CN104135360B - A kind of feedforward timing recovery method suitable for satellite communication burst transmission system - Google Patents
A kind of feedforward timing recovery method suitable for satellite communication burst transmission system Download PDFInfo
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Abstract
The present invention relates to a kind of feedforward timing recovery method suitable for satellite communication burst transmission system, this method is based on slip accumulation method and realizes that timing offset is estimated, accuracy of estimation can be improved, the amount of calculation of timing offset estimation is effectively reduced, and realizes the continuous processing of burst transfer data；This method is when timing offset is estimated to calculate, calculated using signal amplitude, and frame head is detected using computing cross-correlation, the influence that signal frequency deviation can be avoided to estimate timing offset, signal frequency deviation need not be estimated, can be applied under channel circumstance mal-condition, digital receiver sampling clock cycle is set as a quarter of symbol period, operation of receiver frequency is relatively low, it is easy to Project Realization.
Description
Technical field
It is more particularly to a kind of to be applied to satellite burst transfer system the present invention relates to digital wireless communication transmission technique field
The feedforward timing recovery method of system.
Background technology
In wideband satellite communication system receiver, symbol timing recovery is the key factor of influence demodulation receptivity.
Classical timing synchronization algorithm mainly has feedback lock mutually and two methods of feedforward estimation.Wherein, feedback Timing Synchronization is general
Using phase-locked loop structures, it is necessary to which the data for consuming the long period restrain to phaselocked loop, inevitably captured every time
The loss of transmission frame beginning data is caused in journey, and then reduces system spectrum utilization rate.So, it is commonly used in continuously
In data transmission applications such as broadcast transmission system DVB-S2 (second generation satellite digital video broadcast), to the feelings of shorter bursty data
Condition is more difficult to be adapted to.
Feedover the relatively simple for structure of Timing Synchronization, is typically made up of timing offset estimator and interpolation filter.Feedforward
Timing estimation algorithms are suitable in burst transfers of data, such as Interactive Satellite communication system DVB-RCS.Before classical unbound nucleus
Feedback timing estimator generally require every 4 sampled points of symbol with regard to good performance can be reached, its algorithm for estimating mainly using square
The nonlinear operations such as rate, absolute value and logarithm.However, relative to the automatic convergence structure of phaselocked loop, it is extensive in design feedforward timing
When realizing of double calculation method, it is desirable to accurately recover all frame originating point informations and load data, so as to need correctly to recognize all whole frames
Frame header position and rightly handle the data of each tail.
In the data document that the existing reception on short-term burst signal in satellite communication system is demodulated, general Study is fixed
When estimation of deviation algorithm improvement and performance evaluation, be only limitted to theoretical research；Or research Joint Fourier Transformation (DFT), Fu Li
The feedforward Timing Synchronization Project Realization of the technologies such as leaf-size class number is, it is necessary to design accurate DFT the window's positions and length, longer DFT
Processing substantially increases reception system complexity again, causes detector timing properties b seriously to be influenceed by other technologies.Do not have still at present
There is the overall technical architecture that such frame head and postamble accurate timing recovery problem are solved based on feedforward Timing Synchronization structure.
The content of the invention
It is applied to satellite communication burst transmission system it is an object of the invention to overcome the deficiencies of the prior art and provide one kind
Feedforward timing recovery method, this method can ensure that progress is continuous, recover frame head, postamble data exactly, improves timing offset
Accuracy of estimation, effectively reduces the amount of calculation of timing offset estimation, it is not necessary to signal frequency deviation is estimated, channel is can be applied to
Under the conditions of bad environments.
