CN109991628B - Weak navigation signal carrier-to-noise ratio real-time estimation method and device and computer storage medium - Google Patents
Weak navigation signal carrier-to-noise ratio real-time estimation method and device and computer storage medium Download PDFInfo
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- CN109991628B CN109991628B CN201910171823.3A CN201910171823A CN109991628B CN 109991628 B CN109991628 B CN 109991628B CN 201910171823 A CN201910171823 A CN 201910171823A CN 109991628 B CN109991628 B CN 109991628B
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- 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
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Abstract
The invention belongs to the technical field of satellite navigation, and discloses a method and a device for estimating a carrier-to-noise ratio of a weak navigation signal in real time and a computer storage medium. The method comprises the following steps: acquiring actual measurement data under the condition of strong satellite signals, simulating the condition of weak satellite signals, and acquiring simulation data under the condition of weak satellite signals; carrying out nonlinear fitting by utilizing the measured data and the analog data, and establishing a mapping relation between a carrier-to-noise ratio of a satellite signal and signal plus noise energy, wherein the mapping relation comprises a reference carrier-to-noise ratio and reference signal plus noise energy, and the reference carrier-to-noise ratio and the reference signal plus noise energy corresponding to each tracking channel are different; and estimating the signal plus noise energy of the satellite signal corresponding to each tracking channel in real time, and estimating the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel according to a mapping relation established in advance. The method has the advantages of high estimation accuracy, small calculation amount, capability of meeting the real-time requirement and complete matching of dynamic data in the calculation of the filtering period.
Description
Technical Field
The invention relates to the technical field of satellite navigation, in particular to a method and a device for estimating the carrier-to-noise ratio of a weak navigation signal in real time and a computer storage medium, and particularly relates to the carrier-to-noise ratio estimation of the weak navigation signal with the signal power less than-155 dBm.
Background
In the process of acquiring and tracking navigation signals, a base band digital signal processing module of a receiver needs to carry a carrier-to-noise ratio (C/N) 0 ) And (6) estimating. Considering that the operating environment of the receiver changes at any time, the receiver needs to estimate the carrier-to-noise ratio of the navigation signal in real time according to the data of the receiver. In particular, compared with the traditional tracking loop, the Kalman filtering algorithm has obvious advantages in the aspect of navigation signal tracking, and Kalman filtering has huge potential no matter the weak signal or the dynamic signal is tracked. However, the key parameter of the Kalman filtering algorithm is the noise power, so the real-time accurate estimation of the carrier-to-noise ratio is the adaptive Kalman filtering calculationThe method is a precondition for exerting potential.
At present, the existing carrier-to-noise ratio estimation methods mainly include a direct calculation method, a narrowband wideband power ratio method, an add-on-noise channel method, a variance summation method, and the like. The above methods have advantages and disadvantages, wherein, the theory of adding noise channels by direct calculation method is relatively simple and clear, only the correlation value obtained by each channel is needed to be divided by the noise base of the added noise channel, but the disadvantages are that if only one noise channel is available, accidental situations may occur, which results in inaccurate carrier-to-noise ratio estimation and additional channels need to be added; while other methods do not compromise real-time and estimation accuracy under weak signal conditions, especially when the signal power is less than-155 dBm.
Disclosure of Invention
In view of the above, embodiments of the present invention provide a method, an apparatus, and a computer storage medium for estimating a carrier-to-noise ratio of a weak navigation signal in real time, so as to solve at least the above disadvantages of the prior art, and enable the carrier-to-noise ratio to be estimated in real time under a weak signal condition, and the estimation accuracy is high.
In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:
in a first aspect, a method for estimating a carrier-to-noise ratio of a weak navigation signal in real time is provided, which includes:
step 1, acquiring actually measured data under the condition of strong satellite signals; simulating weak satellite signal conditions, and acquiring simulation data under the weak satellite signal conditions; the set of measured data/analog data comprises signal plus noise energy of satellite signals and corresponding carrier-to-noise ratio;
step 2, carrying out nonlinear fitting by utilizing the measured data and the simulated data, and establishing a mapping relation between a carrier-to-noise ratio of a satellite signal and signal plus noise energy; the mapping relation comprises a reference carrier-to-noise ratio and a reference signal plus noise energy, and the reference carrier-to-noise ratio and the reference signal plus noise energy corresponding to each tracking channel are different;
and 3, estimating the signal plus noise energy of the satellite signal corresponding to each tracking channel in real time, and estimating the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel according to the mapping relation established in advance.
