An ultrawideband pulsar signal acquisition and processing system

Abstract

This invention discloses an ultra-wideband pulsar signal acquisition and processing system, relating to the field of high-precision pulsar arrival time observation and scientific research in radio astronomy. It includes a receiving device, a transmission device, and a signal processing device. The receiving device acquires and preprocesses the receiver's dual-polarized signal, outputting a sub-band signal. The transmission device transmits the sub-band signal from the receiving device to the signal processing device. The signal processing device distributes the sub-band signal to the corresponding processing nodes of the ultra-wideband pulsar signal processing unit, invokes multi-threaded parallel pulsar processing threads to perform coherent dedispersion, folding, and arrival time calculation processing, and synthesizes the processed multi-sub-band signals into an ultra-wideband signal. This invention is applicable to ultra-wideband receiver signal acquisition and processing, effectively improving the accuracy of pulsar arrival time observation. The scale of the computing cluster can be adjusted according to the signal processing bandwidth. The system is powerful, flexible, and highly scalable.

Description

Technical Field

[0001] This invention relates to the field of high-precision pulsar arrival time observation and scientific research technology in radio astronomy, and more specifically to an ultra-wideband pulsar signal acquisition and processing system. Background Technology

[0002] Pulsars are a type of rotating neutron star that periodically emits pulses of light. Most are around 10 kilometers in diameter and rotate extremely rapidly. Because pulsars are discovered in the remnants of collapsed supernovae, studying them helps us understand what happens during stellar collapse. They can also reveal the mysteries of the birth and evolution of the universe. The period of each pulsar is not constant; each time a pulsar emits electromagnetic radiation, it loses some rotational energy, and its rotational speed decreases. By measuring the rotational period of a pulsar, we can precisely infer how much its rotational speed has decreased, how much energy it has lost during its evolution, and even how long it can survive before its rotational speed becomes too low to emit light.

[0003] In recent years, using pulsar timing arrays to detect gravitational waves has become a new area of ​​research in astronomy. By monitoring the arrival times of multiple millisecond pulsars with extremely stable rotations distributed at a certain angle in the sky, nano-Hertz gravitational wave signals can be measured. However, gravitational wave signals are extremely weak, and accurately measuring the arrival time of pulsar radiation pulses at Earth is crucial for successful detection.

[0004] Telescope signal receiving systems typically convert radio frequency (RF) signals to intermediate frequency (IF) signals and then transmit them via analog links to a remote equipment room for signal acquisition and processing. The advantage of this method is that it allows digital equipment to be placed far from the telescope, thus reducing electromagnetic interference from electronic devices. However, with the advent of ultra-wideband (UWB) receivers, the disadvantages of this method have become increasingly prominent. Firstly, the attenuation of high-frequency signals in the transmission link is increasing, rendering previous equalizer compensation methods at the receiver ineffective. Secondly, the signal strength and phase fluctuations of UWB signals in the transmission link increase due to variations in ambient temperature.

[0005] Currently, according to the latest research results on ultra-wideband (UWB) observation systems internationally, UWB signals have a significant effect on improving the timing accuracy of pulsars. However, UWB receiving systems generate massive amounts of data. Furthermore, traditional multi-channel dedispersion techniques cannot completely eliminate dispersion effects within subbands. High-precision timing requires the use of coherent dedispersion methods, which eliminate the influence of the interstellar medium on signal propagation through data-intensive computation to form a sharper pulse profile with a higher signal-to-noise ratio, thereby improving timing accuracy. These factors will pose significant challenges to the real-time transmission, distribution, and processing of UWB high-precision pulsar terminal systems.

[0006] Therefore, an ultra-wideband pulsar signal acquisition and processing system is proposed, which is suitable for signal acquisition and processing of ultra-wideband receivers. It has multiple observation modes such as pulsar coherent dedispersion, folding, search, and arrival time, and can effectively improve the accuracy of pulsar arrival time observation, which is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides an ultra-wideband pulsar signal acquisition and processing system, suitable for ultra-wideband receiver signal acquisition and processing. To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An ultra-wideband pulsar signal acquisition and processing system includes: a receiving device, a transmitting device, and a signal processing device.

