CN117269998A - GNSS receiver and noise estimation method - Google Patents
GNSS receiver and noise estimation method Download PDFInfo
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
- G01S19/37—Hardware or software details of the signal processing chain
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- General Physics & Mathematics (AREA)
- Signal Processing (AREA)
- Noise Elimination (AREA)
Abstract
The application discloses a GNSS receiver. The system comprises a tracking channel module and a noise estimation module. The noise estimation module comprises a configuration memory configured to store at least a number of signals and a type of signals corresponding to the number and type of digital baseband signals in the buffered data, a carrier frequency control word, a pseudocode frequency control word, and a pseudocode control word corresponding to the digital baseband signals; and the time division multiplexing control sub-module receives the noise estimation instruction, acquires digital baseband signals of the buffer data from the data buffer unit in sequence, acquires the number of signals and the signal types corresponding to the digital baseband signals from the configuration memory, and provides the number of signals and the signal types for the subsequent module for noise estimation. The application also includes a noise estimation method. According to the technical scheme, the hardware circuit adopts a time division multiplexing mode, so that the GNSS receiver can realize noise estimation of the satellite signals of the whole system and the whole frequency point, the effective utilization rate of hardware resources is improved, and the accuracy of noise estimation is improved.
Description
Technical Field
The present disclosure relates to the field of satellite navigation technologies, and in particular, to a GNSS receiver and a noise estimation method.
Background
The global navigation satellite system (Global Navigation Satellite System, GNSS) can provide high-precision positioning, navigation and timing services for users on the earth's surface and in the near-earth space, and is widely used in the fields of automobile steering, aerospace, communication, measurement and the like. Each satellite navigation system has a plurality of frequency points, and the satellite broadcasts satellite signals to the ground continuously and uninterruptedly all day long.
In the field of satellite navigation technology, GNSS receivers are an important component of GNSS technology, responsible for receiving signals from satellites and calculating the position and time of a user. After receiving signals sent by satellites, a GNSS receiver needs to acquire and track satellite signals. During tracking, the quality of the satellite signal is evaluated. Signal quality is typically measured in terms of signal-to-noise ratio (SNR), which is defined as the ratio between signal power Pr and noise power N, i.e., SNR = Pr/N. The signal-to-noise ratio SNR is typically expressed in decibels. The higher the signal-to-noise ratio, the better the quality of the received signal. The acquisition and tracking performance of a GNSS receiver on satellite signals has a direct correlation with the signal-to-noise ratio. A stable and reliable calculation of the signal-to-noise ratio of the individual channels is necessary for each receiver.
In order to realize noise estimation, a signal tracking channel and a noise estimation channel are allocated to each frequency point of a traditional GNSS receiver, and the ratio of the signal power calculated by the signal tracking channel to the noise power obtained by the noise estimation channel is used as the signal to noise ratio of the frequency point signal.
With the increase of navigation systems, the frequency and the signal type of satellite signals sent by each navigation system are continuously increased, and the number of noise estimation channels required by the GNSS receiver of the whole system with the full frequency point is also increased. This number becomes even greater if the dual antenna reception scheme is reused. This is a significant waste of resources and costs to the receiver, both in terms of software and hardware.
Disclosure of Invention
Aiming at the problems in the prior art, the application provides a GNSS receiver, which comprises a data caching unit, a data processing unit and a data processing unit, wherein the data caching unit is configured to receive a plurality of digital baseband signals and store and generate corresponding cache data according to a fixed sequence, and one path of cache data comprises one or more digital baseband signals; a tracking and noise estimation unit coupled to the data buffer unit and configured to receive the buffered data, track a digital baseband signal in the buffered data, and calculate a noise power of the digital baseband signal; the tracking and noise estimation unit comprises a tracking channel module, a plurality of signal tracking channels and a signal processing unit, wherein the tracking channel module comprises a plurality of signal tracking channels and is configured to track the digital baseband signals and convert the digital baseband signals into navigation signals; each signal tracking channel tracks one of the digital baseband signals; and a noise estimation module coupled to the data buffer unit; the noise estimation module comprises a configuration memory, wherein the configuration memory is configured to store at least the number and the signal type of signals corresponding to the number and the type of digital baseband signals in the cache data, and carrier frequency control words, pseudo code frequency control words and pseudo code control words corresponding to the digital baseband signals; the time division multiplexing control submodule is respectively coupled with the data caching unit and the configuration memory; the time division multiplexing control sub-module receives the noise estimation instruction, acquires digital baseband signals of the buffer data from the data buffer unit in sequence, acquires the number and the signal types of signals corresponding to the digital baseband signals from the configuration memory, and provides the signals to a subsequent module for noise estimation.
