Systems and methods for transmission path compensation for satellite communications

Abstract

Broadband satellite terminals are described that comprise an upconverter and power amplifier that are not collocated. The terminals are configured to automatically calculate an upconverter gain value to account for signal losses and / or gains between the first modem and the power amplifier in local oscillator, frequency, and modulation.

Description

Attnv Dkt No. 101790.0077PCTSYSTEMS AND METHODS FOR TRANSMISSION PATH COMPENSATION FOR SATELLITE COMMUNICATIONSField of the Invention

[0001] The field of the invention is broadband satellite communications.Background

[0002] The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] For satellite communications, especially those for aircraft, a satellite broadband terminal is used which typically includes an antenna system, a radio frequency (RF) transceiver, a modem, a power amplifier (PA), an upconverter, and other components. It is typical for the power amplifier and the upconverter to be collocated in the broadband terminal in a single unit known as a block upconverter (BUC) to conserve space and reduce the likelihood of signal degradation. The BUC receives the intermediate frequency (IF) signal from the modem, upconverts the signal to the required transmission frequency (e.g., Ku-band, Ka-band), and amplifies the upconverted signal to the appropriate power level for transmission to the satellite.

[0004] The upconverter takes a signal generated in a lower frequency band and upconverts it to a higher frequency, ensuring the signal is in the correct frequency range for transmission to the satellite. The power amplifier is responsible for amplifying the signal to a level suitable for transmission to the satellite. The power amplifier is typically placed near the antenna or integrated into the antenna system itself to reduce signal loss.

[0005] An example of this is shown in Figure 1, in which a modem 10 generates an IF signal, which is passed to the BUC 20. An IF Cal File, which is measured during installation of the antenna 30, is used to account for signal losses 15 between the modem and the BUC in frequency and modulation. It is used to calibrate and adjust performance of IF components responsible for converting signals between different frequency bands. A BUC Cal File (BCF), which is measured offline, is used to account for gain variations 25 in local oscillator (LO), IF,Attny Dkt No. 101790.0077PCT temperature, modulation and power between the BUC 20 and the antenna 30. The BCF is a fde used in satellite communication systems to calibrate and adjust the performance of the BUC 20.

[0006] In such systems where the power amplifier and upconverter are collocated, typically the adopted calibration method must estimate all losses and gains of the communication chain between the output of the modem and the input to the antenna. However, such systems lack the ability to calibrate IF and RF components and therefore are unable to calibrate the system when the power amplifier and upconverter are not collocated.

[0007] Gain variations are an important factor to account for, as they can significantly affect signal quality and the overall performance of the system. Gain variations can occur due to antenna variations, path loss, and atmospheric effects, for example.

[0008] All publications identified herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0009] Thus, there is still a need for satellite broadband terminals capable of measuring the loss and gain in a communication chain when the power amplifier and upconverter are not collocated.Summary of The Invention

[0010] The inventive subject matter provides apparatus, systems, and methods for Internet connectivity for aircraft that utilize a broadband satellite terminal to communicate via one or more satellites. Specifically, the systems and methods can utilize transmit path compensation to automatically measure the losses / gains in the transmission chain and set the gain at the upconverter to compensate for losses and / or gains dynamically. It is preferred that the transmit path compensation can be implemented as software within the modem manager.

[0011] The inventive subject matter is terminal agnostic and is useful where the upconverter is not collocated with the power amplifier. The inventive subject matter can be used with different modems and with various satellite types. As used herein, the term “collocated” is defined toAttny Dkt No. 101790.0077PCT mean physical arrangement of components where different pieces of hardware, such as upconverters and power amplifiers, are placed in a single terminal device to support broadband communication services. Thus, items are not collocated if they are placed in distinct and separate devices that may be coupled by an Ethernet or other connection.

[0012] The transmit path compensation preferably utilizes the modem manger’s extended IF range and the upconverter’ s RF amplification range capabilities, along with calibration files to allow the broadband terminal to stay calibrated and online, fulfilling regulatory compliance of radiated transmit power.

