TESTING METHODS FOR CONTROLLED RADIATION DIAGRAM ANTENNA PROCESSING UNITS AND ASSOCIATED SYSTEMS

Abstract

The invention relates to a method comprising receiving, by a computer device, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal from a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals. One or more elements of a phase shift, a time shift, or a power shift are calculated for each of the baseband signals based on the pilot reference signal. Each of the signals in a plurality of baseband signals is adjusted based on the phase shift, time shift, or power shift calculated for each of the baseband signals. Figure for the abstract: Fig 1

Description

Title of the invention: METHODS FOR TESTING CONTROLLED RADIATION PATTERN ANTENNA PROCESSING UNITS AND ASSOCIATED SYSTEMS Domain

[0001] This technology generally relates to systems and methods for testing controlled radiation pattern antenna (CRPA) processing units and related systems. More specifically, the technology relates to methods for testing CRPA processing units using a record and playback system. In addition, the technology further relates to methods and systems for recording the signal from antenna outputs of the global navigation satellite system for testing the CRPA processing units. Context

[0002] Controlled radiation pattern antennas (CRPAs) are often used in GNSS applications to protect GNSS receivers from interference or jammers. CRPAs are typically tested either using GNSS and interference signals received directly from the live sky, or by transmitting artificial GNSS and interference signals inside an anechoic chamber. Using an anechoic chamber allows for better control of phase and time shifts between antenna elements, but adds additional cost to the tests. Radiation-based testing, using either the live sky signal or artificial signals in an anechoic chamber, allows for testing of both the antenna units and the processing units of the CRPA system.It is also possible to test a CRPA system through conductivity tests using wavefront simulators, but these tests only cover the processing unit of the CRPA system with simulated artificial antenna elements and do not take into account the actual CRPA antenna elements.

[0003] Record and playback techniques can be used to bridge the gap between radiation-based testing and conductivity testing for CRPA systems. Using these techniques, GNNS and interference signals can be recorded at the output of each of the CRPA elements (nodes) and later played back in the laboratory environment by connecting the record and playback unit to the antenna element inputs of the CRPA system's processing unit in a repeatable manner. However, current record and playback methods require expensive and dedicated hardware in order to achieve the necessary tight phase alignment between the recorded and played back radio frequency signals. In addition, Current processes do not allow pre-recorded artificial signals to be added to the playback signal. Statement of the invention

[0004] The invention meets this need by proposing a method comprising:

[0005] receiving, by a computing device, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals.

[0006] calculating, by the computing device, one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and

[0007] adjusting, by the computing device, each of a plurality of baseband signals based on the phase offset, time offset, or power offset calculated for each of the baseband signals.

[0008] Thus, the invention provides a method comprising receiving, by a computing device, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal. The pilot reference signal is the same for each of the baseband signals. One or more of a phase offset, a time offset, or a power offset is calculated for each of the baseband signals based on the pilot reference signal. Each of a plurality of baseband signals is adjusted based on the phase offset, the time offset, or the power offset calculated for each of the baseband signals.

[0009] According to a particular aspect of the invention, the calculation of the phase shift, the time shift or the power shift further comprises:

[0010] determining, by the computing device, a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and

[0011] calculating, by the computing device, the phase shift, the time shift or the power shift based on the determined cross-correlation peak.

[0012] According to a particular aspect of the invention, the phase shift, the time shift or the power shift is calculated in real time.

[0013] According to a particular aspect of the invention, the method further comprises determining, by the computing device, one or more navigation data elements for each of the GNSS antennas based on the plurality of signals in baseband.

[0014] According to a particular aspect of the invention, the method further comprises removing, by the computing device, the pilot reference signal from each of the adjusted plurality of baseband signals before storing the baseband signals.

[0015] According to a particular aspect of the invention, the method further comprises generating, by the computing device, the pilot reference signal, wherein the pilot reference signal is generated to avoid degradation of the baseband signals.

[0016] According to a particular aspect of the invention, the method further comprises storing, by the computing device, the adjusted plurality of baseband signals as a baseband IQ file.

[0017] According to a particular aspect of the invention, the method further comprises outputting, by the computing device, the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals that have been recorded at the controlled radiation pattern antenna element outputs from which the baseband signal has been formed for testing the controlled radiation pattern antenna system.

[0018] According to a particular aspect of the invention, the method further comprises:

[0019] outputting, by the computing device, the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals;

[0020] receiving, by the computing device, from a radio frequency receiver, a calibration signal that combines each of the adjusted baseband signals and associated reference signals;

[0021] calculating, by the computing device, one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals; and

[0022] outputting, by the computing device, a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the phase shift, time shift, or power shift calculated for each of the simulated GNSS signals or for each of the simulated interference signals.

[0023] According to a particular aspect of the invention, the calculation of the phase shift, the time shift or the power shift comprises:

[0024] determining, by the computing device, a cross-correlation peak between the calibration signal and at least one of the associated reference signals; and

[0025] calculating, by the computing device, the phase shift, the time shift or the power shift based on the determined cross-correlation peak.

[0026] According to a particular aspect of the invention, the plurality of adjusted baseband signals are continuously output.

[0027] According to a particular aspect of the invention, the method further comprises outputting, by the computing device, a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals to the plurality of radio frequency transmitters.

[0028] The invention also relates to a non-transitory computer-readable storage medium having stored thereon instructions comprising executable code which, when executed by one or more processors, causes the processors to:

[0029] receiving, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals;

[0030] calculating one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and

[0031] adjusting each of a plurality of baseband signals based on the phase offset, time offset, or power offset calculated for each of the baseband signals.

[0032] There is therefore provided a non-transitory machine-readable medium having stored thereon instructions comprising executable code that, when executed by one or more processors, causes the processors to receive, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal from a GNSS antenna and a pilot reference signal. The pilot reference signal is the same for each of the baseband signals. One or more of a phase offset, a time offset, or a power offset is calculated for each of the baseband signals based on the pilot reference signal. Each of a plurality of baseband signals is adjusted based on the phase offset, the time offset, or the power offset calculated for each of the baseband signals.

[0033] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code for calculating the offset of phase, time shift, or power shift that, when performed by one or more processors, causes the processors to:

[0034] determining a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and

[0035] calculating the phase shift, time shift or power shift based on the determined cross-correlation peak.

[0036] According to a particular aspect of the invention, the phase shift, the time shift or the power shift are calculated in real time.

[0037] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to determine one or more navigation data elements for each of the GNSS antennas based on the plurality of baseband signals.

[0038] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to remove the pilot reference signal from each of the adjusted plurality of baseband signals before storing the baseband signals.

[0039] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to generate the pilot reference signal, wherein the pilot reference signal is generated to avoid degradation of the baseband signals.

[0040] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to store the adjusted plurality of baseband signals as a baseband IQ file.

[0041] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to output the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals which have been recorded at the controlled radiation pattern antenna element outputs from which the baseband signal has been formed for testing the controlled radiation pattern antenna system.

[0042] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to:

[0043] outputting the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals;

[0044] receiving from a radio frequency receiver a calibration signal that combines each of the adjusted baseband signals and associated reference signals;

[0045] calculating one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals; and

[0046] outputting a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the phase offset, time offset, or power offset calculated for each of the simulated GNSS signals or for each of the simulated interference signals.

[0047] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code for calculating the phase shift, the time shift or the power shift which, when executed by the one or more processors, causes the one or more processors to:

[0048] determining a cross-correlation peak between the calibration signal and the at least one of the associated reference signals; and

[0049] calculating the phase shift, time shift or power shift based on the determined cross-correlation peak.

[0050] According to a particular aspect of the invention, the plurality of adjusted baseband signals are continuously output.

[0051] According to a particular aspect of the invention, at least one additional instruction is stored on the medium and comprises executable code which, when executed by the one or more processors, causes the one or more processors to output a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals for the plurality of radio frequency transmitters.

[0052] The invention also relates to a GNSS recording and reading apparatus comprising:

[0053] a memory comprising programmed instructions stored thereon and one or more processors configured to be capable of executing the stored programmed instructions for:

[0054] receiving, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal from a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals;

[0055] calculating one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and

[0056] adjusting each of a plurality of baseband signals based on the phase offset, time offset, or power offset calculated for each of the baseband signals.

[0057] Thus, a GNSS recording and playback apparatus is provided which comprises a memory comprising programmed instructions stored thereon and one or more processors configured to be capable of executing the stored programmed instructions to receive, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal from a GNSS antenna and a pilot reference signal. The pilot reference signal is the same for each of the baseband signals. One or more of a phase offset, a time offset, or a power offset are calculated for each of the baseband signals based on the pilot reference signal.Each of a plurality of baseband signals is adjusted based on the phase offset, time offset, or power offset calculated for each of the baseband signals.

