Methods for calibrating antennas

Abstract

This application relates to systems and methods for calibrating antennas. The method for calibrating an antenna includes receiving multiple signals transmitted from an antenna on a spacecraft. The antenna includes multiple phased array elements. The method further includes determining a phase tilt of the phased array elements based at least partially on the signals. The method further includes removing a first portion from the determined phase tilt. This first portion is caused by a first position of the spacecraft, a first attitude of the spacecraft, or both. The method further includes estimating the phase tilt of the phased array elements after removing the first portion. The method further includes generating a reference tilt matrix for the phased array elements. The method further includes comparing the estimated phase tilt with the reference tilt matrix. The method further includes determining a pointing error of the antenna based at least partially on the comparison.

Description

Technical Field

[0001] This disclosure relates to systems and methods for calibrating antennas. More specifically, this disclosure relates to systems and methods for performing point calibration on phased array antennas in orbit. Background Technology

[0002] Spacecraft such as satellites have antennas for communication purposes. It is impossible to perfectly align antennas on the ground. Therefore, antennas are typically aligned after the spacecraft has been launched into space (e.g., into orbit). More specifically, antenna alignment can be calibrated to reduce alignment errors such as fixed alignment errors. As used herein, a "fixed alignment error" refers to the transformation error between two coordinate systems. In the example, the first coordinate system could be the star tracker coordinate system on the spacecraft, which determines the spacecraft's attitude. The second coordinate system could be the phased array antenna coordinate system (e.g., located on the spacecraft).

[0003] Conventional calibration techniques may include antenna beam cutting, which involves wiggling the antenna and then correlating the measurements from the antenna with a predetermined beam pattern. However, wiggling the antenna during beam cutting is a time-consuming process. Therefore, improved systems and methods for calibrating antennas are desired. Summary of the Invention

[0004] A method for calibrating an antenna is disclosed. The method includes receiving multiple signals transmitted from an antenna on a spacecraft. The antenna includes multiple phased array elements. The method further includes determining a phase tilt of the phased array elements based at least partially on the signals. The method further includes determining a first position, a first attitude, or both of the spacecraft. The method further includes removing a first portion from the determined phase tilt. This first portion is caused by the first position, the attitude, or both of the spacecraft. The method further includes estimating the phase tilt of the phased array elements after removing the first portion. The method further includes generating a reference tilt matrix for the phased array elements. The method further includes comparing the estimated phase tilt with the reference tilt matrix. The method further includes determining a pointing error of the antenna based at least partially on the comparison.

[0005] A method for calibrating an antenna on a spacecraft in orbit is also disclosed. The method includes receiving a first plurality of signals at a computing system on the ground. When the spacecraft is in a first position and has a first attitude, the first plurality of signals are transmitted from a transmitter antenna. The transmitter antenna includes a plurality of phased array elements. The method also includes determining a first phase tilt of the phased array elements based at least partially on the first plurality of signals using the computing system. The method also includes determining a first position of the spacecraft. The method also includes determining a first attitude of the spacecraft. The method also includes removing a first portion from the determined first phase tilt. This first portion is caused by the first position of the spacecraft, the attitude of the spacecraft, or both. The method also includes estimating a first phase tilt of the phased array elements after removing the first portion of the first phase tilt. The method also includes receiving a second plurality of signals at a computing system on the ground. When the spacecraft is in a second position and has a second attitude, the second plurality of signals are transmitted from the transmitter antenna. The method also includes determining a second phase tilt of the phased array elements based at least partially on the second plurality of signals using the computing system. The method also includes determining a second position of the spacecraft. The method also includes determining a second attitude of the spacecraft. The method also includes removing a first portion from the determined second phase tilt. The first portion is caused by the spacecraft's second position, the spacecraft's second attitude, or both. The method also includes estimating the second phase tilt of the phased array elements after removing the first portion of the second phase tilt. The method further includes generating a reference tilt matrix for the phased array elements based at least in part on the spacecraft's first and second positions. The method also includes comparing the estimated first phase tilt with the reference tilt matrix to generate a first misalignment error set. The method further includes comparing the estimated second phase tilt with the reference tilt matrix to generate a second misalignment error set. The method also includes determining the intersection of the first and second misalignment error sets. This intersection represents the antenna's pointing error.

[0006] A computing system is also disclosed. The computing system includes one or more processors and a memory system. The memory system includes one or more non-transitory computer-readable media storing instructions that, when executed by at least one of the one or more processors, cause the computing system to perform operations. The operations include receiving multiple signals transmitted from an antenna on a spacecraft. The antenna includes multiple phased array elements. The operations also include determining the phase tilt of the phased array elements, at least partially based on the signals. The operations further include determining a first position, a first attitude, or both of the spacecraft. The operations also include removing a first portion from the determined phase tilt. This first portion is caused by the first position, the first attitude, or both of the spacecraft. The operations also include estimating the phase tilt of the phased array elements after removing the first portion. The operations also include generating a reference tilt matrix for the phased array elements. The operations further include comparing the estimated phased array tilt with the reference tilt matrix. The operations also include determining a pointing error of the antenna, at least partially based on the comparison.