[0013] This approach offers numerous advantages over prior art systems. For example, the inventive subject matter allows for seamless calibration of transmit chain gain for any aircraft platform or across different modems being used with different satellite providers (e.g., changing satellites (LEO / MEO / GEO) and higher / lower gains adjustment). In addition, the systems and methods described herein allow for cost optimization to avoid development costs to support different platforms or modem configurations, as losses and gains can be adjusted for dynamically. This increases the robustness of the broadband terminal and can mitigate installation issues (e.g., due to loose contacts, etc.).

[0014] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.Brief Description of The Drawings

[0015] Figure 1 illustrates a diagram of a prior art communication system where the upconverter and power amplifier are collocated.

[0016] Figure 2 illustrates a schematic of one embodiment of a broadband satellite terminal.

[0017] Figure 3 illustrates a diagram of another embodiment of a broadband satellite terminal where the upconverter and power amplifier are not collocated.

[0018] Figure 4 illustrates a flow chart of one embodiment of a method for determining an upconverter gain value.Attnv Dkt No. 101790.0077PCT

[0019] Figure 5 illustrates an exemplary chart illustrating maximum and minimum power amplifier antenna gains and the result of antenna gain variation on the upconverter gain and modem output power range.Detailed Description

[0020] Throughout the following discussion, numerous references will be made regarding servers, services, interfaces, portals, platforms, or other systems formed from computing devices. It should be appreciated that the use of such terms is deemed to represent one or more computing devices having at least one processor configured to execute software instructions stored on a computer readable tangible, non-transitory medium. For example, a server can include one or more computers operating as a web server, database server, or other type of computer server in a manner to fulfill described roles, responsibilities, or functions.

[0021] The terms, “component”, “module”, "system”, and the like used herein indicate a computer-related entity, hardware, firmware, software, a combination of software and hardware, or execution of software. For example, a component may be a procedure executed in a processor, a processor, an object, an execution thread, a program, and / or a computer, but is not limited thereto. For example, both an application executed in a computing device and a computing device may be components. One or more components may reside within a processor and / or an execution thread. One component may be localized within one computer. One component may be distributed between two or more computers. Further, the components may be executed by various computer readable media having various data structures stored therein. For example, components may communicate through local and / or remote processing according to a signal (for example, data transmitted to another system through a network, such as the Internet, through data and / or a signal from one component interacting with another component in a local system and a distributed system) having one or more data packets.

[0022] Illustrative logical blocks, configurations, modules, circuits, means, logic, and algorithm operations described herein may be implemented by electronic hardware, computer software, or in a combination of electronic hardware and computer software. In order to clearly exemplify interchangeability of hardware and software, the algorithms, steps and / or operations have been generally described in the functional aspects thereof. Whether the functionality is implementedAttnv Dkt No. 101790.0077PCT as hardware or software depends on the specific application or design restraints given to the system.

[0023] Although the discussion herein may focus on an aircraft, it is contemplated that the systems and methods discussed herein could similarly be used on ships, trains, busses, and other vehicles.

[0024] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus, if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.

[0025] The inventive subject matter described herein applies to all broadband satcom terminals where the upconverter is not collocated with the RF power amplifier. While the below discussion provides examples from broadband satellite communication terminals based on an A791 / 792 architecture, other architecture could be used without departing from the scope of invention herein.

[0026] In Figure 2, one embodiment of a satellite broadband terminal 100 is shown, in which one or more antennas 102 is communicatively coupled with the broadband terminal 100. A radome 104 can covers the one or more antennas 102. The broadband terminal 100 may comprise a networking data unit having an antenna control unit (ACU) 130 which is coupled with a modem manager 110 and a frequency conversion unit (FCU) 120 comprising the upconverter (UC).

[0027] The ACU 130 controls the antenna 102 by receiving data from the vehicle’s navigation or other system(s), which can be used for antenna pointing and tracking and to determine to which satellite to connect, for example. For an aircraft, because the location and altitude of the aircraft vary over time, the ACU 130 must change from one satellite to another by reorienting the antenna, acquiring a new signal, and establishing a data link, for example.Attnv Dkt No. 101790.0077PCT

[0028] The modem manager 110 comprises one or more modems, and in this example, comprises a first modem 112 and a second modem 114. Although two modems are shown coupled to the modem manager 110, it is contemplated that a single modem or three or more modems could be coupled to the modem manager 110 without departing from the scope of the invention described herein. The key functionality is the ability to utilize different types of modems and connect with different satellites without having to replace the broadband terminal 100 itself.