The above-mentioned purpose of the present invention is achieved by following technical solution：
A kind of feedforward timing recovery method suitable for satellite communication burst transmission system, comprises the following steps：
(1) over-sampling and a digital quantization are carried out using the ADC docking collections of letters number, and data signal is obtained by matched filter
x(k)：
Wherein, N is the data frame length that satellite communication burst transmission system transmitting terminal is sent, and the data frame is a=
{a1,a2,...,an,…aN}；an, n=1,2 ..., N are the data symbol of burst transfer, and the data symbol is using linear tune
Make and mean power is 1；It is N that the length generated by pseudo-random sequence is included in data frame apLeading symbolIt is N-N with lengthpData loadT is the data symbol an's
Time cycle；M is the sampling number in a data symbol duration, and M values are 4 in satellite digital receiver, i.e.,Wherein TsFor ADC sampling clock cycles；τ is channel timing offset value, i.e. signal time delay and symbol period T ratio
Value, and -0.5≤τ≤0.5；G (t) is satellite communication burst transmission system transmitting terminal forming filter and receiving terminal matched filtering
The shock response of device synthesis, i.e.,Wherein, gT(t) it is transmitting terminal forming filter shock response, gR
(t) it is receiving terminal matched filter shock response,Represent convolutional calculation；W (k) is the channel after over-sampling, matched filtering
White Gaussian noise.
(2) timing offset estimate is calculated, computational methods are as follows：
LM sample point data composition data sequence X=[β is continuously chosen in data-signal x (k)1,β2,…,βLM], its
Middle βi(i=1,2 ..., LM) is, from the sample point data for receiving selection in signal x (k), to utilize the number in the data sequence X
M accumulated value S is obtained according to accumulation calculating is carried out respectively1~SM, wherein L is participates in every time the data amount check of cumulative summation, and F [] is to calculate receiving the function of data；Utilize
Following formula calculates timing offset estimate
Wherein, arg { } is represented and is taken phase operation；
(3) interpolation nodes m, relative timing deviation μ are calculated, computational methods are as follows：
Obtained timing offset estimate is calculated according to the step (2), calculate interpolation nodes m using following formula, relatively fixed
When deviation μ：
(4) interpolated signal is calculated, computational methods are as follows：
Interpolation nodes m, the relative timing deviation μ obtained according to step (3), is counted as follows using cube interpolation method
Calculate, obtaining output signal is：
Wherein, dq(q=-2,1-, 0,1) is interpolation coefficient, and the calculation formula of the interpolation coefficient is as follows：
(5) data frame preamble detecting, detection method is as follows：
The output signal y (n) obtained using step (4), is transmitted data frame preamble detecting, carries out first following related
Calculate：
Wherein, coefficientIf in n=NFWhen, | R (n) |>RT, then n is judged
For bursty data frame frame header position, and the data frame frame header position is labeled as NF, wherein RTFor the decision threshold of default
Value；
(6) when n-th of signal recovers, two paths of data length is chosen in data-signal x (k) (k=1,2 ..., MN) first
For LM data sequence：
Data sequence 1：X1=[x ((n-1) M+1), x ((n-1) M+2) ..., x ((n-1) M+LM)]；
Data sequence 2：X2=[x ((n-1) M+3), x ((n-1) M+4) ..., x ((n-1) M+LM+2)]；
(7) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 1 and obtain timing
Estimation of deviation value, and interpolation nodes m (n) and relative timing deviation μ (n) are obtained using the calculating of step (3) methods described, then
Calculated using step (4) methods described and obtain output signal y (n)；
(8) step (5) described data frame frame header position detection method, the output signal y (n) obtained to step (7) are used
Data frame frame header position detection is carried out, if n=NFWhen, data frame frame head is detected, then frame header position is labeled as NF；
(9) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 2 and obtain timing
Estimation of deviation value, and interpolation nodes m ' (n) and relative timing deviation μ ' (n) are obtained using the calculating of step (3) methods described,
Recycle step (4) methods described calculates and obtains output signal y ' (n)；
(10) step (5) described data frame frame header position detection method, the output signal y ' obtained to step (9) are used
(n) data frame frame header position detection is carried out, if n=NF' when, data frame frame head is detected, then frame header position is labeled as NF′；
(11) in n=1~NFIn the case of, repeat step (6)~(8) obtain output signal y (n) and detect data frame
Frame header position, in n=NFWhen, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF+ 1~NF+N-NpDuring-L, repeat step (6)~(7) obtain output signal y (n)；