[0007] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and do not limit the scope of this teaching as protected by the claims. Attached Figure Description

[0008] The accompanying drawings (which are incorporated in and constitute a part of this specification) illustrate the teachings together with the various aspects described, and are used to explain the principles of the teachings.

[0009] Figure 1 A perspective view of a spacecraft according to an embodiment is shown.

[0010] Figure 2 An illustration is provided showing the pointing error (in degrees) of a transmitter antenna (located on a spacecraft) relative to the time of a single day, according to an embodiment.

[0011] Figure 3 An illustration is provided illustrating a spatial simulation of the pointing error of the transmitter antenna and receiver antenna according to an embodiment.

[0012] Figure 4 An example is shown, according to an embodiment, the view from the Z-axis downwards in the illustration. Figure 3 A diagram showing the location of the components.

[0013] Figure 5 A flowchart illustrating a method for calibrating a transmitter antenna according to an embodiment is provided.

[0014] Figure 6An illustration of the phase tilt of the phased array elements of a transmitter antenna according to an embodiment, which has physical delay variations caused by alignment errors (e.g., physical misalignment) of the array elements of the transmitter antenna and digital delay variations caused by delay errors of the digital signal processor (DSP).

[0015] Figure 7 An example is given of removing DSP delay error according to the implementation method (from...). Figure 6 A diagram illustrating the phase tilt of the phased array elements of the transmitter antenna.

[0016] Figure 8A An illustration is shown according to an embodiment, showing an estimated phase tilt (in degrees) relative to the position (in meters) of the phased array elements of the transmitter antenna.

[0017] Figure 8B A table illustrating the azimuth error (in degrees), elevation error (in degrees), X slope coefficient (in degrees / meter), Y slope coefficient (in degrees / meter), ΔX coefficient (in degrees / meter), and ΔY coefficient (in degrees / meter) according to an embodiment is provided.

[0018] Figure 9 An illustration of a reference slant matrix of phased array elements of a transmitter antenna according to an embodiment is shown.

[0019] Figure 10 An illustration of the correlation of the phase tilt matrix according to an embodiment is shown.

[0020] Figure 11 An illustration is provided according to the implementation method. Figure 10 The diagram in the image is a magnified version of the original image.

[0021] Figure 12A The pointing error of the transmitter antenna and the pointing error of the receiver antenna are illustrated according to an embodiment, showing a phase measurement error of only 2 degrees root mean square (RMS).

[0022] Figure 12B Examples of the pointing errors of the transmitter antenna and receiver antenna according to the embodiments are given, which have a phase measurement error of 6 degrees RMS, a position knowledge error of 50 meters RMS, and an attitude knowledge error of 0.005 degrees RMS.

[0023] Figure 13A An illustration is provided showing the residual pointing error (in degrees) relative to the gateway latitude (in degrees) of the transmitter antenna, according to an embodiment.

[0024] Figure 13BAn illustration is provided illustrating the residual pointing error (in degrees) relative to the portal latitude (in degrees) of the receiver antenna, according to an embodiment.

[0025] Figure 14 A schematic diagram of a computing system for performing at least a portion of a method according to an embodiment is shown.

[0026] It should be noted that some details in the accompanying drawings have been simplified and drawn for ease of understanding, rather than maintaining strict structural precision, detail, and proportion. Detailed Implementation

[0027] Reference will now be made in detail to this teaching, examples of which are illustrated in the accompanying drawings. In the drawings, similar reference numerals are consistently used to identify the same elements. In the following description, reference is made to the accompanying drawings, which form part of the description, and specific examples of practicing this teaching are shown in the drawings by way of illustration. Therefore, the following description is merely exemplary.

[0028] This disclosure relates to systems and methods for performing pointing calibration of spacecraft (e.g., antennas in orbit) to reduce fixed alignment errors and / or array pointing errors. More specifically, this disclosure relates to systems and methods for performing pointing calibration of phased array antennas on a spacecraft using two-dimensional linear fitting phase tilt estimation and error correction. This may include obtaining measurements at two or more different spacecraft positions and / or orientations, and using the measurements to estimate azimuth fixed errors, elevation fixed errors, and yaw fixed errors. The method does not involve wobbling antennas. As a result, this method can be performed much faster than conventional methods for wobbling antennas.

[0029] Figure 1 A perspective view of an aircraft (e.g., a spacecraft) 100 according to an embodiment is illustrated. Spacecraft 100 may be or include a satellite configured to be placed near an orbit (e.g., Earth). Spacecraft 100 may be capable of movement (e.g., rotation) about a first axis (e.g., the X-axis). This movement is referred to as roll of spacecraft 100. Spacecraft 100 may also be capable of movement (e.g., rotation) about a second axis (e.g., the Y-axis). This movement is referred to as pitch of spacecraft 100. Spacecraft 100 may also be capable of movement (e.g., rotation) about a third axis (e.g., the Z-axis). This movement is referred to as yaw of spacecraft 100.

[0030] Spacecraft 100 may include a transmitter antenna 110A and a receiver antenna 110B. The transmitter antenna 110A and receiver antenna 110B may be or include phased array antennas. The transmitter antenna 110A and receiver antenna 110B may each include multiple phased array elements (e.g., ...) of a predetermined pattern. Figure 4 (As shown).