[0029] Other components of the broadband terminal 100 and / or the modem manager 110 may include an electronics package having a main carrier board, at least one processor, memory configured to store one or more software programs, and a power supply. The various components of the broadband terminal 100 are preferably coupled by wired connections such as Ethernet or coaxial cables, although other suitable wired connections or wireless connections could be used without departing from the scope of the invention herein.

[0030] The processor may be formed of one or more cores, and may include a processor, such as a central processing unit (CPU), a general purpose graphics processing unit (GPGPU), and other commercially suitable component. The processor may read a computer program stored in the memory and process data as described herein. It is contemplated that the memory may include at least one type of storage medium among a flash memory type, a hard disk type, a multimedia card micro type, a card type of memory (for example, an SD or XD memory), a Random Access Memory (RAM), a Static Random Access Memory (SRAM), a Read-Only Memory (ROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Programmable Read- Only Memory (PROM), a magnetic memory, a magnetic disk, and an optical disk.

[0031] The broadband terminal 100 generates a signal at the modem manager 110 at a specific power level to be transmitted to the antenna 102 via a transmission chain, which includes constant (e.g, cable losses) and variable contributors. The transmission chain may include a configurable but pre-fixed amplification / gain in the power amplifier 130 to compensate for losses and to ensure, as far as possible, that the input power level lies within the required power level requirements of the power amplifier 130 and antenna 102 are met.Attny Dkt No. 101790.0077PCT

[0032] The modem manager 110 preferably comprises one or more algorithms preferably stored in one or more files to provide for transmit path compensation (TPC) and allow for adjustable gain at the power amplifier 130 to thereby compensate for RF losses with respect to the input requirements of the antenna 102. In this manner, the performance of the broadband terminal 100 aboard the vehicle can be optimized in situations where the power amplifier 130 and the upconverter 120 are not collocated.

[0033] Figure 3 illustrates one embodiment of a schematic for a broadband terminal 200 where the upconverter 220 and power amplifier 230 are not collocated. In such embodiments, the upconverter 220 receives an IF signal generated from the first modem of the modem manager 210 and upconverts the received signal to the required transmission frequency, ensuring the signal is in the correct frequency range for transmission to the satellite (e.g., Ku-band, Ka-band). The power amplifier 230 receives the higher frequency signal from the upconverter 220, and amplifies the received signal as needed to be suitable for transmission from the antenna 240 to a satellite.

[0034] An IF+RF Cal File may be used by the modem manager 210 during the initial setup of the broadband terminal 200 and / or during regular maintenance, for example, to ensure that the IF and RF components are operating within specifications. By applying calibration data from the IF+RF Cal File, the performance of the broadband terminal 200 can be optimized, minimizing distortions or signal losses and ensuring consistent signal quality. Preferably, the IF+RF Cal File is stored within the modem manager 210 to allow for automatic adjustments.

[0035] The IF+RF Cal File can be used by the modem manager 210 to account for signal losses and gains 215 between the modem manager 210 and the power amplifier 230 in LO, frequency, and modulation. The IF+RF Cal File is a set of algorithms that can be used to account for cable loss between the modem manager 210 and the upconverter 220 and between the upconverter 220 and the power amplifier 230. Alternatively, the IF+RF Cal File could be used to account for losses or gains between the modem manager 210 and the power amplifier 230.

[0036] The IF+RF Cal File can be used, for example, by testing the upconverter 220 at different values of upconverter gain. Based on these tests, a specific value of upconverter gain can beAttnv Dkt No. 101790.0077PCT selected that accounts for the losses and / or gains between the modem manager 210 and the power amplifier 230.

[0037] For example, at the installation of the antenna 240, the IF+RF Cal File can be utilized to calibrate the components that handle the IF and RF signals, and to select and / or adjust the upconverter gain value using the steps shown in Figure 4. These steps are repeated for different values of upconverter gain (G) from a minimum gain (Grain) to a maximum gain (Gmax). The differential between each step may vary and is designated as Gstep.

