A phase optimization method for shortwave phase-controlled synthesis based on multi-tone test signals

Abstract

The present invention discloses a shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal, comprising the following steps: S1) determining the number of tones to be transmitted, the tone frequency combination, and the array antenna combination used for transmission at each frequency; S2) performing single-tone synthesis transmission at each tone frequency according to the corresponding array antenna combination and a set additional phase difference combination; S3) a receiving end collecting received signals containing all transmitted tone frequencies; S4) establishing a set of equations based on the transmission configuration parameters and the energy combination of the received signal, and obtaining an estimated value of the transmission phase difference through solution; S5) modifying the additional phase difference in process S2) based on the solved transmission phase difference, and repeating process S2)-S4) until a set iteration termination condition is met. Through the above-mentioned method, the present invention is used to solve the problem of synthesis efficiency being affected by poor synthesis phase setting in shortwave phase-controlled synthesis.

Description

Technical Field

[0001] The present invention relates to the fields of radio electronics and signal processing technology, in particular to a shortwave phase-controlled synthesis phase optimization method based on multi-tone test signals. Background Art

[0002] Shortwave can achieve long-distance skywave transmission through the ionosphere. Compared to satellite communications, it is inexpensive and highly resilient, making it widely used in military communications, civilian emergency communications, and civilian broadcasting. Long-distance shortwave communications or broadcasting require a significant equivalent radiated power. While a single high-power amplifier and large antenna can achieve the desired transmission effect, this approach is often expensive to build and difficult to maintain, resulting in significant costs. A more economical solution for shortwave high-power transmission is to utilize multiple amplifiers and antenna arrays for shortwave phased-control synthesis.

[0003] Shortwave phased synthesis technology feeds the same signal with a set synthetic phase into different transmission channels of the transmitting array, and uses the synthetic phase difference to compensate for the transmission phase difference from different antennas to the receiving antenna, thereby realizing the forward superposition and effective synthesis of the transmission signals of multiple transmitting channels in the receiving area. By changing the phase difference between the transmitting channels, the beam pointing of the transmitting array can be flexibly adjusted to meet the directional high-power transmission requirements in different areas.

[0004] When transmitting high-power signals, to ensure the antenna gain and transmission efficiency, the size of the transmitting antenna is generally proportional to the signal wavelength. For shortwave communication systems with lower operating frequencies and longer wavelengths, the size of the transmitting antenna is often much larger than that of ultra-shortwave and satellite frequency bands. At the same time, to adapt to the different available communication frequency bands at different communication distances and in different skywave propagation environments, broadband shortwave antennas that can operate over a wide frequency band and have high gain are usually used. Logarithmic periodic antennas are a commonly used shortwave, wide-band, high-gain antenna. Due to their high gain and wide frequency band characteristics, logarithmic periodic antennas are also commonly used antennas for shortwave phased-control synthesis. However, their antenna size is large, and the phase center at different frequencies is not fixed and difficult to calculate accurately. In shortwave phased-control synthesis applications, the estimation of the antenna phase center directly affects the accurate calculation of the phase, and affects the synthesis efficiency and equivalent radiated power of the shortwave phased-control synthesis.

[0005] Therefore, in the actual application of shortwave phased-control synthesis, how to more accurately obtain the synthetic phase of shortwave phased-control synthesis and improve the synthesis efficiency of shortwave synthetic transmission has always been the focus and difficulty of shortwave phased-control synthesis. Summary of the Invention

[0006] The main technical problem solved by the present invention is to provide a shortwave phased synthesis phase optimization method based on multi-tone test signals, which solves the problem that the shortwave phased synthesis efficiency is affected by the difficulty in accurately calculating the phased synthesis phase in shortwave phased array synthesis.

[0007] To solve the above technical problems, the present invention adopts a technical solution: providing a shortwave phased array phase optimization method based on a multi-tone test signal, which optimizes the phased array phase of a shortwave phased array by transmitting and receiving a specific multi-tone test signal and solving a set of equations, including the following steps:

[0008] S1) According to the number of antennas in the transmitting array and the actual operating frequency, determine the number of single tones to be transmitted, the combination of single tone frequencies and the array antenna combination used for transmission at each frequency. Transmitting antenna array and actual operating frequency , determine the number of tones to be transmitted , corresponding single tone frequency combination and the number of transmit antennas at each frequency Combined with an array antenna, where the number of transmitted tones meets , while the Tone frequency Array antenna combination on , should satisfy , , and when hour, ;