[0031] Figure 2 Illustration 200 illustrates the pointing error (in degrees) of the transmitter antenna 110A relative to the time of day according to an embodiment. Spacecraft 100 may pass over a gateway on Earth once or more during a day. For example, spacecraft 100 may pass over the gateway four times a day (e.g., every 6 hours). As used herein, "gateway" refers to a ground terminal configured to transmit signals to, receive signals from, and process signals from spacecraft 100 (e.g., using a computing system). References below Figure 14 An exemplary computing system 1400 that can be used at a ground terminal is described.

[0032] The pointing error can be measured each time spacecraft 100 passes over the portal. Figure 2 In the example shown, there are four sets of pointing error measurements: 202, 204, 206, and 208. Each set 202, 204, 206, and 208 may include multiple measurements (e.g., 10 measurements). As shown, the sets of pointing error measurements 202, 204, 206, and 208 can vary over time. For example, the pointing error of the first set 202 may be greater than the pointing error of the second set 204. This could be due to temperature variations throughout the day. Therefore, an average fixed pointing error 210 can be determined based on the sets of pointing error measurements 202, 204, 206, and 208. The average fixed pointing error 210 can at least partially eliminate the fixed pointing error.

[0033] Figure 3 Illustration 300 illustrates a spatial simulation of the pointing error of transmitter 110A and receiver 110B according to an embodiment. In this example, a first element location set 302 and a second location set 304 represent the positions of the phased array elements of transmitter antenna 110A. The first element location set 302 has no pointing error, and the second element location set 304 includes pointing error. A third element location set 306 and a fourth element location set 308 represent the positions of the phased array elements of receiver antenna 110B. The third element location set 306 has no pointing error, and the fourth element location set 308 includes pointing error.

[0034] Figure 4 Illustration 400 shows the element positions 302 viewed downward along the Z-axis in Figure 300 according to an embodiment. As described above, each element position 302 represents the position of a phased array element of the transmitter antenna 110A. As can be seen, the element positions 302 vary along the X and Y axes and generate phase measurement values ​​for each element.

[0035] Figure 5A flowchart illustrating a method 500 for calibrating a transmitter antenna 110A of a spacecraft 100 according to an embodiment is shown. Method 500 can be used to calculate the average value of alignment errors of the transmitter antenna 110A caused by daily factors and / or temperature factors. Although method 500 is described with reference to transmitter antenna 110A, method 500 can also be used, or may be modified, for calibrating receiver antenna 110B.

[0036] The exemplary order of method 500 is described below; however, it should be understood that one or more steps of method 500 may be performed in a different order or may be omitted together. At least a portion of method 500 may be performed when spacecraft 100 is in flight and / or in space. For example, at least a portion of method 500 is performed when transmitter antenna 110A is in orbit.

[0037] Method 500 may include receiving multiple signals from transmitter antenna 110A, as at 502. Signals may be generated by phased array elements of transmitter antenna 110A. Signals may be received at a portal on the ground. For example, signals may be received by computing system 1400 at the portal, and computing system 1400 may measure the signals and / or determine how transmitter antenna 110A should be calibrated based on the signals, as described below. Each of the signals may be or include tones at different (e.g., unique) frequencies.

[0038] Method 500 may also include measuring or determining, at least in part, the phase tilt (also referred to as phase slope) of the phased array elements of the transmitter antenna 110A based on a signal (from 502), as at 504. The phase tilt may be measured by a vector spectrum analyzer (VSA), which may be part of (or in communication with) a computing system 1400. As used herein, “phase tilt” refers to a linear phase transition relative to distance.

[0039] Method 500 may further include determining the position of spacecraft 100 (e.g., in orbit), such as at 506. The position may be measured by a position sensor (e.g., Global Positioning System (GPS)) 120 on spacecraft 100. Method 500 may further include determining the attitude of spacecraft 100 (e.g., in orbit), such as at 508. The attitude may be measured by an attitude sensor 122 on spacecraft 100. The position and attitude may be transmitted from spacecraft 100 to a computing system 1400 at a portal, which makes the determination (at 506 and 508). The position and / or attitude may be determined when a signal is generated at spacecraft 100 (at 502) and / or when a signal is received at the portal.

[0040] The phase tilt (measured at 504) may depend at least in part on the spacecraft's position (determined at 506), the spacecraft 100's attitude (measured at 508), and misalignment errors of the transmitter antenna 110A. To isolate misalignment errors, method 500 may further include removing a first portion of the phase tilt from the phase tilt measured at 504, as at 510. The first portion of the phase tilt is caused by the spacecraft 100's position and / or attitude.

[0041] Figure 6 A diagram 600 illustrates the phase tilt of the phased array elements of a transmitter antenna 110A according to an embodiment, showing a physical delay variation caused by an alignment error 610 (e.g., physical misalignment) of the array elements of the transmitter antenna 110 and a digital delay variation caused by a delay error 620 of the digital signal processor (DSP). Therefore, Figure 6 This includes both physical delay variations and digital delay variations that produce outlier measurements (i.e., DSP delay error 620). The DSP 124 that produces the DSP delay error 620 can be carried on spacecraft 100 (see [reference]). Figure 1 ).