[0058] This technology offers a number of advantages, including providing systems and methods for recording GNSS signals, adjusting the recorded GNSS signals, and playing back recorded GNSS signals to test a CRPA system. The required hardware provides a cost-effective solution for both recording and playback operations. The architecture is also compatible with GNSS simulation systems. In addition, this technology provides methods and systems that enable GNSS recording and playback with continuous correction for time, phase, and / or power offset. In addition, additional artificial or pre-recorded jammers can be associated with the signals during playback for a more complete test of the CRPA system.

[0059] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to:

[0060] determining a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and

[0061] calculate the phase shift, time shift or power shift on the base of the determined cross-correlation peak.

[0062] According to a particular aspect of the invention, the phase shift, the time shift or the power shift are calculated in real time.

[0063] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to determine one or more navigation data elements for each of the GNSS antennas based on the plurality of baseband signals.

[0064] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to remove the pilot reference signal from each of the adjusted plurality of baseband signals before storing the baseband signals.

[0065] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to generate the pilot reference signal, wherein the pilot reference signal is generated to avoid degradation of the baseband signals.

[0066] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to store the adjusted plurality of baseband signals as a baseband IQ file.

[0067] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to output the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals which have been recorded at the controlled radiation pattern antenna element outputs from which the baseband signal has been formed for testing the controlled radiation pattern antenna system.

[0068] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to:

[0069] outputting the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals;

[0070] receive from a radiofrequency receiver, a calibration signal which combines each of the adjusted baseband signals and associated reference signals;

[0071] calculating one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals; and

[0072] outputting a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the phase offset, time offset, or power offset calculated for each of the simulated GNSS signals or for each of the simulated interference signals.

[0073] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to:

[0074] determining a cross-correlation peak between the calibration signal and the at least one of the associated reference signals; and

[0075] calculating the phase shift, time shift or power shift based on the determined cross-correlation peak.

[0076] According to a particular aspect of the invention, the plurality of adjusted baseband signals are continuously output.

[0077] According to a particular aspect of the invention, at least one additional instruction is stored on the apparatus and comprises executable code which, when executed by one or more processors, causes the processors to output a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals for the plurality of radio frequency transmitters. Presentation of figures

[0078] Other aims, characteristics and advantages of the invention will appear more clearly on reading the following description, given as a simple illustrative, and non-limiting, example, in relation to the figures, among which:

[0079] [Fig-1] is a block diagram of an exemplary global navigation satellite system (GNSS) recording system for testing controlled radiation pattern antennas (CRPAs).

[0080] [Fig.2] is a block diagram of a computer device for monitoring the GNSS recording system of [Fig.l].

[0081] [Fig.3] is a block diagram of an exemplary SDR control computing device of the GNSS recording system of [Fig.l].

[0082] [Fig.4] is a flowchart of the method of recording and adjusting GNSS signals using the GNSS recording system of [Fig.l].

[0083] [Fig.5] is a block diagram of the recording and adjustment process of GNSS signals using the GNSS recording system of [Fig.l].

[0084] [Fig.6] is a block diagram illustrating an example of a pre-protocol processing for the GNSS recording system of [Fig.l].

[0085] [Fig.7] is a block diagram of an example GNSS reading system for test the CRPA.

[0086] [Fig.8] is a block diagram of a computer device for reading the system GNSS reading of [Fig.7].

[0087] [Fig.9] is a schematic diagram of a distribution device of the system of GNSS reading of [Fig.7].

[0088] [Fig. 10] is a block diagram of an example of a computer device for monitoring the offset of the GNSS reading system of [Fig.7].

[0089] [Fig. 11] is a flowchart of the method of reading adjusted GNSS signals using the GNSS reading system of [Fig.7].

[0090] [Fig. 12] is a block diagram illustrating an example of a feedback method for the GNSS reading system of [Fig.7]. Detailed description

[0091] An example of an architecture for a global navigation satellite recording system (GNSS) 10 that may be used to record and adjust GNSS signals for testing a plurality of controlled radiation pattern antenna (CRPA) elements 12(1)-12(4) is illustrated in [Fig.l]. Although four CRPA elements 12(1)-12(4) are illustrated, it should be understood that the GNSS recording system 10 could be used with other types and / or numbers of antenna elements used in a GNSS. The GNSS recording system 10 in this example records the GNSS signals received from the output of the CRPA elements 12(1)-12(4). In one example, GNSS signals are received by CRPR elements 12(1)-12(4) from the live sky, although GNSS signals may be provided by a wavefront simulator.

[0092] In this example, the GNSS recording system 10 includes a monitoring computing device 14, a transmitting software defined radio (transmitting SDR) 16, a receiving apparatus 18, receiving software defined radios (receiving SDRs) 20(1)-20(4), a reference clock 22, an SDR controlling computing device 24, and a storage device 26, although other types and / or numbers of other systems, devices, components, and / or other elements in other configurations may be used, such as other types and / or numbers of transmitters and / or receivers or other electronic devices. Although the transmitting SDR 16 and receiving SDRs 20(1)-20(4) are described in this example to record and adjust GNSS signals, it should be understood that each of the SDRs in the recording architecture of the GNSS recording system 10 could be used to provide reception or transmission functionality.

[0093] This technology offers a number of advantages, including providing a relatively low-cost system that uses standard software-defined radios that allow GNSS signals to be captured and recorded from the sky live and apply precise phase, time, and / or power offset adjustment. The recorded GNSS signals can then be played back as described below to test CRPA elements 12(1)-12(4). The system advantageously provides continuous calibration that allows for improved accuracy in terms of phase, time, and / or power adjustments during record and playback operations. The system can also be used to provide artificial or pre-recorded jammers and / or spoofers during playback of the recorded GNSS signals as described below.

[0094] In this example, the GNSS recording system 10 incorporates the monitoring computing device 14 and the SDR control computing device 24, although in other examples, the GNSS recording system 10 may include other types and / or numbers of computing devices. Two separate computing devices are used in this example for the benefits of distributed processing. However, in yet another example, the GNSS recording system 10 may include a single computing device that provides both the SDR monitoring and control functionality described for the monitoring computing device 14 and the SDR control computing device 24 below.

[0095] Referring now to [Fig. 2], in this example, the monitoring computing device 14 includes one or more processors 28, a memory 30, and a communications interface 32 that are coupled together by a bus 34 or other communications link, although the monitoring computing device 14 may include other types and / or numbers of elements in other configurations.

[0096] The processor(s) 28 of the monitoring computing device 14 may execute programmed instructions stored in the memory 30 for any number of functions or other operations illustrated and described by way of the present examples, including the generation of a digital pilot reference signal 36 (as shown in [Fig. 1]), by way of example only. The processor(s) 28 of the monitoring computing device 14 may include one or more graphics processing units (GPUs), CPUs, or general processors with one or more processing cores, for example, although other types of processor(s) may be used.

[0097] The memory 30 of the monitoring computing device 14 stores the programmed instructions for one or more aspects of the present technology as illustrated and described herein, although some or all of the programmed instructions may be stored elsewhere. A variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), hard disk drive (HDD), solid state drives (SSD), flash memory, or other computer-readable media that is read from and written to a magnetic, optical, or other reading and writing system that is coupled to the processor(s) 28, may be used for the memory.

[0098] Accordingly, the memory 30 of the monitoring computing device 14 may store one or more applications that may include executable instructions that, when executed by the monitoring computing device 14, cause the monitoring computing device 14 to perform actions, such as generating the digital pilot reference signal 36, or other reference signals, and to perform other actions illustrated and described by means of the present examples, such as in FIGS. 4-6. The application(s) may be implemented as modules or components of one or more other applications. Further, the application(s) may be implemented as operating system extensions, modules, plugins, or the like.In one example, the application stored on the monitoring computing device 14 is a software-defined GNSS / GPS signal simulator such as the Skydel software produced by Orolia Canada (Montreal, Canada), although one or more other simulation applications for generating the digital pilot reference signal 36, or other reference signals, may be stored in the memory 30 of the monitoring computing device 14.