[0009] S2) Perform single-tone synthesis transmission at each single-tone frequency according to the corresponding array antenna combination and the set additional phase difference combination. Tone frequency , according to the Calculate the additional phase difference of the different transmission channels at the single tone frequency. The transmission channel is in The additional phase at the tone frequency is performed simultaneously Synthetic emission of a single tone frequency;

[0010] S3) The receiving end collects all transmitted single tone frequencies The received signal is then calculated by calculating the received energy at each tone frequency position. , get the energy combination of different single-tone frequency received signals ;

[0011] S4) Using the array antenna combination, additional phase difference combination and received signal energy combination, combined with the physical transmission model to construct the equations, and obtain the estimated value of the transmission phase difference caused by the different transmission delays from different transmitting antennas to receiving antennas through the solution. , and then the phase-controlled synthetic phase that compensates for the phase difference can be obtained ;

[0012] S5) Modify the additional phase difference in step S2) based on the transmission phase difference obtained in step S4), and repeat steps S2) to S4) until the calculated transmission phase difference meets the set convergence condition or reaches the set fixed number of iterations, and output the optimized synthetic phase corresponding to the calculated transmission phase difference: .

[0013] Furthermore, in step S1), in order to facilitate the solution of the equations, the number of transmitting antennas at each single tone frequency is Set to 2, taking into account the number of unknowns to be solved and the removal of ambiguity when solving the equation, the single tone frequency is set to 3 as a group to solve the transmission phase difference of a pair of antennas. In the transmitting array composed of two antennas For independent transmission phase differences, a total of The group tone frequency, therefore, the total number of tones used for transmission To avoid the influence of frequency selective fading, the frequency of each tone in the same array antenna combination should be as close as possible and close to the actual operating frequency. , for The three corresponding tone frequency numbers are: 、 、 ,(in is a positive integer), the corresponding transmit array antenna combination can be selected as ,in , Representatives Round up.

[0014] Furthermore, in step S2), the input signals of the transmission channels corresponding to the different array antennas are single-tone signals with different additional phases set. Group tone frequency using transmit antenna combination When launching, 、 、 The three frequencies set on The transmission channel and The difference of the additional phase of the transmitting channels is 、 、 , then in 、 、 On these three frequencies, The additional phase on each transmit channel is set to 0. The additional phases on the transmit channels are set to 、 、 , considering the errors caused by non-ideal factors such as frequency selective fading and background noise in sky wave transmission in actual application scenarios, the error impact of non-ideal factors is reduced by optimizing the additional phase difference combination. According to the analysis, the additional phase difference 、 、 When the values ​​are different, the non-ideal factors affect the transmission phase difference (No. Second antenna and Antenna frequency The influence of the calculation error of the phase difference caused by different transmission paths is different; in particular, when the additional phase difference 、 、 One of the values ​​is When the non-ideal factors The error caused is minimal; due to the transmission phase difference As the number to be determined is unknown, the first When setting the RF signal, in order to improve the convergence speed, the transmission delay difference obtained by short-wave array antenna simulation can be used. As The estimated value of Set to .

[0015] Furthermore, in step S3), the received energy of each single tone signal is calculated according to the following principle: :

[0016] For the signal received by the receiving antenna, the time domain expression of the signal is first converted into the amplitude spectrum in the frequency domain through FFT transformation. , the frequency domain resolution of the obtained spectrum should be no less than 4 times the minimum value of the single tone frequency interval in the frequency combination;

[0017] Using the amplitude spectrum in the frequency domain Calculate the When the signal energy of a single tone frequency position is selected, the one closest to the transmitted single tone frequency should be selected. The energy of the three spectral lines is taken as the energy of the single tone signal. ,Right now ,in For the The energy of the root spectral line corresponds to the square of the spectral line amplitude value.