[0038] First, the upconverter gain (G) is set to Gm in. The upconverter gain may be compared with Gmax to determine whether to continue with the remaining steps. If G is less than Gmax, gains or losses between the modem manager 210 and the power amplifier 230 are measured for each value of LO, IF, and modulation in a loop. This step may be skipped for the initialization where G = Ginin.

[0039] If the power amplifier does not sense an input signal, the measuring step is aborted for G and G is incremented by Gstep. This is because the upconverter gain G is likely too low. If the power amplifier senses an input signal, it is checked whether the power amplifier warns of overdrive. If so, the measuring step is aborted for G and G is incremented by Gstep. This is because the upconverter gain G is likely too high. These determinations can be in reverse order or could occur at the same time. However, if the power amplifier does not sense an input signal or if the power amplifier warns of overdrive, that gain value G of the upconverter is not deemed to be an acceptable value. Put another way, if the power amplifier senses an input signal and the power amplifier does not warn of overdrive, that value of G is stored in a first set of gain values.

[0040] If the first set of gain values comprises one or more values at the end of the calculations, then the calculations were successful. After completing the calculations, one of the values of upconverter gain G can be selected from the first set of gain values. The value selected may depend on the ultimate goal. For example, the value G selected could be the median value that allows the maximum margin, the lowest value, or the highest value.

[0041] A Power Amplifier Cal File (PCF) is a file used to calibrate the performance of the power amplifier 230. The PCF may contain calibration data that compensates for imperfections, gainAttny Dkt No. 101790.0077PCT variations, and nonlinearities in the performance of the power amplifier. The PCF is typically used during the initial setup of the communications system. The PCF, which is measured offline, is used to account for gain variations 225 in LO, RF, temperature, modulation, and power between the power amplifier 230 and the antenna 240. This ensures the power amplifier 230 maintains a consistent gain and that the output signal remains within the desired power range.

[0042] Figure 5 illustrates a visualization of how the required dynamic range 300 of the modem manager 210 may be determined. The maximum and minimum gain of the power amplifier are shown, as well as the results of antenna gain variation on the upconverter gain G and the first modem output power range, when the upconverter and the power amplifier are not collocated. By using the steps discussed above, it is possible to manage the broadband terminal in many possible ways.

[0043] Once the upconverter gain value has been selected (line 350 in Figure 5), the broadband terminal has determined the transmit chain gain under all possible conditions including, for example, different frequencies, temperatures, power levels, antenna azimuths and elevations, and so forth. As a consequence, the broadband terminal may decide to use this information according to the requirements of the specific satellite network or operator.

[0044] As shown in Figure 5, the maximum allowable EIRP 310 may vary with elevation and / or skew angles due to regulatory requirements. In addition, the gain of the power amplifier 230 and antenna 240 (including radome loss) as measured by EIRP / dBm may vary due to beam scanning, temperature, frequency, and so forth.

[0045] Bar 320 illustrates the input power to meet required EIRP based on the gain of the power amplifier 230 and antenna 240. Bar 330 illustrates the first modem output power and upconverter 220 gain required to be calibrated to meet the input power required by the power amplifier 230 and antenna 240, including harness losses 340A, 340B.

[0046] For example, one satellite network (and modem) may be configured to require a semiconstant IF+RF chain gain, but an antenna gain that is changing (e.g., for flat antennas, the antenna gain changes with the elevation. In such example, the modem may control the EffectiveAttnv Dkt No. 101790.0077PCTIsotropic Radiated Power (EIRP) - the measure of the total power radiated by the antenna in a specific direction - by adjusting its output power level if the antenna gain is changing.

[0047] As another example, another network may be configured to require a semi-constant IF plus RF plus antenna gain. In such example, the broadband terminal may instruct the upconverter to change its gain G, to compensate for a possibly varying antenna gain due to elevation.

[0048] As used herein, and unless the context dictates otherwise, the term "coupled to" is intended to include both direct coupling (in which two elements that are coupled to each other contact each other) and indirect coupling (in which at least one additional element is located between the two elements). Therefore, the terms "coupled to" and "coupled with" are used synonymously.

[0049] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0050] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.Attnv Dkt No. 101790.0077PCT

[0051] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

[0052] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value with a range is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

[0053] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

[0054] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are notAttny Dkt No. 101790.0077PCT expressly referenced. Where the specification claims refers to at least one of something selected from the group consisting of A, B, C .... and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc.

