CN111464195A - A kind of ultrashort wave digital receiving system and method based on broadband beamforming - Google Patents

Abstract

The invention relates to the technical field of electronic communication, in particular to an ultrashort wave digital receiving system and method based on broadband beamforming, comprising a data acquisition module, a signal processing module, a system clock module and a power supply module; the data acquisition module comprises an array antenna and a module A digital conversion module; the signal processing module includes a phase shifter, an integer delay module, a fractional delay module, a sub-array beam output module and a total beam output module. The invention realizes an ultra-short wave digital receiving system based on broadband beam forming by combining high-precision digital time delay and sub-array beam forming. The fractional-order filter is used for delay compensation, which realizes accurate delay compensation of the received signal; the sub-array-level beamforming is used to divide the array antenna into several parts, which reduces the implementation cost; at the same time, the sub-array-level beamforming and digital delay Combined, it can not only reduce the digital delay unit, but also reduce the difficulty of fractional delay implementation.

Description

A kind of ultrashort wave digital receiving system and method based on broadband beamforming

technical field

The invention relates to the technical field of electronic communication, in particular to an ultrashort wave digital receiving system and method based on broadband beamforming.

Background technique

Digital beamforming (DBF) is a digital signal processing technology that weights the signals received by the array and adjusts the weights to achieve effective signal reception. The early digital beamforming research was mainly aimed at narrowband signals, but with the application of array signal processing technology in the fields of radar signals, seismic signals, sonar signals and other broadband signals, the traditional narrowband beamforming algorithm is due to the deviation of beam pointing and main lobe width. no longer applicable. Therefore, how to perform flexible and efficient beamforming of broadband signals has become a hotspot in wireless communication research.

The difference between broadband beamforming and narrowband is that its steering vector is not only affected by the signal incident direction, but also affected by the signal frequency change. To solve this problem, delay compensation is performed on each branch so that each branch receives the same wavefront of the signal at the same time, thereby eliminating the influence of frequency variation on the steering vector. At present, it is relatively mature to realize delay compensation through a digital delay line, but this method can only realize the delay of an integer multiple of the sampling interval, so when the sampling rate is low, the beam pattern will be distorted.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an ultra-short wave digital receiving system and method based on broadband beamforming in view of the above deficiencies in the prior art.

The object of the present invention is achieved through the following technical solutions: an ultrashort wave digital receiving system based on broadband beamforming, comprising a data acquisition module, a signal processing module, a system clock module and a power supply module;

The data acquisition module includes an array antenna and an analog-to-digital conversion module;

The signal processing module includes a phase shifter, an integer delay module, a fractional delay module, a sub-array beam output module and a total beam output module;

The array antenna includes several sub-arrays; each sub-array includes several array elements; the array elements are used to receive antenna signals; Phase shifter;

The integer delay module is used to perform integer multiple compensation for the data passed through the phase shifter; the fractional delay module is used to compensate the fractional part of the delay of the data passed through the integer delay module; the sub-array beam outputs The module is used to beamform the data of all the array elements in each subarray after passing through the phase shifter, integer multiple compensation and time delay module; the total beam output module is used to output the subarray beam output module after all the subarrays have passed through beams for beamforming;

The system clock module is used for providing a clock source for the whole system; the power module is used for providing power supply for the whole system.

The present invention further provides that the integer delay module adopts a filter to complete the integer multiple compensation of the sampling interval.

The present invention further provides that the fractional delay module uses a fractional filter to compensate the fractional part of the delay.

