Digital multi-beam phased-array antenna downlink and channel digital frequency division multiplexing method and phased-array antenna system

Abstract

The invention discloses a digital multi-beam phased-array antenna downlink and channel digital frequency division multiplexing method and a phased-array antenna system.The method comprises the steps that when a digital multi-beam phased-array antenna conducts digital beam forming on a space target, if the bandwidth of a downlink signal of the space target is smaller than the spectral bandwidth of a downlink beam signal channel, the digital multi-beam phased-array antenna conducts digital beam forming on the space target; if yes, the downlink sum path signal and the downlink difference path signal share one downlink beam sum path channel, namely, the same downlink beam signal channel transmits the downlink sum path beam signal and the downlink difference path beam signal at the same time, so that the number of beams formed by the digital multi-beam phased-array antenna system is increased through the downlink beam difference path channel; downlink digital beam signals of the digital multi-beam phased-array antenna comprise downlink sum-path beam signals and downlink difference-path beam signals. According to the invention, the number of beams formed by the digital multi-beam phased-array antenna system can be increased, and the target tracking performance of the digital multi-beam phased-array antenna system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of phased array antennas, and in particular to a digital multi-beam phased array antenna downlink and channel digitized frequency division multiplexing method and a phased array antenna system. Background Art

[0002] Digital multi-beam phased array antennas use a multi-beam working mode and have the technical advantage of full airspace coverage. They can track and control multiple space targets at the same time. In recent years, they have received increasing attention in the research of new antennas and have become a hot area in the research of new antennas.

[0003] One of the biggest technical advantages of digital multi-beam phased array antenna applications is that it can form multiple independent beams, which is equivalent to multiple independent antennas tracking and controlling multiple targets separately. Therefore, the number of targets that the antenna system can work on in parallel is an important performance indicator for the design of digital multi-beam phased array antenna systems. In the design of the antenna system, corresponding to a space target, there is a need for an uplink signal channel and a downlink signal channel, and in order to complete the automatic tracking function of the antenna to the target, a dual-channel self-tracking method is usually used in technology. Therefore, when designing a digital multi-beam phased array antenna system, two downlink signal channels (sum downlink signal channel and difference downlink signal channel) must be designed for each space target. In engineering practice, the downlink digital beam signal of the digital multi-beam phased array antenna system is generally implemented in a multi-level digital beam forming (DBF) unit with a tree structure using large-scale digital integrated circuits, and transmitted between processing units at each level through digital optical fibers. Since the physical interface of the digital optical fiber channel that can be realized between digital beam forming units is limited, the number of targets of the digital multi-beam phased array antenna system is limited. Therefore, how to effectively utilize the downlink signal channel and increase the number of targets that can work in parallel in the digital multi-beam phased array antenna system has become a key technical problem that urgently needs to be broken through. Summary of the invention

[0004] In view of this, the present invention provides a digital multi-beam phased array antenna downlink channel digital frequency division multiplexing method and a phased array antenna system, which utilizes the bandwidth characteristics of the downlink channel of the digital beam phased array antenna system and realizes the multiplexing function of the sum channel by adopting the digital frequency division multiplexing technology of the sum and difference channels.

[0005] The present invention discloses a digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method, which comprises:

[0006] When the digital multi-beam phased array antenna performs digital beamforming on a space target, if the bandwidth of the downlink signal of the space target is smaller than the spectrum bandwidth of the downlink beam signal channel, the downlink sum signal and the downlink difference signal share a downlink beam sum channel, that is, the same downlink beam signal channel simultaneously transmits the downlink sum beam signal and the downlink difference beam signal, so as to increase the number of beams formed by the digital multi-beam phased array antenna system through the downlink beam difference channel; the downlink digital beam signal of the digital multi-beam phased array antenna includes the downlink sum beam signal and the downlink difference beam signal.