[0018] Further, in step S4), the following method is used to utilize the The calculation of the frequency of the tone Second antenna and The equations required to calculate the transmission phase difference of the transmission path of the two antennas are:

[0019] When Group tone frequency using transmit antenna combination When transmitting, at the frequency 、 、 Previous The transmission channel and The additional phase difference of each transmitting channel is 、 、 , let The received signal at the tone frequency is , the amplitude of the single-tone signal transmitted by each antenna at a single frequency is , the receiving antenna receives the The initial phase of the signal transmitted by the secondary antenna is , No. Second antenna and Antenna frequency The phase difference caused by different transmission paths is , then according to the signal transmission model, under ideal conditions, 、 、 The signals received on these three frequencies can be used to construct the following set of equations:

[0020] Formula (1),

[0021] 、 、 and the actual operating frequency If the settings are close enough, the phase difference caused by the transmission delay is approximately equal, so and available Perform unified replacement, and equation (1) can be simplified to:

[0022] Formula (2),

[0023] Combine the first and second equations in equation (2), combine the first and third equations, and square the combined equations. In addition, let the first equation received in step S3) be 、 、 The energy at each frequency is 、 、 , we can get the following set of equations:

[0024] Formula (3),

[0025] Further simplifying formula (3) yields:

[0026] Formula (4).

[0027] Furthermore, in step S4), the transmission phase difference and the optimized composite phase are calculated using the following method:

[0028] For the first equation in (4), let , , , , which can be further simplified as:

[0029] Formula (5),

[0030] In formula (5), there is only one unknown quantity , which can be used to identify Solve the quadratic equation and calculate , the quadratic equation can be calculated to have 2 solutions, and according to Calculate 0 to Within the range There are also two possibilities (the inverse sine angle is blurred between the first and second quadrants, and blurred between the third and fourth quadrants), so the solution calculated by formula (5) is There are 4 possible fuzzy solutions;

[0031] In order to select the correct solution from the four possible fuzzy solutions, the second equation in equation (4) is used as the verification of the fuzzy solution, and the error is selected. The minimum solution is used as the estimated value of the transmission phase difference , where the error as follows:

[0032] ,

[0033] right The antenna combination and single tone frequency are calculated according to the Second antenna and Transmission phase difference of the antenna , further calculate the The transmission phase difference between the second antenna and the first antenna , and obtain the corresponding transmission phase difference combination , thus obtaining the optimized synthetic phase combination for compensating the transmission phase difference: .

[0034] Furthermore, in step S5), the iteration termination condition can be set to a fixed times, or it can be set to the value obtained from two adjacent iterations. The absolute value of the difference is less than a certain threshold.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The optimized shortwave phase-controlled synthesis phase can be obtained through multiple iterations, thereby improving the synthesis efficiency and equivalent radiated power of the shortwave phase-controlled synthesis. In addition to being applicable to shortwave phase-controlled synthesis, the method of the present invention can also be used for phase-controlled synthesis applications in other frequency bands. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of phased composite emission.

[0038] Figure 2 Schematic diagram of a shortwave phase-controlled synthesis phase optimization method based on multi-tone test signals.

[0039] Figure 3 This is a block diagram of the main implementation process of a shortwave phase-controlled synthesis phase optimization method based on multi-tone test signals.

[0040] Figure 4 Schematic diagram of multi-tone test signal.

[0041] Figure 5 Schematic diagram of the iterative calculation of the transmission phase difference.

[0042] Figure 6 Schematic diagram of the iterative situation of phase-controlled synthesis efficiency. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0044] See also Figures 1 to 6 , embodiments of the present invention include:

[0045] Consider a typical communication scenario of a communication transmitting station and a communication receiving station. Assume that the communication transmitting station sets up a transmitting antenna array composed of 4 pairs of shortwave logarithmic periodic antennas, and the communication receiving station uses a single antenna for reception. The communication transmitting station uses 4 pairs of logarithmic periodic antennas to perform phased synthesis communication transmission at a frequency of 10MHz. The communication receiving station is required to receive the signal quality as good as possible. Assuming that at a frequency of 10MHz, the signal is transmitted from the first The second transmitting antenna reaches the receiving antenna and the Phase difference from the transmitting antenna to the receiving antenna The values ​​are as follows:

[0046] .

[0047] The specific implementation process of the present invention for a shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal is as follows:

[0048] S1) Determine the number, frequency and array antenna combination of the transmitted test signals based on the number of transmitting antennas. , you can set Group tone frequencies, with 3 tone frequencies in each group, for a total of 9 test tone frequencies. The frequencies can be set to 9 frequencies with an interval of 100 Hz in the frequency range from 9999.6 kHz to 10000.4 kHz. The array antenna combinations corresponding to the 3 groups of tone frequencies are {1, 2}, {2, 3}, and {3, 4}, respectively.

