A method for amplitude and phase compensation of millimeter-wave broadband radar channels

Abstract

This invention discloses a method for amplitude and phase compensation of a millimeter-wave broadband radar channel, comprising the following steps: S1, performing antenna null alignment under far-field conditions in a microwave anechoic chamber; S2, extracting and calculating the reference amplitude ratio and reference phase difference of the sum and difference paths at different frequency points using the self-calibration signal within the millimeter-wave broadband radar, and storing these values; S3, extracting and calculating the average phase difference between the difference and sum paths at different frequency points using the feed signal received by the millimeter-wave broadband radar, and storing this value; S4, extracting the amplitude ratio and phase difference of the sum and difference paths from the self-calibration at different frequency points of the millimeter-wave broadband radar in real time, calculating and compensating for the changes in the amplitude ratio and phase difference of the real-time self-calibration relative to the fixedly stored reference amplitude ratio and phase difference, and compensating for the fixedly stored average phase difference between the feed differential path and the sum path. This invention utilizes broadband in-system self-calibration and feed calibration to solve the calibration compensation problem of millimeter-wave broadband radar systems.

Description

Technical Field

[0001] This invention relates to the field of radar calibration technology, and in particular to a method for amplitude and phase compensation of millimeter-wave broadband radar channels. Background Technology

[0002] Millimeter-wave radar operates in the millimeter-wave band, typically referring to the 30-300 GHz frequency band with wavelengths of 1-10 mm. The millimeter-wave band offers several advantages: a wider usable bandwidth, higher range resolution, and easier accurate target tracking and identification; a narrower antenna beam, resulting in higher angular resolution and easier detection of small targets. It holds great promise for applications in automotive, guidance, and military fields.

[0003] However, on the one hand, due to the short wavelength of millimeter waves, the self-calibration signal path inside the millimeter wave radar cannot cover the receiving link, and the phase difference introduced by this part of the receiving link may cause the channel phase to flip by 180°, which is a problem that cannot be ignored; on the other hand, the operating bandwidth of millimeter waves is large, and the amplitude and phase differences within the operating bandwidth cannot be characterized by the calibration results of traditional single-frequency signals, nor can they be simply replaced by the calibration results of the data after bandwidth signal accumulation and synthesis, because the results include the effect of amplitude difference weighting within the wide bandwidth. Summary of the Invention

[0004] The purpose of this invention is to propose a method for amplitude and phase compensation of millimeter-wave broadband radar channels, which solves the problems of inability to achieve coverage through in-system self-calibration compensation, channel phase difference calibration compensation, and broadband calibration compensation for differences in millimeter-wave broadband radar receiving channels.

[0005] To achieve the above objectives, the present invention provides a method for amplitude and phase compensation of millimeter-wave broadband radar channels, comprising the following steps:

[0006] S1. Under far-field conditions in a microwave anechoic chamber, perform antenna null alignment;

[0007] S2. Extract and calculate the reference amplitude ratio and reference phase difference of the sum and difference paths at different frequency points through the self-calibration signal of the millimeter-wave broadband radar, and store them in a fixed manner;

[0008] S3. Extract and calculate the average phase difference between the differential path and the sum path at different frequency points from the air-fed signal received by the millimeter-wave broadband radar, and store it in a fixed manner;

[0009] S4. Extract the amplitude ratio and phase difference of the sum and difference paths of the millimeter-wave broadband radar at different frequencies in real time. Calculate and compensate for the changes in the amplitude ratio and phase difference of the sum and difference paths in real time relative to the fixed-stored amplitude ratio and phase difference of the self-calibration reference. Compensate for the average phase difference between the air feed difference path and the sum path in the fixed storage.

[0010] Furthermore, step S1 includes the following steps:

[0011] S11. In a microwave anechoic chamber, the millimeter-wave broadband radar is installed on a two-dimensional turntable, and the two-dimensional turntable is connected to the two-dimensional turntable control device via a cable; the transmitting antenna and receiving antenna of the frequency storage and forwarding signal source are installed on the scanning frame to meet the far-field test conditions.

[0012] S12. Physically align the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration.

[0013] S13. Align the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration.