[0042] Method 500 may also include removing a second portion of the phase tilt, such as at 512, from the phase tilt measured at 504. This second portion of the phase tilt is caused by the DSP delay error 620. An example of this is... Figure 7 As shown in the figure, Figure 7 An example is given of removing DSP delay error 620 (from) according to an implementation method. Figure 6 The phase tilt of the phased array elements of the transmitter antenna 110A is shown in Figure 700. Figure 7 Similar to Figure 3 However, the focus is on the second set of measurements 304 (e.g., the position of the phased array elements of the transmitter antenna 110A with pointing error). Figure 7 Only errors resulting from physical misalignment are shown.

[0043] The DSP 124 has multiple discrete states, each with a different (e.g., unique) digital delay variation. The digital delay variation refers to discrete steps based on the DSP clock frequency (e.g., at fixed intervals such as 60 picoseconds (ps), 120 ps, ​​180 ps, ​​etc.). When the DSP 124 is turned on / powered, it wakes up in one of these discrete states (e.g., randomly). The DSP 124 wakes up with a random discrete step digital delay variation caused by the analog-to-digital converter (ADC) and / or digital-to-analog converter (DAC) and the sampling clock.

[0044] Digital delay variations can be estimated and modified (e.g., corrected) via a DSP delay buffer. However, measurements of the phase at both ends of the transmitter antenna 110A via the computing system 1400 at the portal can include both physical and digital delay variations. By plotting the modified (e.g., corrected) delay variations (e.g., using an initial estimate of the discrete delay offset, the measured modulus of the element delay, and the DSP discrete delay step), the user can determine whether the digital delay variation is overestimated or underestimated. Once the phased array elements affected by incorrect digital delay variations are identified, the final delay buffer settings can be determined.

[0045] Method 500 may also include estimating the phase tilt of the phased array elements of the transmitter antenna 110A, such as at 514. The phase tilt may be estimated after removing the first portion (at 510) and / or removing the second portion (at 512). Figure 8A An example of estimated phase tilt is shown below. Figure 8A Illustration 800 illustrates the phase tilt (in degrees) relative to the position (in meters) of the phased array elements of the transmitter antenna 110A according to an embodiment. Points on illustration 800 (e.g., 802, 804, 806, etc.) represent phase measurements of the phased array elements. For example, each point 802, 804, 806 may represent the phase measurement of the phased array elements at different channels above the portal. Plane 810 represents a 2D multivariate fit of points 802, 804, 806.

[0046] Figure 8B A table illustrating the azimuth error (in degrees), elevation error (in degrees), X slope coefficient (in degrees / meter), Y slope coefficient (in degrees / meter), ΔX coefficient (in degrees / meter), and ΔY coefficient (in degrees / meter) according to an embodiment is provided. These values ​​can be determined using the calculation system 1400 based at least in part on the estimated phase tilt (from 514) of the phased array elements of the transmitter antenna 110A.

[0047] There is a relative linear relationship between the estimated phase tilt (from 514) of the phased array elements of the transmitter antenna 110A and the pointing error of the transmitter antenna 110A. These linear relationships can be used to convert the estimated phase tilt (from 514) into the corresponding pointing error.

[0048] The foregoing portion of method 500 (e.g., steps 502-514) can be performed for the first time using data / measurements from a first spacecraft location in orbit. The foregoing steps of method 500 (e.g., steps 502-514) can then be repeated iteratively once or multiple times using data / measurements from one or more different spacecraft locations in orbit. For simplicity, in the following description, steps 502-514 have been performed / repeated a second time at a second spacecraft location.

[0049] Method 500 may further include generating a reference tilt matrix for the phased array elements of the transmitter antenna 110A at the first and second spacecraft positions, as shown at 516. The reference tilt matrix may be generated at least in part based on the first and second spacecraft positions (from two iterations of 506), the first and second spacecraft attitudes (from two iterations of 506), and the portal position (which is constant). For example, generating the reference tilt matrix may include generating a desired phase tilt for a set of misalignment errors.

[0050] Figure 9 A diagram illustrating the reference tilt matrix of the phased array elements of the transmitter antenna 110A according to an embodiment is shown. As shown, the first axis of diagram 900 represents the roll error (in degrees), the second axis of diagram 900 represents the pitch error (in degrees), and the third axis of diagram 900 represents the yaw error (in degrees). This matrix is ​​generated using the expected phase tilt at each 0.01-degree grating point. Each array can generate four 3D matrices: one matrix for each of the two spacecraft positions, one matrix for the X-slope, and one matrix for the Y-slope. Therefore, four measurements can be used to determine the three unknowns (e.g., roll, pitch, and yaw) for each array.

[0051] Method 500 may further include comparing the estimated phase tilt (at 514) of the phased array elements of the transmitter antenna 110A with a reference tilt matrix (at 516), such as at 518. This can generate a misalignment error set 1002 for the estimated phase tilt matching the position of a first spacecraft and a misalignment error set 1004 for the estimated phase tilt matching the position of a second spacecraft, as shown below. Figure 10 As shown. More specifically, Figure 10A diagram 1000 illustrating the phase tilt matrix correlation according to an embodiment is shown. As shown, the first axis of diagram 1000 represents roll error (in degrees), the second axis of diagram 1000 represents pitch error (in degrees), and the third axis of diagram 1000 represents yaw error (in degrees). Diagram 1000 represents the phase tilt matrix correlation of a single measurement (e.g., one of ten measurements). Diagram 1000 includes a plurality of grating points comprising misalignment error sets 1002 and 1004. The grating points are matched to the measured phase tilt plus a tolerance. Misalignment error set 1002 represents a first estimate of the position of spacecraft 100, and misalignment error set 1004 represents a second estimate of the position of spacecraft 100. The intersection 1006 represents the estimated pointing error.

