation module determines the contour by determining geolocation wherein a difference between beam pattern data for each of the two spot beams matches a relative power level determined for the two spot beams.

4. The system of claim 1, wherein the spectral analysis module determines one of the relative power levels to be determined for two spot beams by determining a ratio of associated repeater path losses for the two spot beams.

5. The system of claim 4, wherein repeater path loss is predetermined and stored in a memory, and wherein the spectrum analysis module determines the ratio by selecting from the stored repeater path loss.

6. The system of claim 4, wherein determining the one of the relative power levels comprises multiplying a ratio of associated repeater path losses by a ratio of measured power levels of the interfering carriers received by the two spot beams.

7. The system of claim 1, wherein the geolocation module determines geolocation by determining a set of isolines for each of three or more relative power levels and identifying points of intersection with lines from each set of isolines.

8. A method for locating an uplink interferer using a high-throughput satellite having multiple co-located spot beam antennas to receive an uplink signal and in which each spot beam has a corresponding geographic coverage area, the coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color-multiplexed pattern, the method comprising:

digitally channelizing the received signals from each of the co-located spot beam antennas to produce a corresponding digitized spectrum;

detecting an interfering carrier in one of the digitized spectra;

determining a relative power level between the interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectra;

for each of the relative power levels, determining a geo-located contour based on the relative power level; and

identifying a geographic location of an upstream interference source based on an intersection between two or more of the contours.

9. The method of claim 8 wherein determining a geo-located contour comprises determining the contour using beam pattern data for two spot beams, one of the relative power levels having been determined for the two spot beams.

10. The method of claim 9, wherein determining the contour comprises determining a geolocation where a difference between beam pattern data for each of the two spot beams matches a relative power level determined for the two spot beams.

11. The method of claim 8, wherein determining the relative power level comprises: for a pair of spot beams associated with one of the relative power levels with which the one of the relative power levels is to be determined, determining a ratio of associated repeater path losses for the pair of spot beams.

12. The method of claim 11, wherein a repeater path loss is predetermined and stored in a memory, and wherein determining the ratio comprises selecting from the stored repeater path losses.

13. The method of claim 11, wherein determining the relative power levels comprises, for the one of the relative power levels, multiplying a ratio of relative repeater path losses by a ratio of measured power levels of the interfering carriers received by the pair of spot beams.

14. The method of claim 8, wherein determining a geographic location comprises determining a set of contours for each of three or more relative power levels, and identifying points of intersection with a line from each set of contours.

15. A method for locating an upstream interferer using a high-throughput satellite having a plurality of co-located spot beam antennas to receive upstream signals and with each spot beam having a respective geographic coverage area, the respective coverage areas of the co-located spot beam antennas being arranged in non-overlapping regions in a color multiplexing pattern, the high-throughput satellite receiving and digitally channelizing the signals from each co-located spot beam antenna to produce a respective digitized spectrum to detect interfering carriers in one of the digitized spectra, the method comprising:

receiving data from the high-throughput satellite over a communications link at a terrestrial network operations center regarding power levels of interfering carriers in three or more of the digitized spectrum;

determining from the data regarding power levels a relative power level between the interfering carrier in the one digitized spectrum and a lower power interfering carrier of the same frequency in two or more of the other respective digitized spectra;

16. The method of claim 15, wherein the data regarding power levels comprises relative power levels determined by the satellite, and wherein determining relative power levels comprises obtaining the relative power levels from the data regarding power levels.

17. The method of claim 15, wherein the data regarding power levels comprises a power level measurement, and wherein determining a relative power level comprises calculating the relative power level from the power level measurement.

18. The method of claim 15 wherein determining a geo-located contour comprises determining the contour using beam pattern data for two spot beams, one of the relative power levels having been determined for the two spot beams.

19. The method of claim 18, wherein determining the contour comprises determining a geolocation where a difference between beam pattern data for each of the two spot beams matches a relative power level determined for the two spot beams.

20. The method of claim 15, wherein determining the relative power level comprises: for a pair of spot beams associated with one of the relative power levels with which the one of the relative power levels is to be determined, determining a ratio of associated repeater path losses for the pair of spot beams.