CN106646012A - Extraction method for emission spectrum envelope of frequency equipment - Google Patents
Extraction method for emission spectrum envelope of frequency equipment Download PDFInfo
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- CN106646012A CN106646012A CN201610812759.9A CN201610812759A CN106646012A CN 106646012 A CN106646012 A CN 106646012A CN 201610812759 A CN201610812759 A CN 201610812759A CN 106646012 A CN106646012 A CN 106646012A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
An extraction method for an emission spectrum envelope of frequency equipment comprises the steps of performing amplitude normalization and frequency normalization on original spectrum data; solving an extreme value by means of differential, firstly performing differential calculation on discrete spectrum data, obtaining a differential vector, then extracting a maximal value in the spectrum data, forming primary maximal valve spectrum data as extracted maximal value point data; 4), performing end point processing on the maximal value point data after normalization processing; and 5), performing curve fitting on the generated maximal value spectrum data in a spline interpolation manner, and obtaining a spectrum envelope line after interpolation processing. The extraction method settles problems such as overhigh coarseness, no time information of the spectrum data and incapability of extracting the envelope by means of Hilbert transform in a traditional spectrum template method. Unified spectrum envelope data are generated through amplitude normalization and frequency normalization. Smoothing of the spectrum envelope data is realized through spline interpolation. The extraction method further has advantages of clear calculation principle and high engineering practicability.
Description
Technical field
The invention belongs to emc testing field, and in particular to one kind frequency equipment emission spectra envelope extraction method,
Can be formed with frequency equipment transmitting spectrum envelope by the process to discrete spectrum data local maximum and the process of end points.
Background technology
With frequency equipment emission spectra be with frequency equip emission characteristics frequency domain representation, be with frequency equipment spectral compatibility analysis and
One of foundation that EMC analysis frequency deviation △ f are calculated.Have that quantity is more, type is more, believe without the time with frequency equipment emission spectra
The features such as breath.
In order to be more easily applied to frequency equipment spectral compatibility analysis and electromagnetic compatibility point with frequency equipment emission spectra
In analysis, its original spectrum measurement data is not typically directly adopted, but using its spectrum envelope.Had such as using spectrum envelope
Lower advantage：1) can be surveyed more than frequency spectrum with the spectral characteristic equipped frequently, particularly sensitive equipment reception bandwidth reflecting for more " true "
During try width；2) memory data output is reduced, spectrum envelope only needs to access key feature points；3) it is easy to turning for different frequent points emission spectra
Change.
At present the data envelopment extraction algorithm described in document mainly has Hilbert converter techniques, spectrum mask method etc., and this two
The subject matter that the method for kind is present is as follows：
(1) Hilbert converter techniques are extracted (temporal information is included i.e. data) suitable for temporal envelope, are the low passes of signal
It is equivalent, it is capable of achieving the separation of modulated signal and carrier signal.Fig. 1 is to extract AM modulated signal envelopes using Hilbert conversion
As a result, from the point of view of the result of calculation, for the data containing temporal information, Hilbert can realize the extraction of its envelope.And use
Frequency equipment transmitting modal data without corresponding temporal information, therefore the method due to cannot be used for equipping carrying for transmitting spectrum envelope with frequency
Take.
(2) spectrum mask method forms (straight line) envelope of frequency spectrum by several straight lines (monotonic decreasing), and its advantage is to deposit
The data volume of storage is substantially reduced, have the disadvantage it is overly conservative, not enough accurately.Fig. 2 is to be sent out using spectrum mask method extraction frequency equipment
The schematic diagram of spectrum envelope is penetrated, from these results the pluses and minuses of the method are clear that.
The content of the invention
The technical problem to be solved in the present invention is, extracts that frequency spectrum is excessively coarse, frequency spectrum data for traditional spectrum mask method
The difficult problems such as envelope can not be extracted without temporal information using Hilbert conversion, there is provided one kind frequency equipment emission spectra envelope extraction
Method, is extracted with frequency equipment spectrum envelope based on local maximum, may be used on spectral compatibility analysis and EMC analysis
In the middle equipment emission spectra Accurate Model with frequency.
