CN202794336U - Radio astronomical narrow-band signal digital analysis terminal based on undersampling technology - Google Patents
Radio astronomical narrow-band signal digital analysis terminal based on undersampling technology Download PDFInfo
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- CN202794336U CN202794336U CN201220428396.6U CN201220428396U CN202794336U CN 202794336 U CN202794336 U CN 202794336U CN 201220428396 U CN201220428396 U CN 201220428396U CN 202794336 U CN202794336 U CN 202794336U
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Abstract
Disclosed is a radio astronomical narrow-band signal digital analysis terminal based on the undersampling technology. The terminal is composed of a front-end anti-alias filter, a wide-input bandwidth analog-digital converter (ADC) and a digital signal processor (DSP) which are connected sequentially, wherein the front-end anti-alias filter is connected with the wide-input bandwidth ADC through a combiner, and the wide-input bandwidth ADC is connected with the DSP through a field-programmable gate array (FPGA). The terminal has the advantages that the data volume and occupied resources for digital signal processing of the whole radio astronomical data acquisition and analysis system can be reduced, the signal analysis accuracy can be improved effectively, and simultaneously, the radio frequency interference (RFI) can be avoided effectively.
Description
Technical field
The utility model is applicable to the Digital Signal Analysis disposal system of radio astronomy narrow band signal, is radio astronomy scope apparatus structure technical field.
Background technology
Traditional radio astronomy digital collection analysing terminal is based on the Nyquist First Law, and namely the sampling rate of sampling thief must be more than or equal to the twice of observation signal highest frequency, the whole inband signaling of recovery that could be complete.Although can take into account like this needs of broadband and narrowband astronomical sight, greatly consume system resource when astronomical signal is observed in the arrowband, and be vulnerable to radio interference (radio frequency interference, RFI).
It is very difficult doing meticulous line contour structure observation under traditional high sampling rate condition.In the certain situation of sampling rate, just must increase FFT conversion points N if obtain higher spectral resolution, this just need to expend the resources such as processor internal multiplier, totalizer and storage unit, so greatly increased the redundant data amount, the no signal frequency range is also needed to analyze simultaneously.
Traditional wideband data collection is with the whole collection of whole frequency range, and radio interference also can be gathered inevitably, gives further to analyze and brings very large difficulty.For example, the window function effect of FFT can cause that vacation composes existing; Because Spurious Free Dynamic Range (SFDR) parameter of ADC has determined the dynamic range of ADC input signal, strong if interference superposeed, also can cause vacation to compose now and can't in aftertreatment, predict and determine.
Another bottleneck of conventional over-sampled radio terminal development is, contradiction between the writing speed of high speed acquisition, signal processing chip, bus transfer speed and storage medium (such as hard disk etc.), the high-speed bus of main flow has PCI-e x 16 Gen1, transmission speed 8.0GB/s at present; PCI-ex 16Gen2, transmission speed 16.0GB/s.SATA interface hard disk writing speed is 70-80MB/s, and the hard disk writing speed of SDD interface can reach about 120MB/s, and big capacity hard disk is difficult in real time all storage of collected data in the high speed acquisition situation of several Gsps like this.
Summary of the invention
The purpose of this utility model provide in order to overcome the defective that above-mentioned prior art exists just a kind of efficient, high precision and economize on resources based on the radio astronomy narrow band signal numerical analysis terminal of owing Sampling techniques.The utility model is achieved by the following technical solution.
A kind of radio astronomy narrow band signal numerical analysis terminal based on owing Sampling techniques, the utility model is characterised in that: be connected with wide input bandwidth analog to digital converter by combiner by the front end frequency overlapped-resistable filter, wide input bandwidth analog to digital converter sequentially connects to form by field programmable gate array and digital signal processor again.
Select the radio astronomy narrow band signal by frequency overlapped-resistable filter, utilize the characteristic of wide input bandwidth ADC under lower sampling rate condition, to realize undistorted collection to the high-frequency narrow-band signal;
By full and accurate observed object frequency range and radio environment investigation, determine passband, stopband and the transitional zone width of wave filter, can effectively suppress this class radio interference when running into strong radio interference, make it and can not be gathered by ADC by the aliasing mode;
Utilize the characteristic of wide input bandwidth ADC, when carrying out the analog to digital conversion, the signal meeting of upper frequency " folds " in the first nyquist sampling district of ADC.When carrying out digital signal processing, need to determine it is signal in which frequency overlapped-resistable filter by resetting the mark mode, finally determine the signal original frequency of current collection.
The utility model mainly solves in traditional radio astronomy terminal based on the radio astronomy narrow band signal numerical analysis terminal of owing Sampling techniques, the contradiction between high sampling rate and the meticulous frequency resolution demand.
