Downlink beam angle tracking angle error voltage forming unit, digital beam forming unit and design method thereof

Abstract

The invention discloses a downlink beam angle tracking angle error voltage forming unit, a digital beam forming unit and a design method thereof. The downlink beam angle tracking angle error voltage forming unit comprises N branches, an angle tracking error voltage parallel transmission processing unit and a beam DDS parameter distribution unit, each branch comprises a difference beam forming unit and an angle tracking error voltage generating unit which are connected in sequence; all the angle tracking error voltage generation units of the N branches are connected with the angle tracking error voltage parallel transmission processing unit; the beam DDS parameter distribution unit is connected with all the angle tracking error voltage generation units of the N branches. The method is simple, reliable and convenient to implement, and the requirement for increasing the number of parallel beams of a digital multi-beam phased-array antenna system in engineering practice can be met.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a downlink beam angle tracking angle error voltage forming unit, a digital beam forming unit and a design method thereof. Background Art

[0002] Digital multi-beam phased array antennas can track and control multiple space targets simultaneously due to their multi-beam working mode and full airspace coverage technical advantages. In recent years, they have received increasing attention in the research of new antennas and have become a hot area of ​​new antenna research.

[0003] One of the greatest technical advantages of digital multi-beam phased array antennas is their ability to form multiple independent beams, effectively enabling multiple independent antennas to track and control multiple targets. Therefore, the number of targets the antenna system can simultaneously address is a crucial performance criterion in the design of digital multi-beam phased array antenna systems. Antenna system design requires both uplink and downlink signal channels for each space target. To enable the antenna to automatically track the target, a dual-channel self-tracking approach is often employed. Therefore, when designing a digital multi-beam phased array antenna system, two downlink signal channels (a sum downlink channel and a difference downlink channel) are required for each space target. In practice, downlink digital beam signals in digital multi-beam phased array antenna systems are typically implemented using large-scale digital integrated circuits within a tree-like, multi-stage digital beamforming (DBF) unit. These signals are then transmitted between each processing unit via digital optical fiber. The limited number of physical digital optical fiber interfaces available between the digital beamforming units limits the number of target beams that can be concurrently addressed by the digital multi-beam phased array antenna system. Therefore, how to effectively utilize the downlink signal channel has become a key technical problem that urgently needs to be broken through. Summary of the Invention

[0004] In light of this, the present application provides a downlink beam angle tracking angle error voltage formation unit, a digital beamforming unit, and a design method thereof. These units are simple, reliable, and easy to implement, meeting the engineering requirements for increasing the number of parallel beams in digital multi-beam phased array antenna systems. This method can be used to design digital multi-beam phased array antenna systems that meet performance requirements in engineering practice.

[0005] The present application discloses a downlink beam angle tracking angle error voltage forming unit, which includes N branches, an angle tracking error voltage parallel transmission processing unit and a beam DDS parameter allocation unit; each branch includes a difference beam forming unit and an angle tracking error voltage generating unit connected in sequence; all the angle tracking error voltage generating units of the N branches are connected to the angle tracking error voltage parallel transmission processing unit; and the beam DDS parameter allocation unit is respectively connected to all the angle tracking error voltage generating units of the N branches.

[0006] Furthermore, the parameter DDS parameter distribution unit is used to receive the angle tracking DDS coefficients and send them to all the angle tracking error voltage generating units of the N branches respectively; The difference beam forming unit in each branch is used to receive the signal transmitted by the space target received by the antenna and form the difference path signal of the beam of each space target, and send the difference path signal of the beam to the angle tracking error voltage generating unit, which is used to receive the difference path signal of the beam and the DDS coefficient sent by the parameter DDS parameter allocation unit and form the angle tracking error voltage; The angular tracking error voltage parallel transmission processing unit is used to receive the angular tracking error voltages sent by all the angular tracking error voltage generating units of the N branches and package them into one angular tracking error voltage.

[0007] Furthermore, each of the angle tracking error voltage generating units includes a beam DDS unit and a tracking angle error voltage demodulation unit connected in sequence; The beam DDS unit is used to receive the DDS parameters sent by the beam DDS parameter distribution unit and divide them into an I-path reference signal and a Q-path reference signal; The tracking angle error voltage demodulation unit is used to coherently demodulate the difference path signal of the beam sent by the receiving difference beam forming unit and the I-path reference signal and Q-path reference signal sent by the beam DDS unit to obtain an angle tracking error voltage; the difference path signal includes an azimuth difference path signal and a pitch difference path signal, and the angle tracking error voltage includes an azimuth error voltage and a pitch error voltage.