[0052] Method 500 may further include determining the intersection 1006 of the first misalignment error set 1002 and the second misalignment error set 1004, as shown at 520. Multiple measurements (e.g., 10 measurements) can be obtained at each spacecraft location. As a result, multiple intersections may exist. This is in Figure 11 As shown in the figure, Figure 11 Illustration 1100 is shown as a magnified portion of illustration 1000 according to an embodiment. As shown, the first axis of illustration 1100 represents roll error (in degrees), the second axis of illustration 1100 represents pitch error (in degrees), and the third axis of illustration 1100 represents yaw error (in degrees). Illustration 1100 shows the estimated pointing error for 10 measurements. Illustration 1100 shows the estimated pointing error. Illustration 1100 includes multiple intersections 1102, 1104, 1106, 1108, etc., representing the estimated pointing errors. Illustration 1100 also shows the final estimated pointing error 1110. The final estimated pointing error 1110 can be determined by filtering and / or averaging the estimated pointing errors 1102, 1104, 1106, 1108, etc.

[0053] Figure 12AThe pointing errors of transmitter antenna 110A and receiver antenna 110B, according to an embodiment, are illustrated, showing a phase measurement error of only 2 degrees root mean square (RMS). The pointing error may include elevation error, azimuth error, and yaw error. The values ​​in Table 1200 can be determined over multiple iterations (e.g., ten) with a phase measurement error of only, for example, 2 degrees RMS. Each iteration has a different fixed pointing error and spacecraft longitude. Within each iteration, multiple (e.g., ten) measurements can be performed using random phase errors on each phased array element. The top row indicates the iteration maximum, which refers to the maximum residual pointing error of the simulated iteration. As can be seen in Table 1200, the maximum residual pointing error is lower than the exemplary pointing error target / object, which in this example is 0.04 degrees elevation, 0.04 degrees azimuth, and 0.06 degrees yaw.

[0054] Figure 12B The pointing errors of transmitter antenna 110A and receiver antenna 110B, according to an embodiment, are illustrated with a phase measurement error of 6 degrees RMS, a position knowledge error of 50 meters RMS, and an attitude knowledge error of 0.005 degrees RMS. The pointing errors may include elevation error, azimuth error, and yaw error. The values ​​in Table 1250 can be determined over multiple iterations (e.g., ten). Each iteration has a different fixed pointing error, spacecraft longitude, and spacecraft telemetry errors (e.g., position and attitude). Within each iteration, multiple (e.g., ten) measurements are performed, each with a random phase error. The top row indicates the maximum value of the iteration. As can be seen in Table 1250, the maximum residual pointing error is below the pointing error target / object, which in this example is 0.04 degrees elevation, 0.04 degrees azimuth, and 0.06 degrees yaw.

[0055] Figure 13A Illustration 1300 illustrates the residual pointing error (in degrees) relative to the portal latitude (in degrees) of the transmitter antenna 110A, according to an embodiment. Figure 13B Illustration 1350 illustrates the residual pointing error (in degrees) relative to the gateway latitude (in degrees) of receiver antenna 110B according to an embodiment. To generate illustrations 1300 and 1350, a parameter scan of the gateway latitude is performed from 0 to 55 degrees in 5-degree increments. Each step involves 100 iterations. The first spacecraft longitude offset is maintained at a random value between 7 and 12 degrees, and the second spacecraft longitude offset is maintained at a random value between -7 and -12 degrees. As can be seen in illustrations 1300 and 1350, the residual pointing error target / objective (e.g., 0.04 degrees elevation, 0.04 degrees azimuth, and 0.06 degrees yaw) is represented by horizontal lines. Targets / objectives can be implemented for various gateway latitude positions.

[0056] Method 500 may further include transmitting a signal from a computing system 1400 at a portal to spacecraft 100, such as at 522, that causes spacecraft 100 to move to reduce pointing error. In one example, the signal may cause spacecraft 100 to physically roll, pitch, and / or yaw to reduce pointing error. In another example, the signal may be received by a DSP 124 on spacecraft 100, and the DSP 124 may then cause phased array elements to electronically (e.g., non-physically) re-point to adjust (reduce) pointing error. The signal may be based on one or more intersections at 520.