In particular, the receiver, wherein the pseudo-code control words comprise standard pseudo-code control words and non-standard pseudo-code control words.
In particular, the receiver further includes a carrier mixing sub-module, where the carrier mixing sub-module is coupled to the time division multiplexing control sub-module and the configuration memory, respectively; the carrier frequency mixing submodule is configured to receive the digital baseband signals transmitted by the time division multiplexing control submodule and the carrier frequency control words output by the configuration memory, and mix the digital baseband signals with the local carrier generated according to the carrier frequency control words.
In particular, the receiver, wherein the noise estimation module includes a pseudo-code correlation sub-module coupled to the carrier mixing sub-module and the configuration memory, respectively; the pseudo code correlation submodule is configured to receive the pseudo code frequency control word and the standard pseudo code control word output by the configuration memory to generate a standard pseudo code sequence, and perform correlation operation on the received output of the carrier frequency mixing submodule and the standard pseudo code sequence to output a plurality of correlation values of the digital baseband signal; the pseudo code correlation submodule comprises a pseudo code numerical control oscillator and is configured to receive a pseudo code frequency control word output by the configuration memory and generate a corresponding digital frequency signal; and the pseudo code generator is configured to receive the standard pseudo code control word output by the configuration memory and the digital frequency signal output by the pseudo code numerical control oscillator, and generate the standard pseudo code sequence.
In particular, the receiver, wherein the noise estimation module includes the pseudo-code correlation sub-module, the pseudo-code correlation sub-module being coupled to the carrier mixing sub-module and the configuration memory, respectively; the pseudo code correlation submodule is configured to receive a pseudo code frequency control word and a non-standard pseudo code control word output by the configuration memory to generate a non-standard pseudo code sequence, and perform correlation operation on the received output of the carrier frequency mixing submodule and the non-standard pseudo code sequence to output a plurality of correlation values of the digital baseband signal; the pseudo code correlation submodule comprises the pseudo code numerical control oscillator and is configured to receive the pseudo code frequency control word and generate a corresponding digital frequency signal; the code buffer is configured to receive the nonstandard pseudo code control word output by the configuration memory and output a binary sequence; and the non-standard pseudo code generation interface is configured to receive the digital frequency signal output by the pseudo code numerical control oscillator and the binary sequence output by the code buffer memory, and generate the non-standard pseudo code sequence.
In particular, the receiver, wherein the pseudo-code correlation sub-module further comprises a pseudo-code selector coupled to the pseudo-code generator, the non-standard pseudo-code generation interface, and the configuration memory, respectively; the pseudo code selector receives the signal type output by the configuration memory, and selects the standard pseudo code sequence or the nonstandard pseudo code sequence to output based on the signal type; and the first correlator and the second correlator are respectively coupled with the pseudo code selector and the carrier frequency mixing submodule and are configured to perform correlation operation on the received output of the carrier frequency mixing submodule and the received pseudo code sequence output by the pseudo code selector so as to obtain a plurality of correlation values of the digital baseband signal.
In particular, the receiver further comprises an integration operator module coupled to the pseudo-code correlation sub-module for receiving a plurality of correlation values of the digital baseband signal output by the pseudo-code correlation sub-module; the integration operation sub-module is configured to receive the correlation values and calculate the correlation values to obtain the noise power of the digital baseband signal.
In particular, the receiver may further comprise a GNSS receiver processor configured to output the noise estimation command at a set time interval.
The application also provides a noise estimation method, which comprises the steps of receiving a plurality of digital baseband signals, and storing the digital baseband signals according to a fixed sequence to generate corresponding cache data, wherein one path of cache data comprises one or a plurality of digital baseband signals; under the control of a noise estimation instruction, acquiring the number and the type of signals corresponding to the number and the type of the digital baseband signals of the cache data; acquiring a digital baseband signal in the cache data; acquiring a carrier frequency control word, a pseudo code frequency control word and a pseudo code control word corresponding to the digital baseband signal according to a signal type corresponding to the type of the digital baseband signal; generating a local carrier according to the carrier frequency control word, and mixing and outputting the digital baseband signal by utilizing the local carrier; generating a pseudo code sequence according to the pseudo code frequency control word and the pseudo code control word, and performing correlation operation by utilizing the pseudo code sequence and the mixed output to obtain a plurality of correlation values of the digital baseband signal; the noise power of the digital baseband signal is calculated and stored.
