CN219304828U - Radio astronomical phase array feed source time domain beam forming terminal - Google Patents

Abstract

The utility model discloses a radio astronomical phase array feed source time domain wave beam synthesis terminal which is characterized by comprising N cascaded RFSOC cards, wherein each RFSOC card comprises M channels, an ADC sampling module and a DDC digital down-conversion module are arranged on each channel, and each RFSOC card further comprises an amplitude phase correction module, a time domain wave beam synthesis module, a wave beam synthesis coefficient storage module, a transmission interface module and a synchronous control module; the DDC digital down-conversion module is used for carrying out digital down-conversion on the input sampling data to obtain a baseband signal after frequency conversion; the data amplitude-phase correction module is used for carrying out amplitude-phase correction on the received baseband signal data of each channel; the beam synthesis coefficient storage module is used for storing a pre-generated beam synthesis coefficient; the time domain beam synthesis module is used for carrying out beam synthesis on the multichannel data after the amplitude phase correction based on the beam synthesis coefficient, and outputting the beam synthesis data after being packaged by the transmission interface module.

Description

Radio astronomical phase array feed source time domain beam forming terminal

Technical Field

The utility model belongs to the technical field of astronomical observation, and particularly relates to a time domain beam forming terminal of a radio astronomical phase array feed source.

Background

In radio astronomical observation, in order to effectively develop observation applications such as pulsar, transient source and the like, high-sensitivity rapid sky patrol is required, and because the caliber of a radio telescope antenna is large and the beam is narrow, the time required for completing one-time sky patrol is extremely long, and in order to improve the sky patrol speed, a plurality of beams are often adopted for observation. In recent years, many countries have begun to try to use small phased array antennas as multi-beam feeds on large and medium radio telescope antennas to form several mutually overlapping instantaneous beams, known as phased array feed (Phased Array Feed, PAF) technology. PAF is used as an international leading technology, so that the efficiency of a traditional waveguide feed source can be maintained, the whole focal plane can be sampled, and more complete information can be obtained from the focal plane. By generating a plurality of tightly overlapped beams, the view field of the radio telescope is effectively enlarged, and the sky patrol efficiency is improved.

The PAF technology is generated by considering that the effective signal collecting range area in the focal plane field of the telescope is limited, the size of the feed horn is also limited by design, and meanwhile, the size of each beam is also dependent on the caliber of the reflecting surface of the telescope, and under the action of the factors, the beams formed by a common feed horn array are not arranged in a mode of overlapping with each other by 3dB, but have a certain gap between the beams. Thus, for the same antenna area, the feed horn array may need to be observed repeatedly (typically n=3, 4) to achieve a tight 3dB overlapping arrangement of beams to fill the entire field of view. The PAF multi-beam synthesis network is used for space scanning or space observation, and as the number of beams is not limited by the number of feed source horns, 3dB tight overlapping among a plurality of beams can be formed in the view field range as long as the computing capacity of the terminal is improved, so that the income brought by the method can be improved by 3-4 times relative to the space observation efficiency of the feed source horn array.

FAST in China is the radio telescope with the largest caliber internationally, and the development of a broadband low-noise large-view-field multi-beam array feed source matched with FAST is enabled to be an antenna patrol device. As the radio telescope with highest sensitivity in the world, FAST enters into the formal operation, and it applies for the actual operation time of the full load of the telescope far beyond the time of the observation machine. By utilizing the phase array feed source technology, the novel multi-beam receiver system equipment FAST is developed, and the contradiction can be greatly relieved. The PAF array forms a plurality of beams by utilizing a multi-unit beam synthesis network, so that the FAST observation field of view can be effectively enlarged, the telescope sky-patrol efficiency is improved, and the FAST international leading position can be further maintained and improved while massive observation applications are met.

The FAST active 19-cell multi-beam receiver uses a mainstream ROACH2 terminal. The system comprises an Xilinx Virtex-6 system FPGA serving as a main processing unit, a PowerPC 440EPx serving as a user interaction and control SOC, and a radio astronomical observation function through the combination of a plurality of FPGA functional modules.