In a second aspect, an apparatus for estimating a carrier-to-noise ratio of a weak navigation signal in real time is provided, the apparatus comprising: a memory and a processor;
the memory for storing a computer program;
the processor is configured to, when running the computer program, perform the steps of the method of the first aspect.
In a third aspect, a computer storage medium is provided, having stored thereon a computer program which, when being executed by a processor, carries out the steps of the method of the first aspect.
Based on the scheme of the invention, the measured data is obtained in advance under the condition of strong satellite signals, meanwhile, the signal generator is used for simulating weak satellite signals, so that the simulated data is obtained under the condition of weak satellite signals, and then the measured data and the simulated data are used for carrying out nonlinear fitting to establish the mapping relation between the carrier-to-noise ratio of the satellite signals and the signal plus noise energy. In this way, whether the current signal is in a strong signal condition or a weak signal condition, the corresponding carrier-to-noise ratio can be obtained through the current signal plus noise power estimation. Therefore, even if the current navigation signal is weak, the invention can accurately estimate the carrier-to-noise ratio, has high estimation accuracy and small calculation amount, can meet the real-time requirement and completely match dynamic data in the calculation of the filtering period.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic flowchart of a method for estimating a carrier-to-noise ratio of a weak navigation signal in real time according to an embodiment of the present invention;
fig. 2 is a schematic composition diagram of a device for estimating a carrier-to-noise ratio of a weak navigation signal in real time according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a schematic flowchart of a method for estimating a carrier-to-noise ratio of a weak navigation signal in real time according to an embodiment of the present invention.
As shown in fig. 1, a method for estimating a carrier-to-noise ratio of a weak navigation signal in real time according to an embodiment of the present invention includes:
step 1, acquiring actually measured data under the condition of strong satellite signals; and simulating the weak satellite signal condition, and acquiring the simulation data under the weak satellite signal condition.
Wherein the set of measured/simulated data includes signal plus noise energy of the satellite signal and a corresponding carrier-to-noise ratio.
It should be noted that the strong satellite signal and the weak satellite signal described in the embodiment of the present invention are relatively speaking, and the signal is considered to be the strong satellite signal as long as the satellite signal can be tracked, and conversely, the signal is the weak satellite signal.
In a preferred implementation manner of the embodiment of the present invention, step 1 may specifically include the following steps:
under the condition of strong satellite signals, calculating the broadband power and the narrowband power of the strong satellite signals in real time, estimating by using a narrowband broadband power ratio method to obtain corresponding carrier-to-noise ratios, and recording the carrier-to-noise ratios and the signal plus noise energy of each strong satellite signal as a group of measured data so as to obtain a plurality of groups of measured data; and generating weak satellite signals with known signal plus noise energy by using a signal generator, estimating to obtain corresponding carrier-to-noise ratios, and recording the carrier-to-noise ratio and the signal plus noise energy of each weak satellite signal as a group of analog data so as to obtain a plurality of groups of analog data.
Further, in the specific step of step 1, calculating the wideband power and the narrowband power of the strong satellite signal in real time under the condition of the strong satellite signal may specifically include:
under the condition of strong satellite signals, a series of coherent integration values I output by a receiver at the kth moment are acquired in real time P (n) and Q P (n), and further calculating to obtain a bandwidth of
Broadband power P of wb (k) And a bandwidth of
Narrow band power P of nb (k)。
Wherein, T coh For coherent integration time, K takes all integers between 1 and K, and M represents the number of coherent integrations.
