CN110346818B - Method and device for inhibiting cross correlation in GNSS signal capture - Google Patents
Method and device for inhibiting cross correlation in GNSS signal capture Download PDFInfo
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- CN110346818B CN110346818B CN201910375215.4A CN201910375215A CN110346818B CN 110346818 B CN110346818 B CN 110346818B CN 201910375215 A CN201910375215 A CN 201910375215A CN 110346818 B CN110346818 B CN 110346818B
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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
- G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
Abstract
A method of suppressing cross-correlation in GNSS signal acquisition, comprising: performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result; calculating SNR and peak ratio of the two-dimensional integration result; and determining whether the satellite signal is acquired according to the comparison result of the SNR and the SNR threshold value and the comparison result of the peak ratio and the peak ratio threshold value. The method and the device can reduce cross-correlation influence in GNSS signal acquisition.
Description
Technical Field
The present disclosure relates to the field of communications technologies, and in particular, to a method and an apparatus for suppressing cross-correlation in Global Navigation Satellite System (GNSS) signal acquisition.
Background
A Global Navigation Satellite System (GNSS) is a Satellite System having a plurality of satellites that transmit signals containing space-time information to a terrestrial receiver, which uses the information to perform positioning. Currently, GNSS includes Galileo system of european union, GPS system of usa, GLONSS system of russia, and beidou system of china. Different navigation satellite systems may transmit different types of signals.
In a Code Division Multiple Access (CDMA) based GNSS, a cross-correlation phenomenon exists between ranging codes of different satellites. When multiple satellites are acquired with co-existing strong and weak signals, cross-correlation from strong signals may result in false alarms for weak signal acquisition and failure to acquire weak signals.
Disclosure of Invention
The application provides a method and a device for inhibiting cross correlation in GNSS signal capture, which can reduce cross correlation influence in the GNSS signal capture.
In one aspect, the present application provides a method for suppressing cross-correlation in GNSS signal acquisition, including: performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result; calculating a signal-to-noise ratio (SNR) and a peak ratio of the two-dimensional integration result; and determining whether the satellite signal is acquired according to the comparison result of the SNR and the SNR threshold value and the comparison result of the peak ratio and the peak ratio threshold value.
In another aspect, the present application provides an apparatus for suppressing cross-correlation in GNSS signal acquisition, including: the first calculation module is suitable for performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result; a second calculation module adapted to calculate the SNR and peak ratio of the two-dimensional integration result; an acquisition determination module adapted to determine whether a satellite signal is acquired based on the comparison of the SNR to an SNR threshold and the comparison of the peak ratio to a peak ratio threshold.
In another aspect, the present application provides a receiver comprising: a receiving antenna adapted to receive satellite signals, a memory adapted to store a computer program which, when executed by the processor, carries out the steps of the above-mentioned method, and a processor.
In another aspect, the present application provides a computer readable storage medium storing a computer program which, when executed, implements the steps of the above method.
In the method, a two-dimensional integration result is obtained by performing correlation calculation between a locally generated ranging code and a received signal; calculating the Signal-to-Noise Ratio (SNR) and the peak Ratio of the two-dimensional integration result; and determining whether the satellite signal is acquired according to the comparison result of the SNR and the SNR threshold and the comparison result of the peak ratio and the peak ratio threshold. By adopting two judgment conditions (namely SNR is compared with an SNR threshold value, and a peak ratio is compared with a peak ratio threshold value) to determine whether the satellite signals are captured, the false alarm caused by cross correlation in GNSS signal capture can be reduced.
In an exemplary embodiment, when the received signal strength is greater than or equal to a first threshold, determining whether a satellite signal is acquired according to a two-dimensional integration result in a first format; when the satellite signal with the signal intensity smaller than the first threshold value is searched, whether the satellite signal is acquired is determined according to the two-dimensional integration result of the second format. The embodiment determines whether to acquire the satellite signal with corresponding signal strength based on the two-dimensional integration results in the two formats, so that the detection rate of the signal can be improved.
Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. Other advantages of the application may be realized and attained by the instrumentalities and combinations particularly pointed out in the specification, claims, and drawings.
Drawings
The accompanying drawings are included to provide an understanding of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the examples serve to explain the principles of the disclosure and not to limit the disclosure.
