CN111314010B - Multi-channel time-delay adjustable FX correlator and implementation method thereof - Google Patents
Multi-channel time-delay adjustable FX correlator and implementation method thereof Download PDFInfo
- Publication number
- CN111314010B CN111314010B CN202010104605.0A CN202010104605A CN111314010B CN 111314010 B CN111314010 B CN 111314010B CN 202010104605 A CN202010104605 A CN 202010104605A CN 111314010 B CN111314010 B CN 111314010B
- Authority
- CN
- China
- Prior art keywords
- channel
- cross
- delay
- radio signals
- correlator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0682—Clock or time synchronisation in a network by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
- H04W56/005—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by adjustment in the receiver
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
Abstract
The invention discloses a multi-channel time-delay adjustable FX correlator and an implementation method thereof, wherein n-channel radio signals are preprocessed by a signal input array module and an AD acquisition array module in sequence and output to an FPGA module; the FPGA module comprises a delay compensation submodule and a frequency domain cross-correlation submodule, wherein the delay compensation submodule receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain cross-correlation functions, and takes the delay corresponding to the peak value of the cross-correlation functions to be issued to each channel; and the frequency domain cross-correlation submodule calculates the n-channel radio signals completing the delay compensation to obtain a cross-power spectrum and stores the cross-power spectrum. By utilizing the parallel operation advantage of the FPGA, the time delay compensation and the cross-correlation calculation are completed while the data of a plurality of channels are acquired, the communication pressure and the operation pressure of an upper computer are reduced, and the requirement on the real-time property is met.
Description
Technical Field
The disclosure relates to the technical field of synthetic aperture in radio astronomy, in particular to a multi-channel FX correlator with adjustable time delay and an implementation method thereof.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
In the field of radio astronomy, the use of radio technology to receive, measure and analyze radio waves emitted by celestial bodies is an important means of studying celestial bodies. The traditional single-aperture radio telescope is limited by the aperture of the antenna due to the diffraction effect, and the large-aperture antenna is extremely difficult to process and difficult to meet the requirement of continuously improving the resolution.
The synthetic aperture radio telescope measures the space frequency spectrum of celestial body target by means of interference imaging technology. The space frequency spectrum and the bright temperature image of the celestial body target are actually a pair of Fourier transform pairs, so that the space frequency spectrum of the celestial body is obtained, and the bright temperature image of the celestial body can be obtained through proper inversion. The coordinates of the spatial frequency spectrum are denoted by (u-v), the image of which is also referred to as a u-v plane image. The value at this coordinate point is called the visibility function. The measurement in the spatial frequency domain is performed by measuring each visibility function on a sampling grid in the u-v plane one by one, and the measurement of each visibility function corresponds to the correlation operation of a pair of antennas. For the synthetic aperture radio telescope with the number of the antennas N in the array, the complex correlation quantity to be carried out reaches N (N-1)/2, and although the number of the antenna array elements subjected to sparse processing is not large, the number of the cross correlations is large.
The correlators are divided into analog correlators and digital correlators. The traditional analog complex correlator consists of a power divider unit, a complex correlator unit and an integral video amplifier unit and is realized by analog circuits such as a power divider, a multiplier, an amplifier and the like. When the number of array elements of the system is increased, the number of baselines is increased in a geometric series, so that when the number of array elements is large, the occupied volume, the occupied quality and the occupied power consumption of analog correlation are both remarkable, and the complexity of the system is greatly increased. Therefore, it is an important technical trend to perform related processing by using a digital processing method.
In the synthetic aperture technology, complete transmission of signals, especially phase transmission of signals is very important, the same wave front of radio signals arrives at different times of each antenna, thereby causing phase difference, and phase synchronization of signals of each channel must be realized through delay compensation before mapping.
The inventor finds that the existing technology for the synthetic aperture radio telescope at least has the problems of large communication pressure, long operation time and more computing resources in the data acquisition and processing process. That is, the existing multi-channel digital correlator mostly adopts a mode of separately performing acquisition and processing, and when data is acquired, the existing multi-channel digital correlator faces the pressure of both transmission and storage, and puts high requirements on a communication part; in the subsequent data processing, a lot of computer resources are used, the data processing speed is not ideal, and for the real-time requirement, the ordinary computer cannot meet the requirement of the operation speed. The acquisition processing discrete correlator compensates the time delay during data processing, so that two times of cross-correlation operation needs to be performed on the data, and the calculated amount is increased.