[0014] Specifically, step S13 is as follows:

[0015] Under the far-field conditions of a microwave anechoic chamber, a millimeter-wave broadband radar operating frequency is selected. A signal at a fixed frequency is transmitted through the transceiver antenna of the millimeter-wave broadband radar. The signal is received, down-converted, stored and forwarded, up-converted and transmitted by the frequency storage and forwarding signal source, and then received by the transceiver antenna of the millimeter-wave broadband radar in an air-feed manner, forming a sum path signal and a difference path signal.

[0016] Control the beam pointing angle of the millimeter-wave broadband radar to adjust it in fixed angular intervals. Calculate and observe the amplitude ratio of the differential signal and the sum signal received at this frequency. The beam pointing angle corresponding to the minimum amplitude ratio is the zero-position alignment position.

[0017] The frequency storage and forwarding signal source includes: an analog source, an up-converter, a down-converter, a receiving antenna, a transmitting antenna, and cables; the analog source is connected to the up-converter and down-converter via cables; the receiving antenna is connected to the down-converter; and the transmitting antenna is connected to the up-converter.

[0018] The millimeter-wave broadband radar provides clock signals, pulse synchronization signals, and frame synchronization signals to the frequency storage and forwarding signal source for signal synchronization between the frequency storage and forwarding signal source and the millimeter-wave broadband radar.

[0019] Furthermore, step S3 includes the following steps:

[0020] S31. Based on the antenna zero-position alignment in step S1, the pointing angle of the millimeter-wave broadband radar beam is deflected along the antenna azimuth and elevation directions.

[0021] S32. The frequency storage and relay signal source transmits an air-fed signal, and the millimeter-wave broadband radar receives the air-fed signal, storing the phase difference φ between the difference path and the sum path at different frequency points. kk (n), where n is the frequency point number and n = 1, 2, ..., N;

[0022] S33. Through multiple measurements, calculate the average phase difference between the differential and sum paths of the air-feed signal at different frequency points.

[0023] Furthermore, step S4 includes the following steps:

[0024] S41. Calculate the change in the amplitude ratio of the sum and difference paths of the real-time in-system self-calibration of the millimeter-wave broadband radar relative to the fixed-stored reference amplitude ratio of the self-calibration sum and difference paths. The calculation formula is ΔA. adj (n)=A' adj (n) / A adj (n), where A' adj (n) represents the amplitude ratio of the sum path and difference path in real-time self-calibration, A adj (n) is the fixed storage of the sum and difference reference amplitudes obtained in step S2;

[0025] S42. Calculate the change in the phase difference between the real-time self-calibrated sum and difference paths relative to the fixed-stored reference phase difference between the self-calibrated sum and difference paths. The calculation formula is: Δφ adj (n)=φ a ' dj (n)-φ adj (n), where φ a ' dj (n) represents the phase difference between the sum and difference paths in real-time self-calibration, φ adj (n) represents the fixed-stored sum and difference path reference phase difference obtained in step S2;

[0026] S43. Compensate for the change in the amplitude ratio of the real-time self-calibrated sum and difference paths relative to the fixed-stored reference amplitude ratio of the self-calibrated sum and difference paths in the difference path data, i.e., A. comp (n)=ΔA adj (n);

[0027] S44. Compensate for the change Δφ between the real-time self-calibrated sum and difference phase difference and the fixed-stored self-calibrated sum and difference reference phase difference in the difference path data. adj (n) and the average phase difference between the differential path and the sum path of the air feeder. The difference, i.e.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This invention proposes a test calibration method that combines air feed calibration and in-machine calibration, which solves the problems of incomplete coverage by in-machine self-calibration and channel phase difference calibration compensation.

[0030] 2. This invention establishes a self-calibration benchmark result and combines it with the real-time self-calibration result of each power-on to achieve real-time compensation for the amplitude and phase difference changes of the self-calibration loop, thus solving the problem of repeated calibration after the millimeter-wave broadband radar receiving system is installed, disassembled, or the echo cable is replaced.

[0031] 3. This invention solves the problem of calibration and compensation for amplitude and phase difference changes in a wide bandwidth signal (including instantaneous wide bandwidth signals and frequency step signals, etc.). It is also applicable to small bandwidth or point frequency signals, has high universality, and has great engineering application value.