FIG. 1 is a block diagram of a GNSS receiver;
FIG. 2 is a flowchart illustrating a method for cross-correlation suppression in GNSS signal acquisition according to an embodiment of the present disclosure;
FIG. 3 is a diagram of a two-dimensional integration result in a first format according to an embodiment of the present disclosure;
FIG. 4 is a diagram of a two-dimensional integration result in a second format provided by an embodiment of the present application;
FIG. 5 is a diagram illustrating an example of an application provided by an embodiment of the present application;
FIG. 6 is a schematic diagram of an apparatus for suppressing cross-correlation in GNSS signal acquisition according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of a receiver according to an embodiment of the present application.
Detailed Description
The present application describes embodiments, but the description is illustrative rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are possible. Any feature or element of any embodiment may be used in combination with or instead of any other feature or element in any other embodiment, unless expressly limited otherwise.
The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in this application may also be combined with any conventional features or elements to form a unique inventive concept as defined by the claims. Any feature or element of any embodiment may also be combined with features or elements from other inventive aspects to form yet another unique inventive aspect, as defined by the claims. Thus, it should be understood that any of the features shown and/or discussed in this application may be implemented alone or in any suitable combination. Accordingly, the embodiments are not limited except as by the appended claims and their equivalents. Furthermore, various modifications and changes may be made within the scope of the appended claims.
Further, in describing representative embodiments, the specification may have presented the method and/or process as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. Other orders of steps are possible as will be understood by those of ordinary skill in the art. Therefore, the particular order of the steps set forth in the specification should not be construed as limitations on the claims. Further, the claims directed to the method and/or process should not be limited to the performance of their steps in the order written, and one skilled in the art can readily appreciate that the sequences may be varied and still remain within the spirit and scope of the embodiments of the present application.
FIG. 1 is a block diagram of a GNSS receiver. As shown in fig. 1, the GNSS receiver may receive signals through an antenna, and the received signals enter a baseband signal processing process after being processed by the rf front end and the digital front end. Wherein the acquisition of the signal is a first step of baseband signal processing, performed by an acquisition engine, for detecting whether the received signal is a signal from a certain GNSS satellite; the acquisition of the signal is followed by signal tracking, bit synchronization and PVT (Position vector and Time) calculation.
The embodiments of the present application provide a method and an apparatus for suppressing cross-correlation in GNSS signal acquisition, which may be applied to an acquisition engine of a GNSS receiver, for example, may be used to acquire a weak satellite signal coexisting with a strong satellite signal.
Fig. 2 is a flowchart of a method for suppressing cross-correlation in GNSS signal acquisition according to an embodiment of the present application. As shown in fig. 2, the method provided by the present embodiment includes the following processes:
s101, performing correlation calculation between a locally generated ranging code and a received signal to obtain a two-dimensional integration result;
s102, calculating SNR and peak ratio of a two-dimensional integration result;
s103, determining whether the satellite signal is acquired according to the comparison result of the SNR and the SNR threshold value and the comparison result of the peak ratio and the peak ratio threshold value.
Wherein, the two-dimensional integration result may include the following two dimensions: code phase, doppler frequency domain. The code phase dimension can be represented by a phase index, the doppler frequency domain dimension can be represented by a doppler frequency band index, and each frequency point indicates a basic unit of the doppler frequency domain search range, that is, one frequency point corresponds to one doppler search unit.
In an exemplary embodiment, the SNR of the two-dimensional integration result may be defined as the maximum peak divided by the noise, and the peak ratio may be defined as the maximum peak divided by the maximum side peak. Wherein the maximum peak value may be a maximum value in the two-dimensional integration result, and the maximum side peak value may be a maximum value except for the maximum peak value and a neighbor of the maximum peak value in the two-dimensional integration result. The neighbors of the maximum peak may include the neighbor of the maximum peak in the code phase dimension, the neighbor of the maximum peak in the doppler frequency domain dimension.
In an exemplary embodiment, S103 may include: when the SNR of the two-dimensional integration result is greater than an SNR threshold value and the peak ratio of the two-dimensional integration result is greater than a peak ratio threshold value, determining that the satellite signal is captured; and when the SNR of the two-dimensional integration result is less than or equal to an SNR threshold value, or the peak ratio of the two-dimensional integration result is less than or equal to a peak ratio threshold value, determining that the satellite signal is not acquired.