[0008] The present application also discloses a digital beamforming unit, which includes a first-stage digital beamforming unit to an M-th-stage digital beamforming unit; the first-stage digital beamforming unit includes the above-mentioned downlink beam angle tracking angle error voltage forming unit.

[0009] Furthermore, the downlink beam angle tracking angle error voltage forming unit in the first-stage digital beamforming unit is used to transparently transmit the generated downlink beam angle tracking error voltage to the M-th-stage digital beamforming unit in sequence.

[0010] Furthermore, the uplink beam signal and downlink beam signal of each beam are transmitted between the first-level digital beamforming unit and the M-th-level digital beamforming unit; the downlink beam angle tracking angle error voltage forming unit of the first-level digital beamforming unit has two independent digital signal channels, one for parallel transmission of the angle tracking DDS coefficients of each beam, and the other for parallel transmission of the angle tracking error voltage of each beam.

[0011] Furthermore, the number of physical digital optical fiber signal channel interfaces between the first-stage digital beamforming unit and the M-th-stage digital beamforming unit is equal to the number of signal channels.

[0012] The present application also discloses a design method for a digital beamforming unit, which is applicable to the digital beamforming unit described above and includes: In the first-stage digital beamforming unit, the downlink difference signal of the target beam is converted into a downlink angular tracking error voltage, and the downlink angular tracking error voltage is transmitted in parallel through a digital optical fiber signal channel interface between the multi-stage digital beamforming units, thereby saving physical digital optical fiber channel interfaces and increasing the number of beams formed by the digital multi-beam phased array antenna system.

[0013] Furthermore, the first-stage digital beamforming unit encapsulates the difference beamforming unit into the downlink beam angle tracking angle error voltage forming unit. The downlink beam angle tracking angle error voltage forming unit only requires two digital optical fiber interfaces, one for parallel transmission of the angle tracking DDS coefficients of each downlink beam, and the other for parallel transmission of the angle tracking error voltage of each downlink beam. The downlink beam difference signal channel of the first-stage digital beamforming unit in the traditional design is allocated for use as a new parallel working beam.

[0014] Furthermore, if the number of digital optical fiber signal channel interfaces between the beamforming units at each level is K, the digital multi-beam phased array antenna system can achieve An independently operating beam.

[0015] Furthermore, each angular tracking error voltage data frame includes a data frame header and the angular tracking error voltages of each beam arranged according to the beam number; the angular tracking error voltage data frame sends the angular tracking error voltage according to the frequency of the preset data, and the back end synchronizes the data frame through the data frame header and decodes the angular tracking error voltage of each beam according to the beam number.

[0016] Due to the adoption of the above technical solution, this application has the following advantages: 1. Solved the problem of increasing the number of formed beams of digital multi-beam phased array antennas. This application extracts the angular tracking error voltage in the primary beamforming unit, which can convert the downlink differential signal transmission of the target beam with a high information rate into the angular tracking error voltage transmission of the target beam with an extremely low information rate, so that all the target downlink differential error voltages of the antenna system can be transmitted through a shared digital optical fiber channel, thereby saving physical digital optical fiber channel interfaces. The physical digital optical fiber channel interfaces saved by this method can then be used to increase the number of beams formed by the digital multi-beam phased array antenna system, increase the number of parallel beams of the antenna system, thereby improving the performance of the digital multi-beam phased array antenna system and solving a key problem in the design of digital multi-beam phased array antenna systems.

[0017] 2. Simple implementation, low resource usage, and reduced system design costs. This application does not require complex circuits and is relatively simple to implement. It utilizes only existing system equipment without the need for additional equipment. It also uses software algorithms to extract the angle tracking error voltage in the primary beamforming unit and transmit all target downlink error voltages through a shared digital optical fiber channel, facilitating automated operation and reducing system design costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 This is a schematic diagram of the traditional digital multi-beam phased array antenna system designing the signal channel according to the beam number.

[0020] Figure 2 This is a schematic diagram of a beamforming unit in a traditional digital multi-beam phased array antenna system processing signal channels according to beam numbers.

[0021] Figure 3 The figure is a schematic diagram of a beamforming unit of a digital multi-beam phased array antenna system according to the method provided by the present application according to the processing signal channel.

