An efficient channel phase mismatch estimation method for digital transmit arrays

Abstract

An efficient channel phase inconsistency estimation method for a digital transmission array comprises: sequentially opening the i-th transmission channel of the transmission array under test, i=1, ..., N, and recording the power p of the signal received by the receiving end when each transmission channel transmits. i ; According to the received power p i The difference is adjusted in the digital domain at the transmitting end to compensate for the difference in receiving power; the first transmitting channel of the array under test is turned on as the reference channel, and the i-th channel of the array under test is turned on in turn to record the receiving signal power of the test receiving device, and the i-th transmitting channel phase and receiving signal power curve are drawn; the minimum position of the curve is found, and the phase inconsistency value between the i-th transmitting channel and the reference channel is determined. Repeat the above steps until the phase inconsistency test of all N channels is completed. The calibration signal of this application only requires a simple point frequency signal, and no additional calibration circuit is required.

Description

Technical Field

[0001] The present application relates to the technical field of calibration methods for digital transmit array antennas, and in particular to an efficient channel phase inconsistency estimation method for a digital transmit array. Background Art

[0002] Digital array antennas using digital beamforming (DBF) technology have the characteristics of fast beam switching, flexible pattern control, and independent multi-beam forming. They have begun to be widely used in radar, mobile communication and satellite communication systems.

[0003] DBF technology controls the direction and shape of the directional pattern through digital domain amplitude and phase weighting, so the inherent amplitude and phase of each active channel are inconsistent. In particular, the phase inconsistency has a great impact on the performance of the array antenna, and effective estimation and calibration are required. Unlike the receive array calibration, which can quickly perform channel phase calibration by calculating the phase difference of each receive channel receiving the calibration source at the same time, the transmit array requires auxiliary receiving equipment for phase calibration, and the calibration is relatively complex and difficult.

[0004] How to quickly and accurately estimate the phase of the transmit channel has become an urgent problem to be solved in the field of low-cost fast array calibration. Summary of the invention

[0005] The present application provides an efficient channel phase inconsistency estimation method for a digital transmission array, which can be used to solve the technical problem of performing fast and accurate phase estimation of a transmission channel.

[0006] The present application provides an efficient channel phase inconsistency estimation method for a digital transmission array, the method comprising:

[0007] Step 1a, turn on the i-th transmission channel of the tested transmission array in turn, i=1,…,N; send a calibration signal to record the signal power p received by the receiving end when each transmission channel is transmitting i ;The calibration signal is a single-frequency continuous wave signal;

[0008] Step 1b, according to the received power p i The difference in the received power is compensated by adjusting the transmit signal level in the digital domain at the transmitting end; the digital domain amplitude compensation coefficient γ i Determined by:

[0009]

[0010] Step 1c, open the first transmission channel of the array under test as the reference channel, and open the i-th channel (i=2, ..., N) of the array under test in turn, according to To adjust the transmission phase of the i-th transmission channel step by step, send a calibration signal, record the received signal power of the test receiving device respectively, and draw a curve of the i-th transmission channel phase and received signal power;

[0011] Step 1d, find the minimum position of the curve and record the corresponding phase value α i ;

[0012] Step 1e, determine the phase mismatch value between the i-th transmission channel and the reference channel

[0013] β i =α i +180°-δ i (θ0,φ0)(i=2,…,N)

[0014] Among them, δ i (θ0, φ0) is the phase difference introduced between the i-th transmitting channel and the reference channel due to the relative spatial angle relationship (θ0, φ0) between the transmitting array under test and the receiving test system, which is determined by the following method:

[0015]

[0016] Among them, (x1, y1) is the position of the reference transmitting unit antenna, (x i ,y i ) is the position of the ith transmitting unit antenna;

[0017] Step 1f, closing the i-th channel;

[0018] Step 1e, repeat steps (1c) to (1f) until the phase inconsistency test of all N channels is completed.