[0009] The receiving device is used to acquire and preprocess the dual-polarized signal of the receiver and output a sub-band signal.

[0010] The transmission device is used to transmit subband signals from the receiving device to the signal processing device;

[0011] The signal processing device is used to allocate the subband signals to the processing nodes corresponding to the ultra-wideband pulsar signal processing unit, call the multi-threaded parallel pulsar processing thread to perform coherent dedispersion, folding and arrival time calculation processing, and synthesize the processed multi-subband signals into an ultra-wideband signal.

[0012] Optionally, the receiving device includes a power divider A, a power divider B, a filter, and a radio frequency signal direct acquisition module; the power divider A and the power divider B respectively divide the received receiver dual-polarization signal into n identical signals, and the n filters filter and select n frequency bands, which are then connected to n radio frequency signal direct acquisition modules for signal acquisition and preprocessing.

[0013] Optionally, the RF signal direct acquisition module includes: an analog-to-digital conversion module, a digital subband division module, a quantization module, a formatting and encapsulation module, and a network module connected in sequence; the analog-to-digital conversion module is connected to a configurator, a calibrator, and a data snapshot module, respectively, and the formatting and encapsulation module is connected to a test signal simulator and a data snapshot module, respectively.

[0014] Optionally, the digital subband division module channels the data collected by the analog-to-digital conversion module into N digital subbands with a bandwidth of XMHz, outputs them to the quantization module to be truncated into mbit complex data, the formatting and encapsulation module formats the channelized digital subbands into VDIF format and encapsulates them into UDP data packets, the data snapshot module outputs the formatted and encapsulated data for viewing, the test signal simulator simulates test signals for debugging, and the formatted and encapsulated data is output through the network module.

[0015] Optionally, the RF signal direct acquisition module provides a reference antenna signal channel to acquire the reference signal and perform adaptive RFI filtering.

[0016] Optionally, the transmission device is an optical fiber link, which transmits the subband signal processed by the receiving device to the data exchange network located at the signal processing device via the optical fiber link.

[0017] Optionally, the signal processing device includes a data exchange network and an ultra-wideband pulsar signal processing unit, wherein the data exchange network and the ultra-wideband pulsar signal processing unit are connected to each other, and the ultra-wideband pulsar signal processing unit is connected to a storage device through the data exchange network.

[0018] Optionally, the storage device saves the synthesized ultra-wideband signal.

[0019] Optionally, the ultra-wideband pulsar signal processing unit includes a digital subband data receiving and distribution module, a shared memory ring buffer, M groups of pulsar processing threads, M groups of buffers, an ultra-wideband data synthesis module, and a processed data transmission module connected in sequence.

[0020] Optionally, the digital subband data receiving and distribution module acquires the subband signal output by the RF signal direct acquisition module from the data exchange network via an optical fiber link and puts it into a shared memory ring buffer. M groups of pulsar processing threads acquire the subband signal data from the shared memory ring buffer and perform coherent dedispersion, folding, and arrival time calculation processing. Each thread processes the data of one subband signal and then puts the processing result into its respective buffer. The ultra-wideband data synthesis module splices the processing results of N X MHz bandwidth subband signals into an N*X MHz bandwidth ultra-wideband result.

[0021] As can be seen from the above technical solution, compared with the prior art, the present invention discloses an ultra-wideband pulsar signal acquisition and processing system, which has the following beneficial effects:

[0022] This invention discloses an ultra-wideband pulsar signal acquisition and processing system, which is suitable for signal acquisition and processing of ultra-wideband receivers. It has multiple observation modes such as pulsar coherent dedispersion, folding, search, and arrival time, which can effectively improve the accuracy of pulsar arrival time observation. The scale of the computing cluster can be adjusted according to the signal processing bandwidth. The system is powerful, flexible, and highly scalable.