[0022] Figure 4 It is a schematic diagram of the principle of a downlink beam angle tracking error voltage forming unit in a beam forming unit according to the method provided in this application.

[0023] Figure 5 It is a schematic diagram of the principle of a beam angle tracking error voltage generating unit in a beam forming unit according to the method provided in this application.

[0024] Figure 6 Schematic diagram of an angular tracking error voltage parallel transmission processing unit in a beamforming unit according to the method provided in the present application.

[0025] Figure 7 It is a schematic diagram of the data frame structure of the parallel transmission of the angular tracking error voltage according to the method provided by the present application.

[0026] Figure 8 Schematic diagram of the signal channel of the digital multi-beam phased array antenna system designed in this application. DETAILED DESCRIPTION

[0027] 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.

[0028] See Figure 1 and Figure 2 The biggest feature of the digital multi-beam phased array antenna system is that it can simultaneously form multiple independent beams for multiple targets at different positions in space and complete the signal transmission and reception of each space target in parallel. Therefore, the number of parallel and independent beams of the system has also become a major performance indicator of the digital multi-beam phased array antenna system. The uplink and downlink (downlink beam signals include downlink sum signals and downlink difference signals) beam signals of the digital multi-beam phased array antenna system are implemented in a tree-structured multi-level digital beamforming (DBF) unit using large-scale digital integrated circuits, and the signals are transmitted between the beamforming units at each level through digital optical fibers. The number of physical digital optical fiber signal channel interfaces that can be realized between digital beamforming units also limits the number of parallel beams that can be realized in the digital multi-beam phased array antenna system. For example Figure 1 As shown in the figure, the traditional digital multi-beam phased array antenna system generally designs the signal channel according to each independent space target, that is, the beam number. Therefore, the system needs to configure three physical optical fiber signal channels for each beam number to realize one uplink signal channel and two downlink signal channels (downlink sum signal and downlink difference signal). Therefore, it can be seen that if the number of digital optical fiber signal channel interfaces between the beamforming units at each level of the system is K, then the traditional digital multi-beam phased array antenna system can only achieve An independent beam. Figure 2As shown in the figure, a traditional digital multi-beam phased array antenna system includes an uplink beam signal forming unit, a downlink beam sum signal forming unit, and a downlink beam difference signal forming unit in the first-level digital beamforming unit. For the design of a traditional digital multi-beam phased array antenna system based on beam number design, these three beam signal channels must be fully designed for each beam number. Therefore, the number of beams that can be operated in parallel on space targets in a traditional digital multi-beam phased array antenna system based on beam number design is limited by the number of physical digital optical fiber signal channel interfaces that can be implemented between the digital beamforming units.

[0029] The technical solution adopted by this application to solve its technical problems is as follows: the downlink digital beam signal of the digital multi-beam phased array antenna includes a downlink sum signal and a downlink difference signal. The downlink digital beam signal formation function is completed in multiple digital beamforming units, and a digital optical fiber channel is used to transmit the beamformed signal between each level of digital beamforming units. Traditionally, the uplink and downlink difference signals are considered to have the same signal bandwidth as the complete downlink sum sampling signal, and therefore require a separate digital optical fiber channel for transmission. If the angle tracking error voltage can be extracted in the primary beamforming unit, the high information rate downlink difference signal transmission of the target beam can be converted into an extremely low information rate angular tracking error voltage transmission of the target beam. Therefore, all target downlink angular tracking error voltages of the antenna system can be transmitted through a shared digital optical fiber channel, achieving the purpose of saving physical digital optical fiber channel interfaces. The physical digital optical fiber channel interfaces saved by this method can then be used to increase the number of beams formed by the digital multi-beam phased array antenna system, thereby improving the performance of the digital multi-beam phased array antenna system.

[0030] See also Figure 1 An embodiment of the present application provides a downlink beam angle tracking angle error voltage forming unit, which includes N branches, an angle tracking error voltage parallel transmission processing unit and a beam DDS parameter allocation unit; each branch includes a difference beam forming unit and an angle tracking error voltage generating unit connected in sequence; all the angle tracking error voltage generating units of the N branches are connected to the angle tracking error voltage parallel transmission processing unit; the beam DDS parameter allocation unit is respectively connected to all the angle tracking error voltage generating units of the N branches.