The structure of the radio astronomical ROACH2 terminal mainly comprises 6 modules, and the specific functions of each module are as follows:

the ADC sampling module is used for realizing the sampling of radio frequency signals with the bandwidth of 0-1 GHz through an ADC chip with the bandwidth of 2 Gsps@8bit;

the FFT operation module carries out frequency spectrum channelized processing on the sampling data of the ADC through FFT operation, and realizes the frequency resolution control requirement of radio astronomical observation on the data by controlling the channelized frequency spectrum operation processing of 2-8K frequency points;

3. the spectrum accumulation control module is used for realizing the time resolution control requirement of radio astronomical observation on data through the operation of spectrum accumulation (integral);

the bit interception module is used for intercepting 8 bits of 32-bit single-precision floating point numbers after FFT operation, so that the 8-bit input 8-bit output requirement of a spectrum analysis terminal is met, and the dynamic range value of an output spectrum can be adjusted;

5. the kilomega transmission module performs UDP or TCP/IP data encapsulation and transmission functions on the calculated frequency spectrum, and can control and set the functions of transmitting a packet header file, a destination IP address, an MAC value and the like;

6. and the receiving and storing module unpacks and saves the transmitted data, and directly stores the data into a hard disk of the target computer through an RDMA mode of the tera-megacard, so that the data storage function of spectrum analysis is completed.

Aiming at the development of the wave beam synthesis technology of a new generation of radio astronomical PAF receiver, the existing radio astronomical digital terminal ROACH2 system cannot meet the requirements of observation and application because of the capacity limitation of a hardware ADC and an FPGA chip, and the key technical indexes such as 2 channel 1GHz@8bit,2K frequency point, 10GbE transmission and the like, can not realize the coverage of higher 8 channel 1-2 GHz multi-channel input, can not meet the high-frequency spectrum resolution observation of 16-32K point FFT operation, and can not meet the high-speed data transmission requirement of 100 Gbps.

The efficient large-field night-sky and imaging of the PAF array are mainly realized through multi-beam with controllable and stable shape, the beam synthesis is the core from the original observed data to the scientific data, and the actual weighting factors, interference suppression and other algorithms are highly dependent on the operation and transmission capability of the terminal. The existing active ROACH2 platform of the FAST-19 beam receiver can not meet the mass processing requirements brought by a novel multi-beam array, so that in combination with the development of the Moore's law in the industry, the digital beam synthesis platform of the RFSOC of the latest generation of FPGA architecture is urgently required to be developed, and the FAST broadband multi-beam PAF beam synthesis terminal is realized through the latest FPGA array mode.

Disclosure of Invention

Aiming at the problems existing in the prior art, the utility model aims to provide a time domain beam forming terminal of a radio astronomical phase array feed source.

The method combines the technical development and PAF development requirements of the international latest radio astronomical receiver, realizes the development of the PAF beam forming terminal system based on a new generation FPGA platform aiming at the existing 7-unit and 19-unit PAF feed source design of FAST, and completes a set of PAF beam forming terminal system based on RFSOC meeting design parameters aiming at FAST-PAF design indexes, and is characterized in that:

1) The method is characterized in that 19 unit design indexes of a FAST-PAF feed source are completely covered, an RFSOC multi-card cascading mode of a single-card 8 channel is adopted to realize full-unit effective coverage of at most 24 paths, the sampling bandwidth of 2-4 Gsps meets the broadband requirement of 500 MHz-2 GHz, the 12bit AD sampling precision is improved, and the data dynamic range meets more observation requirements.

2) The RFSOC kernel digital frequency conversion DDC design is carried out, and the 500MHz frequency conversion moving of the baseband of 1.4-1.9 GHz is realized.

3) And carrying out digital spectrum analysis FPGA kernel design of the RFSOC kernel 16K channel to realize the 16K high-resolution operation channel.

4) And carrying out RFSOC kernel digital beam synthesis design to realize multi-path beam synthesis design of each 5-degree beam scanning of-90 to +90 degrees.

5) Through time domain beam synthesis operation, FPGA resource consumption based on frequency domain FFT operation is reduced, and meanwhile, a multiphase filter bank design, a multi-IP cluster output interface and the like are introduced, so that various beam synthesis algorithm ratios, high-performance frequency spectrum processing and flexible parameter setting are realized.