[0032] 4. This invention has a wide range of applications, applicable to both three-channel millimeter-wave broadband radar channel amplitude and phase compensation with a sum and difference device, and multi-channel digital sum and difference millimeter-wave broadband radar without a sum and difference device. Attached Figure Description

[0033] Figure 1 This is a flowchart of the millimeter-wave broadband radar channel amplitude and phase compensation method of the present invention;

[0034] Figure 2 This is a schematic diagram of the calibration scenario of the present invention;

[0035] Figure 3 The present invention provides the in-system self-calibration and the reference amplitude ratio and reference phase difference of the millimeter-wave broadband radar.

[0036] Figure 4 This refers to the average difference between the air-feed signal and the channel phase difference in this invention. Detailed Implementation

[0037] The technical content, structural features, objectives and effects of the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0038] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0039] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0040] This invention provides a method for amplitude and phase compensation of millimeter-wave broadband radar channels, and the specific construction steps are as follows:

[0041] S1. Under the far-field test conditions in a microwave anechoic chamber, perform antenna null alignment. The specific steps are as follows:

[0042] S11. In a microwave anechoic chamber, the millimeter-wave broadband radar is installed on a two-dimensional turntable, and the two-dimensional turntable is connected to the two-dimensional turntable control device via a cable; the transmitting antenna and receiving antenna of the frequency storage and forwarding signal source are installed on the scanning frame to meet the far-field test conditions.

[0043] Among them, such as Figure 2 As shown, the frequency storage and forwarding signal source includes: an analog source, an up-converter, a down-converter, a receiving antenna, a transmitting antenna, and cables; the analog source is connected to the up-converter and down-converter respectively via cables; the receiving antenna is connected to the down-converter; and the transmitting antenna is connected to the up-converter.

[0044] S12. Physically align (coarsely align) the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration, that is, align the normal of the transceiver antenna of the millimeter-wave broadband radar with the normal of the transmitting antenna of the frequency storage and relay signal source so that the two are basically on the same straight line.

[0045] S13. Align the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration; specifically:

[0046] Under the far-field conditions of a microwave anechoic chamber, a millimeter-wave broadband radar operating frequency can be selected. The signal of the fixed frequency point is transmitted through the transceiver antenna of the millimeter-wave broadband radar. After passing through the receiving antenna of the frequency storage and forwarding signal source, down-converter, and analog source frequency storage and forwarding, it is transmitted through the up-converter and transmitting antenna. Then, it is received by the transceiver antenna of the millimeter-wave broadband radar in an open-feed manner. The sum and difference signals are formed by using a sum and difference converter or digital sum and difference processing.

[0047] By controlling the beam pointing angle of the millimeter-wave broadband radar, it is adjusted in fixed angular intervals within a range not less than its beam width. During this adjustment process, the amplitude ratio of the differential signal and the sum signal received by the air feeder at this frequency is calculated and observed. The beam pointing angle corresponding to the minimum amplitude ratio is the zero-position alignment position.

[0048] S2. Generate a self-calibration signal using a millimeter-wave broadband radar. Feed this self-calibration signal into the sum and difference paths of the millimeter-wave broadband radar with equal amplitude and phase, and extract the reference amplitude ratio A of the sum and difference paths at different frequency points. adj (n) and the reference phase difference φ adj (n), and store them in a fixed location.

[0049] S3. Transmit an air-fed signal through a frequency storage and relay signal source. The millimeter-wave broadband radar receives this air-fed signal and extracts the average phase difference between the difference path and the sum path at different frequency points. And store it in a fixed location. The specific steps are as follows:

[0050] S31. Based on the antenna null alignment in step S1, the millimeter-wave broadband radar beam pointing angle is deflected along the azimuth and elevation directions of the transmitting and receiving antennas. The deflection angle is taken as a reference to be close to the amplitude of the actual received sum and difference signals. The deflection angle generally does not exceed half the beamwidth.

[0051] S32. The frequency storage and relay signal source transmits an air-fed signal, and the millimeter-wave broadband radar receives the air-fed signal, storing the phase difference φ between the difference path and the sum path at different frequency points. kk (n), where n is the frequency point number and n = 1, 2, ..., N;

[0052] S33. Calculate the average phase difference between the differential and sum paths of the air-feed signal at different frequency points through long-term or multiple measurements.

