Method and system for calibrating relative signal time delay of link of deep-space large-aperture antenna

Abstract

The invention discloses a method and system for calibrating relative signal time delay of a link of a deep space large-aperture antenna, and the method comprises the steps: building a coordinate system based on a to-be-calibrated antenna and a reference antenna, and determining a signal phase difference caused by the spatial path difference between the to-be-calibrated antenna and the reference antenna in an antenna array and a satellite; obtaining a downlink signal relative phase difference and an uplink signal relative phase difference of the antenna to be calibrated relative to the reference antenna in the antenna array based on a signal phase difference caused by a space path difference between the antenna to be calibrated and the satellite and between the reference antenna and the satellite; obtaining a relative signal time delay value of a link of the antenna; and according to the relative signal time delay value of the own link of the antenna, compensating the own link of the antenna to be calibrated so as to realize the signal time delay of the own uplink and downlink of each antenna of the calibration array. The method is simple and reliable, and signal delay calibration of an uplink and a downlink of a deep-space large-aperture antenna can be conveniently realized.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a method and system for calibrating the relative signal delay of a deep space large-aperture antenna's own link. Background Art

[0002] Antenna arraying is a method for improving the signal-to-noise ratio (SNR) of received or transmitted signals by combining signals from multiple antennas. Due to its flexibility and low engineering cost, antenna arrays have gained increasing attention in deep space exploration in recent years, becoming a hot area of ​​research for novel antenna systems.

[0003] Signal synthesis in an antenna array typically utilizes delay compensation to align the signal delays of each antenna in the array to a common reference point, thereby improving the signal-to-noise ratio of the received or transmitted signal. The signal delay of each antenna in the array consists of two components: the signal delay along the spatial path and the signal delay along the antenna's own uplink and downlink links. Therefore, a key technical challenge in antenna array implementation is how to calibrate the signal delays of each antenna in the array. A key element in signal delay calibration lies in forming a signal loop to calibrate the loop delay of the signal. In engineering implementation, this is typically accomplished by constructing a far-field calibration tower and using a calibration antenna to loop back the signal to measure the antenna's uplink and downlink signal delays. However, for large-aperture deep-space antennas, the long distances required for far-field conditions make the construction of a far-field calibration tower often difficult to implement. Summary of the Invention

[0004] In view of this, the present application provides a method and system for calibrating the relative signal delay of the deep space large-aperture antenna's own link, which uses the signal transparent forwarding mechanism of the on-orbit satellite to measure the antenna's uplink and downlink delays.

[0005] The present application discloses a method for calibrating the relative signal delay of a deep space large-aperture antenna's own link, which includes:

[0006] Step 1: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, and determine the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna in the antenna array and the satellite. The reference antenna is any antenna in the antenna array, and the antenna to be calibrated is any antenna in the antenna array except the reference antenna.

[0007] Step 2: Based on the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna and the satellite, the relative phase difference of the downlink signal and the relative phase difference of the uplink signal of the antenna to be calibrated relative to the reference antenna in the antenna array are obtained;

[0008] Step 3: Use the phase difference slope estimation method to obtain the relative signal delay value of the antenna's own link;

[0009] Step 4: Compensate the link of the antenna to be calibrated based on the relative signal delay value of the antenna's own link to calibrate the uplink and downlink signal delay of each antenna in the array.

[0010] Furthermore, the step 1 includes:

[0011] Step 11: The uplink signal generated by the antenna link delay calibration unit passes through the antenna's uplink RF channel and is then sent to the space target through the antenna interface. The space target forwards the uplink signal to the downlink frequency point for loopback. After being received by the antenna, the signal is looped back to the antenna link delay calibration unit through the antenna's downlink RF channel. The space target is a satellite.

[0012] Step 12: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, select a virtual far-field target from the line connecting the space target and the coordinate origin of the coordinate system, and obtain the coordinate value of the virtual far-field target in the coordinate system through the azimuth and elevation angles of the virtual far-field target in the coordinate system; based on the coordinate value, obtain the signal phase difference caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite.

[0013] Furthermore, the step 12 includes:

[0014] The baseline of antenna A and antenna B is taken as the x-axis, the midpoint of the baseline is taken as the origin O, and the y-axis is established on the horizontal plane where antenna A and antenna B are located through the origin O. The z-axis is established in the direction perpendicular to the horizontal plane to establish the coordinate system Oxyz. Antenna A is any antenna to be calibrated in the antenna array, antenna B is the reference antenna, and the space target T0 is a satellite.