The Nyquist second theorem shows that sampling rate also can complete collection and restoring signal less than Nyquist rate:
f
sample=2(f
H-f
L)(1+M/N)=2B(1+M/N) (1)
Wherein, B=f
H-f
LBandwidth for bandpass signal; N is for being no more than f
H/ (f
H-f
L) maximum positive integer; M=[f
H/ (f
H-f
L)]-N.When sampling rate satisfies formula (1), can gather with lower speed the bandpass signal of upper frequency.Therefore, when the input bandwidth (input bandwidth) of ADC greater than f
Sample, can adopt inferior nyquist sampling at/2 o'clock.When the input bandwidth upper limiting frequency of input signal upper cut off frequency less than ADC, if when its bandwidth satisfies (1) formula again, we just can finish the free of losses sampling to it.In theory, input bandwidth and the f of ADC
Sample/ 2 ratio is the performance raising multiple that inferior nyquist sampling terminal compares to conventional terminal, and best improvement in performance can reach 5-11 doubly at present.
The utility model concrete methods of realizing is as follows:
When arrowband spectral line signal is observed, a plurality of intermediate-freuqncy signals are input in the combiner, signal in a plurality of intermediate-frequency bands just " mapping " in intermediate-frequency band, design by the location positioning frequency overlapped-resistable filter of each narrow band signal in intermediate-frequency band, each wave filter is the different arrowband spectral line signal of corresponding selection respectively, f
o~ f
nUtilize the wide bandwidth input character of monolithic ADC, outside the first Nyquist district and less than all intermediate-freuqncy signals of ADC input bandwidth, selected rear all energy " aliasing " to the relevant position in the first Nyquist district by frequency overlapped-resistable filter, gather when so just having realized monolithic ADC to many spectral line signals, as shown in Figure 3.
Like this, we have only utilized f
Sample/ 2 signal bandwidth, the actual observation of having finished all narrow band signals in the whole full power bandwidth (ADC ' s input bandwidth).If adopt traditional over-sampling radio astronomy terminal, we need to adopt the sampling rate of the full power bandwidth of twice just can finish collection to these narrow band signals.The low sampling rate of radio astronomy terminal of owing to sample is that resource has been saved in aftertreatment greatly.
Its key is:
1. at first determine in the intermediate-freuqncy signal, frequency location and the width thereof of corresponding arrowband spectral line signal, this is the condition precedent of determining the frequency overlapped-resistable filter passband width;
2. by the radio environment investigation in early stage, determine the relative position of radio interference and arrowband spectral line signal, this is the condition precedent of determining frequency overlapped-resistable filter transitional zone width;
3. to the choosing of ADC, should fully take into account its sampling rate f
Sample, the relation between full power bandwidth (input bandwidth) and the sampling resolution, wider full power bandwidth can cover wider intermediate-freuqncy signal, but the raising of sampling rate can increase the burden of rear end digital signal processor, the quality that how much has also determined the data signal to noise ratio (S/N ratio)s of sampling resolution, the three must take into account consideration for this reason;
4. because to owe Sampling techniques be that signal " aliasing " by other Nyquist district gathers to the first Nyquist district, for this reason rate-aided signal from the zone particularly important, be determined by the mode of signal source single-frequency emission record.
The beneficial effects of the utility model are: the advantage such as the utlity model has efficient, high precision and economize on resources.1. adopting owes to sample is equivalent under lower sampling rate condition broadband signal collection, the performance that the very wide equipment of bandwidth traditionally realized just can reach; 2. lower sampling rate can reduce the intractability of each signal processing module in the digital signal processor of rear end effectively, for example: the exponent number of wave filter, the conversion of FFT is counted etc., and in the constant situation of performance, the analysis precision of digital signal processing is greatly enhanced; 3. lower sampling rate can alleviate the resource consumption pressure of rear end equipment, and for example: the scale of disk needs the resources such as multiplier, totalizer and storer that consume in the digital signal processor.
Description of drawings
Fig. 1 is the utility model draw bail synoptic diagram;
Fig. 2 is the inner draw bail synoptic diagram of digital signal processor system;
Fig. 3 is the different arrowband spectral line signal graph of each wave filter difference corresponding selection.
Specific embodiments
A kind of radio astronomy narrow band signal numerical analysis terminal based on owing Sampling techniques, the utility model is characterised in that: be connected with wide input bandwidth analog to digital converter by frequency combiner in many by the front end frequency overlapped-resistable filter, wide input bandwidth analog to digital converter sequentially connects to form by field programmable gate array and digital signal processor again.