[0007] Furthermore, the downlink sum signal and the downlink difference signal share a downlink beam sum channel, including:

[0008] The center frequency of the downlink difference beam signal is transformed by digital frequency conversion and then moved to the spectrum of the downlink beam sum channel. The downlink sum beam signal is then superimposed with the downlink difference signal to achieve frequency division multiplexing of the downlink sum beam signal and the downlink difference beam signal in the downlink signal channel. The downlink signal channel includes the downlink beam sum channel and the downlink beam difference channel.

[0009] Furthermore, the center frequency of the downlink difference path beam signal is transformed, and the transformed center frequency is If f w ≤4f a , then the downlink sum beam signal and the downlink difference beam signal can be superimposed; where 2f w The bandwidth of the downlink signal channel designed for the digital multi-beam phased array antenna system; 2f a It is the downlink signal bandwidth of the space target.

[0010] Furthermore, for a downlink signal of a target, after a downlink sum beam signal and a downlink difference beam signal are formed in a first-level digital beamforming unit, the downlink sum beam signal and the downlink difference beam signal are superimposed into one signal according to a frequency division multiplexing method; at the same time, the downlink signal channel between digital beamforming units at each level is utilized to send the superimposed signal to the n-th level digital beamforming unit step by step, and finally the n-th level digital beamforming unit distributes the superimposed signal to a back-end information processing system.

[0011] Furthermore, the digital frequency converter of the downlink difference beam signal in the first-stage digital beam forming unit converts the downlink difference beam signal from zero intermediate frequency to the set frequency point f0; finally, the downlink difference beam signal after the frequency conversion is added to the downlink sum beam signal to form a signal sharing a downlink signal channel, that is:

[0012]

[0013] Among them, S 和路信号加差路信号For signals that share a downlink signal channel, S 和路信号 is the downlink and path beam signal, S 差路信号 is the downlink difference beam signal, w0=2πf0.

[0014] The present invention also discloses a digital multi-beam phased array antenna system, which includes a digital beam forming subsystem and a sum and difference path processing unit, wherein the digital beam forming subsystem includes n-stage cascade-connected digital beam forming units, namely, a first-stage digital beam forming unit to an n-stage digital beam forming unit; a downlink beam sum path channel and a downlink beam difference path channel are formed between the n-stage cascade-connected digital beam forming units;

[0015] The first-level digital beamforming unit is used to receive the downlink signal of the space target, form the downlink sum beam signal and the downlink difference beam signal of the downlink signal, and then superimpose the downlink sum beam signal and the downlink difference beam signal into one signal according to the frequency division multiplexing method, and send the superimposed signal to the sum and difference processing unit after passing through the downlink beam difference channel between the digital beamforming units at each level in turn.

[0016] Further, the first-level digital beamforming unit includes a downlink difference beamforming module, a digital frequency converter of the downlink difference beam signal, a stacker, and a downlink sum beamforming module; the downlink difference beamforming module is connected to the stacker through the digital frequency converter of the downlink difference beam signal; the stacker is connected to the downlink sum beamforming module;

[0017] The downlink differential path beam forming module is used to receive the downlink signal and form a downlink differential path beam signal;

[0018] The digital frequency converter of the downlink difference beam signal is used to convert the downlink difference beam signal from zero intermediate frequency to a set frequency point; and send the downlink difference beam signal after frequency conversion to the superimposer;

[0019] The downlink and path beam forming module is used to receive the downlink signal, form the downlink and path beam signals and send them to the adder;

[0020] The adder is used to add the received downlink difference beam signal to the downlink sum beam signal to form a superimposed signal.

[0021] Furthermore, the digital frequency converter of the downlink difference path beam signal includes a digital frequency synthesizer, an operator and a digital filter; the digital frequency synthesizer is connected to the digital filter via the operator;

[0022] The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock;

[0023] The operator is used for mixing the local oscillator signal generated by the digital frequency synthesizer with the downlink difference beam signal to generate a mixed signal;

[0024] The digital filter is used to convert the frequency of the mixing signal to generate a downlink difference beam signal after frequency conversion.