[0057] In the example, the gateway location has 21.66 degrees latitude and 158.05 degrees longitude. Spacecraft longitude offset 1 is randomly located between 7 and 12 degrees, and spacecraft longitude offset 2 is randomly located between -7 and -12 degrees. Pitch rotation is 0.36 degrees per degree of longitude. There are up to 1.9 degrees of random fixed pointing error in roll, pitch, and yaw. Additionally, there are up to 0.1 degrees of random transmitter and receiver pointing skew in roll, pitch, and yaw. Phase measurements are performed using the same portion of Method 500 described above. The simulated measurement phase change is 2 degrees RMS. This assumes a calibrated array (e.g., time-aligned and relative-aligned). Simulations are also run using 6 degrees RMS. The transmitter frequency is 18.95 GHz, and the receiver frequency is 28.75 GHz. Ten measurements are performed at each spacecraft location. As described above, this can be repeated multiple times (e.g., 4 times) throughout the day at various drive levels to calculate the average daily error and / or temperature error. Spacecraft state vector telemetry technology can provide spacecraft position and attitude, which can be used for compensation measurements.

[0058] Figure 14A schematic diagram of a computing system 1400 for performing at least a portion of method 500 according to an embodiment is illustrated. The computing system 1400 may include a computer or computer system 1401A, which may be a standalone computer system 1401A or an arrangement of distributed computer systems. The computer system 1401A includes one or more analysis modules 1402 configured to perform various tasks according to some embodiments, such as one or more methods disclosed herein. To perform these various tasks, the analysis modules 1402 execute independently or in cooperation with one or more processors 1404 connected to one or more storage media 1406. One or more processors 1404 are also connected to network interface 1407 to allow computer system 1401A to communicate with one or more additional computer systems and / or computing systems (such as 1401B, 1401C and / or 1401D) via data network 1409 (note that computer systems 1401B, 1401C and / or 1401D may or may not share the same architecture as computer system 1401A and may be located in different physical locations; for example, computer systems 1401A and 1401B may be located in a processing facility while communicating with one or more computer systems such as 1401C and / or 1401D located in one or more data centers and / or in different countries on different continents).

[0059] The processor may include a microprocessor, a microcontroller, a processor module or subsystem, a programmable integrated circuit, a programmable gate array, or another control or computing device.

[0060] Storage medium 1406 can be implemented as one or more computer-readable or machine-readable storage media. Note that, although in Figure 14 In the example embodiments, storage medium 1406 is depicted as being within computer system 1401A; however, in some embodiments, storage medium 1406 may be distributed within and / or between multiple internal and / or external enclosures of computing system 1401A and / or additional computing systems. Storage medium 1406 may include one or more forms of memory, including semiconductor memory devices such as dynamic or static random access memory (DRAM or SRAM), erasable and programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), and flash memory; disks such as fixed disks, floppy disks, and removable disks; other magnetic media including magnetic tape; optical media such as optical discs (CDs) or digital video discs (DVDs), Blu-ray discs, etc. Disks, or other types of optical storage devices, or other types of storage devices. Note that the instructions discussed above may be set on a single computer-readable or machine-readable storage medium, or on multiple computer-readable or machine-readable storage media distributed across a large system that may have multiple nodes. Such computer-readable or machine-readable storage media are considered part of an article of manufacture (or article of manufacture). An article of manufacture or article of manufacture can refer to any single or multiple manufactured components. The storage medium may be located in a machine that executes the machine-readable instructions, or at a remote location from which machine-readable instructions can be downloaded via a network for execution.

[0061] In some embodiments, the computing system 1400 includes one or more antenna calibration modules 1408 that can perform a portion of the method 500 disclosed herein. It should be understood that the computing system 1400 is merely one example of a computing system, and the computing system 1400 may have more or fewer components than those shown, and may combine components not shown. Figure 14 The additional components depicted in the example embodiments, and / or the computing system 1400 may have the same Figure 14 The different component configurations or arrangements depicted in the text. Figure 14 The various components shown can be implemented in hardware, software, or a combination of both, including one or more signal processing and / or application-specific integrated circuits.

[0062] Furthermore, the steps in the processing methods described herein can be implemented by running one or more functional modules in information processing devices such as general-purpose processors or special-purpose chips (such as ASICs, FPGAs, PLDs, or other suitable devices). These modules, combinations of these modules, and / or their combinations with general hardware are included within the scope of this disclosure.

[0063] Computational interpretation, models, and / or other interpretative assistance can be refined iteratively; this concept applies to the methods discussed herein. This may include the use of algorithms performed on a computational basis (such as on computing devices). Figure 14 The computational system 1400) uses feedback loops, and / or manual control by the user to make a determination on whether the subsurface 3D geological shaping considered for evaluation has become sufficiently accurate for a given step, action, template, model, or curve set.

[0064] Although the numerical ranges and parameters of this disclosure are set to approximate values, the values ​​set in the specific examples are reported as precisely as possible. However, any numerical value inherently includes some error that must be caused by the standard deviation found in its corresponding test measurement. Furthermore, all ranges disclosed herein should be understood to cover any and all subranges included herein.

[0065] While this teaching has been illustrated with reference to one or more embodiments, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. Furthermore, while a particular feature of this teaching has been disclosed with reference to only one of several embodiments, such features may be combined with one or more other features of other embodiments as desired and advantageous to any given or particular function. As used herein, the terms “a,” “an,” and “the / described” may refer to one or more elements or one or more parts of an element. As used herein, the terms “first” and “second” may refer to two different elements or parts of an element. As used herein, the term “at least one of A and B” in a list of references (such as, for example, A and B) means only A, only B, or A and B. Those skilled in the art will recognize that these and other variations are possible. Moreover, to some extent, the terms “comprising,” “having,” “with,” or variations thereof are used in the detailed description or claims, and such terms are intended to be included in a manner similar to the term “including.” Furthermore, in the discussion and claims herein, the term “about” indicates that the listed values ​​may be slightly modified, provided that the modification does not cause the process or structure to deviate from the intended purpose described herein. Finally, “exemplary” indicates that the description is used as an example and not implying that it is ideal.