In this embodiment, by using dual thresholds (i.e., SNR threshold and peak ratio threshold) to determine whether to capture satellite signals, signal detection false alarm caused by cross-correlation in GNSS signal capture can be mitigated. For example, when detecting a weak signal in the presence of a strong signal, the largest peak found in the two-dimensional integration result may be a peak caused by the cross-correlation of the strong signal, rather than the actual weak signal. If the SNR calculated at this time is greater than the SNR threshold, the decision of successful acquisition will become a false alarm in case of only one determination condition. Wherein the maximum side peak value will remain a relatively large value when the maximum peak value is a false alarm caused by cross-correlation, in which case the peak value is small and cannot exceed the peak ratio threshold, i.e. the peak ratio is smaller than the peak ratio threshold. Therefore, the double detection thresholds are used for capturing and judging, and false alarms caused by cross-correlation can be reduced.
In an exemplary embodiment, the setting of the SNR threshold may beDepending on which non-coherent integration is used. For example, a sum of squares approach may be used, i.e. taking the sum of the squares of the in-phase and quadrature components after coherent integration calculations. The noise normalized non-coherent integration cumulative sum can be expressed as
Wherein, IiAnd QiRespectively the in-phase and quadrature components of the coherent integration result. In the absence of a signal, V follows a central chi-squared distribution; in the presence of a signal, V follows a constant KA with a non-centrality parameter2Where K represents the number of incoherent integrations and a is the signal strength. If the allowed false positive probability is P, the SNR threshold can be theoretically set with the probability 1-P by using the inverse cumulative density function of the central chi-squared distribution. In addition, the peak ratio threshold may be set and adjusted according to the actual application implementation. This is not limited by the present application.
In an exemplary embodiment, to improve the signal detection rate in the presence of cross-correlation, two-dimensional integration results in two formats may be used. Exemplarily, S101 may include: when the strength of the received signal is greater than or equal to a first threshold value, performing correlation calculation between a locally generated ranging code and the received signal to obtain a two-dimensional integration result in a first format; and when the satellite signal with the signal intensity smaller than the first threshold value is searched, performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result in a second format. Wherein the first threshold value can be used for distinguishing strong and weak signals. For example, the first threshold may be-136 dBm. However, this is not limited in this application.
As shown in fig. 3, the two-dimensional integration result in the first format may include: a maximum peak, a neighbor of the maximum peak in the doppler frequency domain dimension, a neighbor of the maximum peak in the code phase dimension, and a maximum side peak; the maximum side peak is the maximum value of the two-dimensional integration result except for the maximum peak and the neighbor of the maximum peak. In fig. 3, the triangle mark represents the maximum peak in the two-dimensional integration result, the hexagon mark represents the maximum side peak in the two-dimensional integration result, and the circle mark represents the neighborhood of the maximum peak in the doppler frequency domain dimension and the neighborhood in the code phase dimension, e.g., +/-1 ranging chips. The two-dimensional integration result in the first format occupies less memory space than the two-dimensional integration result in the second format.
In an exemplary embodiment, after obtaining the two-dimensional integration result in the first format, S102 may include: searching a maximum peak value and a maximum side peak value from the two-dimensional integration result in the first format; dividing the maximum peak value by noise to obtain SNR of a two-dimensional integration result in a first format; the peak ratio of the two-dimensional integration result in the first format is obtained by dividing the maximum peak value by the maximum side peak value.
Wherein the noise may be determined according to the following equation: noise ═ sum of all two-dimensional integration results- (max peak + max peak neighbor) ]/(number of two-dimensional integration results-1-number of max peak neighbors). However, this is not limited in this application.
In the present exemplary embodiment, when the SNR of the two-dimensional integration result of the first format is greater than the SNR threshold and the peak ratio of the two-dimensional integration result of the first format is greater than the peak ratio threshold, it may be determined that a satellite signal having a signal strength greater than or equal to the first threshold is acquired; when the SNR is less than or equal to the SNR threshold or the peak ratio is less than or equal to the peak ratio threshold, it is determined that satellite signals having signal strengths greater than or equal to the first threshold have not been acquired. In this embodiment, the two-dimensional integration result using the first format may be configured when searching for strong signals, since the cross-correlation does not affect the decision of successful acquisition of strong satellite signals.
As shown in fig. 4, the two-dimensional integration result in the second format may include: a maximum peak value in each doppler search cell, a neighbor of the maximum peak value in each doppler search cell in a doppler frequency domain dimension, a neighbor of the maximum peak value in each doppler search cell in a code phase dimension, a maximum side peak value of the maximum peak value in each doppler search cell; the maximum side peak value of the maximum peak value in any one doppler search unit may be a maximum value in the doppler search unit except for the maximum peak value and a neighbor of the maximum peak value. In fig. 4, the triangle mark represents the maximum peak in the two-dimensional integration result, the hexagon mark represents the maximum side peak in the two-dimensional integration result, and the circle mark represents the neighborhood of the maximum peak in the doppler frequency domain dimension and the neighborhood in the code phase dimension, e.g., +/-1 ranging chips.