[0053] S4. Real-time extraction of the sum and difference amplitude ratio A' of the internal self-calibrated circuit at different frequencies of the millimeter-wave broadband radar. adj (n), phase difference φ a ' dj (n), calculate and compensate the real-time self-calibrated sum and difference amplitude ratio and phase difference relative to the fixed-stored sum and difference reference amplitude ratio A. adj (n), reference phase difference φ adj The change in (n) is compensated for by the average phase difference between the fixed-stored differential path and the sum path. The specific steps are as follows:

[0054] S41. Calculate the change in the amplitude ratio of the sum and difference paths of the real-time in-system self-calibration of the millimeter-wave broadband radar relative to the fixed-stored reference amplitude ratio of the self-calibration sum and difference paths. The calculation formula is ΔA. adj (n)=A'adj (n) / A adj (n), where A' adj (n) represents the amplitude ratio of the sum path and difference path in real-time self-calibration, A adj (n) is the fixed storage of the sum and difference reference amplitudes obtained in step S2;

[0055] S42. Calculate the change in the phase difference between the real-time self-calibrated sum and difference paths relative to the fixed-stored reference phase difference between the self-calibrated sum and difference paths. The calculation formula is: Δφ adj (n)=φ a ' dj (n)-φ adj (n), where φ a ' dj (n) represents the phase difference between the sum and difference paths in real-time self-calibration, φ adj (n) represents the fixed-stored sum and difference path reference phase difference obtained in step S2;

[0056] S43. Compensate for the change in the amplitude ratio of the real-time self-calibrated sum and difference paths relative to the fixed-stored reference amplitude ratio of the self-calibrated sum and difference paths in the difference path data, i.e., A. comp (n)=ΔA adj (n);

[0057] S44. Compensate for the change Δφ between the real-time self-calibrated sum and difference phase difference and the fixed-stored self-calibrated sum and difference reference phase difference in the difference path data. adj (n) and the average phase difference between the differential path and the sum path of the air feeder. The difference, i.e.

[0058] In this preferred embodiment, such as Figure 1 As shown, the millimeter-wave broadband radar is first installed on a two-dimensional turntable in a rectangular microwave anechoic chamber, and then connected to the power supply and acquisition equipment via cables. The millimeter-wave broadband radar provides clock signals, pulse synchronization signals, and frame synchronization signals to the frequency storage and forwarding signal source for synchronization with the millimeter-wave broadband radar signal. The analog source in the frequency storage and forwarding signal source is connected to the up-converter and down-converter via cables to transmit and receive signals. The up-converter and down-converter complete signal reception and transmission through receiving antennas and transmitting antennas.

[0059] After that, as Figure 2 As shown, the reference amplitude ratio A of different frequency points and path and difference paths is extracted and stored through the self-calibration signal of the millimeter-wave broadband radar. adj (n) and the reference phase difference φ adj (n).

[0060] like Figure 3As shown, based on the antenna null alignment, the millimeter-wave broadband radar beam pointing angle is deflected along the azimuth and elevation directions of the transmitting and receiving antennas. The frequency storage and relay signal source is turned on, and the millimeter-wave broadband radar receives the air-fed signal from the frequency storage and relay signal source, preserving the phase difference φ between the differential path and the sum path at different frequency points. kk (n) is calculated by long-term or multiple measurements to determine the average phase difference between the differential path and the sum path of the air-feed signal at different frequency points.

[0061] Finally, the mean phase difference between the differential path and the sum path is compensated, as well as the amplitude ratio and phase difference change of the sum path and differential path in the millimeter-wave broadband radar's internal self-calibration system.

[0062] In summary, compared with the prior art, the millimeter-wave radar channel amplitude and phase compensation method proposed in this invention can solve the problem that millimeter-wave broadband radar cannot achieve coverage through in-system self-calibration compensation, as well as the problem of non-negligible channel phase difference calibration compensation.