In particular, the method includes that the pseudo code control word includes a standard pseudo code control word and a non-standard pseudo code control word, when the digital baseband signal adopts a standard pseudo code, the standard pseudo code control word and a pseudo code frequency control word are obtained, and the standard pseudo code sequence is generated according to the standard pseudo code control word and the pseudo code frequency control word; or when the digital baseband signal adopts non-standard pseudo code, acquiring the non-standard pseudo code control word and the pseudo code frequency control word, and generating the non-standard pseudo code sequence according to the non-standard pseudo code control word and the pseudo code frequency control word.
Particularly, the method further comprises the steps of judging whether all the digital baseband signals in the cache data are processed, and acquiring the next digital baseband signal when all the digital baseband signals in the cache data are not processed; and when all the digital baseband signals in the cache data are processed, acquiring the next cache data.
Particularly, the method further comprises the steps of judging whether all the processing of the cache data is completed, and acquiring the next cache data when all the processing of the cache data is not completed; otherwise the noise estimation operation ends.
Drawings
Preferred embodiments of the present application will be described in further detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a schematic diagram illustrating a GNSS receiver according to one embodiment of the present application;
FIG. 2 is a schematic diagram illustrating a structure of a noise estimation module according to one embodiment of the present application;
fig. 3 is a flow chart illustrating a noise estimation method according to one embodiment of the present application.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the application may be practiced. In the drawings, like reference numerals describe substantially similar components throughout the different views. Various specific embodiments of the present application are described in sufficient detail below to enable those skilled in the art to practice the teachings of the present application. It is to be understood that other embodiments may be utilized or structural, logical, or electrical changes may be made to the embodiments of the present application.
Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. For the purpose of illustration only, the connection between elements in the figures is meant to indicate that at least the elements at both ends of the connection are in communication with each other and is not intended to limit the inability to communicate between elements that are not connected. In addition, the number of lines between two units is intended to indicate at least the number of signals involved in communication between the two units or at least the output terminals provided, and is not intended to limit the communication between the two units to only signals as shown in the figures.
The application provides a GNSS receiver, the hardware circuit of the GNSS receiver realizes the noise estimation of the satellite signals of the whole system and the whole frequency point in a time division multiplexing mode, and improves the accuracy of the noise estimation while improving the effective utilization rate of hardware resources.
Fig. 1 is a schematic diagram of a GNSS receiver according to an embodiment of the present application.
According to one embodiment, the GNSS receiver 1 comprises an antenna 11, a radio frequency front-end processing unit 12, an intermediate frequency data interface unit 13 and a digital front-end processing unit 14, a data buffering unit 15, a tracking and noise estimation unit 16, an observational amount extraction unit 17, a resolving unit 18, which are coupled in series with each other.
According to one embodiment, the antenna 11 is configured to receive satellite signals.
According to one embodiment, the rf front-end processing unit 12 is configured to receive the satellite signal transmitted by the antenna 11, and convert the satellite signal to an intermediate frequency signal for output after processing by a pre-filter, an amplifier, analog down-conversion, a/D sampling, and the like.
According to one embodiment, the intermediate frequency data interface unit 13 and the digital front-end processing unit 14 perform down-conversion, down-sampling, quantization processing on the intermediate frequency signal, and convert the intermediate frequency signal into a digital baseband signal.
According to one embodiment, the data buffer unit 15 is configured to receive and store digital baseband signals output by the digital front end processing unit 14, which correspond to satellite signals of a full system and full frequency point received by the GNSS receiver. In one embodiment, for the digital baseband signals output by the digital front-end processing unit 14, the data buffer unit 15 stores a plurality of different digital baseband signals with similar frequency points as one path of buffer data in a fixed order. The data buffer unit 15 sequentially stores a plurality of buffer data. Each path of cache data corresponds to a central frequency. In one embodiment, one or more digital baseband signals are included in a way of buffered data.
As shown in table 1, each DFE represents a path of buffered data, and each DFE includes a plurality of different digital baseband signals. Each DFE corresponds to a center frequency. A plurality of different digital baseband signals are stored in a fixed sequence in one path of cache data, and each digital baseband signal can adopt different carrier waves, pseudo codes and the like.
TABLE 1
| Caching data | Center frequency | Bandwidth of a communication device | Comprising signals |
| DFE0 | 1575.42MHz | 25MHz | L1CA\B1C\B1I\E1\G1\QZL1CA |
| DFE1 | 1176.45MHz | 25MHz | L5\B2a\E5a\IRNSSL5\QZL5 |
| DFE2 | 1207.14MHz | 25MHz | B2I\B2b\E5b\L2\QZL2 |
| DFE3 | 1268.52MHz | 25MHz | B3I\E6\QZL6 |
According to one embodiment, the storage order of the buffered data in the data buffer unit 15 and the storage order of the digital baseband signals in the buffered data are controlled by a GNSS receiver processor (not shown).