The technical scheme of the application is as follows:

the radio astronomical phase array feed source time domain wave beam synthesis terminal is characterized by comprising N cascaded RFSOC cards, wherein each RFSOC card comprises M channels, an ADC sampling module 1 and a DDC digital down-conversion module 2 are arranged on each channel, and each RFSOC card further comprises an amplitude phase correction module 3, a time domain wave beam synthesis module 4, a wave beam synthesis coefficient storage module 5, a transmission interface module 6 and a synchronous control module 7; the product of N and M is greater than 19;

the ADC sampling module 1 is used for sampling a received radio frequency signal and sending the radio frequency signal to the DDC digital frequency conversion module 2;

the DDC digital down-conversion module 2 is configured to digitally down-convert the corresponding input sampling data to obtain converted baseband signal data, and transmit the converted baseband signal data to the amplitude-phase correction module 3;

the amplitude-phase correction module 3 is configured to perform amplitude-phase correction on the received baseband signal data of each channel, and input the corrected baseband signal data into the time-domain beam forming module 4;

the beam synthesis coefficient storage module 5 is connected with the time domain beam synthesis module 4 and is used for storing a pre-generated beam synthesis coefficient;

the time domain beam synthesis module 4 is configured to perform beam synthesis on the multi-channel data after the amplitude-phase correction based on the beam synthesis coefficients in the beam synthesis coefficient storage module 5, and input the beam synthesis data into the transmission interface module 6;

the transmission interface module 6 is configured to package and output the beam-formed data;

and the synchronous control module 7 is used for being connected with other synchronous control modules on the RFSOC card and controlling the ADC sampling module on the RFSOC card and the ADC sampling module on the RFSOC card to synchronously sample the received radio frequency signals.

Further, the RFSOC card is an RFSOC of 8 channels, and the value of N is 3.

Further, the ADC sampling module 1 supports wideband sampling of 2-4 Gsps@12bit.

Further, the amplitude phase correction module 3 performs amplitude phase correction on the received baseband signal data of each channel according to the actually measured compensation value of the amplitude phase difference of the multi-radio frequency link.

Further, the teraport of the transmission interface module 6 is configured as an 8x25Gbps transmission mode or a 2x100Gbps transmission mode.

Furthermore, the transmission interface module 6 is connected with a RAID disk array or a GPU server through a tera-megaswitch, and is used for carrying out high-speed parallel storage and subsequent operation processing on output data.

The utility model has the following advantages:

aiming at the development of new generation radio astronomical ultra wideband receiver technology, the key technical indexes of 2 channel 1GHz,2K frequency point, 10GbE transmission and the like of the existing radio astronomical digital terminal ROACH2 system can not meet the requirements of observation and application, and the corresponding FAST 7-unit and 19-unit PAF feed source multichannel digital beam synthesis terminal system still belongs to the vacancy, so that corresponding investigation, design and research and development work are urgently needed to be carried out.

Aiming at the fact that the existing ROACH2 platform of the FAST-19 beam receiver can not meet the mass processing requirements brought by a novel multi-beam array, in order to meet the design parameters of the FAST existing 7-unit PAF feed source and the FAST existing 19-unit PAF feed source, the digital beam synthesis terminal system based on the RFSOC is developed, the full-unit effective coverage of at most 24 paths is realized through the key technical development of a multi-path digital beam synthesis terminal, the sampling bandwidth of 2-4 Gsps meets the broadband requirements of 500 MHz-2 GHz, and the 12bit AD sampling precision is improved, so that the data dynamic range meets more observation requirements. The new generation of high-performance digital terminal development meeting the requirements of broadband, high spectrum resolution, large dynamic range and long time scale stability is realized through the latest generation of FPGA kernel design.