[0066] Furthermore, this disclosure includes implementation schemes pursuant to the following provisions:

[0067] Clause 1. A method (500) for calibrating an antenna (110A), comprising:

[0068] Receive multiple signals transmitted from an antenna (110A) on a spacecraft (100), wherein the antenna includes multiple phased array elements;

[0069] The phase tilt of the phased array element is determined at least in part based on the signal;

[0070] Determine the first position of the spacecraft, the first attitude of the spacecraft, or both;

[0071] Remove the first portion from the determined phase tilt, wherein the first portion is caused by the first position of the spacecraft, the first attitude of the spacecraft, or both;

[0072] After removing the first portion, the phase tilt of the phased array element is estimated;

[0073] Generate the reference tilt matrix of the phased array element;

[0074] The estimated phase tilt is compared with the reference tilt matrix; and

[0075] The pointing error of the antenna is determined at least in part based on the comparison.

[0076] Clause 2. The method according to Clause 1, wherein the signal is received by a computing system (1400) at a portal on the ground, and wherein each of the signals comprises a tone at a different frequency.

[0077] Clause 3. The method according to Clause 1, wherein the first position of the spacecraft, the first attitude of the spacecraft, or both are measured by one or more sensors carried by the spacecraft and launched to a computing system (1400) at the portal on the ground.

[0078] Clause 4. The method according to Clause 1, wherein the first position is removed to isolate the misalignment error (1002, 1004) of the antenna.

[0079] Clause 5. The method according to Clause 1 further includes removing a second portion from the determined phase tilt, the second portion being caused by a delay error from the processor (124) on the spacecraft, wherein the phase tilt is estimated after removing the first portion and the second portion.

[0080] Clause 6. The method according to Clause 1, wherein the reference tilt matrix is ​​generated at least in part based on the first position and the second position of the spacecraft, and wherein the second position of the spacecraft occurs after the first position of the spacecraft.

[0081] Clause 7. The method according to Clause 1, wherein comparing the estimated phase tilt with the reference tilt matrix produces a first misalignment error set (1002) of the estimated phase tilt matching the first position and a second misalignment error set (1004) of the estimated phase tilt matching the second position.

[0082] Clause 8. The method according to Clause 7, wherein determining the pointing error of the antenna includes determining the intersection of the first misalignment error set and the second misalignment error set (1006).

[0083] Clause 9. The method described in Clause 1 further includes calibrating the antenna to reduce the pointing error.

[0084] Clause 10. The method according to Clause 9, wherein calibrating the antenna includes physically or electronically rolling, pitching, yawing, or a combination thereof on the spacecraft.

[0085] Clause 11. A method (500) for calibrating an antenna on a spacecraft (100) in orbit, comprising:

[0086] The first plurality of signals are received at the computing system (1400) on the ground, wherein the first plurality of signals are transmitted from a transmitter antenna (110A) on the spacecraft (100) when the spacecraft is in a first position and has a first attitude, and wherein the transmitter antenna includes a plurality of phased array elements;

[0087] The computing system is used to determine, at least in part, the first phase tilt of the phased array element based on the first plurality of signals;

[0088] Determine the first position of the spacecraft;

[0089] Determine the first attitude of the spacecraft;

[0090] Remove a first portion from the determined first phase tilt, wherein the first portion is caused by the first position of the spacecraft, the first attitude of the spacecraft, or both;

[0091] After removing the first portion of the first phase tilt, the first phase tilt of the phased array element is estimated;

[0092] The second plurality of signals are received at the computing system on the ground, wherein the second plurality of signals are transmitted from the transmitter antenna on the spacecraft when the spacecraft is in a second position and has a second attitude;

[0093] The second phase tilt of the phased array element is determined using the computing system at least in part based on the second plurality of signals;

[0094] Determine the second position of the spacecraft;

[0095] Determine the second attitude of the spacecraft;

[0096] Remove the first portion from the determined second phase tilt, wherein the first portion is caused by the second position of the spacecraft, the second attitude of the spacecraft, or both;

[0097] After removing the first portion of the second phase tilt, the second phase tilt of the phased array element is estimated;

[0098] The reference tilt matrix of the phased array element is generated at least in part based on the first position and the second position of the spacecraft;

[0099] The estimated first phase tilt is compared with the reference tilt matrix to generate a first misalignment error set (1002);

[0100] The estimated second phase tilt is compared with the reference tilt matrix to generate a second misalignment error set (1004); and

[0101] Determine the intersection of the first misalignment error set and the second misalignment error set (1006), wherein the intersection represents the pointing error of the antenna.

[0102] Clause 12. The method according to Clause 11 further includes removing a second portion from the determined first phase tilt, the second portion being caused by a delay error from a processor on the spacecraft, and wherein the first phase tilt is estimated after removing the first portion of the determined first phase tilt and the second portion of the determined first phase tilt.