The present invention is for the solution technical scheme that adopted of above-mentioned technical problem：
One kind frequency equipment emission spectra envelope extraction method, comprises the steps：
(1) amplitude normalization：To original frequency spectrum data, whole frequency spectrum data is traveled through, frequency spectrum maximum is found out, by each
Frequency spectrum data makes the difference with the frequency spectrum maximum, i.e. amplitude normalization is to 0dB；
(2) frequency normalization：On the basis of amplitude normalization, with corresponding reference frequency value f of frequency spectrum maximum0For base
Plinth, by each frequency values and f0Make the difference, i.e. frequency normalization is to 0Hz；
(3) one times maximum is calculated：Extreme value is solved using difference, first Difference Calculation is carried out to discrete frequency spectrum data,
So as to obtain a difference vector, if the symbol of adjacent element is contrary in difference vector, then corresponding points are exactly an extreme value
Point；If previous difference vector element is for just, latter difference vector element is that negative situation correspond to maximum；Then extract
Maximum in frequency spectrum data, forms a maximum frequency spectrum data as the maximum point data extracted；
(4) end points is processed：If frequency spectrum data two ends point value is respectively P ' (1), P ' (n) after normalized, step (3) is carried
The maximum point data two ends point value for taking is respectively env (2), env (n-1), the maximum frequency spectrum data generated after end points process
Endpoint value env (1), env (n) computing formula are respectively：
Env (1)=P ' (1)+0.5 × | P ' (1)-env (2) |
Env (n)=P ' (n)+0.5 × | P ' (n)-env (n-1) |
(5) interpolation：Using the frequency indices in maximum frequency spectrum data and raw spectroscopy data that step (4) is generated, adopt
Spline interpolation mode is used, the maximum frequency spectrum data to generating carries out curve fitting, obtain the spectral enveloping line after interpolation processing.
By such scheme, the step of the step (3) also calculates including secondary maximum, the use violent for spectral change
Frequency is equipped, and according to first enveloped situation is extracted, if envelope smoothness is poor, carries out double extreme extraction, specially：In once pole
On the basis of big value frequency spectrum data, Difference Calculation is carried out again, and extract maximum therein, form secondary maximum spectrum number
According to as the maximum point data extracted.
By such scheme, step (5) the spline interpolation mode includes cubic cube of interpolation and spline cubic spline letters
Two kinds of interpolation method of number.
The present invention has the advantages that compared with prior art：
1st, solve traditional spectrum mask method and extract that frequency spectrum is excessively coarse, frequency spectrum data can not be used without temporal information
The difficult problems such as envelope are extracted in Hilbert conversion, can be according to the characteristics of concrete equipment frequency spectrum data, by using an extreme value or two
Secondary extreme value realizes the extraction of spectrum envelope, and by amplitude normalization and frequency normalization normalized spatial spectrum envelope data is generated, and leads to
Cross spline interpolation and realize the smooth of spectrum envelope data；
2nd, Computing Principle of the present invention is easy to be clear, and engineering practicability is strong.
Description of the drawings
Fig. 1 is that prior art converts the schematic diagram for extracting AM modulated signal envelopes using Hilbert；
Fig. 2 is the schematic diagram that prior art extracts spectrum envelope using spectrum mask method；
Fig. 3 is embodiment of the present invention raw spectroscopy data schematic diagram；
Fig. 4 is the frequency spectrum data schematic diagram after Fig. 3 raw spectroscopy datas are normalized；
Fig. 5 is the signal of embodiment of the present invention normalized spatial spectrum data and the untreated extreme point of end points for extracting
Figure；
Fig. 6 is the signal of the maximum frequency spectrum data generated after embodiment of the present invention normalized spatial spectrum data are processed with end points
Figure；
Fig. 7 is schematic diagram of the embodiment of the present invention using the spectral enveloping line after the interpolation processing of cubic interpolation acquisition；
Fig. 8 is schematic diagram of the embodiment of the present invention using the spectral enveloping line after the interpolation processing of spline interpolation acquisition.
Specific embodiment
Below according to specific embodiment and accompanying drawing is combined, the present invention is further detailed explanation.