Claims

CLAIMSWhat is claimed is:

1. A satellite broadband terminal, comprising: a modem manager configured to receive a first modem having a first output power level range, wherein the first modem is configured to generate a first signal; an upconverter configured to receive the first signal and generate a second signal having a frequency and power that is greater than a frequency and power of the first signal; a power amplifier configured to receive the second signal and increase a gain of the second signal; wherein the modem manager, upconverter, and power amplifier are communicatively coupled, and wherein the upconverter and the power amplifier are not collocated; an antenna communicatively coupled to the power amplifier and configured to transmit the adjusted second signal; wherein the modem manager is configured to automatically determine an upconverter gain value by creating a first set of values and selecting one of the values of the first set as the upconverter gain value; wherein the first set of values is created by setting the modem output power to a preferred fixed value and analyzing for each value of gain G between a minimum gain to a maximum gain incremented by Gstep and for each value of local oscillator (LO), intermediate frequency (IF), and modulation, (i) whether the power amplifier senses an input signal from the upconverter and (ii) whether the power amplifier warns of overdrive based on the value of G; and if the power amplifier senses the input signal and if the power amplifier does not warn of overdrive, assigning that value of G to the first set of values.

2. The satellite broadband terminal of claim 1, wherein the gain of the power amplifier is adjusted to account for at least one of LO, radio frequency, temperature, modulation, and power between the power amplifier and the antenna.

3. The satellite broadband terminal of claim 2, wherein the gain of the power amplifier is adjusted to account for cable loss between the modem and the upconverter and between the upconverter and the power amplifier.

4. The satellite broadband terminal of claim 1, wherein the gain of the upconverter is adjusted to account for losses or gains between the first modem and the power amplifier.

5. The satellite broadband terminal of claim 1, wherein the modem manager is further configured to receive a second modem having a second output power level range.

6. The satellite broadband terminal of claim 5, wherein the first and second modems are different types.

7. The satellite broadband terminal of claim 1, wherein the upconverter gain value is selected from one of the values of the first set.

8. The satellite broadband terminal of claim 1, wherein the modem manager comprises at least one processor and a computer program stored in a non-transitory computer-readable storage medium, wherein the computer program executes the operations for analyzing for each value of gain G between the minimum gain to the maximum gain and creating the first set of values.

9. The satellite broadband terminal of claim 8, further comprising an IF+RF Cal File stored in the non-transitory computer-readable storage medium and executed by the at least one processor of the modem manager, wherein the IF+RF Cal File comprises the operations for analyzing for each value of gain G between the minimum gain to the maximum gain and creating the first set of values.

10. A method for determining an upconverter gain value of a satellite broadband terminal comprising a modem manager including at least one processor and having a first modem, an upconverter, a power amplifier, and an antenna, wherein the modem manager is communicatively coupled with the first modem, the upconverter, and the power amplifier, and wherein the upconverter and the power amplifier are not collocated, the method comprising: analyzing for a fixed value of modem output power and for each value of gain G between a minimum gain to a maximum gain incremented by GstePand for each value oflocal oscillator (LO), intermediate frequency (IF), and modulation, (i) whether the power amplifier senses an input signal from the upconverter and (ii) whether the power amplifier warns of overdrive based on the value of G; if the power amplifier senses the input signal and if the power amplifier does not warn of overdrive, assigning that value of G to the first set of values; automatically selecting one of the first set of values as the upconverter gain value.

11. The method of claim 10, wherein the upconverter gain value is selected from one of the values of the first set.

12. The method of claim 10, wherein the modem manager comprises the at least one processor and a non-transitory computer-readable storage medium.

13. The method of claim 10, wherein the upconverter gain value is selected to account for signal losses and / or gains between the first modem and the power amplifier in LO, frequency, and modulation.

14. The method of claim 13, wherein the upconverter gain value is selected to account for cable loss between the first modem and the upconverter and between the upconverter and the power amplifier.

15. The method of claim 10, wherein the modem manager is further configured to receive a second modem having a second output power level range.

16. The method of claim 15, wherein the first and second modems are different types.

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