Further, in the specific step of step 1, the estimating the carrier-to-noise ratio of the strong satellite signal by using the narrowband wideband power ratio method may specifically include:
calculating narrow band power P nb (k) And broadband power P wb (k) The ratio between: p nw (k)＝P nb (k)/P wb (k)；
P for all K moments nw (k) Averaging to obtain an average ratio:
and estimating and obtaining the carrier-to-noise ratio of the satellite signal according to the average ratio:
wherein the broadband power P wb (k) And narrow band power P nb (k) The calculation formulas of (A) and (B) are respectively as follows:
furthermore, it should be noted that the broadband power P can be understood by those skilled in the art wb (k) I.e., the energy of the satellite signal plus noise.
And 2, carrying out nonlinear fitting by using the measured data and the simulated data, and establishing a mapping relation between the carrier-to-noise ratio of the satellite signal and the signal plus noise energy, wherein the mapping relation comprises a reference carrier-to-noise ratio and a reference signal plus noise energy, and the reference carrier-to-noise ratio and the reference signal plus noise energy corresponding to each tracking channel are different.
For example, the mapping relationship may be a non-linear mapping relationship y = f (x) in which the carrier-to-noise ratio of the satellite signal is a dependent variable y and the signal-to-noise energy x is an independent variable, and the mapping relationship includes a reference carrier-to-noise ratio and a reference signal-to-noise energy. Meanwhile, the reference carrier-to-noise ratio and the reference signal plus noise energy corresponding to each tracking channel are different, because the strength of the received satellite signal is different due to the difference of the positions of each tracking channel of the receiver. Those skilled in the art will appreciate that the carrier-to-noise ratio of the satellite signal is estimated in the tracking process because in practical applications, we do not know the strength of the satellite signal, and therefore the strength of the satellite signal can be estimated by using the carrier-to-noise ratio of the satellite signal, and the carrier-to-noise ratio is used as a basis for judgment and parameter selection.
In addition, since the power fluctuation of the noise is large, when the mapping relationship is established, the sum of the power of the signal and the power of the noise in the carrier-to-noise ratio estimation period (typically, the carrier-to-noise ratio estimation period is 1 second) should be averaged to eliminate the influence of the noise power fluctuation on the carrier-to-noise ratio estimation as much as possible.
And 3, estimating the signal plus noise energy of the satellite signal corresponding to each tracking channel in real time, and estimating the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel according to a mapping relation established in advance.
In a specific implementation manner of the embodiment of the present invention, in step 3, estimating a carrier-to-noise ratio of a satellite signal according to a mapping relationship established in advance, which may specifically include:
and substituting the signal and noise energy of the satellite signal corresponding to each tracking channel into the mapping relation to obtain the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel.
Based on the method, the measured data is obtained in advance under the condition of strong satellite signals, meanwhile, the signal generator is used for simulating weak satellite signals, so that the simulated data is obtained under the condition of weak satellite signals, further, the measured data and the simulated data are used for carrying out nonlinear fitting, and the mapping relation between the carrier-to-noise ratio of the satellite signals and the signal plus noise energy is established. In this way, whether the current signal is in a strong signal condition or a weak signal condition, the corresponding carrier-to-noise ratio can be obtained through the current signal plus noise power estimation. Therefore, even if the current navigation signal is weak, the method can accurately estimate the carrier-to-noise ratio, has high estimation accuracy and small calculation amount, and can meet the real-time requirement and completely match dynamic data in the calculation of the filtering period.
In order to implement the method for estimating the carrier-to-noise ratio of the weak navigation signal in real time provided by the embodiment of the present invention, the embodiment of the present invention further provides a device 20 for estimating the carrier-to-noise ratio of the weak navigation signal in real time, as shown in fig. 2, where the device 20 includes: a memory 201 and a processor 202.
The memory 201 is used for storing a computer program.
The processor 202 is configured to execute the steps of the method for estimating a carrier-to-noise ratio of a weak navigation signal in real time according to the present invention when the computer program is run.
Of course, in practical applications, the apparatus may further include a communication interface 203, as shown in fig. 2. The various components of the apparatus 20 are coupled together by a bus system 204. It is understood that the bus system 204 is used to enable communications among the components. The bus system 204 includes a power bus, a control bus, and a status signal bus in addition to a data bus. For clarity of illustration, however, the various buses are labeled as bus system 204 in fig. 2.