[0049] S2) Set appropriate additional phase difference on each tone frequency and perform synthesis transmission. 3 tone frequencies within the group, using antenna combination Perform single-tone synthesis transmission at frequency 、 、 Set the Second antenna and The additional phase difference of the auxiliary antenna is 、 、 In addition, it is assumed that the initial transmission phase difference estimate obtained by the antenna simulation software has a certain deviation as follows:

[0050] ,

[0051] You can set the first additional phase difference for:

[0052] ,

[0053] other 、 The value of Different values;

[0054] S3) Calculate the energy of the received signal at different tone frequencies. Since the tone frequency interval set in step S1) is 100 Hz, the frequency resolution when calculating the amplitude spectrum should be no less than 25 Hz. That is, take no less than 40 ms of data to perform FFT calculation to obtain the amplitude spectrum.

[0055] S4) Establish the equations and solve the transmission phase difference , for The equations established for the combination of single tone frequency and antenna array are:

[0056] ,

[0057] in, 、 is the ratio calculated using the measured energy values, 、 is the ratio under ideal error-free conditions, 、 The energy ratio measurement error caused by various factors is usually the logarithm of the energy ratio measurement error. 、 Can be controlled within 5dB, that is 、 ;

[0058] Using errors and settings 、 、 Can be calculated separately 、 、 、 The value of , , , , and can solve the following equations:

[0059] ,

[0060] The unknown quantity to be obtained Two values ​​of 、 , proceed in sequence 、 The arcsine transformation gives the four fuzzy solutions of the equation:

[0061] ,

[0062] Substitute the four fuzzy solutions into the following equations one by one, and select the equation that makes the error Minimum value As an estimate of the transmission phase difference , then the synthetic phase used to compensate for the transmission phase difference can be obtained, where the error as follows:

[0063] ;

[0064] S5) Modify the additional phase difference of the multi-tone test signal according to the calculated transmission phase difference, and repeat the above S2), S3), S4) process, where the updated .

[0065] Figure 5 It is the iterative calculation of the transmission phase difference. The horizontal axis is the number of iterations. The transmission phase difference corresponding to the horizontal axis 0 is the initial value obtained using the antenna simulation software. It can be seen that after multiple iterations, the calculated transmission phase difference The transmission phase difference will be close to the ideal .

[0066] Synthesis efficiency of phase-controlled synthesis It can directly reflect the effectiveness of synthetic emission, and its expression is as follows:

[0067] ,

[0068] in, For the The composite phase on each channel is:

[0069] .

[0070] Figure 6 This is the change in synthesis efficiency with the number of iterations when the calculated synthetic phase is used for synthesis. The horizontal axis is the number of iterations, and the synthesis efficiency corresponding to the horizontal axis 0 is the result of synthesis based on the initial value obtained by the antenna simulation software. From the simulation results, it can be seen that the synthesis efficiency increases from the initial 91% to the final 99%, indicating that the synthetic phase optimization method of the present invention can achieve higher synthesis efficiency.

[0071] The present invention provides a shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal, which can obtain an optimized shortwave phase-controlled synthesis phase through multiple iterations, thereby improving the synthesis efficiency and equivalent radiation power of the shortwave phase-controlled synthesis.