Disclosure of Invention
In order to solve the problems, the FX correlator with the adjustable multi-channel delay and the implementation method thereof are provided by the disclosure, the parallel operation advantage of the FPGA is utilized, the compensation of the delay and the cross-correlation calculation are completed while the data of a plurality of channels are acquired, the communication pressure and the operation pressure of an upper computer are reduced, and the requirement on the real-time property is met.
In order to achieve the purpose, the following technical scheme is adopted in the disclosure:
in a first aspect, the present disclosure provides a multi-channel, delay-adjustable FX correlator, comprising: the system comprises a signal input array module, an AD acquisition array module and an FPGA module;
the n-channel radio signals are preprocessed through the signal input array module and the AD acquisition array module in sequence and output to the FPGA module;
the FPGA module comprises a delay compensation submodule and a frequency domain cross-correlation submodule, wherein the delay compensation submodule receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain cross-correlation functions, and takes the delay corresponding to the peak value of the cross-correlation functions to be issued to each channel;
and the frequency domain cross-correlation submodule calculates the n-channel radio signals completing the delay compensation to obtain a cross-power spectrum and stores the cross-power spectrum.
In a second aspect, the present disclosure provides a method for implementing a multi-channel FX correlator with adjustable delay, including:
the received n-channel radio signals are preprocessed through a signal input array module and an AD acquisition array module in sequence and output to an FPGA module;
a delay compensation submodule in the FPGA module receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain a cross correlation function, and takes the delay corresponding to the peak value of the cross correlation function to send to each channel;
and a frequency domain cross-correlation submodule in the FPGA module calculates the n-channel radio signals completing the delay compensation to obtain a cross-power spectrum, and stores the cross-power spectrum.
Compared with the prior art, the beneficial effect of this disclosure is:
aiming at the problems of large communication pressure, long operation time and more required computing resources in the data acquisition and processing process of the synthetic aperture radio telescope, the method utilizes the parallel operation advantage of the FPGA to complete the compensation of time delay and the cross-correlation computation while acquiring the data of a plurality of channels, reduces the communication pressure and the operation pressure of an upper computer and meets the requirement on real-time property.
The time-delay correlator has the computation amount which is far larger than that of the FX correlator and is poor in adaptability, the time-delay correlator is modularized by taking a base line as a unit, and the time-delay correlator needs to be completely reconstructed for an additional antenna unit, while the FX correlator disclosed by the invention is modularized by taking an antenna channel as a unit, and the antenna unit is added, so that the correlator does not need to be completely reconstructed.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is an overall structural view provided in embodiment 1 of the present disclosure;
fig. 2 is a schematic flow chart of a method provided in embodiment 2 of the present disclosure.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Example 1
The digital correlator is divided into a delay correlator and an FX correlator. Ratio n of the number of operations of the delayed correlator to the FX correlatorLAG/nFX≈Nna/(2log2N+na) Where N is the number of operation points, NaThe number of the antennas can be known through simple calculation, and the operation amount of the delay correlator is far larger than that of the FX correlator; the delayed correlator has poor adaptability, the delayed correlator is modularized by taking a base line as a unit, the FX correlator is modularized by taking an antenna channel as a unit, the FX correlator is easier to expand during design, and if an additional antenna unit is added, the delayed correlator needs to be completely reconstructed for design, but the FX correlator does not need.
Therefore, in this embodiment, an FX correlator with adjustable multi-channel delay based on FPGA is provided, which utilizes the advantage of parallel operation of FPGA to complete compensation of delay and cross-correlation calculation while acquiring data of multiple channels, and can acquire and process multi-channel signals at the same time, thereby reducing communication pressure and operation pressure of an upper computer and meeting the requirement for real-time performance.