In an exemplary embodiment, the embodiment of the present invention further provides a computer storage medium, which is a computer readable storage medium, and a computer program is stored thereon, where the computer program is executable by the processor 201 of the apparatus 20 for estimating a carrier-to-noise ratio of a weak navigation signal in real time to complete the steps of the foregoing method. The computer-readable storage medium may be a Memory such as a magnetic random access Memory (FRAM), a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a Flash Memory (Flash Memory), a magnetic surface Memory, an optical disk, or a Compact Disc Read-Only Memory (CD-ROM).
In the several embodiments provided in the present invention, it should be understood that the disclosed method and intelligent device may be implemented in other ways. The above-described device embodiments are merely illustrative, for example, the division of the unit is only a logical functional division, and there may be other division ways in actual implementation, such as: multiple units or components may be combined, or may be integrated into another system, or some features may be omitted, or not implemented. In addition, the coupling, direct coupling or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between the devices or units may be electrical, mechanical or other forms.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed on a plurality of network units; some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (4)
1. A method for estimating a carrier-to-noise ratio of a weak navigation signal in real time is characterized by comprising the following steps:
step 1, acquiring actually measured data under the condition of strong satellite signals; simulating the weak satellite signal condition, and acquiring simulation data under the weak satellite signal condition; wherein, the group of measured data/analog data comprises signal plus noise energy of satellite signals and corresponding carrier-to-noise ratio;
under the condition of strong satellite signals, calculating the broadband power and the narrowband power of the strong satellite signals in real time, estimating by using a narrowband broadband power ratio method to obtain corresponding carrier-to-noise ratios, and recording the carrier-to-noise ratio and the signal plus noise energy of each strong satellite signal as a group of measured data so as to obtain a plurality of groups of measured data;
under the condition of strong satellite signals, a series of coherent integration values I output by a receiver at the kth moment are acquired in real time P (n) and Q P (n), and further calculating to obtain a bandwidth of
Broadband power P of wb (k) And a bandwidth of
Narrow band power P of nb (k)；
Wherein, T coh For coherent integration time, K is an integer between 1 and K, and M represents the coherent integration times;
the method for estimating and obtaining the carrier-to-noise ratio of the strong satellite signal by using the narrow-band broadband power ratio specifically comprises the following steps:
calculating narrow band power P nb (k) And wide bandPower P wb (k) The ratio between: p nw (k)＝P nb (k)/P wb (k)；
Ratio P to all K moments nw (k) Averaging to obtain an average ratio:
and estimating and obtaining the carrier-to-noise ratio of the satellite signal according to the average ratio:
and the number of the first and second groups,
weak satellite signals with known signal plus noise energy are generated by a signal generator, corresponding carrier-to-noise ratios are estimated, and the carrier-to-noise ratio and the signal plus noise energy of each weak satellite signal are recorded as a group of analog data, so that a plurality of groups of analog data are obtained;
step 2, carrying out nonlinear fitting by using the measured data and the simulated data, and establishing a mapping relation between a carrier-to-noise ratio of a satellite signal and signal plus noise energy; the mapping relation comprises a reference carrier-to-noise ratio and a reference signal plus noise energy, and the reference carrier-to-noise ratio and the reference signal plus noise energy corresponding to each tracking channel are different;
step 3, estimating the signal plus noise energy of the satellite signal corresponding to each tracking channel in real time, and further estimating the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel according to the mapping relationship established in advance, specifically comprising:
and substituting the signal and noise energy of the satellite signal corresponding to each tracking channel into the mapping relation to obtain the carrier-to-noise ratio of the satellite signal corresponding to each tracking channel.
2. Method according to claim 1, characterized in that the wide-band power P is wb (k) And narrow band power P nb (k) The calculation formulas of (A) and (B) are respectively as follows:
3. a device for estimating a carrier-to-noise ratio of a weak navigation signal in real time, comprising: a memory and a processor;
the memory for storing a computer program;
the processor, when executing the computer program, performing the steps of the method of any of claims 1 to 2.
4. A computer storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, performs the steps of the method of any of claims 1 to 2.
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