A multi-carrier direction finding method of maximizing forward-backward sequence correlation coefficient

Abstract

The application discloses a multi-carrier direction-finding method based on maximum forward-backward sequence correlation coefficient, and solves the problem of how to determine the direction of a wave by using the forward-backward sequence correlation coefficient maximization of the carrier signal frequency of a transmitting antenna and the multi-carrier signal complex amplitude of a single receiving antenna when the single receiving antenna receives the multi-carrier radio signals synchronously transmitted by two transmitting antennas; the application can not only reduce the volume and weight of a receiving end, reduce the complexity of the receiving end and the maintenance cost of different application occasions, but also improve the portability of a positioning terminal such as an unmanned aerial vehicle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of electronic information technology, and particularly relates to a multi-carrier off-boresight direction finding method based on maximum correlation coefficient of forward and backward sequences. BACKGROUND

[0002] In the field of radio communication and positioning and navigation, off-boresight direction finding has been paid more and more attention with more and more radio signals transmitted by multiple antennas synchronously. Unlike the general Doppler direction finding technology which needs to receive radio signals by an array composed of multiple antennas, the off-boresight direction finding technology only needs to receive the multi-carrier signals synchronously transmitted by multiple antennas by a single receiving antenna, and can realize off-boresight measurement by using the complex amplitude information of the multi-carrier signals, thereby reducing the volume and weight of the receiving end, improving the portability and applicability on the unmanned aerial vehicle platform. In addition, since the receiving end only needs a single antenna and does not need to correct the channels of the receiving antenna, the complexity of the receiving end can be reduced, and the use cost on the unmanned aerial vehicle platform can be reduced.

[0003] When two omnidirectional transmitting antennas are used to transmit radio signals synchronously, the signal received by another omnidirectional receiving antenna is the aliasing of the radio signals synchronously transmitted by the two transmitting antennas. Therefore, in the problem of off-boresight azimuth measurement by using the multi-carrier radio signals received by a single antenna, the off-boresight direction information contained in the phase of the multi-carrier radio signals received by the single antenna needs to be extracted. Since the relationship between the multi-carrier radio signals received by the single antenna and the off-boresight direction is nonlinear, and considering the influence of the noise in the multi-carrier radio signals received by the single antenna on the off-boresight direction finding, a complex signal parameter nonlinear high-precision estimation problem needs to be solved. SUMMARY

[0004] The problem to be solved by the present application is how to determine the off-boresight direction by using the maximum correlation coefficient of forward and backward sequences formed by the carrier signal frequency of the transmitting signal and the complex amplitude of the multi-carrier signal of the received signal of the single receiving antenna when the multi-carrier radio signals synchronously transmitted by two transmitting antennas are received by a single receiving antenna.

[0005] The scheme of the present application is as follows:

[0006] A multi-carrier off-boresight direction finding method based on maximum correlation coefficient of forward and backward sequences, the distance between two radio transmitting antennas is d when the distance is expressed in units of the wavelength of the transmitted signal, the number of carriers of the transmitted signal is N, the frequency of the nth carrier signal is f n , n = 1, 2, …, N; the number of digital signal samples input by the digital-to-analog converter of the two radio transmitters is K, and the digital-to-analog conversion rate is f st ; the analog-to-digital conversion rate of the received signal of the receiving antenna is f sr; the number of searched beam directions is M, θ m is the mth searched beam direction, m = 1, 2, …, M, and the searched beam direction sequence is {θ1, θ2, …, θM} ; including the following steps: M} ; including the following steps:

[0007] S1, setting the signal transmitted by the first transmitting antenna, the digital-to-analog converter according to the digital-to-analog conversion rate f st The input digital signal sample is:

[0008]

[0009] Wherein, k = 0, 1, 2, …, K-1; the signal transmitted by the second transmitting antenna, the digital-to-analog converter according to the digital-to-analog conversion rate f st The input digital signal sample is:

[0010]

[0011] Wherein, k = 0, 1, 2, …, K-1;

[0012] S2, a receiving antenna receives a radio signal, an analog-to-digital converter according to the analog-to-digital conversion rate f sr The sampled digital receiving signal is x(t), wherein t = 0, 1, 2, …, K-1;

[0013] S3, the nth carrier complex amplitude of the receiving signal is determined by the digital receiving signal and the nth carrier signal frequency:

[0014]

[0015] Wherein, n = 1, 2, …, N;

[0016] S4, the nth forward sequence value of the mth searched beam direction θ m Is determined by the mth searched beam direction and the nth carrier complex amplitude of the receiving signal:

[0017]

[0018] Wherein, n = 1, 2, …, N, m = 1, 2, …, M;

[0019] The nth backward sequence value of the mth searched beam direction θ m Is determined by the mth searched beam direction and the nth carrier complex amplitude of the receiving signal:

[0020] v(n, θ m ) = u(N-n+1, θ m )

[0021] Wherein, n = 1, 2, …, N, m = 1, 2, …, M;

[0022] s5、by the m-th off-wave direction θ m of the forward sequence {u(1, θ m ), u(2, θ m ),..., u(N, θ m )} and the backward sequence {v(1, θ m ), v(2, θ m ),..., v(N, θ m )}, determine the m-th off-wave direction θ m corresponding to the forward and backward correlation coefficients:

[0023]

[0024] wherein m = 1, 2,..., M;

[0025] S6, determine the maximum value g(θ M ) in the sequence of the forward and backward correlation coefficients corresponding to the off-wave direction g(θ p ), thereby determining the off-wave direction finding as the corresponding θ p .