Embodiment of the present invention frequency is equipped for certain high-power transmitting equipment, and Fig. 3 is its transmitting modal data, and wherein transverse axis is frequency
Rate, the longitudinal axis is spectrum energy, and embodiment frequency equipment emission spectra envelope extraction method comprises the steps：
(1) amplitude normalization
To original frequency spectrum data, whole frequency spectrum data is traveled through, find out its frequency spectrum maximum Pmax, on this basis, will be every
Individual frequency spectrum data and frequency spectrum maximum PmaxMake the difference：
Pi'=Pi-Pmax
Wherein, Pi' it is to process the spectrum amplitude value after (frequency normalization), PiFor original spectrum amplitude value, 1≤i≤N,
N is frequency spectrum data total number；
Spectrum amplitude is normalized to by 0dB by the step；
(2) frequency normalization
On the basis of amplitude normalization, with frequency spectrum maximum PmaxCorresponding reference frequency value f0Based on, by each frequency
Rate value and f0Make the difference：
fi'=fi-f0
Wherein, fi' for process after frequency values, fiFor the frequency values of original signal spectrum, 1≤i≤N, N are that frequency spectrum data is always individual
Number；
By the step by frequency normalization to 0Hz；Frequency spectrum data after normalization is as shown in Figure 4；
(3) one times maximum is calculated
Because frequency spectrum data is discrete data, differential is replaced to solve extreme value using difference during concrete calculating, first to discrete
Frequency spectrum data carry out Difference Calculation, so as to obtain a difference vector A：
A=diff (P ')
Wherein P ' is the frequency spectrum data after normalization；If the symbol of adjacent element is contrary in difference vector A, then correspondence
Point is exactly an extreme point；If previous difference vector element is for just, latter element is that negative situation correspond to maximum；
Then the maximum in frequency spectrum data is extracted, a maximum frequency spectrum data is formed, as shown in Figure 5；
According to the characteristics of concrete equipment frequency spectrum data, violent for spectral change is equipped with frequency, is carried according to first enveloped
Situation is taken, if envelope smoothness is poor, double extreme extraction is carried out；On the basis of a maximum frequency spectrum data, enter again
Row Difference Calculation, and maximum therein is extracted, secondary maximum frequency spectrum data is formed as the maximum point data extracted；
(4) end points is processed
If frequency spectrum data two ends point value is respectively P ' (1), P ' (n), the maximum point that step (3) is extracted after normalized
Data two ends point value is respectively env (2), env (n-1), maximum frequency spectrum data endpoint value env (1) that generates after end points process,
Env (n) computing formula are respectively：
Env (1)=P ' (1)+0.5 × | P ' (1)-env (2) |
Env (n)=P ' (n)+0.5 × | P ' (n)-env (n-1) |
The maximum frequency spectrum data generated after end points process is as shown in Figure 6；
(5) interpolation
In order that the maximum frequency spectrum data envelope for generating has smooth effect, using the very big of step (4) generation
Frequency indices in value frequency spectrum data and raw spectroscopy data, using spline interpolation mode, typically using cubic (cube interpolation)
With spline (Cubic Spline Interpolation) method, the maximum frequency spectrum data to generating carries out curve fitting, at acquisition interpolation
Spectral enveloping line after reason.Using the spectral enveloping line after cubic interpolation processings as shown in fig. 7, using spline interpolation processings
Spectral enveloping line afterwards is as shown in Figure 8.
Obviously, above-described embodiment is only intended to clearly illustrate example of the present invention, and is not to the present invention
The restriction of embodiment.For those of ordinary skill in the field, it can also be made on the basis of the above description
The change or variation of its multi-form.There is no need to be exhaustive to all of embodiment.And these belong to this
Obvious change that bright spirit is extended out or among changing still in protection scope of the present invention.