[0015] Assume the coordinates of antenna A are (x A ,y A ,z A ), the coordinates of antenna B are (x B ,y B ,z B ), and assume that the azimuth angle of the space target T0 that meets the far-field condition in this coordinate system is φ A , the pitch angle is φ E ; Select a virtual far-field target T1 on the line connecting the origin O and the space target T0, and make the distance L between the virtual far-field target T1 and the origin O T1 Satisfy the far-field condition, that is, L T1 >min 远场 , min 远场is the minimum distance threshold between antenna A and antenna B that meets the far-field condition; the coordinate value (x T1 ,y T1 ,z T1 ):

[0016]

[0017] And the distance L from antenna A and antenna B to the virtual far-field target T1 is obtained according to the following formula: A and L B :

[0018]

[0019] The spatial path difference between antenna A and antenna B and space target T0 is the spatial path difference ΔL between them and virtual far-field target T1. AB Approximately, it is calculated according to the following formula:

[0020] ΔL AB =L A -L B (9)

[0021] The signal phase difference Δθ′ caused by the spatial path difference between antenna A and antenna B and the satellite is calculated according to the following formula: 空间路径AB :

[0022]

[0023] Where: c is the speed of light, and f is the frequency of the calibration signal.

[0024] Furthermore, the step 2 includes:

[0025] Step 21: The antenna link delay calibration unit uses the coherent phase estimation method to process the downlink signal forwarded by the on-orbit satellite received by the antenna to be calibrated and the reference antenna, and obtains the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna. 下行信号AB ;

[0026] Step 22: Based on the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号AB , and the signal phase difference Δθ′ caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite 空间路径AB , the signal phase difference Δθ′ caused by the difference in the downlink between the antenna to be calibrated and the reference antenna is obtained 下行链路AB , i.e. the relative phase difference of the downlink signal;

[0027] Step 23: Based on the relative phase difference of the downlink signal and the loop delay of the signal, the relative phase difference of the uplink of the antenna to be calibrated relative to the reference antenna is obtained.

[0028] Furthermore, the step 21 includes:

[0029] The relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号A1 The expression is:

[0030]

[0031] Where Δθ 空间路径B is the signal phase change caused by the space path between antenna A and the satellite in orbit; Δθ 空间路径B is the signal phase change caused by the space path between antenna B and the satellite in orbit; Δθ 下行链路A is the signal phase change value brought by the downlink of antenna A itself; Δθ 下行链路B is the signal phase change value brought by the downlink of antenna B itself; antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0032] The step 22 includes:

[0033] The signal phase difference caused by the difference in the downlink of antenna A and B is Δθ′ 下行链路AB for:

[0034] Δθ′ 下行链路AB =Δθ 下行信号AB -Δθ′ 空间路径AB (2).

[0035] Furthermore, the step 23 includes:

[0036] Step 231: Time-sharing uplink signals are sent to antennas A and B in the array, and then forwarded by the satellite and received and processed by antennas A and B; the phase change value Δθ of the signal formed by the closed loop between antenna A and the satellite in orbit is measured. 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B ; Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0037] Step 232: Based on the signal phase change value Δθ formed by the closed loop between antenna A and the satellite in orbit 上行环路A The signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B , the signal phase difference caused by the difference in the uplink of antenna A and B is Δθ′ 上行链路AB .

[0038] Furthermore, the step 231 includes:

[0039] The signal phase change value Δθ of the closed loop formed by antenna A and the satellite in orbit 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B They are:

[0040]

[0041] Where Δθ 上行链路A is the phase change of the signal brought by the uplink of antenna A; Δθ 空间路径A is the signal phase change caused by the signal passing through the space path between the satellite and antenna A; Δθ 卫星 The signal phase change value brought by the satellite equipment; Δθ 下行链路A is the phase change of the signal brought by the downlink of antenna A; Δθ 上行链路B is the phase change of the signal brought by the uplink of antenna B; Δθ 空间路径B is the signal phase change caused by the signal passing through the space path between the satellite and antenna B; Δθ 下行链路B is the phase change of the signal brought by the downlink of antenna B;

[0042] The step 232 includes:

[0043] Δθ 上行环路A and Δθ 上行环路B Perform subtraction to obtain the phase difference Δθ 上行环路AB for:

[0044]

[0045] According to formula (4), we can get:

[0046]

[0047] Furthermore, the step 1 includes:

[0048] The relative phase difference of the signal of antenna A relative to antenna B is calibrated with the signal frequency f1. The relative phase difference of the signal of antenna A relative to antenna B's own link is calibrated with the signal frequency f2 Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0049] According to the phase difference slope estimation method, the final relative signal delay difference Δτ of antenna A relative to antenna B is obtained. AB for:

[0050]

[0051] The present application also discloses a system for calibrating the relative signal delay of a deep space large-aperture antenna's own link, and implements the above-mentioned method for calibrating the relative signal delay of a deep space large-aperture antenna's own link, which includes an antenna link delay calibration unit, an antenna array, a satellite, a calculation unit, and a compensation unit; each antenna in the antenna array has an uplink radio frequency channel and a downlink radio frequency channel;

[0052] The antenna link delay calibration unit is used to generate an uplink signal and send it to the uplink radio frequency channel of the antenna in the antenna array; the uplink signal is sent to the satellite through the antenna interface after passing through the uplink radio frequency channel; the satellite is used to forward the uplink signal to the downlink frequency point loopback, and it is received by the antenna in the antenna array; the antenna in the antenna array is used to loop the received signal back to the antenna link delay calibration unit through its downlink radio frequency channel;

[0053] The antenna link delay calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna according to the received signal and send them to the calculation unit;

[0054] The calculation unit is used to obtain the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna based on the signal it receives, and send it to the compensation unit;

[0055] The compensation unit is used to compensate the link of the antenna to be calibrated according to the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna, so as to calibrate the signal delay of the uplink and downlink of each antenna in the array.