[0099] The monitoring computing device 14 is configured to generate the digital pilot reference signal 36 which is sent to the transmit SDR 16, as shown in [Fig. 1]. The communication interface 32 of the monitoring computing device 14 operatively couples and enables communication between the monitoring computing device 14, the transmit SDR 16 and the SDR control computing device 24, all of which are coupled together by one or more communication networks, although other types and / or numbers of connections and / or configurations to another device and / or other elements may be used. In this example, the monitoring computing device 14 is coupled to the transmit SDR 16 by a high data rate (e.g., 10 Gb) Ethernet connection 40, as shown in [Fig.l], and to the SDR 24 control computing device via a low-speed (e.g., 1 Gb) Ethernet connection (not shown), although other topologies may be employed, including . using the same communications network. By way of example only, the communications network(s) may include any number and / or types of communications networks, such as local area network (LAN) or wide area network (WAN) and / or wireless networks described herein, although other types and / or number of protocols and / or communications network(s) may be used.

[0100] Referring again to [Fig.l], the transmit SDR 16 is coupled to the monitoring computing device 14 to receive the digital pilot reference signal 36 generated by the monitoring computing device 14 for the operations described herein.In this example, the transmit SDR 16 is coupled to the monitoring computing device 14 via the 10 Gb Ethernet communications network 40 to receive the digital pilot reference signal 36, although the transmit SDR 16 may receive other signals from the monitoring computing device 14 over other communications networks. By way of example only, the transmit SDR 16 could be the USRP X300 or the USRP N310 manufactured by Ettus Research (Austin, Texas), although other SDRs, or other transmitters, could be used. In addition, the transmit SDR 16 may also have receive functionality to perform other operations as described herein. The transmit SDR 16 is configured to upconvert the digital pilot reference signal 36 to a radio frequency (RF) output of the digital pilot reference signal 42 for use by the receiving apparatus 18 as described below.In this example, the transmit SDR 16 is also coupled to the reference clock 22 to synchronize the transmit SDR 16 with the receive SDRs 20(1)-20(4). The reference clock 22 uses both a 10 MHz clock signal 44 and a 1 PPS clock signal 46 as illustrated in [Fig.l], although other clock signals may be employed for synchronization of the various SDRs employed.

[0101] The receiver apparatus 18 is configured to receive GNSS signals 48(1)-48(4) from the CRPA elements 12(1)-12(4), as well as the RF output of the digital pilot reference signal 42 from the transmit SDR 16. In one example, the receiver apparatus 18 is configured to be coupled to an output of each of the CRPA elements 12(1)-12(4), as well as to an output of the transmit SDR 16. In one example, the GNSS signals 48(1)-48(4) are received from the CRPA antenna elements 12(1)-12(4) from the over-the-air sky. The receiver apparatus 18 may be configured to operate with antennas operating using any navigation system, such as, by way of example only, GPS, BeiDou, Galileo, or GLONASS. Although the receiving apparatus 18 is illustrated as receiving GNSS signals 48(1)-48(4) from four CRPA elements 12(1)-12(4) in [Fig.l], it is to be understood that the receiving apparatus 18 could receive any number of GNSS signals from any number and / or types of antenna elements.

[0102] In this example, the receiver apparatus 18 includes low noise amplifiers (LNAs) 50(1)-50(4) and 2:1 multiplexers 52(1)-52(4), although the receiver apparatus 18 may include other types and / or numbers of elements, such as other analog devices for signal conditioning, in other combinations. The LNAs 50(1)-50(4) amplify the received GNSS signals 48(1)-48(4) to produce amplified GNSS signals 54(1)-54(4). As described below, the amplified GNSS signals 54(1)-54(4) are primarily noise because the GNSS signals 48(1)-48(4) are below the thermal noise floor.The 2:1 multiplexers 52(1)-52(4) are configured to combine each of the amplified GNSS signals 54(1)-54(4) with the RF output of the digital pilot reference signal 42 received from the transmit SDR 16 to form mixed GNSS signals 56(1)-56(4) that include the amplified GNSS signals 54(1)-54(4) plus the RF output of the digital pilot reference signal 42. In this example, the same RF output of the digital pilot reference signal 42 is applied to each of the amplified GNSS signals 54(1)-54(4), which are based on the GNSS signals 48(1)-48(4) received from the CRPA elements 12(1)-12(4). The receiving apparatus 18 outputs the mixed GNSS signals 56(1)-56(4) including the amplified GNSS signals 54(1)-54(4) associated with the same RF output of the digital pilot reference signal 42 to the receiving SDRs 20(1)-20(4).

[0103] In this example, four receive SDRs 20(1)-20(4) are used. By way of example only, the receive SDRs 20(1)-20(4) could be the USRP X300 or the USRP N310 manufactured by Ettus Research (Austin, Texas), although other SDRs, or other radio frequency receivers, could be used. The receive SDRs 20(1)-20(4) are coupled to the receiver apparatus 18 to receive the mixed GNSS signals 56(1)-56(4) for each of the registered CRPA elements 12(1)-12(4), although other types of antenna elements could be registered. Although four receive SDRs 20(1)-20(4) are illustrated, any number of receive SDRs could be used based on the number of antenna elements recorded for testing purposes. The receive SDRs 20(1)-20(4) are configured to down-convert the received mixed RF GNSS signals 56(1)-56(4) to mixed baseband GNSS signals 58(1)-58(4).The mixed baseband GNSS signals 58(1)-58(4) each include the digital pilot reference signal 36. Although the receive SDRs 20(1)-20(4) are described, it should be understood that other radio frequency receivers could be used. In addition, the receive SDRs 20(1)-20(4) may also have transmit functionality to perform other operations as described herein.

[0104] In this example, the receiving SDRs 20(1)-20(4) are coupled to the SDR control computing device 24 via a high-speed Ethernet connection 60 (e.g. example 10 GB), although other topologies may be employed. In this example, the receive SDRs 20(1)-20(4) are also coupled to the reference clock 22 to synchronize the receive SDRs 20(1)-20(4) with the transmit SDR 16. The reference clock 22 uses both the 10 MHz clock signal 44 and the 1 PPS clock signal 46 as illustrated in [Fig.l], although other clock signals may be employed for synchronization.

[0105] Referring now to [Fig. 3], in this example, the SDR control computing device 24 includes one or more processors 62, a memory 64, and a communications interface 66 that are coupled together by a bus 68 or other communications link, although the SDR control computing device 24 may include other types and / or numbers of elements in other configurations. In another example, one or more of the functions of the SDR control computing device 24 may be performed on the monitoring computing device 14.

[0106] In this example, the processor(s) 62 of the SDR control computing device 24 may execute programmed instructions stored in the memory 64 for any number of functions or other operations illustrated and described as examples herein, including calculating phase, time, and / or power offsets for each of the mixed GNSS signals 56(4)-56(4) using the mixed baseband GNSS signals 58(1)-58(4), as well as applying the calculated offsets for phase, time, and / or power adjustment to the mixed baseband GNSS signals 58(1)-58(4) in real time, removing the digital pilot reference signal 36 from the mixed baseband GNSS signals 58(1)-58(4) to form adjusted GNSS signals 59(1)-59(4) (adjusted for phase, time and / or power) (as shown in [Fig.l]), and storing the adjusted baseband GNSS signals in memory 64 or storage device 26 (as shown in [Fig. l]), by way of example. Referring again to [Fig. 3], the processor(s) 62 of the SDR control computing device 24 may comprise one or more CPUs, GPUs, or general processors with one or more processing cores, for example, although other types of processor(s) may be used. In this example, the high-throughput data processing for calculating phase, time, and / or power offsets for each of the mixed baseband GNSS signals 58(1)-58(4) (illustrated in [Fig. l]) is performed using GPUs to provide real-time adjustment, although other types and / or numbers of processors may be used.

[0107] The memory 64 of the SDR control computing device 24 stores the programmed instructions for one or more aspects of the present technology as illustrated and described herein, although some or all of the programmed instructions may be stored elsewhere. The memory 64 of the SDR control computing device 24 may also be used to store the adjusted baseband GNSS signals 59(1)-59(4) generated as described below, although the adjusted baseband GNSS signals 59(1)-59(4) may be stored in other locations, such as on the storage device 26. A variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), hard disk drive (HDD), solid state drives (SSD), flash memory, or other computer-readable media that is read from and written to a magnetic, optical, or other read / write system that is coupled to the processor(s) 62 may be used for the memory 64.

[0108] Accordingly, the memory 64 of the SDR control computing device 24 may store one or more applications that may include executable instructions that, when executed by the SDR control computing device 24, cause the SDR control computing device 24 to perform actions, such as performing a cross-correlation analysis of the mixed baseband GNSS signals 58(1)-58(4) (which each include the digital pilot reference signal 36) to determine the time, phase, and / or power offset as illustrated and described by way of the examples shown herein such as in FIGS. 4-6. The memory 64 of the SDR control computing device 24 may also store the digital pilot reference signal 36 generated by the monitoring computing device 14 and associated with each of the received GNSS signals 48(1)-48(4) from the CRPA elements 12(1)-12(4) (as shown in [Fig.l]). The application(s) may be implemented as modules or components of one or more other applications. In addition, the application(s) may be implemented as operating system extensions, modules, plugins or the like.