According to one embodiment, the GNSS receiver 1 may further comprise a tracking and noise estimation unit 16. The tracking and noise estimating unit 16 is configured to receive the multiple paths of buffered data output by the data storage module 15, track each digital baseband signal in each path of buffered data, and estimate the noise power of the digital baseband signal, thereby estimating the quality of the satellite signal.
According to one embodiment of the present application, the tracking and noise estimation unit 16 comprises a tracking channel module 161. The trace channel module 161 is coupled to the data buffer unit 15 and configured to receive the buffered data and trace the digital baseband signal to convert the digital baseband signal to a navigation signal. In one embodiment, the tracking channel module 161 includes a plurality of signal tracking channels, each tracking a digital baseband signal.
According to one embodiment of the present application, the tracking and noise estimation unit 16 includes a noise estimation module 162. The noise estimation module 162 is coupled to the data buffer unit 15 and configured to obtain the buffered data stored in the data buffer unit 15 and estimate, for example, the noise power of the digital baseband signal in each path of buffered data under the control of the noise estimation instruction output by the GNSS receiver processor.
According to an embodiment of the present application, the GNSS receiver processor outputs the noise estimation command at a set time interval, and the value of the time interval may be configured according to the actual situation, for example, may be set to 2ms, 5ms, 10ms, and so on. In one embodiment, when the noise estimation module 162 receives the noise estimation instruction, the noise estimation module 162 acquires the buffered data one by one in the order in which the buffered data is stored in the data buffering unit 15.
According to an embodiment, the GNSS receiver 1 may further comprise an observation amount extraction unit 17 configured to intercept the navigation signals to obtain navigation messages and observations.
According to an embodiment, the GNSS receiver 1 may further comprise a resolving unit 18 configured to receive the navigation messages and the observations and to perform a positioning resolving with the plurality of navigation data.
Fig. 2 is a schematic diagram of a noise estimation module according to an embodiment of the present application.
According to one embodiment, noise estimation module 262 includes configuration memory 2621. The configuration memory 2621 is configured to store at least the number of signals and the type of signals corresponding to the number and the type of digital baseband signals in the buffered data, and carrier frequency control words, pseudo code frequency control words, and pseudo code control words corresponding to the type of digital baseband signals. In one embodiment, the digital baseband signals that the GNSS receiver is capable of processing correspond to satellite signals at all system-wide and all frequency points, and a plurality of carrier frequency control words, pseudocode frequency control words, and pseudocode control words corresponding to the type of digital baseband signals are stored in configuration memory 2621. The signal configuration memory allocates a corresponding memory address for each of the carrier frequency control word, the pseudocode frequency control word, and the pseudocode control word.
According to one embodiment, the number of signals and the type of signals stored in configuration memory 2621 may be configured by the interactive functions provided by the user through the receiver.
In one embodiment, the pseudo code employed by the digital baseband signal includes standard pseudo code and non-standard pseudo code. The standard pseudo codes comprise standard pseudo codes such as common gold codes and the like; the non-standard pseudo code comprises a special type of pseudo code such as BOC. According to one embodiment, the pseudocode control words stored in configuration memory 2621 include standard pseudocode control words corresponding to standard pseudocode or non-standard pseudocode control words corresponding to non-standard pseudocode. The standard pseudocode control word includes a pseudocode initial phase and a polynomial.
According to one embodiment, noise estimation module 262 includes a time division multiplexing control submodule 2623. The time division multiplexing control sub-module 2623 is coupled to the digital buffer unit 25 and the configuration memory 2621, respectively. The time division multiplexing control sub-module 2623 is configured to receive the noise estimation instruction, sequentially acquire digital baseband signals of the buffered data in the data buffer unit 25, and transmit the digital baseband signals to the subsequent modules.
According to one embodiment, under the control of the noise estimation instruction, the time division multiplexing control sub-module 2623 sequentially acquires the number of signals and the type of signals corresponding to the number and the type of digital baseband signals of the buffered data from the configuration memory 2621.
According to one embodiment, the time division multiplexing control submodule 2623 transmits a control instruction to the configuration memory 2621 based on the type of signal acquired from the configuration memory 2621, and the configuration memory 2621 outputs a carrier frequency control word, a pseudo code control word corresponding to the type of the digital baseband signal under the control of the control instruction.
According to one embodiment, the number of digital baseband signals of the buffered data acquired from the data buffer unit 25 by the time division multiplexing control submodule 2623 corresponds to the number of signals acquired from the configuration memory 2621.