In n=NF+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF+N-NpCalculated during-L and obtain timing offset and estimate
EvaluationInterpolation nodes m (NF+N-Np- L) and relative timing deviation μ (NF+N-Np- L) it is defeated as known quantity
Enter, output signal y (n) is obtained by the computational methods of step (4)；
(12) in n=1~NF' in the case of, repeat step (6), (9)~(10) obtain output signal y ' (n) and detected
Data frame frame header position, in n=NF' when, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF'+1~NF′+N-NpDuring-L, repeat step (6), (9) obtain output signal y ' (n)；
In n=NF′+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF′+N-NpCalculated during-L and obtain timing offset
EstimateInterpolation nodes m ' (NF+N-Np- L) and relative timing deviation μ ' (NF+N-Np- L) as known
Amount input, output signal y ' (n) is obtained by the computational methods of step (4)；
(13) in the calculating process of step (11) and step (12), obtained interpolation base is calculated to n-th and (n+1)th time
Point m (n), m (n+1) are compared, if m (n)=3 and m (n+1)=0 or m (n)=0 and m (n+1)=3, choose y ' (n)
As n-th of Timed Recovery signal and export, otherwise choose y (n) as n-th of Timed Recovery signal and export.
The above-mentioned feedforward timing recovery method suitable for satellite communication burst transmission system, in the step (2),
The data amount check L for participating in every time cumulative summation is positive integer, and value meets L≤N-Np。
The above-mentioned feedforward timing recovery method suitable for satellite communication burst transmission system, in the step (2),
Function calculate F [] circular for modulus calculate or square law calculate, wherein modulus be calculated as F [x]=| x |, square
Rate be calculated as F [x]=| x |2, wherein | | represent Modulus of access computing.
The above-mentioned feedforward timing recovery method suitable for satellite communication burst transmission system, step (5) enters line number
When being detected according to frame frame header position, decision threshold RTSet according to the sensitivity of digital receiver, false dismissal probability and false-alarm probability
Fixed, its span is 0~Np。
The above-mentioned feedforward timing recovery method suitable for satellite communication burst transmission system, it is characterised in that：Adopt
Realize that step (2) is calculated with slip accumulation method, i.e., LM sampling number is stored using FIFO (first in first out) buffer memory
According to [β1,β2,…,βLM], calculating obtains M accumulated value S1、S2、…、SM, after the completion of accumulation calculating, read the M numbers newly inputted
According to d1、d2、…、dM, and M data β is exported simultaneously1、β2、…、βM, then the accumulated value S after updating1'=S1+d1-β1、S2'=S2+
d2-β2、…、SM'=SM+dM-βM。
For data frame a={ a1,a2,...,an,…aN, the timing that feedforward timing recovery method of the invention is obtained is extensive
Complex signalWherein v is signal frequency deviation, and w (n) is the white Gaussian noise of statistical iteration, is using phase
When closing calculating progress preamble detecting：
Wherein, w ' (n) is the independent Gaussian noise item of synthesis, the coherent detection knot when n is the frame head moment
Really：
Wherein w " (n) is the independent Gaussian noise item of synthesis, carries out modulo operation to the R (n), its result is not by signal
Frequency deviation v influences, i.e., timing recovery method of the invention can avoid the influence that signal frequency deviation is estimated timing offset, that is, does not need pair
Signal frequency deviation is estimated.
The present invention has the following advantages that compared with prior art：
(1) feedforward timing recovery method of the invention, has combined frame head capture and has carried out data frame recovery, it can be ensured that connected
Continue, recover frame head, postamble data exactly；
(2) feedforward timing recovery method of the invention, realizes that timing offset is estimated based on accumulation method is slided, can improve and estimate
The degree of accuracy is counted, the amount of calculation of timing offset estimation is effectively reduced, and realizes the continuous processing of burst transfer data；
(3) feedforward timing recovery method of the invention, when timing offset is estimated to calculate, is counted using signal amplitude
Calculate, and frame head is detected using computing cross-correlation, the influence that signal frequency deviation can be avoided to estimate timing offset that is, need not be to signal
Frequency deviation is estimated, can be applied under channel circumstance mal-condition；
(4) feedforward timing recovery method of the invention, digital receiver sampling clock cycle is set as the four of symbol period
/ mono-, operation of receiver frequency is relatively low, it is easy to Project Realization.