[0031] In one embodiment of the present application, the parameter DDS parameter distribution unit is used to receive the angle tracking DDS coefficients and send them to all the angle tracking error voltage generating units of the N branches respectively; The difference beam forming unit in each branch is used to receive the signal transmitted by the space target received by the antenna and form the difference path signal of the beam of each space target, and send the difference path signal of the beam to the angle tracking error voltage generating unit, which is used to receive the difference path signal of the beam and the DDS coefficient sent by the parameter DDS parameter allocation unit and form the angle tracking error voltage; The angular tracking error voltage parallel transmission processing unit is used to receive the angular tracking error voltages sent by all the angular tracking error voltage generating units of the N branches and package them into one angular tracking error voltage.

[0032] In one embodiment of the present application, each of the angle tracking error voltage generating units includes a beam DDS unit and a tracking angle error voltage demodulation unit connected in sequence; The beam DDS unit is used to receive the DDS parameters sent by the beam DDS parameter distribution unit and divide them into an I-path reference signal and a Q-path reference signal; The tracking angle error voltage demodulation unit is used to coherently demodulate the difference path signal of the beam sent by the receiving difference beam forming unit and the I-path reference signal and Q-path reference signal sent by the beam DDS unit to obtain an angle tracking error voltage; the difference path signal includes an azimuth difference path signal and a pitch difference path signal, and the angle tracking error voltage includes an azimuth error voltage and a pitch error voltage.

[0033] An embodiment of the present application further provides a digital beamforming unit, which includes a first-stage digital beamforming unit to an M-th-stage digital beamforming unit; the first-stage digital beamforming unit includes the downlink beam angle tracking angle error voltage forming unit described above.

[0034] In one embodiment of the present application, the downlink beam angle tracking angle error voltage forming unit in the first-stage digital beamforming unit is configured to transparently transmit the generated downlink beam angle tracking error voltage to the M-th-stage digital beamforming unit in sequence.

[0035] In one embodiment of the present application, the uplink beam signal and the downlink beam signal of each beam are transmitted between the first-level digital beamforming unit and the M-th-level digital beamforming unit; the downlink beam angle tracking angle error voltage forming unit of the first-level digital beamforming unit has two independent digital signal channels, one for parallel transmission of the angle tracking DDS coefficients of each beam, and the other for parallel transmission of the angle tracking error voltage of each beam.

[0036] In one embodiment of the present application, the number of physical digital optical fiber signal channel interfaces between the first-stage digital beamforming unit and the M-th-stage digital beamforming unit is equal to the number of signal channels.

[0037] The present application utilizes the characteristics of digital beam phased array antenna and differential beam angle tracking to increase the number of target beams that can operate in parallel in a digital multi-beam phased array antenna system by sharing differential signal channels.

[0038] The present application also provides a method for designing a digital beamforming unit, which is applicable to the digital beamforming unit described in the above embodiment and includes: In the first-stage digital beamforming unit, the downlink difference signal of the target beam is converted into a downlink angular tracking error voltage, and the downlink angular tracking error voltage is transmitted in parallel through a digital optical fiber signal channel interface between the multi-stage digital beamforming units, thereby saving physical digital optical fiber channel interfaces and increasing the number of beams formed by the digital multi-beam phased array antenna system.

[0039] The present application aims to provide a simple, reliable and easy-to-implement method for increasing the number of target beams that can operate in parallel in an antenna system. This method does not require any external equipment and is conducive to the design of a digital multi-beam phased array antenna system that meets the index requirements in engineering practice.

[0040] In one embodiment of the present application, the first-level digital beamforming unit encapsulates the difference beamforming unit into the downlink beam angle tracking angle error voltage forming unit. The downlink beam angle tracking angle error voltage forming unit only requires two digital optical fiber interfaces, one for parallel transmission of the angle tracking DDS coefficients of each downlink beam, and one for parallel transmission of the angle tracking error voltage of each downlink beam. The downlink beam difference signal channel of the first-level digital beamforming unit in the traditional design is allocated for use as a new parallel working beam.

[0041] In one embodiment of the present application, if the number of digital optical fiber signal channel interfaces between the beamforming units at each level is K, the digital multi-beam phased array antenna system can achieve An independently operating beam.

[0042] In one embodiment of the present application, each angular tracking error voltage data frame includes a data frame header and the angular tracking error voltages of each beam arranged according to the beam number; the angular tracking error voltage data frame sends the angular tracking error voltage at a frequency of preset data, and the back end synchronizes the data frame through the data frame header and decodes the angular tracking error voltage of each beam according to the beam number.