According to one embodiment, the time division multiplexing control submodule 2623 may be a circuit capable of both transmitting different signals in different time segments of the same link and implementing control functions.
According to one embodiment, noise estimation module 262 may also include a carrier mixing sub-module 2625. The carrier mixing sub-module 2625 is coupled to the time division multiplexing control sub-module 2623 and the configuration memory 2621, respectively. The carrier mixing sub-module 2625 receives the digital baseband signal transmitted by the time division multiplexing control sub-module 2623 and the carrier frequency control word output by the configuration memory 2621. The carrier mixing sub-module 2625 mixes the received digital baseband signal with the local carrier signal to effect down-conversion of the digital baseband signal to, for example, a zero intermediate frequency signal, in accordance with the received carrier frequency control word to generate the local carrier.
According to one embodiment, the configuration memory 2621 receives the control instruction output by the time division multiplexing control submodule 2623 and outputs a carrier frequency control word corresponding to the type of the digital baseband signal to the carrier mixing submodule 2625 under the control of the control instruction.
According to one embodiment, carrier mixing submodule 2625 includes a carrier numerically controlled oscillator 2625, and sine table 26252 and cosine table 26253. The carrier numerically controlled oscillator 26151, and the sine and cosine tables 26252 and 26253 are configured to generate a digital sine local carrier and a digital cosine local carrier orthogonal to each other based on the acquired carrier frequency control word. The digital sine local carrier and the digital cosine local carrier are collectively referred to as a local carrier.
According to one embodiment, carrier mixing submodule 2625 includes a mixer 2654 and a mixer 26255. Mixer 2654 is coupled to sine table 26252; mixer 26255 is coupled to cosine table 26253, while mixer 2654 and mixer 26255 are coupled to time division multiplexing control submodule 2623, respectively. Mixer 2654 and mixer 26255 are configured to mix the received digital baseband signal with the digital sine local carrier signal and the digital cosine local carrier signal, respectively, down-convert the received digital baseband signal to I-branch and Q-branch zero intermediate frequency signals and output. The I and Q branch zero intermediate frequency signals are collectively referred to as zero intermediate frequency signals.
According to one embodiment, noise estimation module 262 also includes a pseudocode correlation submodule 2627. The pseudo code correlation sub-module 2627 is coupled to the carrier mixing sub-module 2625 and the configuration memory 2621, respectively, receives the pseudo code frequency control word, the pseudo code control word and the signal type corresponding to the type of the digital baseband signal output by the configuration memory 2621, and receives the zero intermediate frequency signal output by the carrier mixing sub-module 2625. The pseudo-code correlation sub-module 2627 is configured to perform pseudo-code correlation on the zero intermediate frequency signal, and output a corresponding correlation value.
According to one embodiment, the configuration memory 2621 outputs the pseudo code frequency control word and the pseudo code control word corresponding to the type of the digital baseband signal to the pseudo code correlation sub-module 2627 under the control of the control instruction output from the time division multiplexing control sub-module 2623. When the digital baseband signal adopts standard pseudo code, the pseudo code control word output by the configuration memory 2621 is the standard pseudo code control word; when the digital baseband signal adopts non-standard pseudo code, the pseudo code control word output by the configuration memory 2621 is a non-standard pseudo code control word.
According to one embodiment, the pseudocode correlation submodule 2627 includes a pseudocode numerical controlled oscillator 26271. The pseudocode numerically controlled oscillator 26271 is coupled to the configuration memory 2621 and configured to receive the pseudocode frequency control words output by the configuration memory 2621 to generate corresponding digital frequency signals.
In one embodiment of the present application, pseudocode correlation submodule 2627 further includes a pseudocode generator 26272. The pseudo code generator 26272 is coupled to the configuration memory 2621 and the pseudo code digital controlled oscillator 26271, respectively, and receives the pseudo code initial phases and polynomials in the standard pseudo code control words output from the configuration memory 2621 and the digital frequency signals output from the pseudo code digital controlled oscillator 2671. The pseudo-code generator 26272 is configured to generate a standard pseudo-code sequence based on receiving the standard pseudo-code control and the digital frequency signal.
In another embodiment, pseudocode correlation submodule 2627 further includes code buffer 26273. The code buffer 26273 is coupled to the configuration memory 2621 and configured to receive the non-standard pseudo-code control words output by the configuration memory 2621 and to generate a binary sequence based on the non-standard pseudo-code control words.