[0025] Furthermore, the sum and difference path processing unit includes a digital frequency synthesizer, an operator, a first digital filter and a second digital filter; the digital frequency synthesizer is connected to the first digital filter through the operator; the first digital filter is connected to the second digital filter through the operator;

[0026] The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock;

[0027] The operator is used to mix the local oscillator signal generated by the digital frequency synthesizer with the superimposed signal to generate a mixed signal;

[0028] The first digital filter is used to transform the frequency of the mixing signal to generate a downlink difference path beam signal;

[0029] The second digital filter is used to transform the frequency of the superimposed signal to generate a downlink and path beam signal.

[0030] Furthermore, it also includes a digital tracking receiver connected to the sum and differential path processing unit, and a digital multi-beam phased array antenna connected to the first-stage digital beam forming unit; the digital multi-beam phased array antenna includes a plurality of antenna units; the plurality of antenna units are used to receive the downlink signal of the space target and send it to the first-stage digital beam forming unit;

[0031] The digital tracking receiver is used to receive the downlink sum beam signal and downlink difference beam signal output by the sum and difference processing unit, and generate an angle error signal for the digital multi-beam phased array antenna to track the space target.

[0032] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0033] 1. The present invention utilizes the characteristic that the downlink sum signal and the downlink difference signal can share a downlink beam sum channel when the digital multi-beam phased array antenna performs digital beamforming on a narrowband space target, and uses the signal channel of one downlink beam to simultaneously transmit the downlink sum signal and the downlink difference signal, thereby increasing the number of beams formed by the digital multi-beam phased array antenna system through the beamforming signal channels saved by this method. This method can increase the number of beams formed by the digital multi-beam phased array antenna system without increasing system resources, solving a key problem in the design of the digital multi-beam phased array antenna system.

[0034] 2. The present invention is simple to implement, occupies less resources, and reduces the system design cost. The present invention does not require complex circuits, and the implementation method is relatively simple. The present invention only uses the original equipment of the system without adding additional equipment. It only uses software algorithms to realize the function of the downlink sum signal and the downlink difference signal sharing a downlink beam sum channel, which is convenient for automatic operation and reduces the system design cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a structural schematic diagram of a digital beam processing unit of a digital multi-beam phased array antenna system.

[0037] Figure 2 It is a schematic diagram of the spectrum occupancy of the sum signal channel and the difference signal channel of the downlink beam of the digital multi-beam phased array antenna system.

[0038] Figure 3 It is a schematic diagram of the spectrum occupancy of the downlink and path beam signals and the difference path signals of the digital multi-beam phased array antenna system sharing the downlink and path.

[0039] Figure 4 It is a schematic diagram of the structure of a digital beam processing subsystem using frequency division multiplexing and channel digitization.

[0040] Figure 5 It is a schematic diagram of the structure of the first-level digital beam processing unit using the channel digital frequency division multiplexing technology.

[0041] Figure 6 It is a structural schematic diagram of a digital frequency converter of a downlink difference beam signal in a first-level digital beam processing unit.

[0042] Figure 7 It is a schematic diagram of the signal processing flow of angular tracking error signal demodulation using channel digitization frequency division multiplexing technology. DETAILED DESCRIPTION

[0043] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all 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 invention.

[0044] Aiming at the requirement of increasing the number of parallel working targets in digital multi-beam phased array antenna system, a digital frequency division multiplexing method based on digital multi-beam phased array antenna and channel is provided to increase the number of parallel beams of the antenna system. The downlink beam signal of the digital multi-beam phased array antenna system includes a downlink sum signal and a downlink difference signal. The two-way digital beam signal is implemented in a multi-level digital beam forming (DBF) unit with a tree structure using large-scale digital integrated circuits and transmitted between processing units at each level through digital optical fiber. Since the physical interface of the digital optical fiber channel that can be realized between digital beam forming units is limited, the number of beams that can be realized by the digital multi-beam phased array antenna system is limited.