[0063] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for amplitude and phase compensation of a millimeter-wave broadband radar channel, characterized in that, Includes the following steps: S1. Under far-field conditions in a microwave anechoic chamber, perform antenna null alignment; S11. In a microwave anechoic chamber, the millimeter-wave broadband radar is installed on a two-dimensional turntable, and the two-dimensional turntable is connected to the two-dimensional turntable control device via a cable; the transmitting antenna and receiving antenna of the frequency storage and forwarding signal source are installed on the scanning frame to meet the far-field test conditions. S12. Physically align the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration. S13. Align the transceiver antenna of the millimeter-wave broadband radar on the two-dimensional turntable with the transmitting antenna of the frequency storage and relay signal source used for calibration at the zero position. Specifically, S13 is: Under the far-field conditions of a microwave anechoic chamber, a millimeter-wave broadband radar operating frequency is selected. A signal at a fixed frequency is transmitted through the transceiver antenna of the millimeter-wave broadband radar. The signal is received, down-converted, stored and forwarded, up-converted and transmitted by the frequency storage and forwarding signal source, and then received by the transceiver antenna of the millimeter-wave broadband radar in an air-feed manner, forming a sum path signal and a difference path signal. The beam pointing angle of the millimeter-wave broadband radar is controlled and adjusted in steps at fixed angular intervals. The amplitude ratio of the differential signal and the sum signal received by the air-fed radar at this frequency is calculated and observed. The beam pointing angle corresponding to the minimum amplitude ratio is the zero-position alignment position. S2. Extract and calculate the reference amplitude ratio and reference phase difference of the sum and difference paths at different frequency points through the self-calibration signal of the millimeter-wave broadband radar, and store them in a fixed manner; S3. Extract and calculate the average phase difference between the differential path and the sum path at different frequency points from the air-fed signal received by the millimeter-wave broadband radar, and store it in a fixed manner; S31. Based on the antenna zero-position alignment in step S1, the pointing angle of the millimeter-wave broadband radar beam is deflected along the antenna azimuth and elevation directions. S32. The frequency storage and relay signal source transmits an air-fed signal, and the millimeter-wave broadband radar receives the air-fed signal, storing the phase difference φ between the difference path and the sum path at different frequency points. kk (n), where n is the frequency point number and n = 1, 2, ... N; S33. Through multiple measurements, calculate the average phase difference between the differential and sum paths of the air-feed signal at different frequency points. S4. Extract the amplitude ratio and phase difference of the sum and difference paths of the millimeter-wave broadband radar at different frequencies in real time. Calculate and compensate for the changes in the amplitude ratio and phase difference of the sum and difference paths in real time relative to the fixed-stored amplitude ratio and phase difference of the self-calibration reference. Compensate for the average phase difference between the air feed difference path and the sum path in the fixed storage.

2. The millimeter-wave broadband radar channel amplitude and phase compensation method as described in claim 1, characterized in that, The frequency storage and forwarding signal source includes: an analog source, an up-converter, a down-converter, a receiving antenna, a transmitting antenna, and cables; the analog source is connected to the up-converter and down-converter respectively via cables; the receiving antenna is connected to the down-converter; and the transmitting antenna is connected to the up-converter.

3. The millimeter-wave broadband radar channel amplitude and phase compensation method as described in claim 1, characterized in that, The millimeter-wave broadband radar provides clock signals, pulse synchronization signals, and frame synchronization signals to the frequency storage and forwarding signal source for signal synchronization between the frequency storage and forwarding signal source and the millimeter-wave broadband radar.

4. The millimeter-wave broadband radar channel amplitude and phase compensation method as described in claim 1, characterized in that, Step S4 includes the following steps: S41. Calculate the change in the amplitude ratio of the sum and difference paths of the real-time in-system self-calibration of the millimeter-wave broadband radar relative to the fixed-stored reference amplitude ratio of the self-calibration sum and difference paths. The calculation formula is ΔA. adj (n)=A' adj (n) / A adj (n), where A' adj (n) represents the amplitude ratio of the sum path and difference path in real-time self-calibration, A adj (n) is the fixed storage of the sum and difference reference amplitudes obtained in step S2; S42. Calculate the change in the phase difference between the real-time self-calibrated sum and difference paths relative to the fixed-stored reference phase difference between the self-calibrated sum and difference paths. The calculation formula is: Δφ adj (n)=φ' adj (n)-φ adj (n), where φ' adj (n) represents the phase difference between the sum and difference paths in real-time self-calibration, φ adj (n) represents the fixed-stored sum and difference path reference phase difference obtained in step S2; S43. Compensate for the change in the amplitude ratio of the real-time self-calibrated sum and difference paths relative to the fixed-stored reference amplitude ratio of the self-calibrated sum and difference paths in the difference path data, i.e., A. comp (n)=ΔA adj (n); S44. Compensate for the change Δφ between the real-time self-calibrated sum and difference phase difference and the fixed-stored self-calibrated sum and difference reference phase difference in the difference path data. adj (n) and the average phase difference between the differential path and the sum path of the air feeder. The difference, i.e.

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