[0023] This invention reduces signal intermodulation distortion caused by octave band crossing of the ultra-wideband signal at the receiver end by decomposing the ultra-wideband signal into multiple radio frequency subbands, avoids ADC saturation caused by electromagnetic interference at the signal acquisition end, and reduces additional interference caused by the superposition of low-frequency interference harmonics to the high-frequency band.

[0024] This invention employs direct radio frequency signal sampling technology, which can eliminate signal strength and phase fluctuations caused by changes in ambient temperature during transmission, thereby improving the fidelity of signal acquisition and transmission. The use of a low-power RFSoC circuit reduces electromagnetic interference from digital devices to the radio telescope, and simplifies electromagnetic shielding and heat dissipation design. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the framework of an ultrawideband pulsar signal acquisition and processing system provided by the present invention.

[0027] Figure 2 This is a schematic diagram of a radio frequency signal direct acquisition module provided by the present invention.

[0028] Figure 3 This is a schematic diagram of an ultrawideband pulsar signal processing unit provided by the present invention.

[0029] Figure 4 This is a schematic diagram of a pulsar observation result provided by the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention discloses an ultra-wideband pulsar signal acquisition and processing system, comprising: a receiving device, a transmitting device, and a signal processing device.

[0032] The receiving device is used to acquire and preprocess the dual-polarized signal of the receiver and output a sub-band signal.

[0033] The transmission device is used to transmit subband signals from the receiving device to the signal processing device;

[0034] The signal processing device is used to allocate the subband signals to the processing nodes corresponding to the ultra-wideband pulsar signal processing unit, call the multi-threaded parallel pulsar processing thread to perform coherent dedispersion, folding and arrival time calculation processing, and synthesize the processed multi-subband signals into an ultra-wideband signal.

[0035] Furthermore, the receiving device includes a power divider A, a power divider B, a filter, and a direct RF signal acquisition module. Power divider A and power divider B each divide the received dual-polarized signal into n identical signals, which are then filtered by n filters to select n frequency bands. These signals are then connected to n direct RF signal acquisition modules for signal acquisition and preprocessing. The direct RF signal acquisition module includes, in sequence, an analog-to-digital conversion module, a digital subband partitioning module, a quantization module, a formatting and encapsulation module, and a network module. The analog-to-digital conversion module is connected to a configurator, a calibrator, and a data snapshot module. The formatting and encapsulation module is connected to a test signal simulator and the data snapshot module. The digital subband partitioning module channelizes the data acquired by the analog-to-digital conversion module into N digital subbands with a bandwidth of X MHz, outputting them to the quantization module for truncation into mbit complex data. The formatting and encapsulation module formats the channelized digital subbands into VDIF format and encapsulates them into UDP data packets. The data snapshot module outputs the formatted and encapsulated data for viewing. The test signal simulator generates test signals for debugging, and the formatted and encapsulated data is output through the network module. The RF signal direct acquisition module provides one reference antenna signal channel to acquire the reference signal and perform adaptive RFI filtering. The RF signal direct acquisition module adopts an RFSoC circuit, which integrates FPGA, ARM, ADC / DAC and 10 / 40 / 100Gb network, and performs 16-channel 2.5Gsps-14bit sampling or 8-channel 5Gsps-14bit sampling on a single chip.

[0036] Furthermore, the transmission device is an optical fiber link, used to transmit the subband signal processed by the receiving device to the data exchange network located at the signal processing device via the optical fiber link.