[0045] Since the digital multi-beam phased array antenna system needs to consider the digital beamforming for a variety of different space targets during design, the bandwidth of the downlink channel of its beam signal must cover the maximum signal bandwidth of all possible space targets. However, in the actual operation of the antenna, the bandwidth of the downlink beamformed signal of a large number of space targets is much smaller than the bandwidth of the downlink beamformed signal channel designed by the antenna system. Therefore, when the digital multi-beam phased array antenna performs digital beamforming for these narrowband space targets, the downlink sum signal and the downlink difference signal can share a downlink beam sum channel, thereby saving a downlink beam signal channel. The signal channel of the beamformed signal saved by this method can then be used to increase the number of beams formed by the digital multi-beam phased array antenna system and improve the performance of the digital multi-beam phased array antenna system in tracking targets.

[0046] The present invention provides an embodiment of a digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method, which includes:

[0047] When the digital multi-beam phased array antenna performs digital beamforming on a space target, if the bandwidth of the downlink signal of the space target is smaller than the spectrum bandwidth of the downlink beam signal channel, the downlink sum signal and the downlink difference signal share a downlink beam sum channel, that is, the same downlink beam signal channel simultaneously transmits the downlink sum beam signal and the downlink difference beam signal, so as to increase the number of beams formed by the digital multi-beam phased array antenna system through the downlink beam difference channel; the downlink digital beam signal of the digital multi-beam phased array antenna includes the downlink sum beam signal and the downlink difference beam signal.

[0048] In this embodiment, the downlink sum signal and the downlink difference signal share a downlink beam sum channel, including:

[0049] The center frequency of the downlink difference beam signal is transformed by digital frequency conversion and then moved to the spectrum of the downlink beam sum channel. The downlink sum beam signal is then superimposed with the downlink difference signal to achieve frequency division multiplexing of the downlink sum beam signal and the downlink difference beam signal in the downlink signal channel. The downlink signal channel includes the downlink beam sum channel and the downlink beam difference channel.

[0050] In this embodiment, the center frequency of the downlink difference path beam signal is transformed, and the center frequency after the transformation is If f w ≤4f a , then the downlink sum beam signal and the downlink difference beam signal can be superimposed; where 2f w The bandwidth of the downlink signal channel designed for the digital multi-beam phased array antenna system; 2f a It is the downlink signal bandwidth of the space target.

[0051] In this embodiment, for a downlink signal of a target, after a downlink sum beam signal and a downlink difference beam signal are formed in a first-level digital beamforming unit, the downlink sum beam signal and the downlink difference beam signal are superimposed into one signal according to a frequency division multiplexing method; at the same time, the downlink signal channel between the digital beamforming units at each level is used to send the superimposed signal to the n-th level digital beamforming unit step by step, and finally the n-th level digital beamforming unit distributes the superimposed signal to the back-end information processing system.

[0052] In this embodiment, the digital frequency converter of the downlink difference beam signal in the first-stage digital beam forming unit converts the downlink difference beam signal from zero intermediate frequency to the set frequency point f0; finally, the downlink difference beam signal after the frequency conversion is added to the downlink sum beam signal to form a signal sharing a downlink signal channel, that is:

[0053]

[0054] Among them, S 和路信号加差路信号 For signals that share a downlink signal channel, S 和路信号 is the downlink and path beam signal, S 差路信号 is the downlink difference beam signal, w0=2πf0.

[0055] The present invention provides an embodiment of a digital multi-beam phased array antenna system, which includes a digital beam forming subsystem and a sum and difference path processing unit, wherein the digital beam forming subsystem includes n-stage cascade-connected digital beam forming units, namely, a first-stage digital beam forming unit to an n-stage digital beam forming unit; a downlink beam sum path channel and a downlink beam difference path channel are formed between the n-stage cascade-connected digital beam forming units;

[0056] The first-level digital beamforming unit is used to receive the downlink signal of the space target, form the downlink sum beam signal and the downlink difference beam signal of the downlink signal, and then superimpose the downlink sum beam signal and the downlink difference beam signal into one signal according to the frequency division multiplexing method, and send the superimposed signal to the sum and difference processing unit after passing through the downlink beam difference channel between the digital beamforming units at each level in turn.