According to one embodiment of the present application, pseudocode correlation submodule 2627 further includes a non-standard pseudocode generation interface 2674. The nonstandard pseudocode generation interface 26274 is coupled to the pseudocode digital controlled oscillator 26271 and the code buffer 26273, respectively, and receives the digital frequency signal output by the pseudocode digital controlled oscillator 26271 and the binary sequence output by the code buffer 26273. The non-standard pseudocode generation interface 2674 is configured to generate a non-standard pseudocode sequence based on the received digital frequency signal and the binary sequence.
The pseudocode correlation submodule 2627 may also include a pseudocode selector 26275, according to one embodiment of the present application. The pseudocode selector 26275 is coupled to the pseudocode generator 26272, the non-standard pseudocode generation interface 26274, and the configuration memory 2621. The pseudocode selector 26275 receives the type of signal output by the configuration memory 2621, the standard pseudocode sequence output by the pseudocode generator 26272, or the nonstandard pseudocode sequence output by the nonstandard pseudocode generation interface 2674. The pseudo code selector 26275 is configured to select a standard pseudo code sequence or a non-standard pseudo code sequence corresponding to the digital baseband signal based on the signal type.
According to one embodiment, pseudocode correlation submodule 2627 further includes a correlator 26276 and a correlator 2677. The correlators 26276 and 2677 are coupled to the carrier mixing submodule 2625 and the pseudocode selector 26275, respectively. The correlators 26276 and 2677 receive the pseudo code sequences output by the pseudo code selector 26275 and the zero intermediate frequency signal output by the carrier mixing sub-module 2625. The correlators 26276 and 2677 are configured to correlate the received zero intermediate frequency signal with the received pseudo code sequence, outputting a plurality of correlation values for the digital baseband signal.
According to one embodiment, when the digital baseband signal processing is complete, the pseudocode correlation sub-module 2627 sends an integration clear instruction to the integration operator sub-module 2629.
In one embodiment, configuration memory 2621 receives control instructions output by time division multiplexing control submodule 2623, configuration memory 2621 outputs carrier frequency control words to carrier mixing submodule 2625, and configuration memory 2621 outputs pseudocode frequency control words and pseudocode control words to pseudocode correlation submodule 2627.
The noise estimation module realizes the noise estimation of the satellite signals of all frequency points of the whole system by setting the pseudo code frequency control word, the standard pseudo code control word and the nonstandard pseudo code control word in the configuration memory.
According to one embodiment, noise estimation module 262 also includes an integration operator module 2629. The integration operator module 2629 is coupled to the pseudo code correlation submodule 2627 and receives a plurality of correlation values of the digital baseband signal output by the pseudo code correlation submodule 2627 and an integration clean-up instruction. The integration operator module 2629 is configured to store the received correlation values and calculate a plurality of correlation values for the digital baseband signal under control of an integration purge instruction. The integration operator module 2629 outputs the calculation result as noise power of the digital baseband signal to the subsequent module.
According to one embodiment, noise estimation module 262 also includes noise power memory 2628. The noise power memory 2628 is coupled to the integration operator module 2629 and configured to receive and store the noise power output by the integration operator module 2629. When all buffered data processing is complete, the noise power memory 2628 sends a noise interrupt signal to the GNSS processor waiting for the GNSS processor to read.
In one embodiment of the present application, the tracking and noise estimation unit 16 includes only one noise estimation module.
Fig. 3 is a flow chart illustrating a noise estimation method according to one embodiment of the present application. According to one embodiment, the noise estimation method is performed by a GNSS receiver.
In step 1001, a plurality of digital baseband signals are received and stored in a fixed order to generate corresponding buffered data, where a path of buffered data includes one or more digital baseband signals.
At step 1002, a noise estimation instruction is received.
According to one embodiment, the noise estimation module receives noise estimation instructions transmitted by the GNSS receiver processor at set time intervals.
In step 1003, the number of signals and the type of signals corresponding to the number and the type of digital baseband signals of the buffered data are acquired.
In step 1004, the digital baseband signals in the buffered data are acquired in sequence.
According to one embodiment, digital baseband signals corresponding to the number of signals and the signal type are sequentially acquired from the buffered data.
In step 1006, a carrier frequency control word, a pseudo code control word, and a pseudo code frequency control word corresponding to the digital baseband signal are acquired according to the signal type corresponding to the type of the digital baseband signal.
In step 1007, a corresponding local carrier is generated from the carrier frequency control word, the digital baseband signal is mixed using the local carrier, and the digital baseband signal is down-converted to, for example, a zero intermediate frequency signal and output.
In step 1008, a pseudo code sequence is generated according to the pseudo code control word and the pseudo code frequency control word, and a plurality of correlation values of the digital baseband signal are obtained by performing correlation operation on the pseudo code sequence and the zero intermediate frequency signal.