[0109] The communication interface 66 of the SDR control computing device 24 operatively couples and communicates between the SDR control computing device 24, the receive SDRs 20(1)-20(4), and the monitoring computing device 14, all of which are coupled together by one or more communication networks, although other types and / or numbers of connections and / or configurations to another device and / or other elements may be used. In this example, the SDR control computing device 24 is coupled to the receive SDRs 20(1)-20(4) by the high data rate Ethernet connection 60 (e.g., 10 Gb) and to the monitoring computing device 14 by a low data rate Ethernet connection (e.g., 1 Gb) (not shown), although other topologies may be employed.By way of example only, the communications network(s) may include one or more local area networks (LANs) or wide area networks (WANs) and / or . wireless networks, although other types and / or number of protocols and / or one or more communication networks may be used.

[0110] Referring again to [Fig. 1], the optional storage device 26 is coupled to the SDR control computing device 24. The storage device 26 may be used to store the adjusted baseband GNSS signals 59(1)-59(4) generated by the SDR control computing device 24 for use, by way of example, in a read operation as described herein. The storage device 26 may include a variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), hard disk drive (HDD), solid state drives (SSD), flash memory, or any other computer-readable medium that is read from and written to a magnetic, optical, or other read and write system.

[0111] Although the monitoring computing device 14, the SDR control computing device 24, and the receiver apparatus 18 are illustrated and described in the illustrative examples herein, other types and / or numbers of systems, devices, components, and / or elements of other topologies may be used. It is to be understood that the systems of the examples described herein are for exemplary purposes, as many variations of the specific hardware and software used to implement the examples are possible, as will be appreciated by those skilled in the art. In some examples, the devices may be part of a rack-mount system.

[0112] Portions of all examples of the technology illustrated and described herein may also be implemented as one or more non-transitory computer-readable media having stored thereon instructions for one or more aspects of the present technology. The instructions of some examples include executable code that, when executed by the processor(s) 28, 62 of the monitoring computing device 14 or the SDR control computing device 24, causes the processor(s) 28, 62 to perform the steps necessary to implement the methods of the examples of this technology that are illustrated and described herein.

[0113] An example for recording and adjusting GNSS signals for phase, time, and / or power offset, such as GNSS signals 48(1)-48(4) received from CRPA elements 12(1)-12(4) as shown in [Fig.l], will now be discussed with reference to Figures 1-6. The example method can be used to generate adjusted GNSS signals that are adjusted for phase, time, and / or power offsets that can be used in a read operation to test CRPA elements 12(1)-12(4), by way of example. [Fig.4] is a flowchart of the example method for recording and adjusting GNSS signals using the GNSS recording system 10 shown in [Fig.l]. [Fig.5] is a flowchart of the data flow for recording and adjusting GNSS signals using the GNSS recording system 10 shown in [Fig.l]. Although [Fig.5] illustrates the example process for only two CRPA elements 12(1) and 12(2), the data flow is the same for each of the CRPA elements 12(1)-12(4) shown in [Fig.l], and can be used for any number and / or type of antenna elements under test.

[0114] Referring again to Figures 4 and 5, in step 400, the receiving apparatus 18 receives the GNSS signals 48(1) and 48(2) from the CRPA elements 12(1) and 12(2). In one example, the GNSS signals 48(1) and 48(2) are received from the CRPA elements 12(1) and 12(2) from the live sky. The receiving apparatus 18 is coupled to the output of the CRPA elements 12(1) and 12(2) to receive the GNSS RF signals 48(1) and 48(2).

[0115] Next, in step 402, each of the GNSS signals 48(1) and 48(2) is amplified by the LNAs 50(1) and 50(2) of the receiving apparatus 18 to produce the amplified GNSS signals 54(1) and 54(2). As shown in [Fig.5], the amplified GNSS signals 54(1) and 54(2) are primarily noise because the GNSS signals 48(1) and 48(2) are below the thermal noise floor.

[0116] In step 404, the receiving apparatus 18 receives the RF output of the digital pilot reference signal 42 from the transmit SDR 16, which is based on the digital pilot reference signal 36 that is generated by the monitoring computing device 14. The monitoring computing device 14 provides the digital pilot reference signal 36 to the transmit SDR 16, which converts the digital pilot reference signal 36 to the RF output of the digital pilot reference signal 42. The RF output of the digital pilot reference signal 42 is provided to an input of the receiving apparatus 18. Any pilot reference signal known in the art may be used, although the pilot reference signal is chosen so that it does not degrade the GNSS signals with which the digital pilot reference signal is combined as described below.

[0117] Next, in step 406, the amplified GNSS signals 54(1) and 54(2) are combined with the RF output of the digital pilot reference signal 42 by 2:1 multiplexers 52(1) and 52(2) of the receiver apparatus 18 to form the mixed GNSS signals 56(1) and 56(2) for each of the CRPA elements 12(1) and 12(2). The mixed GNSS signals 56(1) and 56(2) comprise, respectively, the amplified GNSS signals 54(1) and 54(2) (noise plus GNSS signals 48(1) and 48(2), respectively), as well as the RF output of the digital pilot reference signal 42. The mixed GNSS signals 56(1) and 56(2) are output receive SDRs 20(1) and 20(2), respectively.

[0118] In step 408, the receiving SDRs 20(1) and 20(2) provide downconversion to convert the mixed GNSS signals 56(1) and 56(2) into mixed baseband GNSS signals 58(1) and 58(2) and transmit the mixed baseband GNSS signals 58(1) and 58(2) to the SDR control computing device 24 for preprocessing.

[0119] Next, in step 410, the SDR control computing device 24 determines the phase, time, and / or power offset for two of the exemplary mixed baseband GNSS signals 58(1) and 58(2). In one example, the SDR control computing device 24 performs a cross-correlation analysis for the received mixed baseband GNSS signals 58(1) and 58(2), which are based on the GNSS signals 48(1) and 48(2) received from the CRPA elements 12(1) and 12(2).

[0120] Referring now to [Fig. 6], an exemplary method of determining the phase, time, and / or power offset for two of the exemplary mixed baseband GNSS signals 58(1) and 58(2) using cross-correlation analysis is illustrated. Each of the mixed baseband GNSS signals 58(1) and 58(2) includes the GNSS signal 48(1) and 48(2), respectively, (which are below the thermal noise floor), as well as the digital pilot reference signal 36. The digital pilot reference signal 36 is generated by the monitoring computing device 14 which is also provided to and stored in the memory 64 of the SDR control computing device 24 for the cross-correlation method illustrated in [Fig. 6].To determine the phase, time, and / or power shift, a cross-correlation peak between the mixed baseband GNSS signals 58(1) and 58(2) is obtained using the digital pilot reference signal 36, which is the same for each of the mixed baseband GNSS signals 58(1) and 58(2), although the cross-correlation peak can be determined for other mixed baseband GNSS signals such as the mixed baseband GNSS signals 58(3) and 58(4) as shown in [Fig.l]. The cross-correlation peak is determined using standard techniques. Cross-correlation peaks can be determined between any number of the CRPA elements 12(1)-12(4) under test, as shown in [Fig.l]. Referring again to [Fig.6], each cross-correlation peak contains information that can be extracted from the time, power, and / or phase shift between the received GNSS signals 48(1) and 48(2), for example, as shown in [Fig. 6]. The cross-correlation technique can be performed for each of the CRPR elements 12(1)-12(4), for example in the CRPA system 10 shown in [Fig. 1], although the technique can be employed with other numbers and / or types of antenna elements. Referring again to [Fig. 6], the relative time, power, and / or phase shift between the correlation peaks is measured, averaged, and applied to the mixed baseband GNSS signals 58(1) and 58(2), for example, to compensate for the phase, time, and / or power shift. In one example, the cross-correlation preprocessing is performed in real time using GPUs.

[0121] Referring again to Figures 4 and 5, at step 412, the relative time, power, and / or phase offset may be used by the SDR control computing device 24 to form adjusted GNSS signals 59(1) and 59(2), although other numbers of adjusted GNSS signals may be generated. The digital pilot reference signal 36 may also be removed from the adjusted GNSS signals 59(1) and 59(2). The preprocessing results in adjusted GNSS signals 59(1) and 59(2), for example, that are adjusted in terms of time, power, and / or phase.