The radio astronomical digital beam synthesis system developed by the patent is based on a new generation Xilinx RFSOC FPGA processing unit, 8 paths of 2-4 Gsps@12bit sampling chips are configured on a chip, multi-card synchronous multi-channel coverage can be realized through a synchronous clock technology, SPF28 transmission performance of up to 8-16K frequency points and 2x100GbE is 8 times that of a current universal radio astronomical digital terminal ROACH2 system. The development of the spectrum analysis system can be directly applied to digital beam synthesis of a FAST-19 unit PAF receiver system, makes up for the gap, can expand the working bandwidth (450 MHz is upgraded to 1 GHz) of the existing ROACH2 system, is applied to DVAC and subsequent SKA-P telescopes, and can be explored on other frequency bands according to actual needs.

Drawings

Fig. 1 is a diagram of a radioastronomical 19 element PAF time domain beam forming terminal system.

Reference numerals: the system comprises a 1-ADC sampling module, a 2-DDC digital down-conversion module, a 3-amplitude-phase correction module, a 4-time domain beam synthesis module, a 5-beam synthesis coefficient storage module, a 6-transmission interface module and a 7-synchronous control module.

Detailed Description

The utility model will now be described in further detail with reference to the accompanying drawings, which are given by way of illustration only and are not intended to limit the scope of the utility model.

The main implementation functions of the radio astronomical 19 unit PAF time domain beam forming terminal are as follows: after heterodyne sampling, quantization and coded digital measurement are carried out on multi-input receiving Intermediate Frequency (IF) signals, the signals are transmitted to an FPGA chip core through a data bus, digital down-conversion is carried out to base band data, after multi-path base band data are corrected through amplitude phase correction, beam synthesis operation is carried out, a beam synthesis measurement result of the multi-path signals is obtained, and according to a data matrix with an X axis as an angle and a Y axis as an amplitude, the measurement result is stored in a built-in memory chip of a terminal system. And outputting data to a rear high-speed switch and a storage RAID array through a network interface of the FPGA, and receiving a computer by a terminal to realize further measurement processing, graphic drawing, data storage and other works. And the terminal system chassis integrates and packages the 3 RFSOC cards, and sets a unified power supply and clock synchronization.

The system structure of the radio astronomical 19 unit PAF time domain beam forming terminal is shown in fig. 1, and mainly comprises 7 modules, and the specific functions of each module are as follows:

the RFSOC on-chip ADC sampling module 1 is used for carrying out multipath sampling on radio frequency signals and sending the radio frequency signals to the DDC digital frequency conversion module 2, the ADC supports broadband high-precision sampling processing of 2-4 Gsps@12bit, 8 paths of ADC are carried on a single RFSOC card, and 24 paths of ADC are input in total.

The DDC digital down-conversion module 2 is used for carrying out digital down-conversion on the corresponding input sampling data to obtain the baseband signal data after frequency conversion, and transmitting the baseband signal data after frequency conversion to the amplitude-phase correction module 3.

The amplitude and phase correction module 3 is used for carrying out amplitude and phase correction on the baseband signal data of each channel after the frequency conversion of the module 2, and transmitting the amplitude and phase correction data to the RFSOC card register for carrying out signal amplitude and phase correction by using the compensation value data of amplitude and phase difference in the multi-radio frequency link which is actually measured in advance; the actual amplitude-phase distribution of the sampling of each unit of the antenna array surface is kept consistent with the theoretical amplitude-phase distribution.

The time domain beam synthesis module 4 is used for carrying out beam synthesis operation on the multichannel data after the amplitude phase correction, and carrying out beam synthesis addition operation based on the amplitude and the angle control coefficient value of a given beam synthesis algorithm; taking a single board card as an example, 8 data processing units for receiving 8 paths of signals send out the pointing angle information of the synthesized wave beam through a serial port, and an address decoder in the FPGA analyzes the corresponding wave control parameter address according to the sending-out angle information and reads the parameter data in the ROM. Each channel performs complex multiplication operation between the amplitude and phase corrected data and the beam forming parameters. And finally, adding and summing the complex multiplication results of each channel to obtain a beam synthesis result of a specified angle.

The beam synthesis coefficient storage module 5 is configured to store a pre-generated beam synthesis coefficient, store the amplitude and phase coefficient based on a given beam synthesis algorithm (such as conjugate matching, maximum directivity coefficient, etc.) for the module 4 to call, quantize the data in a fixed-point format, and store the quantized data in the data ROM in the FPGA.