According to one embodiment, when the pseudo code employed by the digital baseband signal is a standard pseudo code, a standard pseudo code control word and a pseudo code frequency control word are acquired, and a standard pseudo code sequence is generated using the standard pseudo code control word and the pseudo code frequency control word.
According to one embodiment, when the pseudo code employed by the digital baseband signal is non-standard pseudo code, non-standard pseudo code control words and pseudo code frequency control words are acquired, and a non-standard pseudo code sequence is generated by using the non-standard pseudo code control words and the pseudo code frequency control words.
In step 1012, the noise power of the digital baseband signal is calculated based on the plurality of correlation values of the digital baseband signal and stored.
In step 1013, it is determined whether all processing of the digital baseband signal in the buffered data is completed. If all processing of the digital baseband signal in the buffered data is complete, then step 1015 is performed; otherwise, acquire the next digital baseband signal, jump to step 1004.
In step 1015, it is determined whether all the buffered data is completely processed. If all processing of the buffered data in the data buffer unit is complete, then step 1016 is performed; otherwise, acquire the next path of cache data, and jump to step 1003.
In step 1016, the noise estimation operation is ended, and a noise interrupt signal is reported to the GNSS processor, waiting for the GNSS processor to read.
The tracking channel module of the GNSS receiver needs to track the digital baseband signal continuously and in real time, while the noise estimation module does not need to track the digital baseband signal continuously and in real time. Therefore, the noise estimation module can not calculate the noise power at the same time for different digital baseband signals; for the same digital baseband signal, the noise estimation module can discontinuously calculate the next noise power value after completing one noise power calculation, so that the load of the GNSS processor for responding to noise interruption is reduced.
According to the GNSS receiver, the hardware circuit adopts a time division multiplexing mode to realize noise power estimation of the satellite signals of all frequency points of the whole system, and the problem of resource waste is solved. Meanwhile, the signals participating in calculation are derived from actual digital baseband signals, so that the accuracy of calculation is further improved. In addition, the GNSS receiver is used for setting the calculation frequency, so that the calculation frequency is flexible and controllable.
The above embodiments are provided for illustrating the present application and are not intended to limit the present application, and various changes and modifications can be made by one skilled in the relevant art without departing from the scope of the present application, therefore, all equivalent technical solutions shall fall within the scope of the present disclosure.
Claims (12)
1. A GNSS receiver comprises a receiver, a receiver and a receiver,
the data caching unit is configured to receive a plurality of digital baseband signals and store and generate corresponding cache data according to a fixed sequence, wherein one path of the cache data comprises one or a plurality of digital baseband signals;
a tracking and noise estimation unit coupled to the data buffer unit and configured to receive the buffered data, track a digital baseband signal in the buffered data, and calculate a noise power of the digital baseband signal; wherein the tracking and noise estimation unit comprises
The tracking channel module comprises a plurality of signal tracking channels and is configured to track the digital baseband signals and convert the digital baseband signals into navigation signals; each signal tracking channel tracks one of the digital baseband signals; and
the noise estimation module is coupled with the data caching unit; wherein the noise estimation module comprises
A configuration memory configured to store at least a number of signals and a type of signals corresponding to a number and a type of digital baseband signals in the buffered data, and a carrier frequency control word, a pseudo code frequency control word, and a pseudo code control word corresponding to the digital baseband signals; and
the time division multiplexing control submodule is respectively coupled with the data caching unit and the configuration memory; the time division multiplexing control sub-module receives a noise estimation instruction, acquires digital baseband signals of the buffer data from the data buffer unit in sequence, acquires the number and the signal types of signals corresponding to the digital baseband signals from the configuration memory, and provides the number and the signal types of the signals to a subsequent module for noise estimation.
2. The receiver of claim 1, wherein the pseudocode control word comprises a standard pseudocode control word or a non-standard pseudocode control word.
3. The receiver of claim 2, wherein the noise estimation module further comprises a carrier mixing sub-module coupled with the time division multiplexing control sub-module and the configuration memory, respectively;
the carrier frequency mixing submodule is configured to receive the digital baseband signals transmitted by the time division multiplexing control submodule and the carrier frequency control words output by the configuration memory, and mix the received digital baseband signals with the local carrier generated according to the carrier frequency control words.