In an exemplary embodiment, after obtaining the two-dimensional integration result in the second format, S102 may include: searching the maximum peak value and the maximum side peak value in each Doppler search unit from the two-dimensional integration result in the second format; for each Doppler search unit, dividing the maximum peak value in the Doppler search unit by the maximum side peak value to obtain the peak value ratio of the Doppler search unit; determining a maximum peak ratio among peak ratios of the plurality of doppler search units; the maximum peak of the doppler search unit in which the maximum peak ratio is located is divided by the noise to obtain the SNR.
In the present exemplary embodiment, when the SNR calculated as described above is greater than the SNR threshold and the maximum peak ratio is greater than the peak ratio threshold, it is determined that a satellite signal having a signal strength less than the first threshold is acquired; when the SNR is less than or equal to the SNR threshold or the maximum peak ratio is less than or equal to the peak ratio threshold, it is determined that satellite signals having signal strengths less than the first threshold are not acquired. In this embodiment, when searching for a weak signal, if the two-dimensional integration result in the first format is adopted, the weak signal cannot be captured due to the cross-correlation, and the detection rate of the weak signal can be improved by adopting the two-dimensional integration result in the second format.
Fig. 5 is a diagram illustrating an application example of the embodiment of the present application. As shown in fig. 5, in the present exemplary embodiment, the capture process can be divided into the following three stages: strong signals are captured (phase 0), medium weak signals are captured (phase 1), and weak signals are captured (phase 2). For example, a strong signal may be a signal having a signal strength greater than or equal to-136 dBm; a medium weak signal may be a signal with a signal strength less than-136 dBm and greater than or equal to-142 dBm; a weak signal may be a signal with a signal strength of less than-142 dBm. However, this is not limited in this application.
In the present exemplary embodiment, in the phase 0 (the strong signal capturing phase), the two-dimensional integration result using the first format may be configured. Searching a maximum peak value and a maximum side peak value in a two-dimensional integration result in a first format, and dividing noise by using the maximum peak value to obtain SNR; dividing the maximum peak value by the maximum side peak value to obtain a peak value ratio; when the SNR is larger than the SNR threshold value and the peak value ratio is larger than the peak value ratio threshold value, judging that a strong signal is successfully captured; and the satellite signals are not successfully acquired in other cases.
In the present exemplary embodiment, in the phase 1 (capturing the medium weak signal phase) and the phase 2 (capturing the weak signal phase), the two-dimensional integration result using the second format can be configured. For example, in stage 1, find the corresponding maximum peak and maximum side peak in each doppler search unit, calculate the peak ratio in each doppler search unit (peak ratio equals to maximum peak divided by maximum side peak); finding the maximum peak ratio from the calculated peak ratios; judging whether the following two conditions are met: the maximum peak ratio is larger than the peak ratio threshold value, and the SNR of the Doppler search unit where the maximum peak ratio is located is larger than the SNR threshold value (the SNR is equal to the maximum peak of the Doppler search unit where the maximum peak ratio is located divided by noise); when the two conditions are met, the medium and weak signals are successfully acquired, and the peak value of the medium and weak signals is the maximum peak value in the Doppler search unit where the maximum peak value ratio is located. When the above two conditions are not satisfied simultaneously, it can be decided that no moderate weak signal is captured. Likewise, in stage 2, it may be determined whether a weak signal is captured based on the two-dimensional integration result in the second format. The processing of stage 2 is similar to that of stage 1, and therefore is not described herein.
Fig. 6 is a schematic diagram of an apparatus for suppressing cross-correlation in GNSS signal acquisition according to an embodiment of the present application. As shown in fig. 6, the apparatus provided in this embodiment includes: a first calculation module 601, a second calculation module 602, and an acquisition determination module 603; the first calculation module 601 is adapted to perform correlation calculation between a locally generated ranging code and a received signal to obtain a two-dimensional integration result; a second calculation module 602 adapted to calculate SNR and peak ratio of the two-dimensional integration result; an acquisition determining module 603 adapted to determine whether a satellite signal is acquired based on the comparison of the calculated SNR with the SNR threshold and the comparison of the calculated peak ratio with the peak ratio threshold.