An ultrashort wave digital receiving method based on broadband beamforming, comprising a data acquisition module and a signal processing module; the data acquisition module comprises an array antenna and an analog-to-digital conversion module; the array antenna comprises N adjacent sub-arrays, Each subarray has M array elements, and the array element spacing is d;

The ultrashort wave digital receiving method based on broadband beamforming includes the following steps:

Signal collection: use array elements to collect antenna signals;

Data conversion: The antenna signal collected by the analog-to-digital conversion module is sampled at KT _s and obtained after analog-to-digital conversion [x ₀ (kTs),x ₁ (kTs),…,x _M-1 (kTs)] ^T ; where K is the coefficient, and T _s is the coefficient collection interval;

Delay compensation processing: perform delay compensation on the data received by each array element; the delay value is [τ ₀ ,τ ₁ ,τ ₂ ,…τ _M-1 ]; the delay of the mth array element is τ _m =dmsinθ/c; where c is the speed of light;

Therefore, the time delay compensation processing includes the integral multiple compensation of the sampling interval L _m =round(dmsinθ/cT _s ) and the compensation for the fractional part of the time delay p _m =τ _m /T _s −L _m ;

Subarray beamforming: the array elements of each subarray are synthesized and the output is

Subarray beamforming: perform delay compensation for each subarray, the compensation value is [η ₀ ,η ₁ ,η ₂ ,...,η _N-1 ], where η _n =nMd sinθ/c, sub-array beamforming The output is

Total beam output: Synthesize all sub-array beams.

The present invention further provides that, in the time delay compensation processing step, a filter is used to complete the integral multiple compensation of the sampling interval.

The present invention further provides that, in the time delay compensation processing step, a fractional filter is used to compensate the fractional part of the time delay.

Beneficial effects of the present invention: The present invention realizes an ultra-short wave digital receiving system based on broadband beamforming by combining high-precision digital time delay and sub-array beamforming. Fractional filter is used for time delay compensation, which realizes continuously variable and precise time delay compensation for the received signal; the array antenna is divided into several parts by sub-array beamforming, which effectively reduces the number of receiving channels and thus reduces the At the same time, the combination of sub-array-level beamforming and digital delay can not only reduce the digital delay unit, but also reduce the difficulty of fractional delay implementation.

Description of drawings

The invention will be further described by using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, under the premise of no creative work, other Attached.

Fig. 1 is a topology diagram of the present invention;

Fig. 2 is the principle block diagram of the data acquisition module of the present invention;

Fig. 3 is the principle block diagram of the signal processing module of the present invention;

Fig. 4 is the principle block diagram of the system clock module of the present invention;

FIG. 5 is a schematic diagram of the fractional delay module of the present invention.

Detailed ways

The present invention will be further described with reference to the following examples.

As can be seen from FIG. 1 to FIG. 5 , an ultrashort wave digital receiving system based on broadband beamforming described in this embodiment includes a data acquisition module, a signal processing module, a system clock module and a power supply module;

The data acquisition module includes an array antenna and an analog-to-digital conversion module;

The signal processing module includes a phase shifter, an integer delay module, a fractional delay module, a sub-array beam output module and a total beam output module;

The array antenna includes several sub-arrays; each sub-array includes several array elements; the array elements are used to receive antenna signals; Phase shifter;

The integer delay module is used to perform integer multiple compensation for the data passed through the phase shifter; the fractional delay module is used to compensate the fractional part of the delay of the data passed through the integer delay module; the sub-array beam outputs The module is used to beamform the data of all the array elements in each subarray after passing through the phase shifter, integer multiple compensation and time delay module; the total beam output module is used to output the subarray beam output module after all the subarrays have passed through beams for beamforming;

The system clock module is used for providing a clock source for the whole system; the power module is used for providing power supply for the whole system. In the ultrashort wave digital receiving system based on broadband beamforming described in this embodiment, the integer delay module uses a filter to complete the integer multiple compensation of the sampling interval. In the ultrashort wave digital receiving system based on broadband beamforming described in this embodiment, the fractional delay module uses a fractional filter to compensate the fractional part of the delay.