Claims (3)
1. it is a kind of with frequency equipment emission spectra envelope extraction method, it is characterised in that to comprise the steps：
(1) amplitude normalization：To original frequency spectrum data, whole frequency spectrum data is traveled through, frequency spectrum maximum is found out, by each frequency spectrum
Data make the difference with the frequency spectrum maximum, i.e. amplitude normalization is to 0dB；
(2) frequency normalization：On the basis of amplitude normalization, with corresponding reference frequency value f of frequency spectrum maximum0Based on, will
Each frequency values and f0Make the difference, i.e. frequency normalization is to 0Hz；
(3) one times maximum is calculated：Extreme value is solved using difference, first Difference Calculation is carried out to discrete frequency spectrum data, so as to
A difference vector is obtained, if the symbol of adjacent element is contrary in difference vector, then corresponding points are exactly an extreme point；If
Previous difference vector element is for just, latter difference vector element is that negative situation correspond to maximum；Then frequency spectrum is extracted
Maximum in data, forms a maximum frequency spectrum data as the maximum point data extracted；
(4) end points is processed：If frequency spectrum data two ends point value is respectively P ' (1), P ' (n) after normalized, what step (3) was extracted
Maximum point data two ends point value is respectively env (2), env (n-1), the maximum frequency spectrum data end points generated after end points process
Value env (1), env (n) computing formula are respectively：
Env (1)=P ' (1)+0.5 × | P ' (1)-env (2) |
Env (n)=P ' (n)+0.5 × | P ' (n)-env (n-1) |
(5) interpolation：Using the frequency indices in maximum frequency spectrum data and raw spectroscopy data that step (4) is generated, using sample
Bar interpolation method, the maximum frequency spectrum data to generating carries out curve fitting, and obtains the spectral enveloping line after interpolation processing.
2. it is according to claim 1 with frequency equipment emission spectra envelope extraction method, it is characterised in that the step (3) is also
The step of calculating including secondary maximum, violent for spectral change is equipped with frequency, and according to first enveloped situation is extracted, if bag
Network smoothness is poor, carries out double extreme extraction, specially：It is poor again on the basis of a maximum frequency spectrum data
Divide and calculate, and extract maximum therein, form secondary maximum frequency spectrum data as the maximum point data extracted.
3. it is according to claim 1 with frequency equipment emission spectra envelope extraction method, it is characterised in that step (5) sample
Bar interpolation method includes two kinds of cubic cube of interpolation and spline Cubic Spline Interpolations method.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107576848A (en) * | 2017-09-27 | 2018-01-12 | 中国电子科技集团公司第五十四研究所 | A kind of template setting and template detection method based on spectrum analysis |
| CN107769866A (en) * | 2017-09-22 | 2018-03-06 | 中国舰船研究设计中心 | A kind of receiver coupled power Forecasting Methodology |
| CN108196237A (en) * | 2017-12-26 | 2018-06-22 | 中南大学 | A kind of method for inhibiting parastic modulation in fmcw radar echo-signal |
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| CN103178806A (en) * | 2011-12-23 | 2013-06-26 | 中国科学院声学研究所 | Envelope extraction method and system for one-dimensional data |
| CN203984361U (en) * | 2014-08-22 | 2014-12-03 | 哈尔滨同为电气股份有限公司 | A kind of low frequency signal envelope of practicality extracts circuit |
| CN104504181A (en) * | 2014-12-10 | 2015-04-08 | 宁波大学 | Signal envelope line extracting method based on sparse recovery |
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| JP2005338558A (en) * | 2004-05-28 | 2005-12-08 | Toshiba Corp | Receiving device |
| CN1875887A (en) * | 2005-06-10 | 2006-12-13 | 深圳迈瑞生物医疗电子股份有限公司 | Method for extracting envelope curve of sound spectrogram |
| CN103178806A (en) * | 2011-12-23 | 2013-06-26 | 中国科学院声学研究所 | Envelope extraction method and system for one-dimensional data |
| CN203984361U (en) * | 2014-08-22 | 2014-12-03 | 哈尔滨同为电气股份有限公司 | A kind of low frequency signal envelope of practicality extracts circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107769866A (en) * | 2017-09-22 | 2018-03-06 | 中国舰船研究设计中心 | A kind of receiver coupled power Forecasting Methodology |
| CN107576848A (en) * | 2017-09-27 | 2018-01-12 | 中国电子科技集团公司第五十四研究所 | A kind of template setting and template detection method based on spectrum analysis |
| CN107576848B (en) * | 2017-09-27 | 2019-07-26 | 中国电子科技集团公司第五十四研究所 | A kind of template setting and template detection method based on spectrum analysis |
| CN108196237A (en) * | 2017-12-26 | 2018-06-22 | 中南大学 | A kind of method for inhibiting parastic modulation in fmcw radar echo-signal |
| CN108196237B (en) * | 2017-12-26 | 2021-06-25 | 中南大学 | Method for inhibiting parasitic amplitude modulation in FMCW radar echo signal |
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