As shown in fig. 1, the multi-channel FX correlator with adjustable delay provided by this embodiment includes a signal input array, an AD acquisition array, a delay compensation module, a frequency domain cross-correlation module, and an upper computer;
the signal input array comprises an antenna array and a simulation front end part, wherein the antenna array receives weak radio signals and converts the weak radio signals into intermediate frequency signals with high signal-to-noise ratio by the simulation front end;
the AD acquisition array converts the intermediate-frequency analog signals into digital signals, and the digital signals are transmitted to the FPGA board card for waiting processing by adopting a JESD204B high-speed data transmission protocol;
the delay compensation module is used for compensating the delay of the radio signals received by different antennas, and because the same wave front of the radio signals reaches different times of each antenna, errors on phases are generated. According to the wiener-xinkinson theorem, the cross-power spectrum and the cross-correlation function of the two signals form a pair of Fourier transform pairs, and the cross-correlation function is a function related to time delay, so that the time delay generated by the cross-power spectrum can be reversely deduced through the cross-power spectrum obtained through calculation, and then compensation is carried out.
The delay compensation process is as follows: default delay compensation is set to 0; supposing that N-channel signal input arrays are arranged, the number of Fourier transform points is N, signals of one channel are taken as a reference, and signals of other channels and cross power spectrums (N-1 groups in total) calculated by the signals are uploaded to an upper computer; then, inverse Fourier transform is carried out to obtain a cross-correlation function, and the time delay corresponding to the peak value of the cross-correlation function is taken and sent to each channel to complete the compensation of the time delay;
wherein, the minimum unit of the delay compensation is the reciprocal of the sampling frequency, for example, when the sampling frequency is 1.25GHz, the minimum delay compensation unit is 0.8 ns; the delay compensation process can be completed by only a small amount of calculation.
The frequency domain cross-correlation module is the core part of the whole system. The input data after delay compensation passes through a Hanning window first, so that the frequency spectrum leakage is reduced; and then, carrying out fast Fourier transform on each path of signal to convert the signal into a frequency spectrum, and carrying out conjugate multiplication on complex amplitudes under each frequency to obtain a cross-power spectrum. In this example, assuming that the number of antennas is m, the number of groups subjected to conjugate multiplication simultaneously is m (m-1)/2.
And the communication between the FPGA and the upper computer adopts a PCIE protocol. The upper computer part has the following three functions that firstly, a cross power spectrum obtained by FPGA calculation is received; secondly, calculating and issuing the delay; and thirdly, storing the obtained cross-power spectrum into a disk.
And judging when saving the disk, if the time delay is adjusted to zero, namely, saving the disk when the phases of all channel signals are aligned, and otherwise, continuing to perform phase compensation.
Example 2
As shown in fig. 2, the present embodiment provides a method for implementing a multi-channel FX correlator with adjustable delay, which includes:
the received n-channel radio signals are preprocessed through a signal input array module and an AD acquisition array module in sequence and output to an FPGA module;
a delay compensation submodule in the FPGA module receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain a cross correlation function, and takes the delay corresponding to the peak value of the cross correlation function to send to each channel;
and a frequency domain cross-correlation submodule in the FPGA module calculates the n-channel radio signals completing the delay compensation to obtain a cross-power spectrum, and stores the cross-power spectrum.
The embodiment aims at the problems of large communication pressure, long operation time and more required computing resources in the data acquisition and processing process of the synthetic aperture radio telescope, utilizes the parallel operation advantage of the FPGA to complete the compensation of time delay and the cross-correlation computation while acquiring the data of a plurality of channels, reduces the communication pressure and the operation pressure of an upper computer, and meets the requirement on real-time property.