[0057] In this embodiment, the first-level digital beamforming unit includes a downlink difference beamforming module, a digital frequency converter of a downlink difference beam signal, a stacker, and a downlink sum beamforming module; the downlink difference beamforming module is connected to the stacker via the digital frequency converter of the downlink difference beam signal; the stacker is connected to the downlink sum beamforming module;

[0058] The downlink differential path beam forming module is used to receive the downlink signal and form a downlink differential path beam signal;

[0059] The digital frequency converter of the downlink difference beam signal is used to convert the downlink difference beam signal from zero intermediate frequency to a set frequency point; and send the downlink difference beam signal after frequency conversion to the superimposer;

[0060] The downlink and path beam forming module is used to receive the downlink signal, form the downlink and path beam signals and send them to the adder;

[0061] The adder is used to add the received downlink difference beam signal to the downlink sum beam signal to form a superimposed signal.

[0062] In this embodiment, the digital frequency converter of the downlink difference path beam signal includes a digital frequency synthesizer, an operator and a digital filter; the digital frequency synthesizer is connected to the digital filter through the operator;

[0063] The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock;

[0064] The operator is used for mixing the local oscillator signal generated by the digital frequency synthesizer with the downlink difference beam signal to generate a mixed signal;

[0065] The digital filter is used to convert the frequency of the mixing signal to generate a frequency-converted downlink difference beam signal.

[0066] In this embodiment, the sum and difference path processing unit includes a digital frequency synthesizer, an operator, a first digital filter and a second digital filter; the digital frequency synthesizer is connected to the first digital filter through the operator; the first digital filter is connected to the second digital filter through the operator;

[0067] The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock;

[0068] The operator is used to mix the local oscillator signal generated by the digital frequency synthesizer with the superimposed signal to generate a mixed signal;

[0069] The first digital filter is used to transform the frequency of the mixing signal to generate a downlink difference path beam signal;

[0070] The second digital filter is used to transform the frequency of the superimposed signal to generate a downlink and path beam signal.

[0071] In this embodiment, it also includes a digital tracking receiver connected to the sum and differential path processing unit, and a digital multi-beam phased array antenna connected to the first-stage digital beam forming unit; the digital multi-beam phased array antenna includes a plurality of antenna units; the plurality of antenna units are used to receive the downlink signal of the space target and send it to the first-stage digital beam forming unit;

[0072] The digital tracking receiver is used to receive the downlink sum beam signal and downlink difference beam signal output by the sum and difference processing unit, and generate an angle error signal for the digital multi-beam phased array antenna to track the space target.

[0073] The digital multi-beam phased array antenna and channel multiplexing technology proposed in the present invention aims to provide a simple, reliable and easy-to-implement method for increasing the number of targets that can work in parallel in an antenna system. This method does not require any external equipment and is conducive to designing a digital multi-beam phased array antenna system that meets the index requirements in engineering practice.

[0074] For ease of understanding, the present invention provides a more specific embodiment:

[0075] See also Figure 1 and Figure 2 The digital multi-beam phased array antenna system consists of an antenna unit, a digital beamforming subsystem, and a backend information processing system. The digital beamforming subsystem is divided into multiple levels of digital beamforming units according to the size of the antenna. The first-level digital beamforming unit is connected to the antenna unit, and the n-th-level digital beamforming unit is connected to the backend information processing system. Figure 1As shown, for a downlink signal of a target, the first-level digital beamforming unit receives the downlink signal sent by the antenna unit, and forms a downlink sum beam signal and a downlink difference beam signal according to the downlink beamforming algorithm. At the same time, the downlink sum beam signal and the downlink difference beam signal are sent to the n-th level digital beamforming unit step by step by using the downlink sum beam signal channel and the downlink difference beam signal channel between the digital beamforming units at each level, and finally the n-th level digital beamforming unit distributes the downlink sum beam signal and the downlink difference beam signal to the back-end information processing system. For an uplink signal of a target, the n-th level digital beamforming unit receives the uplink signal sent by the back-end information processing system, and then uses the uplink beam signal channel between the digital beamforming units at each level to send the uplink signal to the first-level digital beamforming unit step by step, and finally the first-level digital beamforming unit forms the uplink beam signal according to the uplink digital beamforming algorithm and sends it to the antenna unit.