[0103] Clause 13. The method according to Clause 12 further includes removing a second portion from the determined second phase tilt, the second portion being caused by a delay error from the processor on the spacecraft, and wherein the second phase tilt is estimated after removing the first portion of the determined second phase tilt and the second portion of the determined second phase tilt.

[0104] Clause 14. The method described in Clause 11 further includes calibrating the transmitter antenna to reduce the pointing error by physically rolling, pitching, yawing, or a combination thereof on the spacecraft.

[0105] Clause 15. The method according to Clause 11 further includes calibrating the transmitter antenna to reduce the pointing error by electronically re-pointing the phased array elements.

[0106] Clause 16. A computing system (1400), comprising:

[0107] One or more processors (1404); and

[0108] A memory system comprising one or more non-transitory computer-readable media storing instructions that, when executed by at least one of the one or more processors, cause the computing system to perform operations, including:

[0109] Receive multiple signals transmitted from an antenna on a spacecraft (100), wherein the antenna includes multiple phased array elements;

[0110] The phase tilt of the phased array element is determined at least in part based on the signal;

[0111] Determine the first position of the spacecraft, the first attitude of the spacecraft, or both;

[0112] Remove the first portion from the determined phase tilt, wherein the first portion is caused by the first position of the spacecraft, the first attitude of the spacecraft, or both;

[0113] After removing the first portion, the phase tilt of the phased array element is estimated;

[0114] Generate the reference tilt matrix of the phased array element;

[0115] Compare the estimated phase tilt with the reference tilt matrix; and

[0116] The pointing error of the antenna is determined at least in part based on the comparison.

[0117] Clause 17. The computing system according to Clause 16, wherein the operation further comprises removing a second portion from the determined phase tilt, the second portion being caused by a delay error from the processor on the spacecraft, and wherein, after removing the first portion and the second portion, the phase tilt of the phased array element is estimated.

[0118] Clause 18. The computing system according to Clause 16, wherein the reference tilt matrix is ​​generated at least in part based on the first position of the spacecraft and the second position of the spacecraft, wherein the second position of the spacecraft occurs after the first position of the spacecraft.

[0119] Clause 19. The computing system according to Clause 16, wherein comparing the estimated phase tilt with the reference tilt matrix produces a first misalignment error set (1002) of the estimated phase tilt matching the first position and a second misalignment error set (1004) of the estimated phase tilt matching the second position.

[0120] Clause 20. The computing system according to Clause 19, wherein determining the pointing error of the antenna includes determining the intersection of the first misalignment error set and the second misalignment error set (1006).

[0121] It should be understood that variations of the above-disclosed features and functions, or alternatives thereof, can be combined into many other different systems or applications. Various alternatives, modifications, variations, or improvements not currently foreseen or anticipated herein may be made by those skilled in the art and are intended to be covered by the claims.

Claims

1. A method (500) for calibrating an antenna (110A), comprising: Receive multiple signals transmitted from an antenna (110A) on the spacecraft (100), wherein the antenna (110A) includes multiple phased array elements; The phase tilt of the phased array element is determined at least in part based on the signal; Determine the first position of the spacecraft (100), the first attitude of the spacecraft (100), or both; Remove the first portion from the determined phase tilt, wherein the first portion is caused by the first position of the spacecraft (100), the first attitude of the spacecraft (100), or both. After removing the first portion, the phase tilt of the phased array element is estimated; The reference tilt matrix of the phased array element is generated at least in part based on the first position and the second position of the spacecraft (100), the first attitude and the second attitude of the spacecraft (100), and the portal position; The estimated phase tilt is compared with the reference tilt matrix to generate a first misalignment error set (1002) matching the estimated phase tilt at the first position and a second misalignment error set (1004) matching the estimated phase tilt at the second position; and The intersection of the first misalignment error set and the second misalignment error set is determined (1006) to determine the pointing error of the antenna (110A) at least in part based on the comparison.

2. The method of claim 1, wherein the signal is received by a computing system (1400) at a portal on the ground, and wherein each of the signals comprises a tone at a different frequency.

3. The method of claim 2, wherein the first position of the spacecraft (100), the first attitude of the spacecraft (100), or both are measured by one or more sensors carried by the spacecraft (100) and launched to a computing system (1400) at a portal on the ground.

4. The method of claim 1, wherein the first portion is removed to isolate the misalignment error (1002, 1004) of the antenna.

5. The method of claim 1, further comprising removing a second portion from the determined phase tilt, the second portion being caused by a delay error from the processor (124) on the spacecraft (100), wherein the phase tilt is estimated after removing the first portion and the second portion.

6. The method according to any one of claims 1-5, wherein the reference tilt matrix is ​​generated at least in part based on the first position and the second position of the spacecraft (100), and wherein the second position of the spacecraft (100) occurs after the first position of the spacecraft (100).

7. The method of claim 1, further comprising calibrating the antenna (110A) to reduce the pointing error.

8. The method of claim 7, wherein calibrating the antenna (110A) comprises physically or electronically rolling, pitching, yawing, or a combination thereof on the spacecraft (100).

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