In an exemplary embodiment, the acquisition determination module 603 may be adapted to determine whether a satellite signal is acquired based on the comparison of the calculated SNR to the SNR threshold and the comparison of the calculated peak ratio to the peak ratio threshold by: when the calculated SNR is larger than an SNR threshold value and the calculated peak ratio is larger than a peak ratio threshold value, determining that the satellite signal is captured; and when the calculated SNR is less than or equal to the SNR threshold value, or the calculated peak ratio is less than or equal to the peak ratio threshold value, determining that the satellite signal is not acquired.
In an exemplary embodiment, the first calculation module 601 may be adapted to obtain the two-dimensional integration result by performing a correlation calculation between the locally generated ranging code and the received signal by: when the strength of the received signal is greater than or equal to a first threshold value, performing correlation calculation between a locally generated ranging code and the received signal to obtain a two-dimensional integration result in a first format; and when the satellite signal with the signal intensity smaller than the first threshold value is searched, performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result in a second format.
For the related description of the apparatus provided in this embodiment, reference may be made to the description of the method embodiments above, and therefore, the description thereof is not repeated herein.
Fig. 7 is a schematic diagram of a receiver according to an embodiment of the present application. As shown in fig. 7, the receiver 700 provided in this embodiment includes: a receive antenna 703, a memory 701, and a processor 702; the receiving antenna 703 is connected to the processor 702 and adapted to receive satellite signals; the memory 701 is adapted to store a computer program which, when executed by the processor 702, performs the steps of the methods provided by the above embodiments, such as the steps shown in fig. 2.
Those skilled in the art will appreciate that the architecture shown in fig. 7 is merely a schematic illustration of a portion of the architecture associated with the subject application and is not intended to limit the receiver 700 to which the subject application may be applied, and that receiver 700 may include more or fewer components than those shown, or may combine certain components, or have a different arrangement of components.
The processor 702 may include, but is not limited to, a processing device such as a Microprocessor (MCU) or a Programmable logic device (FPGA). The memory 701 may be used to store software programs and modules of application software, such as program instructions or modules corresponding to the method in the embodiment, and the processor 702 executes various functional applications and data processing by executing the software programs and modules stored in the memory 701, such as implementing the method provided in the embodiment. The memory 701 may include high speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, memory 701 may include memory located remotely from processor 702, which may be connected to receiver 700 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
For the related implementation process of the receiver provided in this embodiment, reference may be made to the description of the above method embodiments, and therefore, the description is not repeated herein.
In addition, the present application also provides a computer readable storage medium, which stores a computer program, and when the computer program is executed, the computer program implements the steps of the method provided by the foregoing embodiments, such as the steps shown in fig. 2.
It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.
Claims (8)
1. A method for suppressing cross-correlation in GNSS signal acquisition, comprising:
performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result;
calculating the SNR and the peak value ratio of the two-dimensional integration result, wherein the peak value ratio is the maximum peak value divided by the maximum side peak value; the maximum peak value is the maximum value in the two-dimensional integration result, the maximum side peak value is the maximum value except the maximum peak value and the neighbor of the maximum peak value in the two-dimensional integration result, and the neighbor of the maximum peak value comprises the neighbor of the maximum peak value on the code phase dimension or the neighbor of the maximum peak value on the Doppler frequency domain dimension;
determining whether a satellite signal is acquired according to the comparison result of the SNR and the SNR threshold value and the comparison result of the peak ratio and the peak ratio threshold value;
the obtaining of the two-dimensional integration result by performing correlation calculation between the locally generated ranging code and the received signal includes:
when the strength of the received signal is greater than or equal to a first threshold value, performing correlation calculation between a locally generated ranging code and the received signal to obtain a two-dimensional integration result in a first format;
when the intensity of the received signal is smaller than the first threshold value, performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result in a second format;
wherein the two-dimensional integration result comprises the following two dimensions: code phase, doppler frequency domain;
the two-dimensional integration result in the first format comprises: a maximum peak, a neighbor of the maximum peak in a doppler frequency domain dimension, a neighbor of the maximum peak in a code phase dimension, and a maximum side peak;
the two-dimensional integration result in the second format comprises: a maximum peak in each doppler search cell, a neighbor of the maximum peak in the doppler search cell in a doppler frequency domain dimension, a neighbor of the maximum peak in the doppler search cell in a code phase dimension, a maximum side peak of the maximum peak in the doppler search cell.
