Single-tone continuous wave interference carrier center frequency estimation method and system

Abstract

The invention provides a single-tone continuous wave interference carrier center frequency estimation method and system. The method comprises the following steps: acquiring carrier frequency data output by a frequency locking loop; constructing a carrier frequency data sequence and a carrier frequency data time sequence; performing fitting operation on the carrier frequency data sequence; carrying out interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence; carrying out differential operation on the carrier frequency interpolation sequence to obtain a carrier frequency differential sequence; determining the minimum value of the carrier frequency difference sequence; and estimating the carrier center frequency according to the minimum value of the carrier frequency difference sequence. The method has the advantages that the method can be suitable for a single satellite platform; accurate estimation of the single-tone continuous wave interference carrier center frequency can be realized only by means of a signal processing method.

Description

Technical Field

[0001] The present application belongs to the field of GNSS interference monitoring technology and applications, and specifically relates to a method and system for estimating the center frequency of a single-tone continuous wave interference carrier. Background Art

[0002] The Global Navigation Satellite System (GNSS) is a very important space infrastructure that can provide accurate, all-weather positioning, navigation and timing (PNT) services to users around the world. At present, GNSS has been widely used in many fields such as economic construction, scientific research, national defense and military. Because of this, the inherent vulnerabilities of GNSS have gradually been exposed. In particular, the emergence of malicious GNSS interference has greatly endangered the security of GNSS-based applications and systems. Therefore, GNSS interference monitoring technology and application has become one of the research focuses.

[0003] Single-tone continuous wave interference is a very common and frequent GNSS interference. Researchers have conducted extensive and in-depth research on single-tone continuous wave interference monitoring technology and single-tone continuous wave interference source positioning technology. In the research on single-tone continuous wave interference source positioning technology, it is usually involved in the measurement of the single-tone continuous wave interference Doppler frequency emitted by the single-tone continuous wave interference source. The Doppler frequency value is related to the center frequency of the single-tone continuous wave interference carrier.

[0004] Because the single-tone continuous wave interference source is a non-cooperative signal source, the center frequency of the single-tone continuous wave interference carrier emitted by the single-tone continuous wave interference source is usually unknown and needs to be estimated. However, at present, it is very difficult for a single satellite platform to estimate the center frequency of the single-tone continuous wave interference carrier by relying solely on signal processing methods without any auxiliary means. Summary of the invention

[0005] The purpose of the present invention is to provide a method and system for estimating the center frequency of a single-tone continuous wave interference carrier. The method and system are suitable for a single satellite platform to achieve accurate estimation of the center frequency of a single-tone continuous wave interference carrier by relying only on a signal processing method without auxiliary means, solving the problem that a single satellite platform currently relies only on a signal processing method to accurately estimate the center frequency of a single-tone continuous wave interference carrier without auxiliary means.

[0006] In order to achieve the above object, the present application proposes a method for estimating the center frequency of a single-tone continuous wave interference carrier, comprising:

[0007] Step S101) obtaining carrier frequency data output by a frequency locked loop;

[0008] Step S102) constructing a carrier frequency data sequence and a carrier frequency data time series;

[0009] Step S103) performing a fitting operation on the carrier frequency data sequence;

[0010] Step S104) performing an interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence;

[0011] Step S105) performing a differential operation on the carrier frequency interpolation sequence to obtain a carrier frequency differential sequence;

[0012] Step S106) determining the minimum value of the carrier frequency difference sequence;

[0013] Step S107) Estimate the carrier center frequency according to the minimum value of the carrier frequency difference sequence.

[0014] As an improvement of the above method, the step S102) includes:

[0015] The real-time estimated values ​​of all single-tone continuous wave interference carrier frequencies continuously output by the frequency locked loop are used to construct a carrier frequency data sequence:

[0016] F=[f(1),f(2),f(3),…,f(n),…,f(N)]

[0017] Wherein, F represents the carrier frequency data sequence; N represents the total number of single-tone continuous wave interference carrier frequency real-time estimation values ​​continuously output by the frequency locked loop; f(n) represents the single-tone continuous wave interference carrier frequency real-time estimation value;

[0018] Based on the coherent integration time of the frequency locked loop, a time series corresponding to the carrier frequency data series is constructed:

[0019] T=[T coh ,2T coh ,3T coh ,…,NT coh ]

[0020] Where T represents the time series; T coh Represents the coherent integration time of the frequency locked loop.

[0021] As an improvement of the above method, the step S103) includes:

[0022] The carrier frequency data sequence F is fitted and expressed as:

[0023] [K,S,Mu]=polyfit(T,F,Ord)

[0024] Among them, polyfit(·) represents the polynomial fitting function; Ord represents the polynomial fitting order; K represents the least squares fitting polynomial coefficient; S represents the estimation error; Mu represents the centering and scaling factor; and T represents the time series.