[0076] In order to meet the requirements of downlink beamforming for multiple space targets of the digital multi-beam phased array antenna system, when designing the digital multi-beam phased array antenna system, the spectrum bandwidth designed for the downlink sum beam signal channel and the downlink difference beam signal channel between the digital beamforming units at each level must meet the transmission requirements of the downlink signal with the maximum bandwidth of the target. Therefore, the downlink channel bandwidth must be greater than the maximum downlink signal bandwidth of the target during design. Figure 2 As shown in the figure, the spectrum bandwidth of the downlink sum beam signal channel and the downlink difference beam signal channel between the digital beam forming units of each level of the digital multi-beam phased array antenna system is 2f w The bandwidth of the downlink sum beam signal and downlink difference beam signal of the space target is 2f a , where 2f w >2f a .

[0077] See also Figure 3 and Figure 4 , because for the digital multi-beam phased array antenna system, the bandwidth of the downlink signal of most space targets is much smaller than the spectrum bandwidth of the designed downlink beam signal channel. For example, in the aerospace measurement and control system, the maximum bandwidth of the satellite's downlink low-speed digital transmission signal is about 100MHz, while the downlink signal bandwidth of most aerospace measurement and control targets is less than 20MHz. Therefore, the downlink beam signal channel designed between the digital beamforming units at each level of the digital multi-beam phased array antenna system can use the digital frequency division multiplexing technology of the downlink channel proposed in the present invention for narrowband signals. The same downlink beam signal channel simultaneously transmits the downlink sum beam signal and the downlink difference beam signal, thereby saving one downlink beam signal channel for each downlink beam target of the phased array antenna. Figure 3 As shown, in the target downlink signal bandwidth 2f aMuch smaller than the bandwidth 2f of the downlink signal channel w In this case, the downlink difference beam signal can be digitally converted to the center frequency f0, and then the downlink sum beam signal and the downlink difference beam signal are superimposed to achieve the goal of frequency division multiplexing of the downlink sum beam signal and the downlink difference beam signal in the downlink signal channel.

[0078] In engineering design, the conditions for determining whether narrowband downlink sum and difference signals can be superimposed are as follows:

[0079] f w ≤4f a

[0080] Among them, 2f w The bandwidth of the downlink signal channel designed for the digital multi-beam phased array antenna system; 2f a is the target downlink signal bandwidth.

[0081] The center frequency point f0 of the downlink differential beam signal frequency conversion is calculated according to the following algorithm:

[0082]

[0083] like Figure 4 As shown in the figure, for a downlink signal of a target, after the first-level digital beam forming unit forms the downlink sum beam signal and the downlink difference beam signal, the downlink sum signal and the downlink are superimposed into one signal according to the frequency division multiplexing method. At the same time, the downlink signal channel between the digital beam forming units at each level is used to send the sum signal and the difference signal of the downlink beam to the n-th level digital beam forming unit step by step, and finally the n-th level digital beam forming unit distributes the sum signal and the difference signal of the downlink beam to the back-end information processing system.

[0084] See also Figure 5 and Figure 6 ,like Figure 5 As shown, a digital frequency converter of the downlink difference beam signal is added to the first-level digital beam forming unit, and its function is to convert the downlink difference beam signal from zero intermediate frequency to the set frequency point f0. Finally, the downlink difference beam signal after frequency conversion is added to the downlink sum beam signal to form a signal that shares a downlink signal channel. That is:

[0085]

[0086] Among them, w0=2πf0.