[0072] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal, characterized by: The following steps are involved: S1) According to the number of antennas in the transmitting array and the actual operating frequency, determine the number of single tones to be transmitted, the combination of single tone frequencies and the array antenna combination used for transmission at each frequency. Transmitting antenna array and actual operating frequency , determine the number of tones to be transmitted , corresponding single tone frequency combination and the number of transmit antennas at each frequency Combined with an array antenna, where the number of transmitted tones meets , while the Tone frequency Array antenna combination on ,satisfy , , and when hour, To facilitate the solution of the equations, the number of transmitting antennas at each single tone frequency is Set to 2, taking into account the number of unknowns to be solved and the removal of ambiguity when solving the equation, the single tone frequency is set to 3 as a group to solve the transmission phase difference of a pair of antennas. In the transmitting array composed of two antennas For independent transmission phase differences, a total of The group tone frequency, therefore, the total number of tones used for transmission indivual; S2) Perform single-tone synthesis transmission at each single-tone frequency according to the corresponding array antenna combination and the set additional phase difference combination. Tone frequency , synthesize and transmit according to the corresponding array antenna combination and the set additional phase difference combination at each single tone frequency, where Calculate the first The additional phase on the transmit channel is Single tone synthesis emission on frequency; S3) The receiving end collects the received signals containing all the transmitted single-tone frequencies, and calculates the received energy of each single-tone frequency position to obtain the energy combination of the received signals of different single-tone frequencies. Tone frequency The received signal is calculated and the energy of the received signal at each tone frequency position is calculated. , get the energy combination of the received signal ; S4) Using the array antenna combination, additional phase difference combination and received signal energy combination, combined with the physical transmission model, the equations are constructed, and the transmission phase difference caused by the different transmission delays from different transmitting antennas to receiving antennas is obtained by solving the equations. , and then obtain the phase-controlled synthetic phase that compensates for the phase difference ; Use the following method to use The calculation of the frequency of the tone Second antenna and The equations required to calculate the transmission phase difference of the transmission path of the two antennas are: When Group tone frequency using transmit antenna combination }When launching, The transmission channel and The transmit channels are at frequencies 、 、 The difference of the additional phase is 、 、 , No. Second antenna and Antenna frequency The phase difference caused by different transmission paths is ,frequency 、 、 and operating frequency Set close enough, Second antenna and Antenna frequency The transmission phase difference on the frequency The upper approximation is equal, using Indicates that, in addition, the first 、 、 The energy at each frequency is 、 、 , after simplification, we can get the following system of equations: Formula (1), Solving this set of equations can obtain the transmission phase difference; S5) Modify the additional phase difference in step S2) based on the transmission phase difference obtained in step S4), and repeat steps S2) to S4) until the calculated transmission phase difference meets the set convergence condition or reaches the set fixed number of iterations, and output the optimized synthetic phase corresponding to the calculated transmission phase difference: .

2. The shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal according to claim 1, characterized in that: In step S1), in order to avoid the influence of frequency selective fading, the frequency of each tone of the same array antenna combination is close to the actual working frequency. , for The three corresponding tone frequency numbers are: 、 、 ,in, is a positive integer, and the corresponding transmit array antenna combination is selected as ,in , Representatives Round up.

3. The shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal according to claim 1, characterized in that: In step S2), the input signals of the transmission channels corresponding to different array antennas are single-tone signals with different additional phases set. Group tone frequency using transmit antenna combination When launching, 、 、 The three frequencies set on The transmission channel and The difference of the additional phase of the transmitting channels is 、 、 , then in 、 、 On these three frequencies, The additional phase on each transmit channel is set to 0. The additional phases on the transmit channels are 、 、 To reduce the impact of non-ideal factors, the additional phase difference 、 、 One of the values ​​is , due to the transmission phase difference As the number to be determined is unknown, the first In order to improve the convergence speed, the transmission delay difference obtained by shortwave array antenna simulation is used. As The estimated value of Set to .

4. The shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal according to claim 1, characterized in that: In step S3), the received energy of each single tone signal is calculated according to the following principle: : For the signal received by the receiving antenna, the time domain expression of the signal is first converted into the amplitude spectrum in the frequency domain through FFT transformation. , the frequency domain resolution of the obtained spectrum should be no less than 4 times the minimum value of the single tone frequency interval in the frequency combination; Using frequency domain amplitude spectrum Calculate the When the signal energy of the single tone frequency position is selected, the single tone frequency closest to the transmitted 1 spectral line, and the two spectral lines on the left and right sides of it, calculate the energy sum of these three spectral lines as the energy of the single tone signal ,Right now ,in For the ( ) The energy of the root spectral line corresponds to the square of the spectral value of the spectral line amplitude.

5. The shortwave phase-controlled synthesis phase optimization method based on a multi-tone test signal according to claim 1, characterized in that: In step S4), the transmission phase difference and the optimized composite phase are calculated using the following method: For the first equation in formula (1), let , , , , which can be further simplified as: Formula (2), By solving formula (2) There are 4 possible fuzzy solutions. In order to select the correct solution from the above 4 possible fuzzy solutions, the second equation in formula (1) is used as the verification of the fuzzy solution. The error is selected. The minimum solution is taken as the estimated transmission phase difference , where the error as follows: ， right The antenna combination and single tone frequency are calculated according to the Second antenna and Transmission phase difference of the antenna ( , further calculate the The transmission phase difference between the second antenna and the first antenna , and obtain the corresponding transmission phase difference combination , thus obtaining the optimized synthetic phase combination for compensating the transmission phase difference: .

Images