[0043] In the above embodiments of the present application, see Figure 3Through the analysis of the digital multi-beam phased array antenna system, it is known that the antenna angle tracking error voltage can be transmitted through a 640-bit / s digital transmission channel (the angle tracking error voltage word length is 32 bits and the update rate is 20Hz). If the downlink beam angle tracking error voltage can be directly formed in the first-level digital beamforming unit, then the downlink beam angle tracking error voltage required by the entire system can be achieved through a digital optical fiber signal channel interface between the digital beamforming units (the information rate that a digital optical fiber signal channel can transmit is 20Hz). ) are transmitted in parallel. Figure 3 As shown, the first-level digital beamforming unit includes an uplink beam signal forming unit and a downlink beam and path signal forming unit, and the downlink beam difference path signal forming unit in the traditional design is encapsulated into the downlink beam angle tracking angle error voltage forming unit. The downlink beam angle tracking angle error voltage forming unit only needs two digital optical fiber interfaces, one for parallel transmission of the angle tracking DDS (direct digital frequency synthesis unit) coefficients of each downlink beam, and one for parallel transmission of the angle tracking error voltage of each downlink beam. In this way, only two digital optical fiber signal channels need to be retained to realize the formation of the beam angle tracking error voltage, and the external downlink beam difference path signal channel of the first-level digital beamforming unit in the traditional design is allocated as a new parallel working beam number for use. If the number of digital optical fiber signal channel interfaces between the beamforming units at each level of the system is K, the digital multi-beam phased array antenna system can be realized according to the design of the new method. Taking the digital optical fiber signal channel interface between the beamforming units at each level of the system as K=100 as an example, the traditional digital multi-beam phased array antenna system can only achieve The new method can realize The system performance can be greatly improved by using two independently working beams.

[0044] See Figure 4 、 Figure 5 、 Figure 6 and Figure 7 ,like Figure 4 As shown, in the downlink beam angle tracking angle error voltage forming unit, each difference beam forming unit forms the difference path signal (including the azimuth difference path signal and the elevation difference path signal) of each target beam, and sends each difference path signal to its own angle tracking error voltage generating unit. Together with the corresponding beam DDS parameters allocated by the beam DDS parameter allocation unit, the azimuth error voltage and elevation error voltage of the beam angle tracking are demodulated and sent to the angle tracking error voltage parallel transmission processing unit for data packaging, and finally sent out through a digital optical fiber interface. Figure 5As shown, taking the beam 1 angle tracking error voltage generating unit as an example (the others are exactly the same), the beam 1 DDS unit obtains the beam 1 I-path reference signal and the beam 1 Q-path reference signal based on the received beam 1 DDS parameters and sends them to the tracking angle error voltage demodulation unit. The tracking angle error voltage demodulation unit coherently demodulates the azimuth error signal and the beam 1 elevation difference signal received with these two reference signals to obtain the azimuth error voltage and the elevation error voltage (i.e., the beam 1 angle tracking error voltage), and finally sends the angle tracking error voltage. Figure 6 As shown in FIG, the angular tracking error voltage parallel processing unit receives the angular tracking error voltage sent by each beam, packages the data, and finally sends the packaged angular tracking error voltage through a high-speed digital optical fiber interface. Figure 7 As shown, the angular tracking error voltage data frame includes a data frame header and the angular tracking error voltages for each beam, arranged by beam number. The angular tracking error voltage data frame is transmitted at a frequency of 50 milliseconds per frame. The backend synchronizes the data frames using the data frame header and extracts the angular tracking error voltages for each beam according to the beam number.

[0045] See Figure 8 The signal channel of the digital multi-beam phased array antenna system designed according to the method provided in this application is as follows: Figure 8 As shown, the uplink beam signal and downlink beam signal of each beam are transmitted between the beamforming units at each level. There are also two independent digital signal channels, one for parallel transmission of the DDS coefficients for the angle tracking of each beam, and the other for parallel transmission of the angle tracking error voltage of each beam.

[0046] 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 downlink beam angle tracking angle error voltage forming unit, characterized in that: It includes N branches, an angular tracking error voltage parallel transmission processing unit and a beam DDS parameter allocation unit; each branch includes a difference beam forming unit and an angular tracking error voltage generating unit connected in sequence; all the angular tracking error voltage generating units of the N branches are connected to the angular tracking error voltage parallel transmission processing unit; and the beam DDS parameter allocation unit is respectively connected to all the angular tracking error voltage generating units of the N branches.