[0087] like Figure 6As shown, in the digital frequency converter of the downlink differential beam signal, according to the system given frequency control word, a DDS (digital frequency synthesizer) uses the system clock to generate the desired local oscillator signal, and then generates the desired downlink differential beam signal after frequency conversion by mixing and digital filtering.

[0088] See also Figure 7 , before the downlink sum beam signal and the difference beam signal of the frequency division multiplexing downlink signal channel are distributed to the digital tracking receiver for processing through the nth level digital beam forming unit, the downlink sum beam signal and the difference beam signal need to be separated. Figure 7 As shown, a sum and difference signal separation processing unit is added in front of the digital tracking receiver, wherein the sum signal of the downlink beam is obtained by digital filtering; and the difference signal of the downlink beam is obtained by down-conversion plus mathematical filtering.

[0089] According to the above-mentioned design method of the present invention, the number of synthesized beams of the phased array antenna system can be increased by using the method of frequency division multiplexing downlink channels of downlink sum beam signals and downlink difference beam signals for space targets that meet the conditions. For example, if the number of receiving targets designed for the digital multi-beam phased array antenna system is 16, then the traditional system needs to design 16 downlink sum beam signal channels and 16 downlink difference beam signal channels. If 10 of the 16 targets meet the narrowband downlink signal conditions required by the present invention, the method of frequency division multiplexing downlink channels of the present invention can be used for the 20 downlink signal channels of the 10 targets originally designed, and the 20 downlink signal channels can be used to realize beam synthesis of the 20 narrowband downlink targets. Therefore, by using the method of the present invention, the number of receiving targets designed for the original phased array antenna system can be increased from 16 to 26 without increasing system resources, thereby greatly improving the performance of the antenna system.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention 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 invention 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 invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method, characterized in that: include: When the digital multi-beam phased array antenna performs digital beamforming on a space target, if the bandwidth of the downlink signal of the space target is smaller than the spectrum bandwidth of the downlink beam signal channel, the downlink sum signal and the downlink difference signal share a downlink beam sum channel, that is, the same downlink beam signal channel simultaneously transmits the downlink sum beam signal and the downlink difference beam signal, so as to increase the number of beams formed by the digital multi-beam phased array antenna system through the downlink beam difference channel; the downlink digital beam signal of the digital multi-beam phased array antenna includes the downlink sum beam signal and the downlink difference beam signal.

2. The digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method according to claim 1, characterized in that: The downlink sum signal and the downlink difference signal share a downlink beam sum channel, including: The center frequency of the downlink difference beam signal is transformed by digital frequency conversion and then moved to the spectrum of the downlink beam sum channel. The downlink sum beam signal is then superimposed with the downlink difference signal to achieve frequency division multiplexing of the downlink sum beam signal and the downlink difference beam signal in the downlink signal channel. The downlink signal channel includes the downlink beam sum channel and the downlink beam difference channel.

3. The digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method according to claim 2, characterized in that: The center frequency of the downlink difference beam signal is transformed, and the center frequency after transformation is If f w ≤4f a , then the downlink sum beam signal and the downlink difference beam signal can be superimposed; where 2f w The bandwidth of the downlink signal channel designed for the digital multi-beam phased array antenna system; 2f a It is the downlink signal bandwidth of the space target.

4. The digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method according to claim 2, characterized in that: For a downlink signal of a target, after the downlink sum beam signal and the downlink difference beam signal are formed in the first-level digital beamforming unit, the downlink sum beam signal and the downlink difference beam signal are superimposed into one signal according to the frequency division multiplexing method; at the same time, the downlink signal channel between the digital beamforming units at each level is used to send the superimposed signal to the n-th level digital beamforming unit step by step, and finally the n-th level digital beamforming unit distributes the superimposed signal to the back-end information processing system.