[0019] Optionally, the test conditions required by the method include:

[0020] Tested transmitting array system, test receiving system and test control module;

[0021] The transmit array system under test includes a transmit digital beamforming module, a radio frequency transmit channel module and a transmit antenna array; the transmit digital beamforming module is used to complete the amplitude and phase weighting of the transmit calibration signal, channel phase calibration, digital up-conversion and digital-to-analog conversion; the radio frequency transmit channel module is used to amplify, mix, up-convert and filter the intermediate frequency analog signal, and then send it to the transmit antenna array for external radiation;

[0022] The test receiving system includes: a connected test receiving antenna and a spectrum analyzer;

[0023] The test control module reads the power value of the received signal;

[0024] The test control module realizes the control and data transmission of the tested transmit array system and the spectrum analyzer through the control and data interface, and completes the efficient channel phase inconsistency estimation method of the digital transmit array.

[0025] Compared with the prior art, this application has the following advantages:

[0026] The calibration signal of the present application only requires a simple point frequency signal, and the method of estimating the inherent phase difference of two transmitting channels in time-sharing order has the characteristics of simple calibration waveform, convenient test system construction, and no need for additional calibration circuit for the digital transmitting array under test.

[0027] The method proposed in the present application utilizes the principle of spatial anti-phase superposition and cancellation of two coherent point-frequency sinusoidal signals to estimate the phase difference between channels. Compared with the method of directly estimating the phase difference between channels, it has the significant advantage of high phase estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a circular array structure with N=7 provided in an embodiment of the present application;

[0029] Figure 2 It is a block diagram of system components of digital transmit array channel calibration provided by an embodiment of the present application;

[0030] Figure 3 is a workflow diagram of digital transmit array channel phase calibration provided by an embodiment of the present application;

[0031] Figure 4 The embodiment of the present application provides a method for changing the phase values ​​of channels 2 to 7 to be measured when implementing the phase calibration of the transmitting channel, and reading the power curve from the spectrum analyzer. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0033] The following first introduces the embodiments of the present application in conjunction with the accompanying drawings.

[0034] The present application provides an efficient channel phase inconsistency estimation method for a digital transmission array, the method comprising:

[0035] The far-field condition is satisfied between the digital transmitting array under test and the test receiving system, and the angular relationship (θ0, φ0) between the two is precisely known; wherein θ0 is the elevation angle relationship between the digital transmitting array under test and the test receiving system, and φ0 is the azimuth angle relationship between the digital transmitting array under test and the test receiving system.

[0036] Step 1a, turn on the i-th transmission channel of the tested transmission array in turn, i = 1, ..., N. Send a calibration signal and record the signal power p received by the receiving end when each transmission channel is transmitting. i ;The calibration signal is a single-frequency continuous wave signal;

[0037] Step 1b, according to the received power p i The difference in the received power is compensated by adjusting the transmit signal level in the digital domain at the transmitting end; the digital domain amplitude compensation coefficient γ i Determined by:

[0038]

[0039] Step 1c, open the first transmission channel of the array under test as the reference channel, and open the i-th channel (i=2, ..., N) of the array under test in turn, according to To adjust the transmission phase of the i-th transmission channel step by step, send a calibration signal, record the received signal power of the test receiving device respectively, and draw a curve of the i-th transmission channel phase and received signal power;

[0040] Step 1d, find the minimum position of the curve and record the corresponding phase value α i ;

[0041] Step 1e, determine the phase mismatch value between the i-th transmission channel and the reference channel

[0042] β i =α i +180°-δ i (θ0,φ0)(i=2,…,N)

[0043] Among them, δ i (θ0, φ0) is the phase difference introduced between the i-th transmitting channel and the reference channel due to the relative spatial angle relationship (θ0, φ0) between the transmitting array under test and the receiving test system, which is determined by the following method:

[0044]

[0045] Among them, (x1, y1) is the position of the reference transmitting unit antenna, (x i ,y i ) is the position of the ith transmitting unit antenna;

[0046] Step 1f, closing the i-th channel;

[0047] Step 1e, repeat steps (1c) to (1f) until the phase inconsistency test of all N channels is completed.