[0122] At step 514, the adjusted GNSS signals 59(1) and 59(2) may then be stored in baseband either on the memory 64 of the SDR control computing device 24 or in the separate storage device 26. In one example, the adjusted GNSS signals are stored as binary files. The recording operation described allows for multiple synchronized phase-coherent recordings. The preprocessing described in connection with [Fig. 6] allows for precise control of time and / or phase offsets. The continuous calibration allows for very precise phase, time, and / or power adjustments during recording and playback of GNSS signals.

[0123] Referring again to [Fig. 1], in one example, the phase shift may be maintained below about 2 degrees. In one example, the recorded adjusted GNSS signals 59(1)-59(4) may be used for trajectory and attitude information (yaw, pitch, roll) using a GNSS receiver. In some examples, a standalone antenna and GNSS receiver may be used during recording for the trajectory and attitude information. The trajectory and attitude information may be used during playback, as described below, such that the directional jammers are consistent with the receiver dynamics as described below. The adjusted GNSS signals 59(1)-59(4) may then be used, for example, in a playback operation to test the CRPA elements as described below.The stored adjusted GNSS signals 59(1)-59(4) can be used to reproduce the original GNSS signals 48(1)-48(4) received at each CRPA element 12(1)-12(4) as shown in [Fig.l].

[0124] An exemplary architecture for a GNSS readout system 70 that may be used for reading recorded adjusted GNSS signals, as described above, to test the plurality of CRPA elements 12(1)-12(4) (as illustrated in [Fig. 1]) is illustrated in [Fig. 7]. In this example, the GNSS readout system 70 includes a wavefront readout apparatus 72 that incorporates a readout computing device 74 and an offset monitoring computing device 76, transmit software-defined radios (transmit SDRs) 78(1)-78(4), a distribution device 80, a receive software-defined radio (receive SDR) 82, and a reference clock 84, although other types and / or numbers of other systems, dis positives, components, and / or other elements in other configurations can be used. This technology offers a number of advantages, including providing a relatively inexpensive and easily expandable GNSS readout system 70 that allows for the readout of recorded GNSS signals with precise adjustment of phase, power, and / or time offsets. The system also allows for the readout signals to be combined with additional simulated signals, such as directional interference signals. For example, simulated signals can be formed as in U.S. Patent Application No. 16 / 837,706.

[0125] In one example, the GNSS recording system 10 ([Fig.l]) and the GNSS reading system 70 ([Fig.7]) may be combined into a single system. For example, the computing devices described may be interchanged and the transmitting and receiving radios may be used to have both transmitting and receiving functionality.

[0126] Referring again to [Fig. 7], in this example, the wavefront reading apparatus 72 incorporates the reading computing device 74 and the offset monitoring computing device 76, although in other examples, the wavefront reading apparatus 72 may include other types and / or numbers of devices. Two separate computing devices may be used for the benefits of distributed processing. In yet another example, the wavefront reading apparatus 72 may include a single computing device that provides both reading and offset monitoring functionality.

[0127] Referring now to [Fig. 8], in this example, the reading computing device 74 includes one or more processors 86, a memory 88, and a communications interface 90 that are coupled together by a bus 92 or other communications link, although the reading computing device 74 may include other types and / or numbers of elements in other configurations.

[0128] The processor(s) 86 of the reading computing device 74 may execute programmed instructions stored in the memory 88 for any number of functions or other operations illustrated and described by way of examples herein, including reading GNSS signals stored in the memory or generating simulated GNSS signals, by way of example only. The processor(s) 86 of the reading computing device 74 may include one or more graphics processing units (GPUs), CPUs, or general processors with one or more processing cores, for example, although other types of processor(s) may be used.

[0129] The memory 88 of the reading computer device 74 stores the programmed instructions for one or more aspects of the present technology as illustrated and described herein, although some or all of the programmed instructions may be stored elsewhere. A variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), hard disk drive (HDD), solid state drives (SSD), flash memory, or other computer-readable media that is read from and written to a magnetic, optical, or other read / write system that is coupled to the processor(s) 86 may be used for the memory 88.

[0130] Accordingly, the memory 88 of the reading computing device 74 may store one or more applications that may include executable instructions that, when executed by the reading computing device 74, cause the reading computing device 74 to perform actions, such as reading stored GNSS signals, such as the adjusted GNSS signals 59(1)-59(4) generated by the GNSS recording system 10 as described in the examples of FIGS. 4-6, or generating other simulated signals, and to perform other actions illustrated and described by means of the present examples. The application(s) may be implemented as modules or components of one or more other applications. In addition, the application(s) may be implemented as operating system extensions, modules, plugins or the like.In one example, the application stored on the simulation computing device is a software-defined GNSS / GPS simulator such as the Skydel software produced by Orolia Canada (Montreal, Canada), although other simulation application(s) for generating simulated GNSS and interference signals may be stored in the memory of the playback computing device 74.

[0131] Referring again to [Fig. 7], the readout computing device 74 is configured to output the pre-recorded stored GNSS signals, such as the adjusted GNSS signals 59(1)-59(4), as digital complex IQ baseband signals 94(1)-94(4), as shown in [Fig. 7]. The readout computing device 74 may also include simulated GNSS or interference signals associated with the digital complex IQ baseband signals 94(1)-94(4). The term interference is used to refer to unintentional and intentional jammers, as well as spoofers and repeaters, which may be simulated, although other interference signals may be used.

[0132] In one example, thermal noise forming part of the recorded GNSS signals, such as the recorded adjusted GNSS signals 59(1)-59(4) in the example of Figures 4-6, is used as a reference pilot for the digital complex IQ baseband signals 94(1)-94(4). It is not necessary to add an artificial pilot signal for each of the CRPA elements 12(1)-12(4) (as shown in [Fig.l]) because the thermal noise is different for each of the GNSS signals 48(1)-48(4) from the CRPA elements 12(1)-12(4) which are recorded as described above with reference to Figures 4 to 6. The natural pilot reference provided by thermal noise is used to monitor time, phase and / or power offset.

[0133] Referring again to [Fig. 7], the recorded adjusted GNSS signals 59(1)-59(4) stored in the readout computing device 74, or any other pre-recorded GNSS signals, may be read out to operate on any navigation system, such as, by way of example only, GPS, BeiDou, Galileo, or GLONASS. In one example, the recorded signals may include simulated interference signals such as, by way of example only, spoofers, repeaters, or jammers, although other interference signals may be generated. Each of the pre-recorded GNSS signals is coherent. The readout computing device 74 may also output the pre-recorded GNSS signals to the offset monitoring computing device 76, by way of example, which may use thermal noise in the feedback process.

[0134] The communication interface 92 of the playback computing device 74 operatively couples and enables communication between the playback computing device 74, the transmit SDRs 78(1)-78(4), and the offset monitoring computing device 76, all of which are coupled together by one or more communication networks, although other types and / or numbers of connections and / or configurations to other device and / or elements may be used. In this example, the playback computing device 74 is coupled to the transmit SDRs 78(1)-78(4) by a high data rate Ethernet connection 96 (e.g., 10 Gb) and to the offset monitoring computing device 76 by a low data rate Ethernet connection 97 (e.g., 1 Gb), although other topologies may be employed, including use of the same communication network.By way of example only, the communications network(s) may include any number and / or types of communications networks, such as local area network (LAN) or wide area network (WAN) and / or wireless networks described herein, although other types and / or number of protocols and / or communications network(s) may be used.

[0135] Referring again to [Fig. 7], in this example, four transmit SDRs 78(1)-78(4) are used. By way of example only, the transmit SDR 78(1)-78(4) could be the USRP X300 or the USRP N310 manufactured by Ettus Research (Austin, Texas), although other SDRs, or other transmitters, could be used. The transmit SDRs 78(1)-78(4) are coupled to the readout computing device 74 of the wavefront readout apparatus by a high data rate Ethernet connection 96 72 (e.g., 10 Gb) to receive the digital complex IQ baseband signals 94(1)-94(4) representing the recorded GNSS signals, although that any number of transmit SDRs 78(1)-78(4) may be used to receive the digital complex IQ baseband signals 94(1)-94(4). Although the transmit SDRs 78(1)-78(4) are described, it is to be understood that other radio frequency transmitters could be used. The digital complex IQ baseband signals 94(1)-94(4) are continuously transmitted in real time to the transmit SDRs 78(1)-78(4). Each of the transmit SDRs 78(1)-78(4) receives an independent one of the digital complex IQ baseband signals 94(1)-94(4) corresponding to a recorded CRPA element 12(1)-12(4), as shown in [Fig.l], from the playback computing device 74.