[0037] Furthermore, the signal processing device includes a data exchange network and an ultra-wideband pulsar signal processing unit. The data exchange network and the ultra-wideband pulsar signal processing unit are connected via a data link. The ultra-wideband pulsar signal processing unit is also connected to a storage device via the data exchange network. The storage device is used to store the synthesized ultra-wideband signal. The ultra-wideband pulsar signal processing unit includes, in sequence, a digital sub-band data receiving and distribution module, a shared memory ring buffer, M groups of pulsar processing threads, M groups of buffers, an ultra-wideband data synthesis module, and a processed data transmission module. The digital sub-band data receiving and distribution module acquires the sub-band signal output from the RF signal direct acquisition module via an optical fiber link from the data exchange network and places it into the shared memory ring buffer. The M groups of pulsar processing threads acquire the sub-band signal data from the shared memory ring buffer and perform coherent dedispersion, folding, and time-of-arrival calculation processing. Each thread processes the data of one sub-band signal and then places the processing result into its respective buffer. The ultra-wideband data synthesis module concatenates the processing results of N X MHz bandwidth sub-band signals into an N*X MHz bandwidth ultra-wideband result.

[0038] In a specific implementation, an ultra-wideband pulsar signal acquisition and processing system, such as... Figure 1 As shown, it includes: a power divider, a filter, a direct RF signal acquisition module, a 100Gb data exchange network, an ultra-wideband pulsar signal processing unit, and a data storage unit.

[0039] Power divider A and power divider B divide the received receiver's dual-polarized signals RFPol_A and RFPol_B into three identical signals, respectively. These signals are then filtered by filters 1, 2, and 3 to select the Band 1, Band 2, and Band 3 frequency bands, respectively. These are then connected to RF signal direct acquisition modules 1, 2, and 3 for signal acquisition and preprocessing. The processed digital subband signal is transmitted via a 100Gb fiber optic link to a 100Gb data exchange network located in the signal processing room. It is then distributed to the corresponding processing nodes of the ultra-wideband pulsar signal processing unit, where multi-threaded parallel pulsar processing threads are invoked to perform coherent dedispersion, folding, and time-of-arrival adjustments. The multi-subband data is then synthesized into an ultra-wideband signal, which is finally sent to the data storage unit for storage.

[0040] In a specific implementation, the RF signal direct acquisition module provides a reference antenna signal channel for reference signal acquisition and processing under the adaptive RFI filtering function.

[0041] In a specific implementation, the RF signal direct acquisition module acquires and preprocesses the three input RF signals, such as... Figure 2As shown, the system includes: an analog-to-digital conversion module, a digital subband partitioning module, a quantization module, a formatting and encapsulation module, a 100Gb network module, data snapshots 1 and 2, a configurator, a calibrator, and a test signal simulator. The analog-to-digital conversion module acquires three RF signals: Pol_A, Pol_B, and Ref_A. The configurator configures parameters such as the sampling rate, synchronization characteristics, mixing parameters, decimation mode, bus clock, and Nyquist interval of the analog-to-digital conversion module. The calibrator calibrates the quadrature modulation amplitude and phase of the analog-to-digital conversion module. Data snapshot 1 allows viewing the data acquired by the analog-to-digital conversion module. The digital subband partitioning module channelizes the data acquired by the analog-to-digital conversion module into N digital subbands with a bandwidth of X MHz, and outputs them to the quantization module, which truncates them into m-bit complex numbers (m / 2-bit real part + m / 2-bit imaginary part). The formatting and encapsulation module formats the channelized digital subband into VDIF (VLBI data exchange format) and encapsulates it into UDP (User Datagram Protocol) packets. Each packet is 8224 bytes in size (32-byte header, 8192 bytes of data). Data snapshot 2 allows viewing the data output packaged by the formatting and encapsulation module. The test signal simulator can simulate test signals for debugging. The formatted and encapsulated data is finally output through two 100Gb network modules.

[0042] Pulsar signals are affected by the interstellar medium, causing dispersion. To compensate for this effect, dedispersion processing is required to restore the broadened signal to its true pulse value. Since the signals arriving at Earth from pulsars are extremely weak, long-term observation and folding based on the pulsar's period are necessary to improve the signal-to-noise ratio. Pulsar arrival time observations demand extremely high accuracy and precision from the terminal system; coherent dedispersion processing of pulsars can provide even higher accuracy in pulsar arrival time.