The transmission interface module 6 is used for packaging and transmitting the beam forming data of the module 4, realizing multi-path data transmission by a high-speed optical interface of 2x100Gbps, and performing UDP or TCP/IP data packaging and transmitting functions on the beam forming data, wherein the functions of transmitting a packet header file, a destination IP address, a MAC value and the like can be controlled and set; and meanwhile, RFSOC on-board Linux system control and kernel loading are carried out through the gigabit network port, and gigabit data packaging and transmission after Snapshot Snapshot sampling are carried out on module 3 amplitude phase correction data and module 4 beam synthesis data, so that a real-time result monitoring function in the beam synthesis process is realized.

And the synchronous control module 7 is used for synchronizing among cards of the multiple RFSOC boards, realizing synchronous acquisition of 24 paths of signals in total of 3x8, and simultaneously providing subsequent processing calibration of the stored wave beam synthesized data for the clock timing synchronous mark of 24 paths of ADC (analog to digital converter) of the 3 boards.

Table 1 shows the total table of technical parameters of the radio astronomical 19 unit PAF time domain beam forming terminal

Table 2 is a radio astronomical 19 unit PAF time domain beam forming terminal beam forming coefficient configuration table

															real w1	0.1460 971	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097	0.146 097
real w2	- 0.4179 04	- 0.417 9	- 0.417 9	- 0.417 9	- 0.417 9	- 0.417 9	- 0.417 9	- 0.417 9	- 0.417 89	- 0.417 88	- 0.417 87	- 0.417 86	- 0.417 84	- 0.417 82
															real w3	0.7594 459	0.759 446	0.759 446	0.759 444	0.759 44	0.759 432	0.759 418	0.759 394	0.759 357	0.759 303	0.759 229	0.759 128	0.758 996	0.758 827
real w4	-1	-1	-1	- 0.999 99	- 0.999 98	- 0.999 96	- 0.999 92	- 0.999 85	- 0.999 7	- 0.999 58	- 0.999 36	- 0.999 06	- 0.998 67	- 0.998 17
															real w5	1	1	0.999 998	0.999 991	0.999 971	0.999 928	0.999 852	0.999 725	0.999 532	0.999 25	0.998 857	0.998 327	0.997 631	0.996 739
real w6	- 0.7594 46	- 0.759 45	- 0.759 44	- 0.759 43	- 0.759 41	- 0.759 36	- 0.759 27	- 0.759 12	- 0.758 89	- 0.758 56	- 0.758 09	- 0.757 46	- 0.756 64	- 0.755 58
															real w7	0.4179 042	0.417 904	0.417 902	0.417 896	0.417 877	0.417 837	0.417 765	0.417 646	0.417 46	0.417 199	0.416 83	0.416 332	0.415 678	0.414 84
real w8	- 0.1460 97	- 0.146 1	- 0.146 1	- 0.146 09	- 0.146 08	- 0.146 07	- 0.146 03	- 0.145 97	- 0.145 89	- 0.145 76	- 0.145 59	- 0.145 35	- 0.145 04	- 0.144 64
imag w1	0	0	0	0	0	0	0	0	0	0	0	0	0	0
															imag w2	5.12E- 17	5.00E -05	0.000 2	0.000 45	0.000 8	0.001 25	0.001 799	0.002 449	0.003 198	0.004 047	0.004 996	0.006 044	0.007 192	0.008 439
imag w3	- 1.86E- 16	- 0.000 18	- 0.000 73	- 0.001 64	- 0.002 91	- 0.004 54	- 0.006 54	- 0.008 9	- 0.011 62	- 0.014 71	- 0.018 16	- 0.021 97	- 0.026 13	- 0.030 67
															imag w4	3.67E- 16	0.000 359	0.001 435	0.003 23	0.005 741	0.008 97	0.012 916	0.017 578	0.022 956	0.029 049	0.035 856	0.043 376	0.051 607	0.060 547
imag w5	- 4.90E- 16	- 0.000 48	- 0.001 91	- 0.004 31	- 0.007 66	- 0.011 96	- 0.017 22	- 0.023 44	- 0.030 61	- 0.038 73	- 0.047 8	- 0.057 82	- 0.068 79	- 0.080 69
															imag w6	4.65E- 16	0.000 454	0.001 817	0.004 088	0.007 267	0.011 354	0.016 347	0.022 247	0.029 052	0.036 76	0.045 368	0.054 873	0.065 27	0.076 553
imag w7	- 3.07E- 16	- 0.000 3	- 0.001 2	- 0.002 7	- 0.004 8	- 0.007 5	- 0.010 79	- 0.014 69	- 0.019 18	- 0.024 27	- 0.029 95	- 0.036 22	- 0.043 08	- 0.050 51
															imag w8	1.25E- 16	0.000 122	0.000 489	0.001 101	0.001 957	0.003 058	0.004 402	0.005 991	0.007 823	0.009 897	0.012 212	0.014 766	0.017 558	0.020 584