[0136] The transmit SDRs 78(1)-78(4) are configured to upconvert the pre-recorded digital complex IQ baseband signals 94(1)-94(4) to radio frequency (RF) outputs 98(1)-98(4). In this example, each of the transmit SDRs 78(1)-78(4) generates a corresponding one of the RF outputs 98(1)-98(4) used to play back a pre-recorded GNSS signal. In one example, each of the transmit SDRs 78(1)-78(4) also generates an RF output for a simulated interference signal 100(1)-100(4) associated with the pre-recorded GNSS signals, although other types and / or numbers of RF outputs may be used. In this example, the reference clock 84 is coupled to each of the transmit SDRs 78(1)-78(4) and the receive SDR 82 to synchronize each of the transmit SDRs 78(1)-78(4) and the receive SDR 82. The reference clock 84 uses both a 10 MHz clock signal 102 and a 1 PPS clock signal 104 as illustrated in [Fig.7], although other clock signals may be used for synchronization.

[0137] In this example, the distribution device 80 is coupled to each of the transmit SDRs 78(1)-78(4) to receive the RF outputs 98(1)-98(4) for the pre-recorded GNSS signals and the second RF outputs for simulated interference signals 100(1)-100(4), respectively, from each of the transmit SDRs 78(1)-78(4), although the distribution device 80 may receive other types and / or numbers of signals. Referring more specifically to [Fig. 9], in one example, the distribution device 80 includes a GNSS channel 106 and an interference channel 108. The GNSS channel 106 and the interference channel 108 each include a number of passive RF elements including multiplexers / couplers, although the distribution device 80 may include other types and / or numbers of passive or active elements in other configurations, such as attenuators that are used to adjust the power levels of the RF signals. [Fig.9] illustrates the distribution device 80 receiving signals from sixteen transmitters in four groups of four. While the processing of the signals from the four transmitting SDRs 78(1)-78(4) is described in connection with the example shown in [Fig.9], the distribution device . 80 can work with additional transmitting SDRs or other types of radios / transmitters, as shown in [Fig.9], in the same way.

[0138] The distribution device 80 is configured to receive the RF outputs 98(1)-98(4) for the pre-recorded GNSS signals via the GNSS channel 106, and the optional second RF outputs for generating the simulated interference signals 100(1)-100(4) via the interference channel 108. The distribution device 80 combines the RF outputs 98(1)-98(4) for the pre-recorded GNSS signals at a 4:1 multiplexer 110 and the second RF outputs for the simulated interference signals 100(1)-100(4) at a 4:1 multiplexer 112 to form a combined GNSS signal 117 and a combined interference signal 119, respectively. Using four inputs allows coverage of the entire GNSS spectrum for both the 98(1)-98(4) RF outputs of pre-recorded GNSS signals and the 100(1)-100(4) simulated interference signals.The distribution device 80 then splits the combined GNSS signal 117 and a combined interference signal 119 into each channel using 1:2 couplers 114 and 116, respectively, to provide a pre-recorded GNSS output signal 118 and a GNSS calibration signal 120, as well as an interference output signal 122 and an interference calibration signal 124 for examples where a simulated interference signal is also used.

[0139] In examples where the pre-recorded GNSS output signal 118 is combined with the simulated interference output signal 122, the distribution device 80 combines the pre-recorded GNSS output signal 118 and the simulated interference output signal 122 using a 2:1 multiplexer 126 to generate a combined pre-recorded simulated interference / GNSS signal 128. The distribution device 80 is coupled to a CRPA system to provide the pre-recorded GNSS signal for testing the CRPA processing unit, such as the CRPA element processing unit 12(1)-12(4) shown in [Fig. 1], using the pre-recorded simulated interference / GNSS signal 128. [Fig. 9] shows an example where four combined pre-recorded simulated interference / GNSS signals are generated, but other numbers of signals can be generated using other numbers of SDR or other types of transmitters.

[0140] Referring again to [Fig. 7], the distribution device 80 outputs the pre-stored GNSS calibration signal 120 and the interference calibration signal 124 to the receiving SDR 82. In one example, multiple GNSS calibration signals and interference signals may be combined before being output to the receiving SDR 82. In this example, the receiving SDR 82 is coupled to the distribution device 80 to receive the pre-stored GNSS calibration signal 120 and the optional interference calibration signal 124. By way of example only, the receiving SDR 82 could be the USRP X300 or the USRP N310 manufactured by Ettus Research (Austin, Texas), although other SDRs could be used for the receive SDR 82. The receive SDR 82 is configured to down-convert the received RF signals for the pre-stored GNSS calibration signal 120 and the optional interference calibration signal 124 back to baseband. Although the receive SDR 82 is described, it should be understood that other radio frequency receivers could be used. In this example, the receive SDR 82 is coupled to the offset monitoring computing device 76 via a high-speed Ethernet connection 130 (e.g., 10 Gb), although other topologies could be employed.

[0141] Referring now to [Fig. 10], in this example, the shift monitoring computing device 76 includes one or more processors 132, a memory 134, and a communications interface 136 that are coupled together by a bus 138 or other communications link, although the shift monitoring computing device 76 may include other types and / or numbers of elements in other configurations. In another example, one or more of the functions of the shift monitoring computing device 76 may be performed on the playback computing device 74.

[0142] In this example, the processor(s) 132 of the offset monitoring computing device 76 may execute programmed instructions stored in the memory 134 for any number of functions or other operations illustrated and described by means of the present examples, including monitoring phase, time, and / or power offsets for the pre-stored GNSS calibration signal 120 and / or the interference calibration signal 124, as well as providing feedback to the readout computing device 74 for phase, time, and / or power adjustment. The processor(s) 132 of the offset monitoring computing device 76 may include one or more CPUs, GPUs, or general processors with one or more processing cores, for example, although other types of processor(s) may be used.

[0143] The memory 134 of the shift monitoring computing device 76 stores the programmed instructions for one or more aspects of the present technology as illustrated and described herein, although some or all of the programmed instructions may be stored elsewhere. A variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), hard disk drive (HDD), solid state drives (SSD), flash memory, or any other computer-readable medium that is read from and written to a magnetic, optical, or other read and write system that is coupled to the processor(s) may be used for the memory 134.

[0144] Therefore, the memory 134 of the shift monitoring computing device 76 may store one or more applications that may include executable instructions that, when executed by the offset monitoring computing device 76, cause the offset monitoring computing device 76 to perform actions, such as performing a cross-correlation analysis of the pre-recorded GNSS calibration signal 120 and / or the interference calibration signal 124 to determine the time and / or phase offset as illustrated and described by way of the present examples as in Figures 11 and 12. The application(s) may be implemented as modules or components of other application(s). Further, the application(s) may be implemented as operating system extensions, modules, plugins, or the like.

[0145] The communication interface 136 of the shift monitoring computing device 76 operatively couples and communicates between the shift monitoring computing device 76, the receiving SDR 82, and the playback computing device 74, all of which are coupled together by one or more communication networks, although other types and / or numbers of connections and / or configurations to other device and / or elements may be used. In this example, the shift monitoring computing device 76 is coupled to the receiving SDR 82 by the high data rate Ethernet connection 96 (e.g., 10 Gb) and to the playback computing device 74 by the low data rate Ethernet connection 97 (e.g., 1 Gb), although other topologies may be employed.By way of example only, the communications network(s) may include local area network(s) (LAN) or wide area network(s) (WAN) and / or wireless networks, although other types and / or number of protocols and / or communications network(s) may be used.

[0146] Although the readout computing device 74, the offset monitoring computing device 76, and the distribution device 80 are illustrated and described in the illustrative examples herein, other types and / or numbers of systems, devices, components, and / or elements of other topologies may be used. It is to be understood that the systems of the examples described herein are for exemplary purposes, as many variations of the specific hardware and software used to implement the examples are possible, as will be appreciated by those skilled in the art. In some examples, the devices may be part of a rack-mount system. In addition, the GNSS readout system 70 ([Fig. 7]) may be coupled with and / or share hardware with the GNSS recording system 10 ([Fig. 1]) described above.

[0147] Portions of all examples of the technology illustrated and described herein may also be implemented as one or more non-transitory computer-readable media having stored thereon instructions for one or more aspects of the present technology. The instructions of some examples include executable code that, when executed by the processor of the simulation computing device or the offset monitoring computing device 76, causes the processor to perform the steps necessary to implement the methods of the examples of this technology that are illustrated and described herein.