[0043] In a specific implementation, the ultra-wideband pulsar signal processing unit acquires the digital subband signal output by the RF signal direct acquisition module from a 100Gb data exchange network, calls a multi-threaded parallel pulsar processing thread to perform coherent dedispersion, folding, and time-of-arrival observation processing, and synthesizes the multi-subband data into an ultra-wideband signal, which is finally sent to the data storage unit for storage. Figure 3As shown, the system includes: a digital subband data receiving and distribution module, a shared memory ring buffer, pulsar processing threads, a buffer, an ultra-wideband data synthesis module, and a processed data transmission module. The digital subband data receiving and distribution module acquires the digital subband signal output from the RF signal direct acquisition module via a 100Gb link from a 100Gb data exchange network and places it into the shared memory ring buffer. M pulsar processing threads acquire digital subband data from the shared memory ring buffer and perform coherent dedispersion, folding, and time-of-arrival observation processing. Each thread processes one digital subband of data and then places the processing result into its respective buffer. The ultra-wideband data synthesis module concatenates the processing results of N X MHz bandwidth digital subbands into an N*X MHz bandwidth ultra-wideband result, which is finally sent to the data storage unit for storage by the processed data transmission module.

[0044] In a specific implementation, the RF System-on-Chip (RFSoC) is a low-power, high-performance, and highly integrated chip that integrates abundant resources such as FPGA, ARM, ADC / DAC, and 10 / 40 / 100Gb networks. A single chip can achieve up to 16 channels of 2.5Gsps-14bit sampling or 8 channels of 5Gsps-14bit sampling, which is highly suitable for the need for direct acquisition of broadband RF signals in radio astronomy. The RF signal direct acquisition module of this invention is designed using RFSoC, dividing the 704-4032MHz RF signal into three analog sub-bands for separate acquisition. The frequency ranges of the three analog sub-bands, band1, band2, and band3, are 704-1344MHz, 1344-2368MHz, and 2368-4032MHz, respectively. The sampling rates of the three RF signal direct acquisition modules are 4096MSPS, 2560MSPS, and 4096MSPS, respectively, with a sampling accuracy of 14 bits. The digital subband partitioning module channelizes the ultra-wideband signal into 26 digital subbands with a bandwidth of 128MHz. The output digital subbands of the RF signal direct acquisition modules 1, 2, and 3 are 5, 8, and 13 respectively. The quantization module truncates the data into 32-bit complex numbers (16-bit real part + 16-bit imaginary part) and distributes them to the ultra-wideband pulsar signal processing unit for real-time processing through two 100Gb network ports. The ultra-wideband pulsar signal processing unit includes nine GPU servers, each equipped with four GPU accelerator cards, receiving and processing data from three dual-polarized digital subbands.

[0045] An ultrawideband pulsar observation experiment was conducted using a 26-meter radio telescope. An L-band cryogenic receiver was employed to track and observe the pulsar J0332+5434. Signals from four digital subbands were acquired and processed, corresponding to a radio frequency range of 1028-1540 MHz. The observation duration was 32 seconds. The observation results, after dispersion and folding processing, are as follows: Figure 4 As shown, the pulsar outline is clearly visible, the signal-to-noise ratio is good, and it matches the data published internationally.