Brief description of the drawings
Fig. 1 is feedforward timing recovery algorithm flow chart of the invention；
Fig. 2 realizes structural representation for the data frame frame header position detection of the present invention；
Fig. 3 is the feedforward Timed Recovery schematic diagram of joint frame head capture in the embodiment of the present invention；
Fig. 4 is the timing offset estimation mean square error performance statistics knot in the embodiment of the present invention during signal frequency deviation v=0.2
Really；
Fig. 5 is false-alarm probability and the statistical result of false dismissal probability in the embodiment of the present invention；
Embodiment
The present invention is described in further detail with specific embodiment below in conjunction with the accompanying drawings：
As shown in figure 1, a kind of feedforward timing recovery method suitable for satellite communication burst transmission system, including following step
Suddenly：
(1) over-sampling and a digital quantization are carried out using the ADC docking collections of letters number, and data signal is obtained by matched filter
x(k)：
Wherein, N is the data frame length that satellite communication burst transmission system transmitting terminal is sent, and the data frame is a=
{a1,a2,...,an,…aN}；an(n=1,2 ..., N) is the data symbol of burst transfer, and the data symbol is using linear tune
Make and mean power is 1；It is N that the length generated by pseudo-random sequence is included in data frame apLeading symbolIt is N-N with lengthpData loadT is the data symbol an's
Time cycle；M is the sampling number in a data symbol duration, and M values are 4 in satellite digital receiver, i.e.,, wherein TsFor ADC sampling clock cycles；τ is channel timing offset value, i.e. signal time delay and symbol period T's
Ratio, and -0.5≤τ≤0.5；G (t) is satellite communication burst transmission system transmitting terminal forming filter and receiving terminal matching filter
The shock response of ripple device synthesis, i.e.,, wherein, gT(t) it is transmitting terminal forming filter shock response, gR
(t) it is receiving terminal matched filter shock response,Represent convolutional calculation；W (k) is the channel after over-sampling, matched filtering
White Gaussian noise.
(2) timing offset estimate is calculated, computational methods are as follows：
LM sample point data composition data sequence X=[β is continuously chosen in data-signal x (k)1,β2,…,βLM], its
Middle βi(i=1,2 ..., LM) is, from the sample point data for receiving selection in signal x (k), to utilize the number in the data sequence X
M accumulated value S is obtained according to accumulation calculating is carried out respectively1~SM, wherein L is participates in every time the data amount check of cumulative summation, and L is positive integer, and value meets L≤N-Np, F []
To calculate the function for receiving data；
The present invention realizes above-mentioned accumulation calculating using accumulation method is slided, i.e., using FIFO (first in first out) buffer memory
Store LM sample point data [β1,β2,…,βLM], calculating obtains M accumulated value S1、S2、…、SM, after the completion of accumulation calculating, read
Take the M data d newly inputted1、d2、…、dM, and M data β is exported simultaneously1、β2、…、βM, then the accumulated value S after updating1'=
S1+d1-β1、S2'=S2+d2-β2、…、SM'=SM+dM-βM。
Timing offset estimate is calculated using following formula：
Wherein, arg { } is represented and is taken phase operation；
(3) interpolation nodes m, relative timing deviation μ are calculated, computational methods are as follows：
Obtained timing offset estimate is calculated according to the step (2), calculate interpolation nodes m using following formula, relatively fixed
When deviation μ：
(4) interpolated signal is calculated, computational methods are as follows：
Interpolation nodes m, the relative timing deviation μ obtained according to step (3), is counted as follows using cube interpolation method
Calculate, obtaining output signal is：