[0148] An exemplary GNSS readout method for testing a CRPA system and optional interference simulation will now be described with reference to Figures 7-12. Referring more specifically to [Fig. 11], in step 1100, the readout computing device 74 obtains pre-recorded GNSS signals, such as the adjusted GNSS signals 59(1)-59(4). The pre-recorded GNSS signals may be stored in the memory 88 of the readout computing device 74, or may be obtained from another source such as the SDR control computing device 24 or the storage device 26 shown in [Fig.l].The reading computing device 74 may also optionally generate simulated interference signals to associate with the pre-recorded GNSS signals to provide signal pairs 94(1)-94(4). The optional simulated interference signals may include, by way of example only, spoofers, repeaters, or jammers, although other interference signals may be generated. The term interference is used to refer to unintentional and intentional jammers, as well as spoofers and repeaters, which may be simulated. In one example, each of the pre-recorded GNSS signals is coherent.In one example, the optional simulated interference signals are produced using a simulator stored on the simulation computing device such as Skydel software produced by Orolia Canada (Montreal, Canada), although other simulation application(s) for generating simulated interference and GNSS signals may be used. In this example, modulation for the plurality of pairs of pre-recorded GNSS signals and interference signals is performed using graphics processing units (GPUs) of the playback computing device 74, although other processing techniques may be used. In one example, thermal noise that is part of the recorded GNSS signals is used as a reference driver.

[0149] Next, in step 1102, the plurality of pairs of pre-recorded GNSS signals and interference signals 94(1)-94(4) are output as baseband signals to the four transmit SDRs 78(1)-78(4), although any number of transmit SDRs may be used in the described playback method. In one example, at least sixteen transmitters are used as shown in [Fig. 8]. The plurality of pairs of pre-recorded GNSS signals and simulated interference signals 94(1)-94(4) are streamed in real time as digital complex IQ baseband signals to the transmit SDRs 78(1)-78(4). Each of the transmit SDRs 78(1)-78(4) receives a baseband signal in depending for each of the plurality of pairs of pre-recorded GNSS signals and simulated interference signals 94(1)-94(4) from the reading computing device 74.

[0150] In step 1104, the transmit SDRs 78(1)-78(4) upconvert the digital complex IQ baseband signals for the plurality of pairs of pre-recorded GNSS signals and simulated interference signals 94(1)-94(4) received from the readout computing device 74 into radio frequency (RF) outputs for the pre-recorded GNSS signals 98(1)-98(4) and into RF outputs for the optional interference signals 100(1)-100(4), and transmit these RF outputs to the distribution device 80. Each of the transmit SDRs 78(1)-78(4) optionally uses two RF outputs including the RF outputs for the pre-recorded GNSS signal 98(1)-98(4) and the RF outputs for the simulated interference signal 100(1)-100(4), respectively, although only one RF output can be used when reading only the pre-recorded GNSS signal.The RF outputs for the pre-recorded GNSS signals 98(1)-98(4) are output to the GNSS channel 106 of the distribution device 80, while the RF outputs for the simulated interference signals 100(1)-100(4) are output to the interference channel 108 of the distribution device 80, as shown in [Fig. 8]. The transmit SDRs 78(1)-78(4) are synchronized using the 10 MHz clock signal 102 and the 1 PPS clock signal 104 from the reference clock 84, for example purposes only.

[0151] Next, in step 1106, the distribution device 80 combines the RF outputs for the pre-recorded GNSS signals 98(1)-98(4) in the 4:1 multiplexer 110 of the GNSS channel 106 and the RF outputs for the simulated interference signals 100(1)-100(4) in the 4:1 multiplexer 112 of the interference channel 108 to generate the combined GNSS signal 117 and the combined simulated interference signal 119, respectively. Combining the four signals for each of the RF outputs for the pre-recorded GNSS signals 98(1)-98(4) and the RF outputs for the simulated interference signals 100(1)-100(4) to generate the combined GNSS signal 117 and the combined simulated interference signal 119, respectively, enables coverage of the entire GNSS spectrum.

[0152] In step 1108, the distribution device 80 divides the received RF outputs into each channel comprising the combined GNSS signal 117 and the combined simulated interference signal 119, respectively, to create an output path and a calibration path. As illustrated in [Fig. 5], the distribution device 80 divides the combined GNSS signal and the combined simulated interference signals 119 using the 1:2 couplers 114 and 116, respectively. In this system, the distribution device 80 generates the pre-recorded GNSS output signal 118 and the pre-recorded GNSS calibration signal 120 into the GNSS channel 106. The distribution device 80 also generates the interference output signal 122 and the interference calibration signal 124 in the interference channel 108.

[0153] In step 1110, each of the divided pre-recorded GNSS output signals 118 and the simulated interference output signal 122 along the output path are then combined in the 2:1 multiplexer 126 and are output in various channels of the distribution device 80 to the antenna element inputs of the CRPA element 12(1)-12(4) from which they originate for reading out the pre-recorded GNSS signals and the simulated interference signals to test the CRPA system.

[0154] Next, in step 1112, the pre-recorded GNSS calibration signal 120 and the simulated interference calibration signal 124 are output, respectively, to the inputs of the receive SDR 82, as shown in [Fig. 4]. In one example, a plurality of calibration signals are combined by the distribution device 80 in each channel. The distribution device 80 provides the pre-recorded GNSS calibration signal 120 and the simulated interference calibration signal 124 to the receive SDR 82 via the RF inputs.

[0155] In step 1114, the receiving SDR 82 downconverts the received RF signals including the pre-stored GNSS calibration signal 120 and the simulated interference calibration signal 124 to baseband and transmits the baseband signals to the offset monitoring computing device 76 for further processing.

[0156] Next, in step 1116, the offset monitoring computing device 76 determines a phase, time, and / or power offset for the simulated pre-recorded GNSS output signal 120 using the pre-recorded baseband GNSS calibration signal, which includes thermal noise as a reference signal. In this example, the phase, time, and / or power offsets are determined using a cross-correlation technique as described with reference to [Fig. 12] below.

[0157] [Fig. 12] illustrates an exemplary method of determining the phase, time, and / or power offset for two of the exemplary pre-recorded GNSS signals associated with antenna elements from which the GNSS signals were recorded, such as the adjusted GNSS signals 59(1) and 59(2) generated in the examples of Figures 4-6. Although the method is described for two signals, it should be understood that the exemplary method could be applied to any number of pre-recorded GNSS signals. The pre-recorded adjusted GNSS signals 59(1) and 59(2) each include thermal noise 140(1) and 140(2), respectively, which is used as a reference. In other examples, the pre-recorded GNSS signals may also include the pilot reference signal that was used in the recording and adjustment operation as described above, although in other examples, the pilot may have been removed before the pre-recorded signals are stored.

[0158] The pre-recorded adjusted GNSS signals 59(1) and 59(2) are output with a simulated interference signal in the baseband signal pairs 94(1) and 94(2) by the readout computing device 74 to the transmit SDRs 78(1) and 78(2) where they are converted into RF signals comprising the GNSS RF output signals 98(1) and 98(2) and the RF simulated interference signals 100(1) and 100(2). The pre-recorded GNSS signals and their associated thermal noise (the thermal noise is different for each antenna element) in the illustrated example, are output by the transmit SDRs 78(1) and 78(2) as RF outputs, which are combined by the distribution device 80 into a calibration GNSS signal.The combined signals in the calibration GNSS signal are then converted back to baseband by the receiving SDR 82 and transmitted to the offset monitoring computing device 76 for cross-correlation processing.

[0159] To determine the phase, time and / or power shift, a cross-correlation peak is obtained for each of the thermal noise signals associated with the pre-recorded GNSS signals, such as the adjusted GNSS signals 59(1) and 59(2) using standard techniques. Each cross-correlation peak contains information about the time, power and / or phase shift between the reference from the combined GNSS calibration signal 120. The relative time, power and / or phase shift between two correlation peaks is measured, averaged and applied to the combined pre-recorded GNSS signals to compensate for the phase, time and / or power shift.

[0160] Next, in step 1118, the offset monitoring computing device 76 provides the determined phase, time, and / or power offsets to the readout computing device 74. The readout computing device 74 uses the phase and time offset to adjust the modulation of the pre-recorded GNSS signals that are part of the baseband signals, and the exemplary method is repeated.

[0161] The systems and methods of the present technology advantageously enable recording GNSS signals, adjusting the recorded GNSS signals, and replaying recorded GNSS signals for testing a CRPA system. The required hardware provides a cost-effective solution for both recording and playback operations. The architecture is also compatible with GNSS simulation systems. In addition, this technology provides methods and systems that enable GNSS recording and playback with continuous correction for time, phase, and / or power offset. Furthermore, additional artificial or pre-recorded jammers may be associated with the signals during playback for a more comprehensive test of the CRPA system.