In this embodiment, an ultra-short wave digital receiving system based on broadband beamforming is realized by combining high-precision digital time delay and subarray-level beamforming. It can effectively complete the reception of wideband signals with an instantaneous bandwidth of 400MHz. The system uses fractional-order filter for time delay compensation, which realizes continuously variable and precise time delay compensation for the received signal; and uses sub-array-level beamforming to divide the array antenna into several parts, which effectively reduces the number of receiving channels. This reduces the implementation cost; at the same time, the combination of sub-array beamforming and digital delay can not only reduce the digital delay unit, but also reduce the difficulty of fractional delay implementation.

As shown in Figure 2, the data acquisition module includes an AD9208 chip, an FPGA module, a DSP module, a clock module and a power supply module; the AD9208 chip is connected to the FPGA module, is responsible for the collection of radio frequency signals, and converts the data after analog-to-digital conversion. It is transmitted to the FPGA module; the FPGA module transmits the data from the AD9208 chip to the outside through the QSFP28 optical fiber, and the FPGA module can also transmit part of the received data to the DSP module through SRIO or cache it in the DDR3; the DSP module can The data transmitted by the FPGA module is processed, and the result is sent out through the Gigabit Ethernet of the DSP module; the power supply module is connected with the AD9208 chip, the FPGA module, the DSP module, and the clock module to supply power; the clock module Connect with AD9208 chip, FPGA module and DSP module to provide clock frequency.

As shown in FIG. 3 , the signal processing module includes an FPGA module, a DSP module, a clock module and a power supply module; the FPGA module performs arithmetic processing on the data transmitted from the data acquisition module to realize beamforming; the power supply module and AD9208 chip, FPGA module, DSP module and clock module are connected to supply power; the clock module is connected with AD9208 chip, FPGA module and DSP module to provide clock frequency.

As shown in Figure 4, the system clock module includes an FPGA module, a clock module and a power supply module; the power supply module is connected to an AD9208 chip, an FPGA module, a DSP module and a clock module for power supply; the clock module adopts The LMK04821 ultra-low jitter, ultra-low noise JESD204B dedicated clock chip can dynamically adjust the output clock phase to provide the clock frequency.

As shown in FIG. 5 , the fractional delay module completes fractional delay compensation for the received data of M array elements.

An ultrashort wave digital receiving method based on broadband beamforming described in this embodiment includes a data acquisition module and a signal processing module; the data acquisition module includes an array antenna and an analog-to-digital conversion module; the array antenna includes an evenly divided N adjacent subarrays, each subarray has M array elements, and the array element spacing is d;

The ultrashort wave digital receiving method based on broadband beamforming includes the following steps:

Signal collection: use array elements to collect antenna signals;

Data conversion: The antenna signal collected by the analog-to-digital conversion module is sampled at KT _s and obtained after analog-to-digital conversion [x ₀ (kTs),x ₁ (kTs),…,x _M-1 (kTs)] ^T ; where K is the coefficient, and T _s is the coefficient collection interval;

Delay compensation processing: perform delay compensation on the data received by each array element; the delay value is [τ ₀ ,τ ₁ ,τ ₂ ,…τ _M-1 ]; the delay of the mth array element is τ _m = dm sinθ/c; where c is the speed of light;

Therefore, the time delay compensation processing includes compensating integer times of sampling interval L _m =round(dm sinθ/cT _s ) and compensating the fractional part of time delay p _m =τ _m /T _s -L _m ;

Subarray beamforming: the array elements of each subarray are synthesized and the output is

Subarray beamforming: perform delay compensation for each subarray, the compensation value is [η ₀ ,η ₁ ,η ₂ ,...,η _N-1 ], where η _n =nMd sinθ/c, sub-array beamforming The output is

Total beam output: Synthesize all sub-array beams.

In the ultrashort wave digital receiving method based on broadband beamforming described in this embodiment, in the time delay compensation processing step, a filter is used to complete the integer multiple compensation of the sampling interval. In the ultrashort wave digital receiving method based on broadband beamforming described in this embodiment, in the time delay compensation processing step, a fractional order filter is used to compensate the fractional part of the time delay.