5. The digital multi-beam phased array antenna downlink and channel digital frequency division multiplexing method according to claim 4, characterized in that: The digital frequency converter of the downlink difference beam signal in the first-stage digital beam forming unit converts the downlink difference beam signal from zero intermediate frequency to the set frequency point f0; finally, the downlink difference beam signal after frequency conversion is added to the downlink sum beam signal to form a signal sharing a downlink signal channel, that is: Among them, S 和路信号加差路信号 For signals that share a downlink signal channel, S 和路信号 is the downlink and path beam signal, S 差路信号 is the downlink difference beam signal, w0=2πf0.

6. A digital multi-beam phased array antenna system, characterized in that: It includes a digital beam forming subsystem and a sum and difference processing unit, wherein the digital beam forming subsystem includes n-stage cascade-connected digital beam forming units, namely, a first-stage digital beam forming unit to an n-stage digital beam forming unit; a downlink beam sum channel and a downlink beam difference channel are formed between the n-stage cascade-connected digital beam forming units; The first-level digital beamforming unit is used to receive the downlink signal of the space target, form the downlink sum beam signal and the downlink difference beam signal of the downlink signal, and then superimpose the downlink sum beam signal and the downlink difference beam signal into one signal according to the frequency division multiplexing method, and send the superimposed signal to the sum and difference processing unit after passing through the downlink beam difference channel between the digital beamforming units at each level in turn.

7. The digital multi-beam phased array antenna system according to claim 6, characterized in that: The first-level digital beamforming unit includes a downlink difference beamforming module, a digital frequency converter of a downlink difference beam signal, a stacker, and a downlink sum beamforming module; the downlink difference beamforming module is connected to the stacker via the digital frequency converter of the downlink difference beam signal; the stacker is connected to the downlink sum beamforming module; The downlink differential path beam forming module is used to receive the downlink signal and form a downlink differential path beam signal; The digital frequency converter of the downlink difference beam signal is used to convert the downlink difference beam signal from zero intermediate frequency to a set frequency point; and send the downlink difference beam signal after frequency conversion to the superimposer; The downlink and path beam forming module is used to receive the downlink signal, form the downlink and path beam signals and send them to the adder; The adder is used to add the received downlink difference beam signal to the downlink sum beam signal to form a superimposed signal.

8. The digital multi-beam phased array antenna system according to claim 7, characterized in that: The digital frequency converter of the downlink difference path beam signal comprises a digital frequency synthesizer, an operator and a digital filter; the digital frequency synthesizer is connected to the digital filter via the operator; The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock; The operator is used for mixing the local oscillator signal generated by the digital frequency synthesizer with the downlink difference beam signal to generate a mixed signal; The digital filter is used to convert the frequency of the mixing signal to generate a downlink difference beam signal after frequency conversion.

9. The digital multi-beam phased array antenna system according to claim 6, characterized in that: The sum and difference processing unit includes a digital frequency synthesizer, an operator, a first digital filter and a second digital filter; the digital frequency synthesizer is connected to the first digital filter through the operator; the first digital filter is connected to the second digital filter through the operator; The digital frequency synthesizer is used to generate the local oscillator signal from the system given frequency control word and the system clock; The operator is used to mix the local oscillator signal generated by the digital frequency synthesizer with the superimposed signal to generate a mixed signal; The first digital filter is used to transform the frequency of the mixing signal to generate a downlink difference path beam signal; The second digital filter is used to transform the frequency of the superimposed signal to generate a downlink and path beam signal.

10. The digital multi-beam phased array antenna system according to claim 6, characterized in that: It also includes a digital tracking receiver connected to the sum and differential path processing unit, and a digital multi-beam phased array antenna connected to the first-stage digital beam forming unit; the digital multi-beam phased array antenna includes a plurality of antenna units; the plurality of antenna units are used to receive downlink signals of space targets and send them to the first-stage digital beam forming unit; The digital tracking receiver is used to receive the downlink sum beam signal and downlink difference beam signal output by the sum and difference processing unit, and generate an angle error signal for the digital multi-beam phased array antenna to track the space target.

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