Wherein, dq(q=-2,1-, 0,1) is interpolation coefficient, and the calculation formula of the interpolation coefficient is as follows：
(5) data frame preamble detecting, detection method is as follows：
The output signal y (n) obtained using step (4), is transmitted data frame preamble detecting, carries out first following related
Calculate：
Wherein, coefficientIf in n=NFWhen, | R (n) |>RT, then n is judged
For bursty data frame frame header position, and the data frame frame header position is labeled as NF, wherein RTFor the decision threshold of default
Value, the decision threshold RTSet according to the sensitivity of digital receiver, false dismissal probability and false-alarm probability, its span
For 0~Np；
(6) when n-th of signal recovers, two paths of data length is chosen in data-signal x (k) (k=1,2 ..., MN) first
For LM data sequence：
Data sequence 1：X1=[x ((n-1) M+1), x ((n-1) M+2) ..., x ((n-1) M+LM)]；
Data sequence 2：X2=[x ((n-1) M+3), x ((n-1) M+4) ..., x ((n-1) M+LM+2)]；
(7) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 1 and obtain timing
Estimation of deviation value, and interpolation nodes m (n) and relative timing deviation μ (n) are obtained using the calculating of step (3) methods described, then
Calculated using step (4) methods described and obtain output signal y (n)；
(8) step (5) described data frame frame header position detection method, the output signal y (n) obtained to step (7) are used
Data frame frame header position detection is carried out, if n=NFWhen, data frame frame head is detected, then frame header position is labeled as NF；
(9) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 2 and obtain timing
Estimation of deviation value, and interpolation nodes m ' (n) and relative timing deviation μ ' (n) are obtained using the calculating of step (3) methods described,
Recycle step (4) methods described calculates and obtains output signal y ' (n)；
(10) step (5) described data frame frame header position detection method, the output signal y ' obtained to step (9) are used
(n) data frame frame header position detection is carried out, if n=NF' when, data frame frame head is detected, then frame header position is labeled as NF′；
(11) in n=1~NFIn the case of, repeat step (6)~(8) obtain output signal y (n) and detect data frame
Frame header position, in n=NFWhen, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF+ 1~NF+N-NpDuring-L, repeat step (6)~(7) obtain output signal y (n)；
In n=NF+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF+N-NpCalculated during-L and obtain timing offset and estimate
Evaluation, interpolation nodes m (NF+N-Np- L) and relative timing deviation μ (NF+N-Np- L) it is defeated as known quantity
Enter, output signal y (n) is obtained by the computational methods of step (4)；
(12) in n=1~NF' in the case of, repeat step (6), (9)~(10) obtain output signal y ' (n) and detected
Data frame frame header position, in n=NF' when, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF'+1~NF′+N-NpDuring-L, repeat step (6), (9) obtain output signal y ' (n)；
In n=NF′+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF′+N-NpCalculated during-L and obtain timing offset
Estimate, interpolation nodes m ' (NF+N-Np- L) and relative timing deviation μ ' (NF+N-Np- L) as known
Amount input, output signal y ' (n) is obtained by the computational methods of step (4)；
(13) in the calculating process of step (11) and step (12), obtained interpolation base is calculated to n-th and (n+1)th time
Point m (n), m (n+1) are compared, if m (n)=3 and m (n+1)=0 or m (n)=0 and m (n+1)=3, choose y ' (n)
As n-th of Timed Recovery signal and export, otherwise choose y (n) as n-th of Timed Recovery signal and export.
Embodiment：
In the present embodiment, according to DVB-RCS standards, return link uses ATM cell pattern, when Turbo code code efficiency is
When 1/2 and use QPSK is modulated, data frame length N=472, frame head length NpFor 48, data load length N-NpFor 424, progress
The data length L=100 of data accumulation.
