CN104507106B - The recognition methods of 8PSK signals and PI/4-DQPSK signals - Google Patents
The recognition methods of 8PSK signals and PI/4-DQPSK signals Download PDFInfo
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- CN104507106B CN104507106B CN201410854073.7A CN201410854073A CN104507106B CN 104507106 B CN104507106 B CN 104507106B CN 201410854073 A CN201410854073 A CN 201410854073A CN 104507106 B CN104507106 B CN 104507106B
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Abstract
A kind of recognition methods of 8PSK signals and PI/4 DQPSK signals, including：Instantaneous phase is extracted from the i/q signal after down coversion；Based on the instantaneous phase, the phase difference of adjacent symbol is calculated；Phase difference calculating center normalization instantaneous phase based on the adjacent symbol is poor；Instantaneous phase difference calculating parameter is normalized based on the center；Calculate the Absoute of the nonlinearity in parameters component；Signal identification is carried out according to the Absoute, it is PI/4 DQPSK signals that the Absoute, which is equal to zero, and it is 8PSK signals that the Absoute, which is more than zero,.Technical scheme of the present invention can be simple and effective identification 8PSK signals and PI/4 DQPSK signals.
Description
Technical field
The present invention relates to radio monitoring field, more particularly to a kind of identification side of 8PSK signals and PI/4-DQPSK signals
Method.
Background technology
In radio monitoring field, it is often necessary to the signals such as the service of illegal wireless electricity, interference source are identified, it is only insighted
Do not go out signal, foundation could be provided for spectrum management.Current existing Modulation Identification method is mainly based upon extraction feature and carries out
Know method for distinguishing, extraction feature is mainly the following：Include the temporal characteristics of amplitude, frequency and phase, count measure feature and
Transform domain feature etc..Wherein statistics measure feature (such as Higher Order Cumulants) and transform domain (such as wavelet transformation) Feature Engineering calculates multiple
Miscellaneous, real-time is poor.Current relatively effective identification feature method is the number that British scholar A.K.Nandi and Azzouz et al. are proposed
Word Modulation Signals Recognition algorithm (DMRAs), use is exactly that the key characterization parameters such as instantaneous envelope, phase and frequency are used as modulation
Know another characteristic, the algorithm calculating speed is fast, and classifying quality is apparent, is easier to realize in engineering, but between certain signals do not have
Corresponding feature extraction algorithm, such as the identification between QPSK and OQPSK, the knowledge between 8PSK signals and PI/4-DQPSK signals
Not, DMRAs does not provide corresponding feature extraction parameter.
Therefore how simple and effective identification 8PSK signals and PI/4-DQPSK signals becomes current urgent problem to be solved
One of.
Invention content
Technical scheme of the present invention solve the technical issues of be how simple and effective identification 8PSK signals and PI/4-
DQPSK signals.
In order to achieve the above-mentioned object of the invention, the present invention provides a kind of identification sides of 8PSK signals and PI/4-DQPSK signals
Method, including：
Instantaneous phase is extracted from the i/q signal after down coversionWherein I (i),
Q (i) is the roads I signal and the roads Q signal after quadrature frequency conversion, 0 ＜ i ＜ Ns, NsFor sampling number；
Based on the instantaneous phaseCalculate the phase difference of adjacent symbol0 ＜ i
＜ Nr, NrFor symbolic number, Nr=Ns/(fs/rs), rsFor symbol rate, fsFor sample rate；
Phase difference based on the adjacent symbolCalculating center normalizes instantaneous phase difference Δ φNL(i)：0 ＜ i ＜ Nr, NrFor symbolic number；
Based on center normalization instantaneous phase difference Δ φNL(i) calculating parameter Δ φa(i)：
Calculate the parameter, Δ φaNonlinear component Absoute σaaΔp：
According to the Absoute σaaΔpCarry out signal identification, σaaΔp=0 is PI/4-DQPSK signals, σaaΔp＞
0 is 8PSK signals.
Optionally, the instantaneous phaseArc tangent uses cordic algorithm.
Optionally, described to be based on the instantaneous phaseCalculate the phase difference of adjacent symbolIncluding to the I/Q
Signal carries out bit synchronization, to be equal to the symbol rate rsRate after Timed Recovery goes out symbol in the best time, calculate phase
The instantaneous phase answeredAnd obtain the phase difference of the adjacent symbol
Optionally, described the best time determines according to the bit-synchronization algorithm of use.
Optionally, it is based on the instantaneous phaseCalculate the phase difference of adjacent symbolFor when carrier synchronization, meter
It is poor to calculate the center normalization instantaneous phase
Optionally, the i/q signal is that signal to be identified is become digital signal by A/D samplings, to the number
Signal carries out frequency gained under orthogonal digital.
It is optionally, described that by signal to be identified, by A/D samplings, to become digital signal include by the letter to be identified
The range that number analog down is sampled to A/D, and meet over-sampling law or bandpass sampling law.
The present invention takes above technical scheme, compared with prior art, has the following advantages：
Using the difference of 8PSK signals and PI/4-DQPSK signal phase saltus steps, simplify 8PSK signals and PI/4-DQPSK letters
Number identification step, and technical scheme of the present invention is easy to operate, easily operated realization, realizes that speed is fast, as a result accurately.
Description of the drawings
Fig. 1 is the flow chart of the recognition methods of 8PSK signals and PI/4-DQPSK signals provided in an embodiment of the present invention；
Fig. 2 is that the phase of 8PSK signals provided in an embodiment of the present invention redirects figure；
Fig. 3 is that the phase of PI/4-DQPSK signals provided in an embodiment of the present invention redirects figure.
Specific implementation mode
To make the above purposes, features and advantages of the invention more obvious and understandable, below in conjunction with the accompanying drawings to the present invention
Specific implementation mode be described in detail.
Detail is elaborated in the following description in order to fully understand the present invention.But the present invention can with it is a variety of not
Other manner described here is same as to implement, those skilled in the art can do class without violating the connotation of the present invention
Like popularization.Therefore the present invention is not limited by following public specific implementation mode.
Fig. 1 is the flow chart of the recognition methods of 8PSK signals and PI/4-DQPSK signals provided in an embodiment of the present invention, under
Face combines Fig. 1 (only with verbal description in Fig. 1, not showing that mathematics identifies) to be described in detail.
Step S1 extracts instantaneous phase from the i/q signal after down coversion
Step S2 is based on the instantaneous phaseCalculate the phase difference of adjacent symbol
Step S3, the phase difference based on the adjacent symbolCalculating center normalizes instantaneous phase difference Δ φNL(i)；
Step S4, based on center normalization instantaneous phase difference Δ φNL(i) calculating parameter Δ φa(i)；
Step S5 calculates the parameter, Δ φaNonlinear component Absoute σaaΔp；According to described absolute
It is worth standard deviationaaΔpCarry out signal identification, σaaΔp=0 is PI/4-DQPSK signals, σaaΔp＞ 0 is 8PSK signals.
In the step S1, the i/q signal is that signal to be identified is become digital signal by A/D samplings, to institute
It states digital signal and carries out frequency gained under orthogonal digital.It is described that signal to be identified is become digital signal and include by A/D samplings
The signal imitation to be identified is down-converted to the range of A/D samplings, and meets over-sampling law or bandpass sampling law.
In the step S1, the instantaneous phaseArc tangent uses cordic algorithm.
It is described to be based on the instantaneous phase in the step S2Calculate the phase difference of adjacent symbolIncluding to institute
It states i/q signal and carries out bit synchronization, to be equal to the symbol rate rsThe fixation of (chip rate of signal source, abbreviation chip rate)
Rate is after the best time Timed Recovery goes out symbol (as used Gardner algorithms in the maximum of the symbol after shaping filter
The value moment recovers symbol, specifically please refers to Gardner algorithms or other bit-synchronization algorithms), calculate corresponding instantaneous phaseAnd obtain the phase difference of the adjacent symbolDescribed the best time is according to use
Bit-synchronization algorithm determine.
In the step S3, it is based on the instantaneous phaseCalculate the phase difference of adjacent symbolTo work as carrier synchronization
When, it is poor to calculate the center normalization instantaneous phaseWherein, NrFor symbolic number, Nr=Ns/
(fs/rs), rsFor symbol rate, fsFor sample rate.
In the step S4, based on center normalization instantaneous phase difference Δ φNL(i) calculating parameter Δ φa(i)(Δ
φa(i) it is to Δ φNL(i) parameter that the center of progress normalizes again)：
In the step S5, calculating parameter Δ φaNonlinear component Absoute σaaΔp：
Citing is described in detail below：
The recognition methods of current 8PSK signals and PI/4-DQPSK signals is that Digital modulation identification algorithm (is also referred to as
DMRAs algorithms), the principle of DMRAs Modulation Identifications is as follows：Identified signal is sampled by A/D (if signal frequency is too
Greatly, RF front-end circuit is needed in hardware, and identified signal imitation is down-converted to the range that A/D can be sampled, energy first
Meet over-sampling or bandpass sampling law) become digital signal, digital signal forms orthogonal I/ after orthogonal digital down coversion
Then Q signal utilizes i/q signal to calculate amplitude, frequency and phase instantaneous characteristic parameters, then using instantaneous characteristic parameters as defeated
Enter, calculates signal identification characteristic parameter using DMRAs algorithms, finally carry out signal identification using signal identification characteristic parameter.
The formula that the instantaneous characteristic parameters such as amplitude, frequency and phase are calculated using i/q signal is as follows：
Wherein a (i) is discrete instantaneous amplitude,For instantaneous phase, f (i) is instantaneous frequency.
Signal identification characteristic parameter is calculated using instantaneous characteristic parameters, classical DMRAs signal identification characteristic parameters
Mainly have following：
(1) the maximum value γ of the spectrum density of zero center normalization instantaneous amplitudemax；
(2) zero center normalizes the standard deviation of non-weak signal section instantaneous amplitudea；
(3) zero center normalizes the standard deviation of non-weak signal section instantaneous amplitude absolute valueaa；
(4) standard deviation of the non-weak signal section instantaneous phase nonlinear component of zero centerdp；
(5) standard deviation of the absolute value of the non-weak signal section instantaneous phase nonlinear component of zero centerap；
(6) zero center normalizes the standard deviation of non-weak signal section instantaneous frequency absolute valueaf；
(7) parameter phiaNonlinear component Absoute σaap；
(8) the Absoute σ of the nonlinear component of parameter faaaf；
(9) spectrum symmetry P；
(10) compactness (Fourth-order moment) of zero center normalization instantaneous amplitude
(11) compactness (Fourth-order moment) of zero center normalization instantaneous frequency
Since the spectrogram of 8PSK and PI/4-DQPSK is identical with planisphere, signal knowledge can not be carried out with above-mentioned 11 formula
Not.
The purpose of the present invention is the differences using 8PSK and PI/4-DQPSK phase hits, to σaapIt is improved, completes
Signal identification between 8PSK and PI/4-DQPSK.
The σ of DMRAsaapFormula is as follows：
Wherein φaTo carry out the parameter that centralization obtains, table again to the absolute value through centralization treated instantaneous phase
Show as follows：
Whereinan(i) be the signal after Timed Recovery instantaneous normalization width
Degree, maIt is the average value of the instantaneous amplitude of the signal after Timed Recovery；NsFor sampling number；φNL(i) it is through at centralization
The nonlinear component of instantaneous phase after reason.In carrier synchronization, φNL(i) it calculates as follows：
In upper two formula,For instantaneous phase.taIt is an amplitude decision threshold level for judging weak signal section, it is low
When this level threshold, the phase of signal is very sensitive to noise, can cause larger phase distortion.C is in data acquisition system { φNL
(i) } a inn(i) ＞ taSignal number, that is, belong to the number of non-weak signal value.
σaapIt is used for distinguishing 8PSK, 16QAM signal and QPSK signals in signal identification.For QPSK signals, φa
There are two level value, φ for parameteraThe absolute value of parameter is a constant value, so σaap=0；And for 8PSK or 16QAM signals
For, φaThere are four level value, φaThe absolute value of parameter is not a constant, so σaap＞ 0.Therefore this feature value can by with
In distinguishing 8PSK, 16QAM signal and QPSK, but σaap8PSK and PI/4-DQPSK signals cannot directly be distinguished.
PI/4-DQPSK is improved on the basis of QPSK, QPSK phases, which redirect mode, to be had 0 °, and 90 °, 180 ° ,-
90 ° } totally 4 kinds of situations can be such that the secondary lobe of signal increases, influence spectral performance when generating when redirecting of 180 degree.In order to solve this
I/Q two paths of signals is generated the time interval of a symbol, effectively prevents two by a problem, improved OQPSK modulation systems
Road symbol signal changes simultaneously, and to making phase redirect only { 90 °, -90 ° }, solves the problems, such as that 180 ° substantially redirect, and
PI/4-DQPSK is the combination of both modulation systems, the good characteristic with two methods.Its phase redirected 45 °,
135 °, -45 °, -135 ° }, maximum phase saltus step is 135 °, is not in 180 ° of substantially saltus step in QPSK, equally improves
Spectral characteristic, planisphere are identical as 8PSK.Fig. 2 and Fig. 3 gives 8PSK and the phase of PI/4-DQPSK redirects figure.
Since the adjacent symbol phases of PI/4-DQPSK have 4 hop values, maximum saltus step is ± 3 π/4, and the adjacent code of 8PSK
It is π that first phase, which has 8 hop values, maximum saltus step,.According to this of 8PSK and PI/4-DQPSK feature, DMRAs can be referred to and calculated
Classical characteristic parameter σ in methodaap, for the identification between 8PSK and PI/4-DQPSK after improvement, the specific method is as follows：
Instantaneous phase is extracted from the i/q signal after down coversion
For calculating σaap, arc tangent can realize with cordic algorithm.In order to calculate the saltus step of adjacent symbol phases
ValueAlso bit synchronization is carried out to i/q signal, to be equal to symbol rate rsFixed rate in the best time Timed Recovery
After going out symbol, calculate correspondingPhase difference to obtain adjacent symbol is：
By φNL(i) instantaneous phase inReplace with the hop value of adjacent symbol phasesIt can obtain center
Normalize instantaneous phase difference Δ φNL(i)：
NrFor symbolic number, Nr=Ns/(fs/rs), rsFor symbol rate, fsFor sample rate, NsFor sampling number.
By φa(i) φ in formulaNL(i) Δ φ is usedNL(i) it replaces, calculates Δ φa(i)：
By σaapIn φa(i) Δ φ is useda(i) it replaces, can obtain：
Whereinan(i) be the signal after Timed Recovery instantaneous normalization width
Degree, maIt is the average value of the instantaneous amplitude of the signal after Timed Recovery.
For PI/4-DQPSK signals,Only π/4,3 π/4 two value, therefore Δ φa(i) there are two parameter
Level value, σaaΔp=0；And for 8PSK signals, Δ φa(i) there are four level value, σaaΔpTherefore ＞ 0 utilizes the spy
Value indicative can be used for distinguishing 8PSK and PI/4-DQPSK signals.
The present invention takes above technical scheme, compared with prior art, has the following advantages：
Using the difference of QPSK signals and OQPSKI signal phase saltus steps, simplify the identification of QPSK signals and OQPSK signals
Step, and technical scheme of the present invention is easy to operate, easily operated realization, realizes that speed is fast, as a result accurately.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (7)
1. a kind of recognition methods of 8PSK signals and PI/4-DQPSK signals, which is characterized in that including：
Instantaneous phase is extracted from the i/q signal after down coversion Wherein I (i), Q (i) are
The roads I signal after quadrature frequency conversion and the roads Q signal, 0 ＜ i ＜ Ns, NsFor sampling number；
Based on the instantaneous phaseCalculate the phase difference of adjacent symbol
NrFor symbolic number, Nr=Ns/(fs/rs), rsFor symbol rate, fsFor sample rate；
Phase difference based on the adjacent symbolCalculating center normalizes instantaneous phase difference Δ φNL(i)：NrFor symbolic number；
Based on center normalization instantaneous phase difference Δ φNL(i) calculating parameter Δ φa(i)：
Calculating parameter Δ φaNonlinear component Absoute σaaΔp：Wherein an(i) it is by fixed
The instantaneous normalization amplitude of signal, m after Shi HuifuaIt is the average value of the instantaneous amplitude of the signal after Timed Recovery, taIt is to sentence
The decision threshold level of one amplitude of disconnected weak signal section, C is in set { φNL(i) } a inn(i) ＞ taAn(i) of signal
Number；
According to the Absoute σaaΔpCarry out signal identification, σaaΔp=0 is PI/4-DQPSK signals, σaaΔp＞ 0 is
8PSK signals.
2. the recognition methods of 8PSK signals and PI/4-DQPSK signals as described in claim 1, which is characterized in that described instantaneous
PhaseArc tangent uses cordic algorithm.
3. the recognition methods of 8PSK signals and PI/4-DQPSK signals as described in claim 1, which is characterized in that described to be based on
The instantaneous phaseCalculate the phase difference of adjacent symbolIncluding carrying out bit synchronization to the i/q signal, to be equal to
The symbol rate rsRate after Timed Recovery goes out symbol in the best time, calculate corresponding instantaneous phaseAnd obtain institute
State the phase difference of adjacent symbol
4. the recognition methods of 8PSK signals and PI/4-DQPSK signals as claimed in claim 3, which is characterized in that described best
Moment determines according to the bit-synchronization algorithm of use.
5. the recognition methods of 8PSK signals and PI/4-DQPSK signals as described in claim 1, which is characterized in that based on described
Instantaneous phaseCalculate the phase difference of adjacent symbolWhen carrier synchronization, to calculate the center normalization instantaneous phase
Difference
6. the recognition methods of 8PSK signals and PI/4-DQPSK signals as described in claim 1, which is characterized in that the I/Q
Signal is that signal to be identified is become digital signal by A/D samplings, and orthogonal digital down coversion is carried out to the digital signal
Gained.
7. the recognition methods of 8PSK signals and PI/4-DQPSK signals as claimed in claim 6, which is characterized in that described to wait for
It includes that the signal imitation to be identified is down-converted to what A/D was sampled that the signal of identification becomes digital signal by A/D samplings
Range, and meet over-sampling law or bandpass sampling law.
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| CN1395400A (en) * | 2002-07-05 | 2003-02-05 | 清华大学 | Automatic identification method of conventional digital signal modulation mode having no need of a priori knowledge |
| CN104022837A (en) * | 2014-05-28 | 2014-09-03 | 广州海格通信集团股份有限公司 | Method of recognizing communication signal modulation mode based on feature extraction |
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| CN1395400A (en) * | 2002-07-05 | 2003-02-05 | 清华大学 | Automatic identification method of conventional digital signal modulation mode having no need of a priori knowledge |
| CN104022837A (en) * | 2014-05-28 | 2014-09-03 | 广州海格通信集团股份有限公司 | Method of recognizing communication signal modulation mode based on feature extraction |
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