Although specific embodiments of the utility model have been disclosed for illustrative purposes, it will be appreciated by those skilled in the art that the utility model may be implemented with the help of a variety of examples: various alternatives, variations and modifications are possible without departing from the spirit and scope of the utility model and the appended claims. Therefore, it is intended that the utility model not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this utility model, but that the utility model will have the scope indicated by the scope of the appended claims.

Claims (6)

1. The radio astronomical phase array feed source time domain beam synthesis terminal is characterized by comprising N cascaded RFSOC cards, wherein each RFSOC card comprises M channels, an ADC sampling module (1) and a DDC digital down-conversion module (2) are arranged on each channel, and each RFSOC card further comprises an amplitude-phase correction module (3), a time domain beam synthesis module (4), a beam synthesis coefficient storage module (5), a transmission interface module (6) and a synchronous control module (7); the product of N and M is greater than 19;

the ADC sampling module (1) is used for sampling a received radio frequency signal and sending the radio frequency signal to the DDC digital down-conversion module (2);

the DDC digital down-conversion module (2) is used for carrying out digital down-conversion on the corresponding input sampling data to obtain converted baseband signal data and transmitting the converted baseband signal data to the amplitude-phase correction module (3);

the amplitude-phase correction module (3) is used for carrying out amplitude-phase correction on the received baseband signal data of each channel and inputting the corrected data into the time domain beam forming module (4);

the beam synthesis coefficient storage module (5) is connected with the time domain beam synthesis module (4) and is used for storing a pre-generated beam synthesis coefficient;

the time domain beam synthesis module (4) is used for carrying out beam synthesis on the multichannel data after the amplitude phase correction based on the beam synthesis coefficients in the beam synthesis coefficient storage module (5), and inputting the beam synthesis data into the transmission interface module (6);

the transmission interface module (6) is used for outputting the beam synthesis data after packaging;

and the synchronous control module (7) is used for being connected with the synchronous control modules on the other RFSOC cards and controlling the ADC sampling modules on the RFSOC cards and the ADC sampling modules on the other RFSOC cards to synchronously sample the received radio frequency signals.

2. The radioastronomical phased array feed source time domain beam forming terminal according to claim 1, wherein the RFSOC card is an RFSOC of 8 channels, and N takes a value of 3.

3. The radioastronomical phased array feed source time domain beam forming terminal according to claim 2, characterized in that the ADC sampling module (1) supports wideband sampling of 2-4 gsps@12bit.

4. A radio astronomical phase array feed source time domain beam forming terminal according to claim 1, 2 or 3, characterized in that the amplitude and phase correction module (3) performs amplitude and phase correction on the received baseband signal data of each channel by using the compensation value of the amplitude and phase difference of the actually measured multi-radio frequency link.

5. A radioastronomical phased array feed time domain beam forming terminal according to claim 1 or 2 or 3, characterized in that the tera port of the transmission interface module (6) is configured as an 8x25Gbps transmission mode or a 2x100Gbps transmission mode.

6. The radioastronomical phased array feed source time domain beam forming terminal according to claim 1, wherein the transmission interface module (6) is connected with a RAID disk array or a GPU server through a tera switch, and is used for performing high-speed parallel storage and subsequent operation processing on output data.

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