[0025] As an improvement of the above method, the step S104) includes:

[0026] Construct an interpolated time series with high temporal resolution:

[0027]

[0028] Among them, T i represents the interpolation time series; M represents the interpolation multiple; subscript i represents interpolation; T coh represents the coherent integration time of the frequency locked loop;

[0029] Based on the fitting result of the carrier frequency data sequence F, the carrier frequency data sequence F is interpolated, which is expressed as:

[0030] [F i ,D]=polyval(K,T i ,S,Mu)

[0031] Among them, F i represents the carrier frequency interpolation sequence; D represents the interpolation standard deviation; polyval(·) represents the interpolation function; K represents the least squares fitting polynomial coefficient; S represents the estimation error; Mu represents the centering and scaling factor.

[0032] As an improvement of the above method, the step S105) includes:

[0033] Based on the carrier frequency interpolation sequence F i , the carrier frequency interpolation sequence is differentiated and expressed as:

[0034] F d (m) = F i (m+1)-F i (m)

[0035] Where m represents the carrier frequency interpolation sequence F i Ordinal number; F i (m) represents the carrier frequency interpolation sequence F i The mth element of d represents the carrier frequency difference sequence; F d (m) represents the mth element of the carrier frequency difference sequence; the subscript d represents the difference.

[0036] As an improvement of the above method, the step S106) includes:

[0037] Based on the carrier frequency difference sequence F d , determine the minimum value of the carrier frequency difference sequence and the ordinal number corresponding to the minimum value, expressed as:

[0038] [V,I]=min(F d )

[0039] Where min(·) represents the minimum value determination function; V represents the carrier frequency difference sequence F d The minimum value of; I represents the carrier frequency difference sequence F d The ordinal number corresponding to the minimum value of .

[0040] As an improvement of the above method, the step S107) includes:

[0041] Based on the carrier frequency interpolation sequence F i and the carrier frequency difference sequence F d The ordinal number I corresponding to the minimum value of determines the center frequency of the single-tone continuous wave interference carrier:

[0042] f c =F i (I)

[0043] Among them, f c Represents the estimated value of the center frequency of the single-tone continuous wave interference carrier; the subscript c represents the carrier.

[0044] The present application also provides a single-tone continuous wave interference carrier center frequency estimation system, which is implemented based on the above method, and the system includes:

[0045] The frequency locking loop is used to track and process the single-tone continuous wave interference and output a real-time estimation value of the single-tone continuous wave interference carrier frequency at a set time interval;

[0046] Constructing a time series module for acquiring carrier frequency data output by a frequency locked loop, and constructing a carrier frequency data sequence and a carrier frequency data time series;

[0047] A fitting module, used for performing a fitting operation on a carrier frequency data sequence;

[0048] An interpolation module, used for performing an interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence;

[0049] A differential module, used for performing differential operation on a carrier frequency interpolation sequence to obtain a carrier frequency differential sequence;

[0050] A minimum value determination module, used to determine the minimum value of the carrier frequency difference sequence; and

[0051] The center frequency estimation module is used to estimate the carrier center frequency according to the minimum value of the carrier frequency difference sequence.

[0052] Compared with the prior art, the advantages of this application are:

[0053] 1. The method proposed in the present invention can be applied to a single satellite platform;

[0054] 2. The method proposed in the present invention can achieve accurate estimation of the center frequency of the single-tone continuous wave interference carrier only by relying on signal processing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Shown is a flow chart of a method for estimating the center frequency of a single-tone continuous wave interference carrier;

[0056] Figure 2 Shown is the structural block diagram of the single-tone continuous wave interference carrier center frequency estimation system. DETAILED DESCRIPTION

[0057] The technical solution of the present application is described in detail below with reference to the accompanying drawings.

[0058] like Figure 1 As shown, a single-tone continuous wave interference carrier center frequency estimation method proposed by the present invention comprises:

[0059] Step S101) obtaining carrier frequency data output by a frequency locked loop;

[0060] The frequency-locked loop (FLL) is generally used to track and process single-tone continuous wave interference. The frequency-locked loop is set to the same frequency every time T. coh Output a real-time estimate value f(n) of the single-tone continuous wave interference carrier frequency (unit: Hz). coh represents the coherent integration time of the frequency locked loop; n represents the ordinal number of the real-time estimated value of the single-tone continuous wave interference carrier frequency output by the frequency locked loop.

[0061] Step S102) constructing a carrier frequency data time series;

[0062] A carrier frequency data sequence is constructed using all the single-tone continuous wave interference carrier frequency real-time estimation values ​​continuously output by the frequency locked loop: F = [f(1), f(2), f(3), ..., f(N)], wherein F represents the carrier frequency data sequence; and N represents the total number of the single-tone continuous wave interference carrier frequency real-time estimation values ​​continuously output by the frequency locked loop.

[0063] Based on the coherent integration time of the frequency locked loop, a time series corresponding to the carrier frequency data sequence is constructed: T = [T coh,2T coh ,3T coh ,…,NT coh ]. Where T represents the time series.

[0064] Step S103) fitting carrier frequency data;

[0065] Usually, the signal input to the frequency locked loop contains both single-tone continuous wave interference and noise, and may also contain other signal components. Therefore, the single-tone continuous wave interference carrier frequency real-time estimation value f(n) output by the frequency locked loop fluctuates on a micro scale, but conforms to the real-time change trend of the carrier frequency on a macro scale.

[0066] In order to eliminate the fluctuation of f(n) at the microscopic scale, the carrier frequency data sequence F is first fitted. The fitting operation is expressed as:

[0067] [K,S,Mu]=polyfit(T,F,Ord) (1)

[0068] Where polyfit(·) represents the polynomial fitting function; Ord represents the polynomial fitting order; K represents the least squares fitting polynomial coefficient; S represents the estimation error; and Mu represents the centering and scaling factor.

[0069] Step S104) performing an interpolation operation on the carrier frequency data;

[0070] Before interpolating the carrier frequency data, first construct an interpolation time series with high time resolution: Among them, T i represents the interpolation time series; M represents the interpolation multiple; and the subscript i represents interpolation.

[0071] Based on the fitting result of the carrier frequency data sequence F, the carrier frequency data sequence F is interpolated. The interpolation operation is expressed as:

[0072] [F i ,D]=polyval(K,T i ,S,M u ) (2)

[0073] Among them, F i represents the carrier frequency interpolation sequence; D represents the interpolation standard deviation; polyval(·) represents the interpolation function.

[0074] Step S105) performing a differential operation on the carrier frequency interpolation sequence;

[0075] Based on the carrier frequency interpolation sequence F i , the carrier frequency interpolation sequence is differentiated. The differential operation is expressed as:

[0076] F d (m) = F i (m+1)-F i (m) (3)

[0077] Where m represents the carrier frequency interpolation sequence F i Ordinal number; F i (m) represents the carrier frequency interpolation sequence F i The mth element of d represents the carrier frequency difference sequence; F d (m) represents the mth element of the carrier frequency difference sequence; the subscript d represents the difference.

[0078] Step S106) determining the minimum value of the carrier frequency difference sequence;

[0079] Based on the carrier frequency difference sequence F d , determine the minimum value of the carrier frequency difference sequence and the ordinal number corresponding to the minimum value. The operation of determining the minimum value of the carrier frequency difference sequence and the ordinal number corresponding to the minimum value is expressed as:

[0080] [V,I]=min(F d ) (4)

[0081] Where min(·) represents the minimum value determination function; V represents the carrier frequency difference sequence F d The minimum value of; I represents the carrier frequency difference sequence F d The ordinal number corresponding to the minimum value of .

[0082] Step S107) estimating the carrier center frequency;

[0083] Based on the carrier frequency interpolation sequence F i and the carrier frequency difference sequence F d The ordinal number I corresponding to the minimum value of can determine the center frequency of the single-tone continuous wave interference carrier:

[0084] f c =F i (I) (5)

[0085] Among them, f c Represents the estimated value of the center frequency of the single-tone continuous wave interference carrier; the subscript c represents the carrier.

[0086] like Figure 2 As shown, the present application also provides a single-tone continuous wave interference carrier center frequency estimation system, which is implemented based on the above method, and the system includes:

[0087] The frequency locking loop is used to track and process the single-tone continuous wave interference and output a real-time estimation value of the single-tone continuous wave interference carrier frequency at a set time interval;

[0088] Constructing a time series module for acquiring carrier frequency data output by a frequency locked loop, and constructing a carrier frequency data sequence and a carrier frequency data time series;

[0089] A fitting module, used for performing a fitting operation on a carrier frequency data sequence;

[0090] An interpolation module, used for performing an interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence;

[0091] A differential module, used for performing differential operation on a carrier frequency interpolation sequence to obtain a carrier frequency differential sequence;

[0092] A minimum value determination module, used to determine the minimum value of the carrier frequency difference sequence;

[0093] The center frequency estimation module is used to estimate the carrier center frequency according to the minimum value of the carrier frequency difference sequence.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application is described in detail with reference to the embodiments, a person skilled in the art should understand that any modification or equivalent replacement of the technical solution of the present application does not depart from the spirit and scope of the technical solution of the present application and should be included in the scope of the claims of the present application.

Claims

1. A method for estimating the center frequency of a single-tone continuous wave interference carrier, comprising: Step S101) obtaining carrier frequency data output by a frequency locked loop; Step S102) constructing a carrier frequency data sequence and a carrier frequency data time series; Step S103) performing a fitting operation on the carrier frequency data sequence; Step S104) performing an interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence; Step S105) performing a differential operation on the carrier frequency interpolation sequence to obtain a carrier frequency differential sequence; Step S106) determining the minimum value of the carrier frequency difference sequence; Step S107) Estimate the carrier center frequency according to the minimum value of the carrier frequency difference sequence.

2. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, wherein: The step S102) comprises: The real-time estimated values ​​of all single-tone continuous wave interference carrier frequencies continuously output by the frequency locked loop are used to construct a carrier frequency data sequence: F=[f(1),f(2),f(3),…,f(n),…,f(N)] Wherein, F represents the carrier frequency data sequence; N represents the total number of single-tone continuous wave interference carrier frequency real-time estimation values ​​continuously output by the frequency locked loop; f(n) represents the single-tone continuous wave interference carrier frequency real-time estimation value; Based on the coherent integration time of the frequency locked loop, a time series corresponding to the carrier frequency data series is constructed: T=[T coh ,2T coh ,3T coh ,…,NT coh ] Where T represents the time series; T coh Represents the coherent integration time of the frequency locked loop.

3. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, wherein: The step S103) comprises: The carrier frequency data sequence F is fitted and expressed as: [K,S,Mu]=polyfit(T,F,Ord) Among them, polyfit(·) represents the polynomial fitting function; Ord represents the polynomial fitting order; K represents the least squares fitting polynomial coefficient; S represents the estimation error; Mu represents the centering and scaling factor; and T represents the time series.

4. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, wherein: The step S104) comprises: Construct an interpolated time series with high temporal resolution: Among them, T i represents the interpolation time series; M represents the interpolation multiple; subscript i represents interpolation; T coh represents the coherent integration time of the frequency locked loop; Based on the fitting result of the carrier frequency data sequence F, the carrier frequency data sequence F is interpolated, which is expressed as: [F i ,D]=polyval(K,T i ,S,M u ) Among them, F i represents the carrier frequency interpolation sequence; D represents the interpolation standard deviation; polyval(·) represents the interpolation function; K represents the least squares fitting polynomial coefficient; S represents the estimation error; Mu represents the centering and scaling factor.

5. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, wherein: The step S105) comprises: Based on the carrier frequency interpolation sequence F i , the carrier frequency interpolation sequence is differentiated and expressed as: F d (m)=F i (m+1)-F i (m) Where m represents the carrier frequency interpolation sequence F i Ordinal number; F i (m) represents the carrier frequency interpolation sequence F i The mth element of d represents the carrier frequency difference sequence; F d (m) represents the mth element of the carrier frequency difference sequence; the subscript d represents the difference.

6. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, wherein: The step S106) comprises: Based on the carrier frequency difference sequence F d , determine the minimum value of the carrier frequency difference sequence and the ordinal number corresponding to the minimum value, expressed as: [V,I]=min(F d ) Where min(·) represents the minimum value determination function; V represents the carrier frequency difference sequence F d The minimum value of; I represents the carrier frequency difference sequence F d The ordinal number corresponding to the minimum value of .

7. The method for estimating center frequency of a single-tone continuous wave interference carrier according to claim 1, characterized in that: The step S107) comprises: Based on the carrier frequency interpolation sequence F i and the carrier frequency difference sequence F d The ordinal number I corresponding to the minimum value of determines the center frequency of the single-tone continuous wave interference carrier: f c =F i (I) Among them, f c Represents the estimated value of the center frequency of the single-tone continuous wave interference carrier; the subscript c represents the carrier.

8. A single-tone continuous wave interference carrier center frequency estimation system, based on the method described in any one of claims 1 to 7, characterized in that: The system comprises: The frequency locking loop is used to track and process the single-tone continuous wave interference and output a real-time estimation value of the single-tone continuous wave interference carrier frequency at a set time interval; Constructing a time series module for acquiring carrier frequency data output by a frequency locked loop, and constructing a carrier frequency data sequence and a carrier frequency data time series; A fitting module, used for performing a fitting operation on a carrier frequency data sequence; An interpolation module, used for performing an interpolation operation on the carrier frequency data to obtain a carrier frequency interpolation sequence; A differential module, used for performing differential operation on a carrier frequency interpolation sequence to obtain a carrier frequency differential sequence; A minimum value determination module, used to determine the minimum value of the carrier frequency difference sequence; and The center frequency estimation module is used to estimate the carrier center frequency according to the minimum value of the carrier frequency difference sequence.

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