[0026] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present application are: using the method proposed in the present application, only a single receiving antenna is needed to receive the multi-carrier radio signals synchronously transmitted by two transmitting antennas to realize off-wave direction finding, which not only can reduce the volume and weight of the receiving end, reduce the complexity of the receiving end and the maintenance cost of different application scenarios, but also can improve the portability of the positioning terminal such as unmanned aerial vehicle. DETAILED DESCRIPTION

[0027] All features disclosed in this specification, or all steps of any methods or processes disclosed in this specification, can be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0028] Any feature disclosed in this specification, unless stated otherwise, can be replaced by any equivalent or similar feature. That is, unless stated otherwise, each feature is one example only of a generic series of equivalent or similar features.

[0029] In the present embodiment, the distance between the two radio transmitting antennas is half of the wavelength of the transmitted signal carrier, i.e. d = 0.5, the number of transmitted signal carriers is N = 121, and the frequency of the n-th carrier is f n= -600 + 10(n-1) kHz, n = 1, 2,..., N; the sampling number of the input signal of the digital-analog converter is K = 3000, and the sampling rate of the digital-analog conversion and the analog-digital conversion is 3 MHz.

[0030] When the actual departure direction is uniformly distributed between 25 degrees and 26 degrees, the search sequence of the departure direction is {θ m = 21 + 0.01(m-1)} degrees, m = 1, 2,..., M, M = 901, and the ratio of the carrier power to the noise power spectrum density of the received signal at one receiving antenna is 24 dB, 2000 independent experiments are performed. The statistical result shows that the standard deviation of the measured departure direction is 0.3873 degrees by using the method.

[0031] It can be seen that the application provides a multi-carrier departure direction finding method with maximum forward-backward correlation coefficient, a single receiving antenna is used to receive the multi-carrier signals synchronously transmitted by two transmitting antennas, the correlation coefficient of the forward-backward sequence formed by the carrier frequency of the transmitting signal and the carrier complex amplitude of the received signal of the single receiving antenna is maximized, and the purpose of measuring the departure direction of the radio signal is achieved.

[0032] The application is not limited to the foregoing specific embodiments. The application extends to any novel feature or any new combination disclosed in this specification, and any novel method or process step or any new combination disclosed.

Claims

1. A method for maximizing the correlation coefficient of the forward and backward sequences of a multi-carrier direction finding system, wherein the distance between two transmitting antennas is defined as d = λ / 2, the number of carriers of the transmitted signal is Nc, the frequency of the nth carrier signal is fn, the number of digital signal samples input to the digital-to-analog converters of the two transmitting antennas is Ns, the digital-to-analog conversion rate is fs, the analog-to-digital conversion rate of the received signal of the receiving antenna is fr, and the number of searched directions of departure is N, characterized in that the nth searched direction of departure is θn = 2πn / N, and the search sequence of the directions of departure is θn = 2πn / N, n = 0, 1, 2,..., N-1. The method comprises the following steps: ​​​​​​​​​​​​​ S1: setting signals transmitted by two transmitting antennas, and inputting first digital signal samples into a digital-to-analog converter at a digital-to-analog conversion rate according to the signals transmitted by the transmitting antennas to obtain a first analog signal; ； Second digital signal samples are: ； S2: setting a receiving antenna to receive a radio signal, determining a digital receiving signal sampled by an analog-to-digital converter at an analog-to-digital conversion rate as , S3: determining an n-th carrier complex amplitude of the received signal according to the digital received signal and a frequency of the n-th carrier signal. ； S4: The search results for the first... The first off-wave direction and the first received signal The carrier complex amplitude is first determined to search for the first... Each wave direction The The forward sequence values ​​are: ； The first wave direction of the search is re-determined as the first backward sequence value: ； S5: determine the corresponding forward and backward correlation coefficients of the first wave departure direction of the search corresponding to the first wave departure direction of the search by the first forward sequence and the backward sequence of the first wave departure direction ​​​​​​ ； S6: determining the maximum value in the sequence of forward and backward correlation coefficients corresponding to the departure direction of the search , thereby determining the departure direction of arrival as the corresponding , thereby determining the departure direction of arrival as the corresponding , wherein: .

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