[0046] This invention provides an ultra-wideband pulsar signal acquisition and processing system. The system decomposes the ultra-wideband signal into multiple radio frequency (RF) subbands. A high-performance, highly integrated, low-power RFSoC circuit is used to directly sample the RF signal at the receiver front end. The wideband signal is then converted into multiple digital subbands and transmitted to a distributed computing cluster via a 100Gb network. A multi-threaded parallel pulsar processing thread is invoked to perform coherent dedispersion and online folding processes. The multi-subband data is then synthesized and finally sent to a data storage unit for storage, achieving high-fidelity acquisition of ultra-wideband signals and high-precision real-time processing of pulsar signals.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A system for acquiring and processing ultra-wideband pulsar signals, characterized in that, include: Receiving device, transmitting device, and signal processing device, The receiving device is used to acquire and preprocess the dual-polarized signal of the receiver and output a sub-band signal. The receiving device includes: power divider A, power divider B, filters, and a radio frequency signal direct acquisition module; power divider A and power divider B respectively divide the incoming receiver dual-polarized signal into n identical signals, and n filters filter and select n frequency bands, which are then connected to n radio frequency signal direct acquisition modules for signal acquisition and preprocessing. The RF signal direct acquisition module includes: an analog-to-digital conversion module, a digital subband division module, a quantization module, a formatting and encapsulation module, and a network module connected in sequence; the analog-to-digital conversion module is connected to a configurator, a calibrator, and a data snapshot module, respectively; the formatting and encapsulation module is connected to a test signal simulator and a data snapshot module, respectively. The digital subband division module channels the data collected by the analog-to-digital conversion module into N digital subbands with a bandwidth of X MHz, and outputs them to the quantization module to be truncated into m-bit complex data. The formatting and encapsulation module formats the channelized digital subbands into VDIF format and encapsulates them into UDP data packets. The data snapshot module outputs the formatted and encapsulated data for viewing. The test signal simulator simulates test signals for debugging. The formatted and encapsulated data is output through the network module. The transmission device is used to transmit subband signals from the receiving device to the signal processing device; The signal processing device is used to allocate the subband signals to the processing nodes corresponding to the ultra-wideband pulsar signal processing unit, call the multi-threaded parallel pulsar processing thread to perform coherent dedispersion, folding and arrival time calculation processing, and synthesize the processed multi-subband signals into an ultra-wideband signal.

2. The ultra-wideband pulsar signal acquisition and processing system according to claim 1, characterized in that, The radio frequency signal direct acquisition module provides a reference antenna signal channel to acquire the reference signal and perform adaptive RFI filtering.

3. The ultra-wideband pulsar signal acquisition and processing system according to claim 1, characterized in that, The transmission device is an optical fiber link, which transmits the subband signal processed by the receiving device to the data exchange network located at the signal processing device via the optical fiber link.

4. The ultra-wideband pulsar signal acquisition and processing system according to claim 1, characterized in that, The signal processing device includes a data exchange network and an ultra-wideband pulsar signal processing unit, wherein the data exchange network and the ultra-wideband pulsar signal processing unit are connected to each other, and the ultra-wideband pulsar signal processing unit is connected to a storage device through the data exchange network.

5. The ultra-wideband pulsar signal acquisition and processing system according to claim 4, characterized in that, The storage device saves the synthesized ultra-wideband signal.

6. The ultra-wideband pulsar signal acquisition and processing system according to claim 4, characterized in that, The ultra-wideband pulsar signal processing unit includes: a digital subband data receiving and distribution module, a shared memory ring buffer, M groups of pulsar processing threads, M groups of buffers, an ultra-wideband data synthesis module, and a processed data transmission module connected in sequence.

7. The ultra-wideband pulsar signal acquisition and processing system according to claim 6, characterized in that, The digital subband data receiving and distribution module acquires the subband signal output by the RF signal direct acquisition module from the data exchange network via an optical fiber link and places it into a shared memory ring buffer. M groups of pulsar processing threads acquire the subband signal data from the shared memory ring buffer and perform coherent dedispersion, folding, and time-of-arrival calculations. Each thread processes the data of one subband signal and then places the processing result into its respective buffer. The ultra-wideband data synthesis module concatenates the processing results of N X MHz bandwidth subband signals into an N... Ultra-wideband results with X MHz bandwidth.

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