The above is merely a preferred embodiment of the present disclosure and is not intended to limit the present disclosure, which may be variously modified and varied by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (9)
1. A multi-channel, delay-adjustable FX correlator, comprising: the system comprises a signal input array module, an AD acquisition array module and an FPGA module;
the n-channel radio signals are preprocessed through the signal input array module and the AD acquisition array module in sequence and output to the FPGA module;
the FPGA module comprises a delay compensation submodule and a frequency domain cross-correlation submodule, wherein the delay compensation submodule receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain cross-correlation functions, and takes the delay corresponding to the peak value of the cross-correlation functions to be issued to each channel;
the frequency domain cross-correlation submodule calculates the n-channel radio signals completing the delay compensation to obtain a cross-power spectrum and stores the cross-power spectrum;
the frequency domain cross-correlation submodule performs windowing on the n-channel radio signals subjected to delay compensation, performs fast Fourier transform on the windowed n-channel radio signals to convert the n-channel radio signals into frequency spectrums, and performs conjugate multiplication on complex amplitudes under various frequencies to obtain cross power spectrums;
the FX correlator is modularized by taking an antenna channel as a unit, and the antenna unit is added, so that the correlator is not required to be completely reconstructed, namely, the signal is input into an antenna array submodule in the array module to receive n-channel radio signals.
2. The multi-channel, delay-adjustable FX correlator according to claim 1, wherein the signal input array block further comprises an analog front-end block, which converts it to an intermediate frequency signal with a high signal-to-noise ratio.
3. The FX correlator with multi-channel adjustable delay according to claim 1, wherein the AD acquisition array module performs analog-to-digital conversion on the radio signals processed by the signal input array module, and transmits the obtained digital signals to the FPGA module by using a data transmission protocol.
4. The multi-channel, delay-adjustable FX correlator according to claim 1, wherein the minimum unit for delay compensation is the inverse of the sampling frequency.
5. The multi-channel, delay-adjustable FX correlator according to claim 1, wherein the n-channel rf signals with delay compensation are windowed to reduce spectral leakage.
6. The FX correlator with adjustable multi-channel delay according to claim 1, wherein, with m antennas, m groups are conjugate multiplied simultaneously by m (m-1)/2.
7. The multi-channel, delay-adjustable FX correlator, according to claim 5, wherein the windowing uses Hanning windows.
8. The FX correlator with multi-channel adjustable delay according to claim 1, wherein the delay compensation is determined when the cross power spectrum is stored, and if the delay compensation is adjusted to zero, i.e. the phases of the n-channel radio signals are all aligned, the stores are performed; otherwise, continuing to perform delay compensation.
9. A multi-channel FX correlator implementation method with adjustable time delay is characterized by comprising the following steps:
the received n-channel radio signals are preprocessed through a signal input array module and an AD acquisition array module in sequence and output to an FPGA module;
a delay compensation submodule in the FPGA module receives the preprocessed n-channel radio signals, takes one channel radio signal as a reference, performs inverse Fourier transform on cross power spectrums corresponding to the rest n-1 channel radio signals to obtain a cross correlation function, and takes the delay corresponding to the peak value of the cross correlation function to send to each channel;
the frequency domain cross-correlation submodule in the FPGA module calculates the n-channel radio signals which finish the delay compensation to obtain a cross-power spectrum, and stores the cross-power spectrum;
the frequency domain cross-correlation submodule performs windowing on the n-channel radio signals subjected to delay compensation, performs fast Fourier transform on the windowed n-channel radio signals to convert the n-channel radio signals into frequency spectrums, and performs conjugate multiplication on complex amplitudes under various frequencies to obtain cross power spectrums;
the FX correlator is modularized by taking an antenna channel as a unit, and the antenna unit is added, so that the correlator is not required to be completely reconstructed, namely, the signal is input into an antenna array submodule in the array module to receive n-channel radio signals.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010104605.0A CN111314010B (en) | 2020-02-20 | 2020-02-20 | Multi-channel time-delay adjustable FX correlator and implementation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010104605.0A CN111314010B (en) | 2020-02-20 | 2020-02-20 | Multi-channel time-delay adjustable FX correlator and implementation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111314010A CN111314010A (en) | 2020-06-19 |