[0048] The test conditions required by the method include:

[0049] Tested transmitting array system, test receiving system and test control module;

[0050] The transmit array system under test includes a transmit digital beamforming module, a radio frequency transmit channel module and a transmit antenna array; the transmit digital beamforming module is used to complete the amplitude and phase weighting of the transmit calibration signal, channel phase calibration, digital up-conversion and digital-to-analog conversion; the radio frequency transmit channel module is used to amplify, mix, up-convert and filter the intermediate frequency analog signal, and then send it to the transmit antenna array for external radiation;

[0051] The test receiving system includes: a connected test receiving antenna and a spectrum analyzer;

[0052] The test control module reads the power value of the received signal;

[0053] The test control module realizes the control and data transmission of the tested transmit array system and the spectrum analyzer through the control and data interface, and completes the efficient channel phase inconsistency estimation method of the digital transmit array

[0054] The present application is described below in conjunction with specific embodiments.

[0055] The present invention is aimed at a digital transmitting array and proposes a method for estimating the phase difference between channels by utilizing the principle of spatial anti-phase superposition cancellation of two coherent point-frequency sinusoidal signals. That is, when the phase difference between two coherent point-frequency signals with the same power is 180°, the synthesized signal is in an anti-phase cancellation state and the power is minimum.

[0056] Use in examples Figure 1 The antenna array structure shown in Table 1 shows the position of each element in the example (x i ,y i )(i=1,2,……,7), λ0 is the array operating wavelength.

[0057] Table 1: Array element position table

[0058]

[0059] The spatial angle between the tested transmitting array and the tested receiving device is (θ0, φ0) = (10°, 60°). Table 2 gives the phase difference between the channels to be tested introduced by this spatial angle.

[0060] Table 2: Phase difference table of the channel to be tested

[0061]

[0062] The calibration test conditions include: the tested transmit array system, the test receiving antenna, the spectrum analyzer and the PC test control software, such as Figure 2 shown.

[0063] The transmit array system under test includes a transmit digital beamforming module, a radio frequency transmit channel module and a transmit antenna array. The transmit digital beamforming module completes the amplitude and phase weighting of the transmit calibration signal, channel phase calibration, digital up-conversion and digital-to-analog conversion; the radio frequency transmit channel module amplifies, mixes, up-converts and filters the intermediate frequency analog signal, and then sends it to the transmit antenna array for external radiation.

[0064] The test receiving antenna is connected to the spectrum analyzer. The test control software can read the power value of the received signal.

[0065] The test control software realizes the control and data transmission of the tested transmitting array system and the spectrum analyzer through the control and data interface, and completes the relevant work flow of the method of the present invention discussed below.

[0066] Figure 3 The flow chart of the transmission channel calibration system of the present invention is given, which mainly includes the following steps:

[0067] (1) Open transmission channels 1 to 7 in sequence and record the power value p received by the receiving antenna when each channel transmits separately. i (i=1,2,…,7). Taking the power p1 of channel 1 as the reference, the power difference with other channels is calculated in turn. According to formula (1), the corresponding power compensation coefficient is calculated in the test control software and sent to the tested transmitting array system to complete the receiving power compensation of each channel. Table 3 shows the comparison table of the initial power, compensation coefficient and compensated power of each channel. It can be seen that the power after compensation is approximately the same, ensuring the effect of subsequent anti-phase superposition cancellation.

[0068] Table 3: Compensation effect comparison table

[0069]

[0070] (2) Open the first transmit channel as the reference array element.

[0071] (3) Open the second transmitting channel, set the corresponding phase value in the test control software with Δφ=5° as the step, generate the calibration coefficient corresponding to the second transmitting channel and send it to the transmitting array system under test, control the second transmitting channel to transmit the calibration signal for phase adjustment, and read the spectrum analyzer power value through the test control software. Traverse 360° and record the power value corresponding to the phase value.