[0056] Furthermore, the antenna link delay calibration unit is composed of a link selection unit, a link calibration signal generator, a signal phase compensation unit and a link phase calibration unit;

[0057] The link calibration signal generator is used to generate a link phase calibration signal and send it to the link selection unit; the link phase calibration signal is an uplink signal;

[0058] The link selection unit is used to select one link from the received signals and send it to the antenna to be calibrated and the reference antenna;

[0059] The signal phase compensation unit is used to obtain the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite based on the received looped downlink signals sent by the antenna to be calibrated and the reference antenna, and send it to the link phase calibration unit;

[0060] The link phase calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna itself based on the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite.

[0061] Due to the adoption of the above technical solution, this application has the following advantages:

[0062] This approach solves the problem of calibrating the relative signal delay of large-aperture antenna links. Leveraging the transparent forwarding capabilities of on-orbit satellites, this method establishes a calibration loop between the antennas in the array and the satellite, effectively calibrating the relative signal delay of each antenna in the array. This approach enables signal synthesis in large-aperture antenna arrays, resolving a key issue in large-aperture antenna array system design.

[0063] The present invention is simple to implement, consumes few resources, and reduces system design costs. Complex circuitry is not required, and implementation is relatively simple. The present invention utilizes existing system equipment, eliminating the need for additional equipment. It also uses a software algorithm to calibrate the relative signal delay of the array antenna system's signal link, facilitating automated operation and reducing system design costs.

[0064] The purpose is to provide a simple, reliable and easy-to-implement method for calibrating the signal delay of the uplink and downlink of deep space large-aperture antennas. This method does not require any external equipment and is convenient for designing deep space large-aperture antenna array systems that meet the index requirements in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0066] Figure 1 This is a schematic diagram of the antenna in an embodiment of the present application using a far-field space target to calibrate the relative delay difference of the antenna's own link.

[0067] Figure 2 It is a structural diagram of the antenna link delay difference calibration embodiment of the present application.

[0068] Figure 3 It is a structural diagram of the antenna link delay calibration unit of an embodiment of the present application.

[0069] Figure 4 This is a schematic diagram of the antenna of an embodiment of the present application using a far-field space target to calibrate the antenna's own downlink phase difference.

[0070] Figure 5 This is a schematic diagram of the antenna of an embodiment of the present application using a far-field space target to calibrate the antenna's own uplink phase difference.

[0071] Figure 6 It is a schematic diagram of the time delay difference caused by the spatial path difference of the signal from the calculation antenna to the far-field space target in an embodiment of the present application.

[0072] Figure 7 This is a flow chart of the antenna of an embodiment of the present application using a far-field space target to calibrate the relative delay difference of the antenna's own link. DETAILED DESCRIPTION

[0073] The present application is further described with reference to the accompanying drawings and embodiments. The embodiments described are only a part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present application.

[0074] A crucial technical challenge in implementing antenna arrays is calibrating the signal delays of each antenna in the array, both uplink and downlink. Traditionally, antenna delay calibration is accomplished by building a far-field calibration tower and looping back signals from a calibration antenna on the tower. However, building a far-field calibration tower for large-aperture deep-space antennas is difficult to implement, so alternative methods are needed.

[0075] See also Figure 1 The present application provides an embodiment of a method for calibrating the relative signal delay of an antenna's own link, which includes:

[0076] Step 1: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, and determine the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna in the antenna array and the satellite. The reference antenna is any antenna in the antenna array, and the antenna to be calibrated is any antenna in the antenna array except the reference antenna.

[0077] Step 2: Based on the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna and the satellite, the relative phase difference of the downlink signal and the relative phase difference of the uplink signal of the antenna to be calibrated relative to the reference antenna in the antenna array are obtained;

[0078] Step 3: Use the phase difference slope estimation method to obtain the relative signal delay value of the antenna's own link;

[0079] Step 4: Compensate the link of the antenna to be calibrated based on the relative signal delay value of the antenna's own link to calibrate the uplink and downlink signal delay of each antenna in the array.

[0080] This application utilizes the transparent forwarding function of on-orbit communication satellites, which is simple, reliable and easy to implement. It can meet the needs of self-link delay calibration of large-aperture antennas in engineering practice. Using this method, a deep-space large-aperture antenna array system that meets the index requirements can be designed in engineering practice.

[0081] Optionally, step 1 includes:

[0082] Step 11: The uplink signal generated by the antenna link delay calibration unit passes through the antenna's uplink RF channel and is then sent to the space target through the antenna interface. The space target forwards the uplink signal to the downlink frequency point for loopback. After being received by the antenna, the signal is looped back to the antenna link delay calibration unit through the antenna's downlink RF channel. The space target is a satellite.

[0083] Step 12: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, select a virtual far-field target from the line connecting the space target and the coordinate origin of the coordinate system, and obtain the coordinate value of the virtual far-field target in the coordinate system through the azimuth and elevation angles of the virtual far-field target in the coordinate system; based on the coordinate value, obtain the signal phase difference caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite.

[0084] Optionally, step 12 includes:

[0085] The baseline of antenna A and antenna B is taken as the x-axis, the midpoint of the baseline is taken as the origin O, and the y-axis is established on the horizontal plane where antenna A and antenna B are located through the origin O. The z-axis is established in the direction perpendicular to the horizontal plane to establish the coordinate system Oxyz. Antenna A is any antenna to be calibrated in the antenna array, antenna B is the reference antenna, and the space target T0 is a satellite.

[0086] Assume the coordinates of antenna A are (x A ,y A ,z A ), the coordinates of antenna B are (x B ,y B ,z B ), and assume that the azimuth angle of the space target T0 that meets the far-field condition in this coordinate system is φ A , the pitch angle is φ E ; Select a virtual far-field target T1 on the line connecting the origin O and the space target T0, and make the distance L between the virtual far-field target T1 and the origin O T1 Satisfy the far-field condition, that is, L T1 >min 远场 , min远场 is the minimum distance threshold between antenna A and antenna B that meets the far-field condition; the coordinate value (x T1 ,y T1 ,z T1 ):

[0087]

[0088] And the distance L from antenna A and antenna B to the virtual far-field target T1 is obtained according to the following formula: A and L B :

[0089]

[0090] The spatial path difference between antenna A and antenna B and space target T0 is the spatial path difference ΔL between them and virtual far-field target T1. AB Approximately, it is calculated according to the following formula:

[0091] ΔL AB =L A -L B (9)

[0092] The signal phase difference Δθ′ caused by the spatial path difference between antenna A and antenna B and the satellite is calculated according to the following formula: 空间路径AB :

[0093]

[0094] Where: c is the speed of light, and f is the frequency of the calibration signal.

[0095] Optionally, step 2 includes:

[0096] Step 21: The antenna link delay calibration unit uses the coherent phase estimation method to process the downlink signal forwarded by the on-orbit satellite received by the antenna to be calibrated and the reference antenna, and obtains the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna. 下行信号AB ;

[0097] Step 22: Based on the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号AB , and the signal phase difference Δθ′ caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite 空间路径AB , the signal phase difference Δθ′ caused by the difference in the downlink between the antenna to be calibrated and the reference antenna is obtained 下行链路AB , i.e. the relative phase difference of the downlink signal;

[0098] Step 23: Based on the relative phase difference of the downlink signal and the loop delay of the signal, the relative phase difference of the uplink of the antenna to be calibrated relative to the reference antenna is obtained.

[0099] Optionally, step 21 includes:

[0100] The relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号AB The expression is:

[0101]

[0102] Where Δθ 空间路径A is the signal phase change caused by the space path between antenna A and the satellite in orbit; Δθ 空间路径B is the signal phase change caused by the space path between antenna B and the satellite in orbit; Δθ 下行链路A is the signal phase change value brought by the downlink of antenna A itself; Δθ 下行链路B is the signal phase change value brought by the downlink of antenna B itself; antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0103] The step 22 includes:

[0104] The signal phase difference caused by the difference in the downlink of antenna A and B is Δθ′ 下行链路AB for:

[0105] Δθ′ 下行链路AB =Δθ 下行信号AB -Δθ′ 空间路径AB (2).

[0106] Optionally, step 23 includes:

[0107] Step 231: Time-sharing uplink signals are sent to antennas A and B in the array, and then forwarded by the satellite and received and processed by antennas A and B; the phase change value Δθ of the signal formed by the closed loop between antenna A and the satellite in orbit is measured. 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B ; Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0108] Step 232: Based on the signal phase change value Δθ formed by the closed loop between antenna A and the satellite in orbit 上行环路A The signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B , the signal phase difference caused by the difference in the uplink of antenna A and B is Δθ′ 上行链路AB .

[0109] Optionally, step 231 includes:

[0110] The signal phase change value Δθ of the closed loop formed by antenna A and the satellite in orbit 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B They are:

[0111]

[0112] Where Δθ 上行链路A is the phase change of the signal brought by the uplink of antenna A; Δθ 空间路径A is the signal phase change caused by the signal passing through the space path between the satellite and antenna A; Δθ 卫星 The signal phase change value brought by the satellite equipment; Δθ 下行链路A is the phase change of the signal brought by the downlink of antenna A; Δθ 上行链路B is the phase change of the signal brought by the uplink of antenna B; Δθ 空间路径B is the signal phase change caused by the signal passing through the space path between the satellite and antenna B; Δθ 下行链路B is the phase change of the signal brought by the downlink of antenna B;

[0113] The step 232 includes:

[0114] The phase difference Δθ measured by the two loops of antenna A and B is 上行环路AB for:

[0115]

[0116] According to formula (4), we can get:

[0117]

[0118] Optionally, step 1 includes:

[0119] The relative phase difference of the signal of antenna A relative to antenna B is calibrated with the signal frequency f1. The relative phase difference of the signal of antenna A relative to antenna B's own link is calibrated with the signal frequency f2 Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna;

[0120] According to the phase difference slope estimation method, the final relative signal delay difference Δτ of antenna A relative to antenna B is obtained. AB for:

[0121]

[0122] The present application also provides an embodiment of a system for calibrating the relative signal delay of an antenna's own link, which implements the method for calibrating the relative signal delay of an antenna's own link as described in the above embodiment, comprising an antenna link delay calibration unit, an antenna array, a satellite, a calculation unit, and a compensation unit; each antenna in the antenna array has an uplink radio frequency channel and a downlink radio frequency channel;

[0123] The antenna link delay calibration unit is used to generate an uplink signal and send it to the uplink radio frequency channel of the antenna in the antenna array; the uplink signal is sent to the satellite through the antenna interface after passing through the uplink radio frequency channel; the satellite is used to forward the uplink signal to the downlink frequency point loopback, and it is received by the antenna in the antenna array; the antenna in the antenna array is used to loop the received signal back to the antenna link delay calibration unit through its downlink radio frequency channel;

[0124] The antenna link delay calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna according to the received signal and send them to the calculation unit;

[0125] The calculation unit is used to obtain the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna based on the signal it receives, and send it to the compensation unit;

[0126] The compensation unit is used to compensate the link of the antenna to be calibrated according to the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna, so as to calibrate the signal delay of the uplink and downlink of each antenna in the array.

[0127] Optionally, the antenna link delay calibration unit is composed of a link selection unit, a link calibration signal generator, a signal phase compensation unit and a link phase calibration unit;

[0128] The link calibration signal generator is used to generate a link phase calibration signal and send it to the link selection unit; the link phase calibration signal is an uplink signal;

[0129] The link selection unit is used to select one link from the received signals and send it to the antenna to be calibrated and the reference antenna;

[0130] The signal phase compensation unit is used to obtain the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite based on the received looped downlink signals sent by the antenna to be calibrated and the reference antenna, and send it to the link phase calibration unit;

[0131] The link phase calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna itself based on the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite.

[0132] This application does not require the establishment of a far-field calibration tower for the antenna array system, and can meet the requirements for the antenna calibration's own link signal delay, thereby simplifying the system design.

[0133] For ease of understanding, this application provides a more specific embodiment:

[0134] See Figure 1 and Figure 2 Through the signal forwarding function of the satellite in orbit, the antennas in the antenna array can be used to calibrate the signal delay of the antenna's own link. Figure 1 As shown, two antennas A and B can establish uplink and downlink signal loops with the satellite in orbit. By comparing the delay difference of the signal loops of the two antennas, the relative delay difference of the uplink and downlink of antennas A and B can be measured. Figure 2 As shown, the antenna link delay calibration unit generates an uplink signal and sends it to the uplink RF link of the antenna, which is then sent to the space target through the antenna interface. The space target forwards the signal to the downlink frequency point loopback, and after being received by the antenna, it is looped back to the antenna link delay calibration unit through the downlink RF link of the antenna for processing.

[0135] See Figure 3 The antenna link delay calibration unit consists of a link selection unit, a link calibration signal generator, a signal phase compensation unit, and a link phase calibration unit. The link calibration signal generator generates a link phase calibration signal and sends it to antenna A or antenna B after link selection. Simultaneously, antennas A and B receive the looped downlink signal, which is then passed through the signal phase compensation unit and sent to the line phase calibration unit to determine the relative phase difference between the uplink and downlink of antennas A and B. This phase difference is then sent to the system monitoring process to determine the relative delay difference of the antennas themselves.

[0136] See Figure 4 , antennas A and B receive downlink signals forwarded by on-orbit satellites, and the antenna link delay calibration unit performs correlation processing. According to the coherent phase estimation method, the relative phase difference Δθ of the signals received by antennas A and B can be obtained. 下行信号AB The relative phase difference includes the relative signal delay difference caused by the path difference of the signals received by antennas A and B, and the relative signal phase difference caused by the difference in the downlink of antennas A and B, that is:

[0137]

[0138] Where: Δθ空间路径A is the signal phase change caused by the space path between antenna A and the satellite in orbit; Δθ 空间路径B is the signal phase change caused by the space path between antenna B and the satellite in orbit; Δθ 下行链路A is the signal phase change value brought by the downlink of antenna A itself; Δθ 下行链路B is the signal phase change value brought by the downlink of antenna B itself; the signal phase difference caused by the difference in the spatial paths of antennas A and B is Δθ′ 空间路径AB =Δθ 空间路径A -Δθ 空间路径B The signal phase difference caused by the difference in the downlink of antenna A and B is Δθ′ 下行链路AB =Δθ 下行链路A -Δθ 下行链路B .

[0139] If we know the signal phase difference Δθ′ caused by the difference in the spatial paths of antennas A and B 空间路径AB The signal phase difference Δθ′ caused by the difference in the spatial paths of antennas A and B can be deducted from the signal phase compensation unit in the antenna link delay calibration unit. 空间路径AB Finally, the signal phase difference caused by the difference in the downlink of antenna A and B is Δθ′ 下行链路AB , that is:

[0140] Δθ′ 下行链路AB =Δθ 下行信号AB -Δθ′ 空间路径AB (2)

[0141] See Figure 5 , the calibration of the relative phase difference of the antenna's own uplink can be obtained through the loop delay of the signal. Figure 5 As shown, antennas A and B in the array send uplink signals in a time-sharing manner, and after being forwarded by the satellite, they are received and processed by antennas A and B. The signal phase change value Δθ of the closed loop formed by antenna A and the satellite in orbit can be measured through algorithm processing. 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B for:

[0142]

[0143] Where Δθ 上行链路A is the phase change of the signal brought by the uplink of antenna A; Δθ 空间路径A is the signal phase change caused by the signal passing through the space path between the satellite and antenna A; Δθ 卫星 The signal phase change value brought by the satellite equipment; Δθ 下行链路Ais the phase change of the signal brought by the downlink of antenna A; Δθ 上行链路B is the phase change of the signal brought by the uplink of antenna B; Δθ 空间路径B is the signal phase change caused by the signal passing through the space path between the satellite and antenna B; Δθ 下行链路B is the phase change of the signal brought by the downlink of antenna B. The phase difference Δθ measured by the two loops of antenna A and B is 上行环路AB for:

[0144]

[0145] Since the signal phase difference Δθ′ caused by the difference in the downlink of antennas A and B has been obtained in formula (2), 下行链路AB , and knowing the signal phase difference Δθ′ caused by the difference in the spatial paths of antennas A and B 空间路径AB Therefore, the signal phase difference caused by the difference in the uplink of antenna A and B can be obtained by deducting these two phase differences in the signal phase compensation unit in the antenna link delay calibration unit, which is Δθ′ 上行链路AB , that is:

[0146]

[0147] See Figure 6 Since the distance between the satellite and antennas A and B is generally more than several hundred kilometers, which is much greater than the far-field conditions of antennas A and B, the far-field conditions of the satellite to the antenna can be used to calculate the relative spatial phase difference Δθ′ caused by the spatial path difference between antennas A and B and the satellite. 空间路径AB .like Figure 6 As shown, the baseline of antennas A and B is selected as the x-axis, the midpoint of the baseline is selected as the origin O, and the y-axis is established on the horizontal plane where antennas A and B are located through the origin, and the z-axis is established in the direction perpendicular to the horizontal plane to establish the coordinate system Oxyz. Assume that the coordinates of antenna A are (x A ,y A ,z A ), the coordinates of antenna B are (x B ,y B ,z B ), and assume that the azimuth angle of the space target T0 that meets the far-field condition in this coordinate system is The pitch angle is A virtual far-field target T1 can be selected on the line connecting the origin O and T0, and the distance L between T1 and the origin O is T1 Satisfy the far-field condition, that is, L T1 >min 远场 , here min 远场is the minimum distance threshold of the far-field condition of antennas A and B. Therefore, the coordinate value (x T1 ,y T1 ,z T1 ):

[0148]

[0149] And according to the following algorithm, the distance L from antenna A and B to the virtual far-field target T1 is obtained: A and L B :

[0150]

[0151] According to the previous analysis, the spatial path difference between antennas A and B and the real satellite T0 can be expressed as the spatial path difference ΔL between the two antennas and the virtual far-field target T1. AB To approximate, it is calculated according to the following algorithm:

[0152] ΔL AB =L A -L B (9)

[0153] The spatial path difference ΔL between antennas A and B is obtained. AB After that, the phase difference Δθ′ of the signal caused by the difference in spatial paths between antennas A and B can be calculated according to the following algorithm: 空间路径 AB:

[0154]

[0155] Where: c is the speed of light; f is the frequency of the calibration signal.

[0156] See Figure 7 ,like Figure 7 As shown in the figure, the process of calibrating the relative signal delay of the antenna's own link for satellite is as follows: Using the satellite in orbit according to the above method, the relative phase difference of the signal of antenna A relative to antenna B's own link is calibrated at the signal frequency f1. The relative phase difference of the signal of antenna A relative to antenna B's own link is calibrated with the signal frequency f2 According to the phase difference slope estimation method, the final relative signal delay difference Δτ of antenna A relative to antenna B is obtained. AB for:

[0157]

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present application should be included in the scope of protection of the claims of the present application.

Claims

1. A method for calibrating the relative signal delay of a deep space large-aperture antenna's own link, characterized in that: include: Step 1: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, and determine the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna in the antenna array and the satellite; The reference antenna is any antenna in the antenna array, and the antenna to be calibrated is any antenna in the antenna array except the reference antenna. Step 2: Based on the signal phase difference caused by the spatial path difference between the antenna to be calibrated and the reference antenna and the satellite, the relative phase difference of the downlink signal and the relative phase difference of the uplink signal of the antenna to be calibrated relative to the reference antenna in the antenna array are obtained; Step 3: Use the phase difference slope estimation method to obtain the relative signal delay value of the antenna's own link; Step 4: Compensate the link of the antenna to be calibrated based on the relative signal delay value of the antenna's own link to calibrate the uplink and downlink signal delay of each antenna in the array.

2. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 1, characterized in that: The step 1 comprises: Step 11: The uplink signal generated by the antenna link delay calibration unit passes through the antenna's uplink RF channel and is then sent to the space target through the antenna interface. The space target forwards the uplink signal to the downlink frequency point for loopback. After being received by the antenna, the signal is looped back to the antenna link delay calibration unit through the antenna's downlink RF channel. The space target is a satellite. Step 12: Establish a coordinate system based on the antenna to be calibrated and the reference antenna, select a virtual far-field target from the line connecting the space target and the coordinate origin of the coordinate system, and obtain the coordinate value of the virtual far-field target in the coordinate system through the azimuth and elevation angles of the virtual far-field target in the coordinate system; based on the coordinate value, obtain the signal phase difference caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite.

3. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 2, characterized in that: The step 12 comprises: The baseline of antenna A and antenna B is taken as the x-axis, the midpoint of the baseline is taken as the origin O, and the y-axis is established on the horizontal plane where antenna A and antenna B are located through the origin O. The z-axis is established in the direction perpendicular to the horizontal plane to establish the coordinate system Oxyz. Antenna A is any antenna to be calibrated in the antenna array, antenna B is the reference antenna, and the space target T0 is a satellite. Assume the coordinates of antenna A are (x A ,y A ,z A ), the coordinates of antenna B are (x B ,y B ,z B ), and assume that the azimuth angle of the space target T0 that meets the far-field condition in this coordinate system is φ A , the pitch angle is φ E ; Select a virtual far-field target T1 on the line connecting the origin O and the space target T0, and make the distance L between the virtual far-field target T1 and the origin O T1 Satisfy the far-field condition, that is, L T1 >min 远场 , min 远场 is the minimum distance threshold between antenna A and antenna B that meets the far-field condition; the coordinate value (x T1 ,y T1 ,z T1 ): And the distance L from antenna A and antenna B to the virtual far-field target T1 is obtained according to the following formula: A and L B : The spatial path difference between antenna A and antenna B and space target T0 is the spatial path difference ΔL between them and virtual far-field target T1. AB Approximately, it is calculated according to the following formula: ΔL AB =L A -L B (9) The signal phase difference Δθ′ caused by the spatial path difference between antenna A and antenna B and the satellite is calculated according to the following formula: 空间路径AB : Where: c is the speed of light, and f is the frequency of the calibration signal.

4. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 1, characterized in that: The step 2 includes: Step 21: The antenna link delay calibration unit uses the coherent phase estimation method to process the downlink signal forwarded by the on-orbit satellite received by the antenna to be calibrated and the reference antenna, and obtains the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna. 下行信号AB ; Step 22: Based on the relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号AB , and the signal phase difference Δθ′ caused by the spatial path difference between the antenna to be calibrated, the reference antenna and the satellite 空间路径AB , the signal phase difference Δθ′ caused by the difference in the downlink between the antenna to be calibrated and the reference antenna is obtained 下行链路AB , i.e. the relative phase difference of the downlink signal; Step 23: Based on the relative phase difference of the downlink signal and the loop delay of the signal, the relative phase difference of the uplink of the antenna to be calibrated relative to the reference antenna is obtained.

5. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 4, characterized in that: The step 21 includes: The relative phase difference Δθ between the signals received by the antenna to be calibrated and the reference antenna 下行信号AB The expression is: Where Δθ 空间路径A is the signal phase change caused by the space path between antenna A and the satellite in orbit; Δθ 空间路径B is the signal phase change caused by the space path between antenna B and the satellite in orbit; Δθ 下行链路A is the signal phase change value brought by the downlink of antenna A itself; Δθ 下行链路B is the signal phase change value brought by the downlink of antenna B itself; antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna; The step 22 includes: The signal phase difference caused by the difference in the downlink of antenna A and B is Δθ′ 下行链路AB for: Δθ′ 下行链路AB =Δθ 下行信号AB -Δθ′ 空间路径AB (2)。 6. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 4, characterized in that: The step 23 includes: Step 231: Time-sharing uplink signals are sent to antennas A and B in the array, and then forwarded by the satellite and received and processed by antennas A and B; the phase change value Δθ of the signal formed by the closed loop between antenna A and the satellite in orbit is measured. 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B ; Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna; Step 232: Based on the signal phase change value Δθ formed by the closed loop between antenna A and the satellite in orbit 上行环路A The signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B , the signal phase difference caused by the difference in the uplink of antenna A and B is Δθ′ 上行链路AB .

7. The method for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 6, characterized in that: The step 231 includes: The signal phase change value Δθ of the closed loop formed by antenna A and the satellite in orbit 上行环路A And the signal phase change value Δθ of the closed loop formed by antenna B and the satellite in orbit 上行环路B The expressions are: Where Δθ 上行链路A is the phase change of the signal brought by the uplink of antenna A; Δθ 空间路径A is the signal phase change caused by the signal passing through the space path between the satellite and antenna A; Δθ 卫星 The signal phase change value brought by the satellite equipment; Δθ 下行链路A is the phase change of the signal brought by the downlink of antenna A; Δθ 上行链路B is the phase change of the signal brought by the uplink of antenna B; Δθ 空间路径B is the signal phase change caused by the signal passing through the space path between the satellite and antenna B; Δθ 下行链路B is the phase change of the signal brought by the downlink of antenna B; The step 232 includes: Δθ 上行环路A and Δθ 上行环路B Perform subtraction to obtain the phase difference Δθ 上行环路A1 for: According to formula (4), we can get:

8. The method for calibrating the relative signal delay of a deep space large aperture antenna according to claim 6, characterized in that: The step 1 comprises: The relative phase difference of the signal of antenna A relative to antenna B is calibrated with the signal frequency f1. The relative phase difference of the signal of antenna A relative to antenna B's own link is calibrated with the signal frequency f2 Antenna A is any antenna to be calibrated in the antenna array, and antenna B is the reference antenna; According to the phase difference slope estimation method, the final relative signal delay difference Δτ of antenna A relative to antenna B is obtained. AB for:

9. A system for calibrating the relative signal delay of a deep space large-aperture antenna's own link, implementing the method for calibrating the relative signal delay of a deep space large-aperture antenna's own link according to any one of claims 1 to 8, characterized in that: It includes an antenna link delay calibration unit, an antenna array, a satellite, a calculation unit, and a compensation unit; each antenna in the antenna array has an uplink radio frequency channel and a downlink radio frequency channel; The antenna link delay calibration unit is used to generate an uplink signal and send it to the uplink radio frequency channel of the antenna in the antenna array; The uplink signal is sent to the satellite through the antenna interface after passing through the uplink radio frequency channel; The satellite is used to forward the uplink signal to the downlink frequency point for loopback, and the signal is received by the antenna in the antenna array; the antenna in the antenna array is used to loop the received signal back to the antenna link delay calibration unit through its downlink radio frequency channel; The antenna link delay calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna according to the received signal and send them to the calculation unit; The calculation unit is used to obtain the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna based on the signal it receives, and send it to the compensation unit; The compensation unit is used to compensate the link of the antenna to be calibrated according to the relative signal delay value between the link of the antenna to be calibrated and the link of the reference antenna, so as to calibrate the signal delay of the uplink and downlink of each antenna in the array.

10. The system for calibrating the relative signal delay of a deep space large-aperture antenna according to claim 9, characterized in that: The antenna link delay calibration unit is composed of a link selection unit, a link calibration signal generator, a signal phase compensation unit and a link phase calibration unit; The link calibration signal generator is used to generate a link phase calibration signal and send it to the link selection unit; the link phase calibration signal is an uplink signal; The link selection unit is used to select one link from the received signals and send it to the antenna to be calibrated and the reference antenna; The signal phase compensation unit is used to obtain the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite based on the received looped downlink signals sent by the antenna to be calibrated and the reference antenna, and send it to the link phase calibration unit; The link phase calibration unit is used to obtain the relative phase difference of the uplink and downlink of the antenna to be calibrated and the reference antenna itself based on the phase difference corresponding to the loops formed by the antenna to be calibrated and the reference antenna with the satellite.

Images