In this embodiment, an ultra-short wave digital receiving system based on broadband beamforming is realized by combining high-precision digital time delay and subarray-level beamforming. The system uses fractional-order filter for time delay compensation, which realizes continuously variable and precise time delay compensation for the received signal; and uses sub-array-level beamforming to divide the array antenna into several parts, which effectively reduces the number of receiving channels. This reduces the implementation cost; at the same time, the combination of sub-array beamforming and digital delay can not only reduce the digital delay unit, but also reduce the difficulty of fractional delay implementation.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that , the technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims (6)

1. An ultrashort wave digital receiving system based on broadband beam forming is characterized in that: the system comprises a data acquisition module, a signal processing module, a system clock module and a power supply module;

the data acquisition module comprises an array antenna and an analog-to-digital conversion module;

the signal processing module comprises a phase shifter, an integer time delay module, a fraction time delay module, a subarray beam output module and a total beam output module;

the array antenna comprises a plurality of sub-arrays; each subarray comprises a plurality of array elements; the array element is used for receiving antenna signals; the analog-to-digital conversion module is used for performing analog-to-digital conversion on the antenna signals acquired by the array elements and then transmitting the antenna signals to the phase shifter;

the integer time delay module is used for carrying out integer multiple compensation on the data passing through the phase shifter; the fractional time delay module is used for compensating the time delay fractional part of the data passing through the integer time delay module; the subarray beam output module is used for carrying out beam synthesis on data of all array elements in each subarray after passing through the phase shifter, the integral multiple compensation and the time delay module; the total beam output module is used for carrying out beam synthesis on beams of all the subarray beam output modules after the subarray passes through;

the system clock module is used for providing a clock source for the whole system; the power supply module is used for providing power supply for the whole system.

2. The ultrashort wave digital receiving system based on broadband beam forming of claim 1, wherein: and the integer time delay module adopts a filter to complete the integer multiple compensation of the sampling interval.

3. The ultrashort wave digital receiving system based on broadband beam forming of claim 1, wherein: and the fractional delay module adopts a fractional order filter to compensate the delay decimal part.

4. An ultrashort wave digital receiving method based on broadband beam forming is characterized in that: the device comprises a data acquisition module and a signal processing module; the data acquisition module comprises an array antenna and an analog-to-digital conversion module; the array antenna comprises N adjacent sub-arrays which are equally divided, wherein each sub-array is provided with M array elements, and the array element interval is d;

the ultrashort wave digital receiving method based on broadband beam forming comprises the following steps:

and (3) signal acquisition: acquiring antenna signals by using array elements;

conversion of data: antenna signal KT acquired by array element by adopting analog-to-digital conversion module_sSampling and analog-to-digital converting to obtain [ x₀(kTs),x₁(kTs),…,x_M-1(kTs)]^T(ii) a Where K is the coefficient, T_sA coefficient acquisition interval;

and (3) time delay compensation processing: performing time delay compensation on the data received by each array element; wherein the delay value is [ tau ]₀,τ₁,τ₂,…τ_M-1](ii) a Wherein the time delay of the m array element is tau_mDmsin θ/c; wherein c is the speed of light;

the delay compensation process includes sample interval integer multiple compensation L_m＝round(dmsinθ/cT_s) And compensating for the fractional delay p_m＝τ_m/T_s-L_m；

Sub-array beam synthesis: the array elements of each subarray are synthesized and output as

Sub-array beam forming, wherein each sub-array is subjected to time delay compensation with the compensation value of [ η ]₀,η₁,η₂,…,η_N-1]Wherein η_nThe output of subarray level beamforming is nMd sin theta/c

Total beam output: and synthesizing all the subarray beams.

5. The ultrashort wave digital receiving method based on broadband beam forming of claim 4, wherein: in the time delay compensation processing step, a filter is adopted to complete the integral multiple compensation of the sampling interval.

6. The ultrashort wave digital receiving method based on broadband beam forming of claim 4, wherein: in the delay compensation processing step, a fractional order filter is adopted to compensate the delay fractional part.

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