2. The method of claim 1, wherein determining whether a satellite signal is acquired based on the comparison of the SNR to an SNR threshold and the comparison of the peak ratio to a peak ratio threshold comprises:
determining that a satellite signal is acquired when the SNR is greater than the SNR threshold and the peak ratio is greater than the peak ratio threshold;
determining that no satellite signal is acquired when the SNR is less than or equal to the SNR threshold or the peak ratio is less than or equal to the peak ratio threshold.
3. The method of claim 1, wherein the calculating the SNR and the peak-to-peak ratio of the two-dimensional integration result comprises:
searching a maximum peak value and a maximum side peak value from the two-dimensional integration result in the first format;
dividing the maximum peak value by noise to obtain the SNR of the two-dimensional integration result in the first format;
and dividing the maximum peak value by the maximum side peak value to obtain the peak value ratio of the two-dimensional integration result in the first format.
4. The method of claim 1, wherein the calculating the SNR and the peak-to-peak ratio of the two-dimensional integration result comprises:
searching the maximum peak value and the maximum side peak value in each Doppler search unit from the two-dimensional integration result in the second format;
for each Doppler search unit, dividing the maximum peak value in the Doppler search unit by the maximum side peak value to obtain the peak value ratio of the Doppler search unit;
determining a maximum peak ratio among peak ratios of the doppler search unit;
and dividing the maximum peak value of the Doppler search unit where the maximum peak value ratio is positioned by the noise to obtain the SNR.
5. An apparatus for suppressing cross-correlation in GNSS signal acquisition, comprising:
the first calculation module is used for performing correlation calculation between the locally generated ranging code and the received signal to obtain a two-dimensional integration result;
the second calculation module is used for calculating the signal-to-noise ratio SNR and the peak value ratio of the two-dimensional integration result, and the peak value ratio is the maximum peak value divided by the maximum side peak value; the maximum peak value is the maximum value in the two-dimensional integration result, the maximum side peak value is the maximum value except the maximum peak value and the neighbor of the maximum peak value in the two-dimensional integration result, and the neighbor of the maximum peak value comprises the neighbor of the maximum peak value on the code phase dimension or the neighbor of the maximum peak value on the Doppler frequency domain dimension;
an acquisition determination module adapted to determine whether a satellite signal is acquired based on the comparison of the SNR to an SNR threshold and the comparison of the peak ratio to a peak ratio threshold;
the first calculation module is configured to perform correlation calculation between a locally generated ranging code and a received signal in the following manner to obtain a two-dimensional integration result:
when the satellite signal with the signal strength greater than or equal to the first threshold value is searched, performing correlation calculation between a locally generated ranging code and the received signal to obtain a two-dimensional integration result in a first format;
when the satellite signal with the signal intensity smaller than the first threshold value is searched, performing correlation calculation between a locally generated ranging code and the received signal to obtain a two-dimensional integration result in a second format;
wherein the two-dimensional integration result comprises the following two dimensions: code phase, doppler frequency domain;
the two-dimensional integration result in the first format comprises: a maximum peak, a neighbor of the maximum peak in a doppler frequency domain dimension, a neighbor of the maximum peak in a code phase dimension, and a maximum side peak;
the two-dimensional integration result in the second format comprises: a maximum peak in each doppler search cell, a neighbor of the maximum peak in the doppler search cell in a doppler frequency domain dimension, a neighbor of the maximum peak in the doppler search cell in a code phase dimension, a maximum side peak of the maximum peak in the doppler search cell.
6. The apparatus of claim 5, wherein the acquisition determination module is configured to determine whether a satellite signal is acquired based on the comparison of the SNR to the SNR threshold and the comparison of the peak ratio to the peak ratio threshold by:
determining that a satellite signal is acquired when the SNR is greater than the SNR threshold and the peak ratio is greater than the peak ratio threshold;
determining that no satellite signal is acquired when the SNR is less than or equal to the SNR threshold or the peak ratio is less than or equal to the peak ratio threshold.
7. A receiver, comprising: a receiving antenna for receiving satellite signals, a memory for storing a computer program which, when executed by the processor, carries out the steps of the method according to any one of claims 1 to 4, and a processor.
8. A computer-readable storage medium, characterized in that a computer program is stored which, when being executed, realizes the steps of the method according to any one of claims 1 to 4.
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