4. The receiver of claim 3, wherein the noise estimation module comprises a pseudocode correlation sub-module coupled with the carrier mixing sub-module and the configuration memory, respectively;
the pseudo code correlation submodule is configured to receive the pseudo code frequency control word and the standard pseudo code control word output by the configuration memory to generate a standard pseudo code sequence, and perform correlation operation on the received output of the carrier frequency mixing submodule and the standard pseudo code sequence to output a plurality of correlation values of the digital baseband signal; wherein the pseudo code correlation sub-module comprises
The pseudo code numerical control oscillator is configured to receive the pseudo code frequency control word output by the configuration memory and generate a corresponding digital frequency signal;
and the pseudo code generator is configured to receive the standard pseudo code control word output by the configuration memory and the digital frequency signal output by the pseudo code numerical control oscillator, and generate the standard pseudo code sequence.
5. The receiver of claim 3, wherein the noise estimation module comprises the pseudocode correlation sub-module coupled with the carrier mixing sub-module and the configuration memory, respectively;
the pseudo code correlation submodule is configured to receive a pseudo code frequency control word and a non-standard pseudo code control word output by the configuration memory to generate a non-standard pseudo code sequence, and perform correlation operation on the received output of the carrier frequency mixing submodule and the non-standard pseudo code sequence to output a plurality of correlation values of the digital baseband signal; wherein the pseudo code correlation sub-module comprises
The pseudo code numerical control oscillator is configured to receive the pseudo code frequency control word output by the configuration memory and generate a corresponding digital frequency signal;
the code buffer is configured to receive the nonstandard pseudo code control word output by the configuration memory and output a binary sequence; and
the non-standard pseudo code generation interface is configured to receive the digital frequency signal output by the pseudo code numerical control oscillator and the binary sequence output by the code buffer memory, and generate the non-standard pseudo code sequence.
6. The receiver of any of claims 4 or 5, wherein the pseudocode correlation sub-module further comprises a pseudocode selector coupled with the pseudocode generator, the non-standard pseudocode generation interface, and the configuration memory, respectively; the pseudo code selector receives the signal type output by the configuration memory, and selects the standard pseudo code sequence or the nonstandard pseudo code sequence to output based on the signal type; and
and the first correlator and the second correlator are respectively coupled with the pseudo code selector and the carrier frequency mixing submodule and are configured to perform correlation operation on the received output of the carrier frequency mixing submodule and the received pseudo code sequence output by the pseudo code selector so as to obtain a plurality of correlation values of the digital baseband signal.
7. The receiver of claim 6, further comprising an integration operator module coupled to the pseudo-code correlation sub-module that receives a plurality of correlation values of the digital baseband signal output by the pseudo-code correlation sub-module; the integration operation sub-module is configured to receive the correlation values and calculate the correlation values to obtain the noise power of the digital baseband signal.
8. The receiver of claim 1, wherein the GNSS receiver processor outputs the noise estimation instructions at set time intervals.
9. A noise estimation method includes
Receiving a plurality of digital baseband signals, and storing the digital baseband signals according to a fixed sequence to generate corresponding cache data, wherein one path of cache data comprises one or more digital baseband signals;
under the control of a noise estimation instruction, acquiring the number and the type of signals corresponding to the number and the type of the digital baseband signals of the cache data;
acquiring a digital baseband signal in the cache data;
acquiring a carrier frequency control word, a pseudo code frequency control word and a pseudo code control word corresponding to the digital baseband signal according to a signal type corresponding to the type of the digital baseband signal;
generating a local carrier according to the carrier frequency control word, and mixing and outputting the digital baseband signal by utilizing the local carrier;
generating a pseudo code sequence according to the pseudo code frequency control word and the pseudo code control word, and performing correlation operation by utilizing the pseudo code sequence and the mixed output to obtain a plurality of correlation values of the digital baseband signal; the noise power of the digital baseband signal is calculated and stored.
10. The method of claim 9, wherein the pseudocode control words comprise standard pseudocode control words and non-standard pseudocode control words,
when the digital baseband signal adopts standard pseudo codes, acquiring the standard pseudo code control words and the pseudo code frequency control words, and generating the standard pseudo code sequence according to the standard pseudo code control words and the pseudo code frequency control words; or when the digital baseband signal adopts non-standard pseudo code, acquiring the non-standard pseudo code control word and the pseudo code frequency control word, and generating the non-standard pseudo code sequence according to the non-standard pseudo code control word and the pseudo code frequency control word.
11. The method of claim 9 or 10, further comprising determining whether all processing of the digital baseband signal in the buffered data is complete,
when all the digital baseband signals in the cache data are not processed, acquiring the next digital baseband signal;
and when all the digital baseband signals in the cache data are processed, acquiring the next cache data.
12. The method of claim 11, further comprising determining whether all processing of the buffered data is complete, and when all processing of the buffered data is not complete, obtaining a next buffered data; otherwise the noise estimation operation ends.
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