In order to design the radio environment situation that the front end frequency overlapped-resistable filter at first must investigation radio observatory this locality, at first according to the indices of the frequency spectrum Relative position determination frequency overlapped-resistable filter between radio interference and the radio astronomy signal: passband width, stopband attenuation and transition band width.
Then by a combiner radio astronomy signal of being selected by frequency overlapped-resistable filter in many intermediate frequencies is merged to one tunnel output.
By wide input, low sampling rate ADC the output signal of combiner is carried out analog to digital conversion, the digital signal after the conversion is sent in the back end signal processor system, carry out various digital signal processing.
Digital signal processor system adopts digital signal processing module+embedded core processor mode, wherein digital signal processing module is used for carrying out digital signal processing extraction radio astronomy information, embedded core processor is used for coordinating various processing modules, and finishes the transport communication to computing machine.
In digital information processing system, at first select signal by the optimal filter that designs for different frequency signals, and further suppress to disturb, further reduce data transfer rate by subtracting sample mode subsequently, so that follow-up digital signal processing.The data that will subtract after the sampling are carried out the FFT conversion, extract frequency spectrum profiles information.Data are imported in the embedded core processor after will processing at last, by the bus transfer module on the core processor deal with data are transported in the computing machine and store.
In addition, collection signal reset to be marked with determine that its original frequency must adopt: use signal generator to inject and radio astronomy signal homogenous frequency signal from each radio receiver inlet, and close simultaneously antenna input signal and other receiver input signals, only have Injection Signal to be gathered by ADC this moment, and the signal that is obtained by the digital signal processor system analysis can be calculated and know the original signal frequency.The rest may be inferred, and all observation signals all can this method be determined.
Claims (1)
1. one kind based on the radio astronomy narrow band signal numerical analysis terminal of owing Sampling techniques, it is characterized in that: be connected with wide input bandwidth analog to digital converter by combiner by the front end frequency overlapped-resistable filter, wide input bandwidth analog to digital converter sequentially connects to form by field programmable gate array and digital signal processor again.
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| CN201220428396.6U CN202794336U (en) | 2012-08-27 | 2012-08-27 | Radio astronomical narrow-band signal digital analysis terminal based on undersampling technology |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105510712A (en) * | 2015-08-14 | 2016-04-20 | 中国科学院云南天文台 | Radio astronomy narrow band spectral line observation platform based on agile transceiver |
| CN107967407A (en) * | 2017-12-19 | 2018-04-27 | 中国科学院上海天文台 | A kind of radio astronomy data processing method |
| CN107990983A (en) * | 2017-11-21 | 2018-05-04 | 北京空间机电研究所 | A kind of digital lack sampling method of narrow spectral coverage interference signal |
| CN114002500A (en) * | 2021-10-28 | 2022-02-01 | 中国科学院云南天文台 | Radio astronomical spectrometer system |
| CN116449099A (en) * | 2023-03-16 | 2023-07-18 | 广州致远仪器有限公司 | Spectrum analysis circuit |
-
2012
- 2012-08-27 CN CN201220428396.6U patent/CN202794336U/en not_active Expired - Lifetime
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105510712A (en) * | 2015-08-14 | 2016-04-20 | 中国科学院云南天文台 | Radio astronomy narrow band spectral line observation platform based on agile transceiver |
| CN105510712B (en) * | 2015-08-14 | 2018-06-12 | 中国科学院云南天文台 | Radio astronomy narrowband spectral line observation platform based on agile transceiver |
| CN107990983A (en) * | 2017-11-21 | 2018-05-04 | 北京空间机电研究所 | A kind of digital lack sampling method of narrow spectral coverage interference signal |
| CN107990983B (en) * | 2017-11-21 | 2020-05-12 | 北京空间机电研究所 | Digital undersampling method for narrow-spectrum interference signal |
| CN107967407A (en) * | 2017-12-19 | 2018-04-27 | 中国科学院上海天文台 | A kind of radio astronomy data processing method |
| CN107967407B (en) * | 2017-12-19 | 2021-05-04 | 中国科学院上海天文台 | Radio astronomical data processing method |
| CN114002500A (en) * | 2021-10-28 | 2022-02-01 | 中国科学院云南天文台 | Radio astronomical spectrometer system |
| CN114002500B (en) * | 2021-10-28 | 2023-08-29 | 中国科学院云南天文台 | Radio astronomical spectrometer system |
| CN116449099A (en) * | 2023-03-16 | 2023-07-18 | 广州致远仪器有限公司 | Spectrum analysis circuit |
| CN116449099B (en) * | 2023-03-16 | 2024-03-22 | 广州致远仪器有限公司 | Spectrum analysis circuit |
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