2. The downlink beam angle tracking angle error voltage forming unit according to claim 1, characterized in that: The parameter DDS parameter distribution unit is used to receive the angle tracking DDS coefficients and send them to all the angle tracking error voltage generating units of the N branches respectively; The difference beam forming unit in each branch is used to receive the signal transmitted by the space target received by the antenna and form the difference path signal of the beam of each space target, and send the difference path signal of the beam to the angle tracking error voltage generating unit, which is used to receive the difference path signal of the beam and the DDS coefficient sent by the parameter DDS parameter allocation unit and form the angle tracking error voltage; The angular tracking error voltage parallel transmission processing unit is used to receive the angular tracking error voltages sent by all the angular tracking error voltage generating units of the N branches and package them into one angular tracking error voltage.

3. The downlink beam angle tracking angle error voltage forming unit according to claim 1, characterized in that: Each of the angle tracking error voltage generating units includes a beam DDS unit and a tracking angle error voltage demodulating unit connected in sequence; The beam DDS unit is used to receive the DDS parameters sent by the beam DDS parameter distribution unit and divide them into an I-path reference signal and a Q-path reference signal; The tracking angle error voltage demodulation unit is used to coherently demodulate the difference path signal of the beam sent by the receiving difference beam forming unit and the I-path reference signal and Q-path reference signal sent by the beam DDS unit to obtain an angle tracking error voltage; the difference path signal includes an azimuth difference path signal and a pitch difference path signal, and the angle tracking error voltage includes an azimuth error voltage and a pitch error voltage.

4. A digital beamforming unit, characterized in that It comprises a first-stage digital beamforming unit to an M-th-stage digital beamforming unit; the first-stage digital beamforming unit comprises the downlink beam angle tracking angle error voltage forming unit according to any one of claims 1 to 3.

5. The digital beamforming unit according to claim 4, characterized in that The downlink beam angle tracking angle error voltage forming unit in the first-stage digital beamforming unit is used to transparently transmit the generated downlink beam angle tracking error voltage to the M-th-stage digital beamforming unit in sequence.

6. The digital beamforming unit according to claim 4, characterized in that The uplink beam signal and downlink beam signal of each beam are transmitted between the first-level digital beamforming unit and the M-th-level digital beamforming unit. The downlink beam angle tracking angle error voltage forming unit of the first-level digital beamforming unit has two independent digital signal channels, one for parallel transmission of the angle tracking DDS coefficients of each beam, and the other for parallel transmission of the angle tracking error voltage of each beam.

7. The digital beamforming unit according to claim 4, characterized in that The number of physical digital optical fiber signal channel interfaces between the first-stage digital beamforming unit and the M-th-stage digital beamforming unit is equal to the number of signal channels.

8. A design method for a digital beamforming unit, applicable to the digital beamforming unit according to any one of claims 4 to 7, characterized in that: include: In the first-stage digital beamforming unit, the downlink difference signal of the target beam is converted into a downlink angular tracking error voltage, and the downlink angular tracking error voltage is transmitted in parallel through a digital optical fiber signal channel interface between the multi-stage digital beamforming units, thereby saving physical digital optical fiber channel interfaces and increasing the number of beams formed by the digital multi-beam phased array antenna system.

9. The design method of a digital beamforming unit according to claim 8, characterized in that: The first-stage digital beamforming unit encapsulates the difference beamforming unit into the downlink beam angle tracking angle error voltage forming unit. The downlink beam angle tracking angle error voltage forming unit only requires two digital optical fiber interfaces, one for parallel transmission of the angle tracking DDS coefficients of each downlink beam, and the other for parallel transmission of the angle tracking error voltage of each downlink beam. The downlink beam difference signal channel of the first-stage digital beamforming unit in the traditional design is allocated to be used as a new parallel working beam.

10. The design method of a digital beamforming unit according to claim 8, characterized in that: If the number of digital optical fiber signal channel interfaces between the beamforming units at each level is K, the digital multi-beam phased array antenna system can achieve An independently operating beam.

11. The design method of a digital beamforming unit according to claim 8, wherein: Each angular tracking error voltage data frame contains a data frame header and the angular tracking error voltages of each beam arranged according to the beam number; the angular tracking error voltage data frame sends the angular tracking error voltage at a preset data frequency, and the back end synchronizes the data frame through the data frame header and decodes the angular tracking error voltage of each beam according to the beam number.

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