[0072] (4) Select the phase values ​​corresponding to the two minimum power values ​​in step (3) and reduce the step size within the corresponding phase range. Repeat step (3) to read the power value at the corresponding phase and record it.

[0073] (5) Plot the recorded power data in the test control software, such as Figure 4 As shown in the figure, read the shift value α2 when the power value is the smallest.

[0074] (6) According to equations (2) and (3), the phase difference β2 of the second transmission channel relative to the reference channel can be obtained.

[0075] (7) Turn off array element No. 2.

[0076] (8) Repeat steps (3) to (7) to complete the calculation of the phase inconsistency coefficients of the 3rd to 7th transmission channels, as shown in Table 4.

[0077] Table 4: Coefficient table

[0078]

[0079] Compared with the prior art, this application has the following advantages:

[0080] The calibration signal of the present application only requires a simple point frequency signal, and the method of estimating the inherent phase difference of two transmitting channels in time-sharing order has the characteristics of simple calibration waveform, convenient test system construction, and no need for additional calibration circuit for the digital transmitting array under test.

[0081] The method proposed in the present application utilizes the principle of spatial anti-phase superposition and cancellation of two coherent point-frequency sinusoidal signals to estimate the phase difference between channels. Compared with the method of directly estimating the phase difference between channels, it has the significant advantage of high phase estimation accuracy.

[0082] The above-described embodiments of the present application do not constitute a limitation on the protection scope of the present application.

Claims

1. An efficient channel phase inconsistency estimation method for a digital transmit array, characterized in that: The method comprises: Step 1a, turn on the i-th transmission channel of the tested transmission array in turn, i=1,…,N; send a calibration signal, and record the signal power p received by the receiving end when each transmission channel is transmitting. i ;The calibration signal is a single-frequency continuous wave signal; Step 1b, according to the received power p i The difference in the received power is compensated by adjusting the transmit signal level in the digital domain at the transmitter end; the digital domain amplitude compensation coefficient γ i Determined by: Step 1c, open the first transmission channel of the array under test as the reference channel, and open the i-th channel (i=2, ..., N) of the array under test in turn, according to To adjust the transmission phase of the i-th transmission channel step by step, send a calibration signal, record the received signal power of the test receiving device respectively, and draw a curve of the i-th transmission channel phase and received signal power; Step 1d, find the minimum position of the curve and record the corresponding phase value α i ; Step 1e, determine the phase mismatch value between the i-th transmission channel and the reference channel b i =a i +180°-d i (θ0,φ0)(i=2,…,N) Among them, δ i (θ0, φ0) is the phase difference introduced between the i-th transmitting channel and the reference channel due to the relative spatial angle relationship (θ0, φ0) between the transmitting array under test and the receiving test system, which is determined by the following method: Among them, (x1, y1) is the position of the reference transmitting unit antenna, (x i ,y i ) is the position of the ith transmitting unit antenna; Step 1f, closing the i-th channel; Step 1e, repeat steps (1c) to (1f) until the phase inconsistency test of all N channels is completed.

2. The method according to claim 1, characterized in that The test equipment required by the method includes: Tested transmitting array system, test receiving system and test control module; The transmit array system under test includes a transmit digital beamforming module, a radio frequency transmit channel module and a transmit antenna array; the transmit digital beamforming module is used to complete the amplitude and phase weighting of the transmit calibration signal, channel phase calibration, digital up-conversion and digital-to-analog conversion; the radio frequency transmit channel module is used to amplify, mix, up-convert and filter the intermediate frequency analog signal, and then send it to the transmit antenna array for external radiation; The test receiving system includes a connected test receiving antenna and a spectrum analyzer; The test control module reads the power value of the received signal; The test control module realizes the control and data transmission of the tested transmit array system and the spectrum analyzer through the control and data interface, and completes the efficient channel phase inconsistency estimation method of the digital transmit array.

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