[0162] Having thus described the basic concept of the invention, it will appear rather to those skilled in the art art that the foregoing detailed description is intended to be presented by way of example only and is not limiting. Various alterations, improvements, and modifications will occur and are intended for those skilled in the art, although not expressly indicated herein. Such alterations, improvements, and modifications are intended to be suggested herein, and are within the spirit and scope of the invention. Furthermore, the stated order of processing elements or sequences, or the use of numbers, letters, or other designations accordingly, is not intended to limit the claimed processes to any order except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and their equivalents.

Claims

Claims

1. A method comprising: receiving, by a computing device, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals; calculating, by the computing device, one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and adjusting, by the computing device, each of a plurality of baseband signals based on the calculated phase offset, time offset, or power offset for each of the baseband signals.

2. The method of claim 1, wherein calculating the phase shift, time shift, or power shift further comprises: determining, by the computing device, a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and calculating, by the computing device, the phase shift, time shift, or power shift based on the determined cross-correlation peak.

3. The method of claim 1, wherein the phase shift, time shift or power shift is calculated in real time.

4. The method of claim 1, further comprising determining, by the computing device, one or more navigation data elements for each of the GNSS antennas based on the plurality of baseband signals.

5. The method of claim 1, further comprising removing, by the computing device, the pilot reference signal from each of the adjusted plurality of baseband signals before storing the baseband signals.

6. The method of claim 1, further comprising generating, by the computing device, the pilot reference signal, wherein the pilot reference signal is generated to avoid degradation of baseband signals.

7. The method of claim 1, further comprising storing, by the computing device, the adjusted plurality of baseband signals as a baseband IQ file.

8. The method of claim 1, further comprising outputting, by the computing device, the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals that were recorded at the controlled radiation pattern antenna element outputs from which the baseband signal was formed for testing the controlled radiation pattern antenna system.

9. The method of claim 1, further comprising: outputting, by the computing device, the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals; receiving, by the computing device, from a radio frequency receiver, a calibration signal that combines each of the adjusted baseband signals and associated reference signals; calculating, by the computing device, one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals;and outputting, by the computing device, a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the phase offset, time offset, or power offset calculated for each of the simulated GNSS signals or for each of the simulated interference signals.;

10. The method of claim 9, wherein calculating the phase shift, time shift, or power shift comprises: determining, by the computing device, a cross-correlation peak between the calibration signal and at least one of the calibration signals associated reference; and the calculation, by the computing device, of the phase shift, time shift or power shift based on the determined cross-correlation peak.

11. The method of claim 9, wherein the plurality of adjusted baseband signals are continuously output.

12. The method of claim 9, further comprising outputting, by the computing device, a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals to the plurality of radio frequency transmitters.

13. A non-transitory computer-readable storage medium having stored thereon instructions comprising executable code that, when executed by one or more processors, causes the processors to: receive, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals; calculate one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and adjust each of a plurality of baseband signals based on the phase offset, time offset, or power offset calculated for each of the baseband signals.

14. The medium of claim 13 having stored thereon at least one further instruction comprising executable code for calculating the phase shift, time shift, or power shift which, when executed by one or more processors, causes the processors to: determine a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and calculate the phase shift, time shift, or power shift based on the determined cross-correlation peak.

15. The medium of claim 13, wherein the phase shift, time shift or power shift are calculated in real time.

16. The medium of claim 13 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to determine one or more navigation data elements for each of the GNSS antennas based on the plurality of baseband signals.

17. The medium of claim 13 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to remove the pilot reference signal from each of the adjusted plurality of baseband signals prior to storing the baseband signals.

18. The medium of claim 13 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to generate the pilot reference signal, wherein the pilot reference signal is generated to avoid degradation of the baseband signals.

19. The medium of claim 13 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to store the adjusted plurality of baseband signals as a baseband IQ file.

20. The medium of claim 13 having stored thereon at least one further instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to output the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals which have been recorded at the controlled radiation pattern antenna element outputs from which the baseband signal has been formed for testing the controlled radiation pattern antenna system.

21. The medium of claim 13 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to: output the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals; receiving from a radio frequency receiver a calibration signal that combines each of the adjusted baseband signals and associated reference signals; calculating one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals; and outputting a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the calculated phase offset, time offset, or power offset for each of the simulated GNSS signals or for each of the simulated interference signals.

22. The medium of claim 21 having stored thereon at least one additional instruction comprising executable code for calculating the phase shift, the time shift or the power shift which, when executed by the one or more processors, causes the one or more processors to: determine a cross-correlation peak between the calibration signal and the at least one of the associated reference signals; and calculate the phase shift, the time shift or the power shift based on the determined cross-correlation peak.

23. The medium of claim 21, wherein the plurality of adjusted baseband signals are continuously output.

24. The medium of claim 21 having stored thereon at least one additional instruction comprising executable code which, when executed by the one or more processors, causes the one or more processors to output a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals for the plurality of radio frequency transmitters.

25. A GNSS recording and playback apparatus comprising: a memory comprising programmed instructions stored thereon and one or more processors configured to be capable of executing the stored programmed instructions to: receiving, from a plurality of radio frequency receivers, a plurality of baseband signals, each of the plurality of baseband signals being generated from a radio frequency signal of a GNSS antenna and a pilot reference signal, wherein the pilot reference signal is the same for each of the baseband signals; calculating one or more of a phase offset, a time offset, or a power offset for each of the baseband signals based on the pilot reference signal; and adjusting each of a plurality of baseband signals based on the calculated phase offset, time offset, or power offset for each of the baseband signals.

26. The apparatus of claim 25 having stored thereon at least one additional instruction comprising executable code which, when executed by one or more processors, causes the processors to: determine a cross-correlation peak between at least two of the plurality of baseband signals based on the pilot reference signal; and calculate the phase offset, time offset, or power offset based on the determined cross-correlation peak.

27. ​​The apparatus of claim 25, wherein the phase shift, time shift or power shift are calculated in real time.

28. The apparatus of claim 25 wherein there is stored at least one additional instruction comprising executable code which, when executed by one or more processors, causes the processors to determine one or more navigation data elements for each of the GNSS antennas based on the plurality of baseband signals.

29. Apparatus according to claim 25 having stored thereon at least one additional instruction comprising executable code which, when executed by one or more processors, causes the processors to remove the pilot reference signal from each of the adjusted plurality of baseband signals before storing the baseband signals.

30. Apparatus according to claim 25 having stored thereon at least one further instruction comprising executable code which, when executed by one or more processors, causes the processors to generate the pilot reference signal, in which the pilot reference signal is generated to avoid degradation of the baseband signals.

31. Apparatus according to claim 25 having stored thereon at least one further instruction comprising executable code which, when executed by one or more processors, causes the processors to store the adjusted plurality of baseband signals as a baseband IQ file.

32. Apparatus according to claim 25 having stored thereon at least one further instruction comprising executable code which, when executed by one or more processors, causes the processors to output the plurality of adjusted baseband signals to an input of a controlled radiation pattern antenna unit as signals which have been recorded at the controlled radiation pattern antenna element outputs from which the baseband signal has been formed for testing the controlled radiation pattern antenna system.

33. The apparatus of claim 25 having stored thereon at least one further instruction comprising executable code that, when executed by one or more processors, causes the processors to: output the plurality of adjusted baseband signals to a plurality of radio frequency transmitters, wherein each of the adjusted baseband signals includes thermal noise that provides a reference signal for each of the adjusted baseband signals; receive from a radio frequency receiver a calibration signal that combines each of the adjusted baseband signals and associated reference signals; calculate one or more of a phase offset, a time offset, or a power offset for each of the plurality of adjusted baseband signals based on the calibration signal and the associated reference signals for each of the plurality of baseband signals;and outputting a corrected plurality of adjusted baseband signals to the plurality of radio frequency transmitters based on the phase shift, time shift, or power shift calculated for each of the simulated GNSS signals or for each of the simulated interference signals.;

34. Apparatus according to claim 33 having stored thereon at least one further instruction comprising executable code which, when executed by one or more processors, causes the processors to: determine a cross-correlation peak between the calibration signal and the at least one of the associated reference signals; and calculate the phase shift, time shift or power shift based on the determined cross-correlation peak.

35. The apparatus of claim 33, wherein the plurality of adjusted baseband signals are continuously output.

36. Apparatus according to claim 33 having stored thereon at least one further instruction comprising executable code which, when executed by one or more processors, causes the processors to output a plurality of pairs of simulated interference signals associated with the plurality of adjusted baseband signals for the plurality of radio frequency transmitters.

Images