| CN111314010B true CN111314010B (en) | 2021-03-02 |
Family
ID=71147073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010104605.0A Active CN111314010B (en) | 2020-02-20 | 2020-02-20 | Multi-channel time-delay adjustable FX correlator and implementation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111314010B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112188610B (en) * | 2020-08-18 | 2023-08-01 | 天津七所精密机电技术有限公司 | Burst dense data fusion processing and high-precision synchronization device and method thereof |
| CN113702804B (en) * | 2021-07-26 | 2024-02-09 | 西安空间无线电技术研究所 | Correlation error correction method in multichannel digital correlator |
| CN115308520B (en) * | 2022-10-10 | 2023-01-24 | 杭州三海电子有限公司 | Method, program and circuit for determining delay time of multichannel sequential sampling current |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1866048A (en) * | 2005-05-17 | 2006-11-22 | 中国科学院空间科学与应用研究中心 | Digital correlator with sample delay phase shift and phase compensating method thereof |
| CN104820207A (en) * | 2015-05-08 | 2015-08-05 | 中国科学院新疆天文台 | Real-time correlator based on FPGA, GPU and CPU mixed architecture |
| CN108332063A (en) * | 2018-01-29 | 2018-07-27 | 中国科学院声学研究所 | A kind of pipeline leakage positioning method based on cross-correlation |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1276250A3 (en) * | 2001-07-10 | 2003-04-16 | Rojal GmbH | Apparatus for controlling a plurality of shadowing devices |
| CN108390686A (en) * | 2018-03-08 | 2018-08-10 | 山东大学 | Radio observation receiver system and radio wave signal processing method |
-
2020
- 2020-02-20 CN CN202010104605.0A patent/CN111314010B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1866048A (en) * | 2005-05-17 | 2006-11-22 | 中国科学院空间科学与应用研究中心 | Digital correlator with sample delay phase shift and phase compensating method thereof |
| CN104820207A (en) * | 2015-05-08 | 2015-08-05 | 中国科学院新疆天文台 | Real-time correlator based on FPGA, GPU and CPU mixed architecture |
| CN108332063A (en) * | 2018-01-29 | 2018-07-27 | 中国科学院声学研究所 | A kind of pipeline leakage positioning method based on cross-correlation |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111314010A (en) | 2020-06-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111314010B (en) | Multi-channel time-delay adjustable FX correlator and implementation method thereof | |
| CN111044971B (en) | Two-dimensional interferometer direction finding system | |
| CN110058193B (en) | Digital multi-beam angle measurement method and system based on single receiving channel | |
| US20160337052A1 (en) | System and method for test and/or calibration of multi-channel rf communication devices | |
| CN111510227B (en) | High-probability broadband signal accurate measurement system and method | |
| CN114488064B (en) | Distance-speed joint estimation method | |
| CN107329127B (en) | A kind of phase linearity analysis method and system for radar system DBF Function detection | |
| CN111679278B (en) | W-waveband unmanned aerial vehicle synthetic aperture radar real-time imaging system based on FPGA | |
| CN101403791B (en) | Fast real-time space spectrum estimation ultra-resolution direction-finding device and method thereof | |
| CN114355152A (en) | Multi-channel radio frequency chip testing device and testing method | |
| CN115792372A (en) | Multichannel ultra-wideband undersampling instantaneous frequency measurement method | |
| CN109283258A (en) | A kind of detection system based on ultrasonic phase array | |
| CN106908754A (en) | L-type acoustic vector-sensor array row ESPRIT decorrelation LMS method for parameter estimation | |
| CN104950282B (en) | Sparse reconstruct is realized in continuous domain broadband signal super-resolution direction-finding method and device | |
| CN113740811A (en) | Multichannel ground penetrating radar anti-interference method and system based on time division multiplexing | |
| CN113960523A (en) | Universal ultra-wideband correction direction-finding method and system based on FPGA | |
| Unlersen et al. | FPGA based fast bartlett DoA estimator for ULA antenna using parallel computing | |
| CN111367196B (en) | W-band broadband variable fraction time delay method and system | |
| CN115361741B (en) | High-precision channel signal delay automatic calibration device and method | |
| CN111443336B (en) | Method for reducing data transmission throughput of FMCW radar system | |
| CN110873864B (en) | Linear array laser radar range profile simulation device and method | |
| CN114826456B (en) | Calibration method for channel clock offset in multi-coset sampling | |
| CN210243826U (en) | Radar multichannel signal preprocessing device and pulse compression unit thereof | |
| CN113203997B (en) | FPGA-based radar super-resolution direction finding method, system and application | |
| CN111934737B (en) | Time delay compensation method of broadband digital array |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |