CN109714286A - A kind of carrier frequency bias estimation of Pi/8D8PSK demodulation - Google Patents
A kind of carrier frequency bias estimation of Pi/8D8PSK demodulation Download PDFInfo
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Abstract
The present invention provides a kind of carrier frequency bias estimations of Pi/8D8PSK demodulation, digital quadrature down conversion, low-pass filtering are carried out to Pi/8D8PSK intermediate-freuqncy signal, obtain the baseband signal of Pi/8D8PSK modulation, bit synchronization operation is carried out to baseband signal using square timing recovery algorithm, by the data windowed function after bit synchronization, energy leakage is reduced；In order to avoid frequency resolution does not reach requirement when frequency deviation is smaller, frequency offset estimation accuracy is caused to be deteriorated, to FFT operation is carried out after 16 side's operation of data after adding window, to FFT operation result modulus, maximum corresponding frequency point is calculated multiplied by resolution bandwidth again divided by 16, obtains offset estimation value；To improve the he number that frequency resolution bandwidth suitably increases sampling；In order to improve operation efficiency, calls FFTW to realize FFT operation, realize the improvement to the frequency excursion algorithm of DFT.With popularizing for complicated algorithm software implementation implementation method, above method Project Realization complexity is substantially reduced.Relative to existing DFT frequency excursion algorithm, precision and efficiency are improved, energy leakage inhibition is also improved, Project Realization is convenient for.
Description
Technical field
The invention belongs to wirelessly communicate testing field, in particular to a kind of Nonlinear Transformation in Frequency Offset Estimation side of pi/8D8PSK demodulation
Method.
Background technique
In wireless communication systems, with the rapid development of software and radio technique and Digital Signal Processing, totally
Word modulation-demodulation technique is widely used.Pi/8D8PSK modulation system has availability of frequency spectrum height and lesser envelope
The characteristics of fluctuating, is allowed in performance have more preferably spectrum efficiency in nonlinear channel better than 8PSK modulation mode.Receiving end carries
The frequency shift (FS) of wave generates the influence of very severe to communication system, does not only result in constellation point and rotates, but will make the bit error rate
It sharply increases, so Nonlinear Transformation in Frequency Offset Estimation is one of the key link of Pi/8D8PSK demodulation.Common method is M-Power at present
Offset estimation and offset estimation based on DFT, M-Power frequency excursion algorithm basic thought is that (M is order of modulation by taking M
16) power removal receives the modulation intelligence in signal, the influence of difference delay removal constant phase error is then conjugated, to estimate
Count out frequency deviation.Realize that block diagram is as shown in Figure 1.
C (i)=S1 (i) S1*(i-1)
Wherein, T is chip rate, and n is total data volume, i.e. he number, and imag () is real part, and real () is imaginary part.
The arithmetic accuracy is high, but restricted application.
Frequency excursion algorithm based on DFT is using DFT frequency spectrum come estimating carrier frequency offset point, and block diagram is as shown in Figure 2.
If the base band pi/8D8PSK signal after quadrature frequency conversion indicates are as follows:
G in formulaTIt (t-nT) is symbol pulses signal, T is code-element period, chip rate Rs=1/T, Δ f are carrier frequency
Partially.
DFT operation, the actual sample rate of data, that is, chip rate R are carried out to the data after bit synchronizations, frequency spectrum will be in Δ
Occurs peak value spectral line at f, we can estimate frequency deviation Δ f=by searching for the position PointOffset of maximum value spectral line
PointOffset is multiplied by frequency resolution bandwidth RBW.When Δ f is positive value (actual frequency f0 > carrier frequency fc), amplitude is most
Big spectral line is between 0~N/2；When Δ f is negative value (actual frequency f0 < carrier frequency fc), the spectral line position of amplitude maximum
Between N/2~N-1.
DFT algorithm can estimation range be: | Δ f |≤Rs.The algorithm scope of application is wider, but since there are grid for the algorithm
Column effect and energy leakage, precision be not high.Its estimated accuracy is related with FFT points N, and N is higher, then precision is higher, while operation
It measures also bigger.
Summary of the invention
The present invention provides a kind of Pi/8D8PSK demodulation carrier frequency bias estimation, to Pi/8D8PSK intermediate-freuqncy signal into
Row digital quadrature down conversion, low-pass filtering obtain the baseband signal of Pi/8D8PSK modulation, using a square timing recovery algorithm pair
Baseband signal carries out bit synchronization operation, by the data windowed function after bit synchronization, reduces energy leakage；In order to avoid frequency deviation is smaller
When frequency resolution do not reach requirement, cause frequency offset estimation accuracy to be deteriorated, to carrying out FFT after 16 side's operation of data after adding window
Operation calculates maximum corresponding frequency point multiplied by resolution bandwidth again divided by 16, obtains frequency deviation and estimate to FFT operation result modulus
Evaluation；To improve the he number that frequency resolution bandwidth suitably increases sampling；In order to improve operation efficiency, FFTW is called to come real
Existing FFT operation, realizes the improvement to the frequency excursion algorithm of DFT.
The present invention is realized according to following technical scheme:
A kind of carrier frequency bias estimation of Pi/8D8PSK demodulation, which comprises the following steps:
Step S1: digital quadrature down conversion, low-pass filtering are carried out to Pi/8D8PSK intermediate-freuqncy signal, obtain Pi/8D8PSK tune
The baseband signal X (n) of system:
X (n)=XI (n)+j*XQ (n)
The imaginary part deal of j expression complex signal；
Step S2: bit synchronization operation is carried out to baseband signal using square timing recovery algorithm, first calculating largest sample
The deviation post Ph of point, range are greater than -1/2, less than 1/2:
X (n) is the baseband signal of Pi/8D8PSK modulation before bit synchronization, is plural form, and L is the code element number of a frame data,
N is the sampling number of a symbol, since Ph range is greater than -1/2, less than 1/2, so if the Ph calculated is less than 0, Ph
=Ph+1.0；
The largest sample point of one frame data are as follows:
InterMax (i)=(Ph+i) * N+1；I=0,1 ..., L-1
Orthogonal signalling after bit synchronization are as follows:
I (i)=XI (InterMax (i))；I=0,1 ..., L-1
Q (i)=XQ (InterMax (i))；I=0,1 ..., L-1；
Step S3: I (n), Q (n) after bit synchronization carry out multiplying window, obtain Ic (n), Qc (n), window function Win
(n), generated by Matlab, type be hanning window, length L,
Ic (i)=I (i) * Win (i)；I=0,1 ..., L-1
Qc (i)=Q (i) * Win (i)；I=0,1 ..., L-1
I (n) after bit synchronization, that Q (n) is write as plural form is as follows:
BitSyncSym (n)=Ic (n)+j*Qc (n)；
The imaginary part deal of j expression complex signal；
Step S4: to the 16 power operation BitSyncSym (n) of data after adding window16, FFT operation is then carried out, is obtained
FFTSym (n), FFT count FFT_Len value as L, call FFTW to realize FFT operation, frequency resolution bandwidth is symbol speed
Rate SymSample is divided by FFT_Len；
Step S5: to FFT operation result FFTSym (n) modulus, the corresponding Frequency point of maximum value MaxMag of mould is calculated
PointOffset, PointOffset, again divided by 16, obtain offset estimation value Δ f multiplied by frequency resolution bandwidth.
Step S6: frequency deviation compensation is carried out to the signal after bit synchronization using offset estimation value Δ f, wherein the letter after bit synchronization
Number BitSym (n)=I (n)+j*Q (n), therefore the compensated signal of frequency deviation:
Compared with prior art, the present invention have it is following the utility model has the advantages that
Relative to existing DFT frequency excursion algorithm, the present invention improves precision and efficiency, and complexity substantially reduces, right
Energy leakage inhibition be also improved, be convenient for Project Realization, this method can estimation range be: | Δ f |≤Rs/ 16, for frequency deviation compared with
Hour, it is very suitable to.
Detailed description of the invention
Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other feature of the invention,
Objects and advantages will become more apparent upon:
Fig. 1 is that M-Power frequency excursion algorithm realizes block diagram；
Fig. 2 is that the frequency excursion algorithm based on DFT realizes block diagram；
Fig. 3 is that Nonlinear Transformation in Frequency Offset Estimation of the invention realizes block diagram.
Specific embodiment
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, several changes and improvements can also be made.These belong to the present invention
Protection scope.
Fig. 3 is that Nonlinear Transformation in Frequency Offset Estimation of the invention realizes block diagram, as shown in figure 3, a kind of Pi/8D8PSK of the invention is demodulated
Carrier frequency bias estimation, comprising the following steps:
Step S1: digital quadrature down conversion, low-pass filtering are carried out to Pi/8D8PSK intermediate-freuqncy signal, obtain Pi/8D8PSK tune
The baseband signal X (n) of system realizes that system block diagram is as shown in Figure 3；
X (n)=XI (n)+j*XQ (n)
The imaginary part deal of j expression complex signal；
Step S2: bit synchronization operation is carried out to baseband signal using square timing recovery algorithm, first calculating largest sample
The deviation post Ph of point, range are greater than -1/2, less than 1/2:
X (n) is the baseband signal of Pi/8D8PSK modulation before bit synchronization, is plural form, and L is the code element number of a frame data,
N is the sampling number of a symbol, since Ph range is greater than -1/2, less than 1/2, so if the Ph calculated is less than 0, Ph
=Ph+1.0；
The largest sample point of one frame data are as follows:
InterMax (i)=(Ph+i) * N+1；I=0,1 ..., L-1
Orthogonal signalling after bit synchronization are as follows:
I (i)=XI (InterMax (i))；I=0,1 ..., L-1
Q (i)=XQ (InterMax (i))；I=0,1 ..., L-1
Step S3: I (n), Q (n) after bit synchronization carry out multiplying window, obtain Ic (n), Qc (n), window function Win
(n), generated by Matlab, type be hanning window, length L,
Ic (i)=I (i) * Win (i)；I=0,1 ..., L-1
Qc (i)=Q (i) * Win (i)；I=0,1 ..., L-1
I (n) after bit synchronization, that Q (n) is write as plural form is as follows:
BitSyncSym (n)=Ic (n)+j*Qc (n)；
The imaginary part deal of j expression complex signal；
Step S4: to the 16 power operation BitSyncSym (n) of data after adding window16, FFT operation is then carried out, is obtained
FFTSym (n), FFT count FFT_Len value as L, call FFTW to realize FFT operation, frequency resolution bandwidth is symbol speed
Rate SymSample is divided by FFT_Len；
Step S5: to FFT operation result FFTSym (n) modulus, the corresponding Frequency point of maximum value MaxMag of mould is calculated
PointOffset, PointOffset, again divided by 16, obtain offset estimation value Δ f multiplied by frequency resolution bandwidth.
Step S6: frequency deviation compensation is carried out to the signal after bit synchronization using offset estimation value Δ f, wherein the letter after bit synchronization
Number BitSym (n)=I (n)+j*Q (n), therefore the compensated signal of frequency deviation:
The DFT of complex signal is unilateral spectrum, and when carrier wave frequency deviation is positive value, the spectral line of amplitude maximum is between 0~N/2；
When carrier wave frequency deviation is negative value, the spectral line of amplitude maximum is between N/2~N-1, so the frequency excursion algorithm using FFT can
Effectively to estimate that frequency deviation value can also estimate the positive and negative values of frequency deviation.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make a variety of changes or modify within the scope of the claims, this not shadow
Ring substantive content of the invention.In the absence of conflict, the feature in embodiments herein and embodiment can any phase
Mutually combination.
Claims (1)
1. a kind of carrier frequency bias estimation of Pi/8D8PSK demodulation, which comprises the following steps:
Step S1: carrying out digital quadrature down conversion, low-pass filtering to Pi/8D8PSK intermediate-freuqncy signal, obtains Pi/8D8PSK modulation
Baseband signal X (n):
X (n)=XI (n)+j*XQ (n)
The imaginary part deal of j expression complex signal；
Step S2: bit synchronization operation is carried out to baseband signal using square timing recovery algorithm, calculates largest sample point first
Deviation post Ph, range are greater than -1/2, less than 1/2:
X (n) is the baseband signal of Pi/8D8PSK modulation before bit synchronization, is plural form, and L is the code element number of a frame data, and N is
The sampling number of one symbol, since Ph range is greater than -1/2, less than 1/2, so if the Ph calculated is less than 0, Ph=
Ph+1.0；
The largest sample point of one frame data are as follows:
InterMax (i)=(Ph+i) * N+1；I=0,1 ..., L-1
Orthogonal signalling after bit synchronization are as follows:
I (i)=XI (InterMax (i))；I=0,1 ..., L-1
Q (i)=XQ (InterMax (i))；I=0,1 ..., L-1；
Step S3: I (n), Q (n) after bit synchronization carry out multiplying window, obtain Ic (n), Qc (n), and window function is Win (n), by
Matlab generate, type be hanning window, length L,
Ic (i)=I (i) * Win (i)；I=0,1 ..., L-1
Qc (i)=Q (i) * Win (i)；I=0,1 ..., L-1
I (n) after bit synchronization, that Q (n) is write as plural form is as follows:
BitSyncSym (n)=Ic (n)+j*Qc (n)；
The imaginary part deal of j expression complex signal；
Step S4: to the 16 power operation BitSyncSym (n) of data after adding window16, FFT operation is then carried out, is obtained
FFTSym (n), FFT count FFT_Len value as L, call FFTW to realize FFT operation, frequency resolution bandwidth is symbol speed
Rate SymSample is divided by FFT_Len；
Step S5: to FFT operation result FFTSym (n) modulus, the corresponding Frequency point of maximum value MaxMag of mould is calculated
PointOffset, PointOffset, again divided by 16, obtain offset estimation value Δ f multiplied by frequency resolution bandwidth.
Step S6: frequency deviation compensation is carried out to the signal after bit synchronization using offset estimation value Δ f, wherein the signal after bit synchronization
BitSym (n)=I (n)+j*Q (n), therefore the compensated signal of frequency deviation:
FreqOffsetBitSym (n)=BitSym (n) * e-j*2*π*Δf*n。
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112162153A (en) * | 2020-08-31 | 2021-01-01 | 南京亿杰明信息技术有限公司 | Sine wave signal frequency estimation method based on phase straight line fitting |
| CN113406386A (en) * | 2021-06-23 | 2021-09-17 | 中国电子科技集团公司第二十九研究所 | Signal frequency accurate estimation method based on digital down-conversion |
| CN113542173A (en) * | 2021-07-28 | 2021-10-22 | 上海微波技术研究所（中国电子科技集团公司第五十研究所） | Carrier frequency offset suppression method, system, medium and device based on automatic frequency control |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101795250A (en) * | 2010-04-16 | 2010-08-04 | 成都天奥信息科技有限公司 | Demodulation method and device of D8PSK (differential 8-ary phase shift keying) modulation signals of VDL (VHF (very high frequency) digital link) communication system |
| CN102790659A (en) * | 2012-07-18 | 2012-11-21 | 福建先创通信有限公司 | Method for transmitting data packet in mobile communication system |
| US20130121350A1 (en) * | 2008-03-31 | 2013-05-16 | Sirius XM Radio, Inc. | Overlay Modulation of COFDM Using Phase and Amplitude Offset Carriers |
-
2019
- 2019-01-11 CN CN201910028823.8A patent/CN109714286B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20130121350A1 (en) * | 2008-03-31 | 2013-05-16 | Sirius XM Radio, Inc. | Overlay Modulation of COFDM Using Phase and Amplitude Offset Carriers |
| CN101795250A (en) * | 2010-04-16 | 2010-08-04 | 成都天奥信息科技有限公司 | Demodulation method and device of D8PSK (differential 8-ary phase shift keying) modulation signals of VDL (VHF (very high frequency) digital link) communication system |
| CN102790659A (en) * | 2012-07-18 | 2012-11-21 | 福建先创通信有限公司 | Method for transmitting data packet in mobile communication system |
Non-Patent Citations (2)
| Title |
|---|
| TIANHUA XU ET AL: "Analytical BER performance in differential n-PSK coherent transmission system influenced by equalization enhanced phase noise", 《OPTICS COMMUNICATIONS》 * |
| 钱者凤: "QPSK信号的矢量分析研究与实现", 《信息技术》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112162153A (en) * | 2020-08-31 | 2021-01-01 | 南京亿杰明信息技术有限公司 | Sine wave signal frequency estimation method based on phase straight line fitting |
| CN113406386A (en) * | 2021-06-23 | 2021-09-17 | 中国电子科技集团公司第二十九研究所 | Signal frequency accurate estimation method based on digital down-conversion |
| CN113406386B (en) * | 2021-06-23 | 2023-04-25 | 中国电子科技集团公司第二十九研究所 | Signal frequency accurate estimation method based on digital down-conversion |
| CN113542173A (en) * | 2021-07-28 | 2021-10-22 | 上海微波技术研究所（中国电子科技集团公司第五十研究所） | Carrier frequency offset suppression method, system, medium and device based on automatic frequency control |
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