(1) over-sampling and a digital quantization are carried out using the ADC docking collections of letters number, and data signal is obtained by matched filter
X (k) (k=1,2 ..., 4 × 472)；
(2) by 400 sampled data x (1), x (2) ..., x (400) order deposit FIFO in, will wherein x (1), x (5),
X (9) ..., x (397) carries out square law calculating, and the result of calculation carried out cumulative to obtain accumulated value S respectively1；Wherein x
(2), x (6), x (10) ..., x (398) carries out square law calculating, and the result of calculation carried out cumulative to obtain accumulated value respectively
S2；The like, obtain accumulated value S3And S4, and calculate timing offset estimate using following formula
Obtained timing offset estimate is calculated using above formula, calculate interpolation nodes m (1), relative timing deviation μ
(1), calculated using cube interpolation method and obtain output signal y (1)：
FIFO order exports four sampled data x (1), x (2), x (3), x (4), and four sampled data x (401) of reading,
Four accumulated values are updated, wherein S by x (402), x (403), x (404)1=S1+|x(401)|2-|x(1)|2, S2=S2+|
x(402)|2-|x(2)|2, S3=S3+|x(403)|2-|x(3)|2, S3=S3+|x(403)|2-|x(3)|2, S4=S4+|x(404)
|2-|x(4)|2, and calculate timing offset estimate using the accumulated value after updating, calculate interpolation nodes m (2), relatively fixed
When deviation μ (2), calculated using cube interpolation method and obtain output signal y (2)；
The like, calculating obtains output signal y (1)~y (48), is carried out using the output signal y (1)~y (48)
Data frame frame header position detects that what data frame frame header position was detected realizes structural representation as shown in Fig. 2 after y (48) calculating
Data frame head is detected, mark frame header position is 48；
As shown in figure 3, in n=49~372, continuing to calculate timing offset estimate, calculating interpolation nodes m (n),
Relative timing deviation μ (n), is calculated using cube interpolation method and obtains output signal y (n)；
In n=373~472, timing offset estimate is utilized, interpolation nodes m (372), relative timing deviation μ
(372), calculated using cube interpolation method and obtain output signal y (n)；
(3) step (2) identical processing method is used, is handled after input data is postponed into two data sampled points,
I.e. using 400 sampled data x (3), x (2) ..., x (402) is calculated and is obtained timing offset estimate τ ' (1), interpolation nodes m '
(1), calculated using cube interpolation method and obtain output signal y ' (1)；As the processing method of step (2) obtains n=1~472
When output signal y ' (n)；
(4) in step (2), carried out if calculating obtained interpolation nodes m (n), m (n+1) to n-th and (n+1)th time
Compare, if m (n)=3 and m (n+1)=0 or m (n)=0 and m (n+1)=3, choose y ' (n) and be used as n-th of Timed Recovery
Signal is simultaneously exported, and is otherwise chosen y (n) as n-th of Timed Recovery signal and is exported.
If value signal normalizes frequency deviation v=0.2, the degree of accuracy of the timing offset estimation obtained using the inventive method is square
Error statistics result illustrates that the timing offset that the present invention is used is estimated as shown in figure 4, result during with signal frequency deviation v=0 is consistent
Meter method is not influenceed by signal frequency deviation, can be without carrying out signal frequency deviation estimation.
If value signal normalizes frequency deviation v=0.2, data frame frame header position detection threshold RT=37, signal to noise ratio snr=
4dB and SNR=3dB false-alarm probability PfWith false dismissal probability (1-Pd) statistical result is as shown in Figure 5.
Claims (5)
1. a kind of feedforward timing recovery method suitable for satellite communication burst transmission system, it is characterised in that including following step
Suddenly：
(1) over-sampling and a digital quantization are carried out using the ADC docking collections of letters number, and data signal x is obtained by matched filter
(k)：
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Wherein, N is the data frame length that satellite communication burst transmission system transmitting terminal is sent, and the data frame is a={ a1,
a2,...,an,…aN}；an, n=1,2 ..., N are the data symbol of burst transfer, the data symbol using linear modulation and
Mean power is 1；It is N that the length generated by pseudo-random sequence is included in data frame apLeading symbol
It is N-N with lengthpData loadT is the data symbol anTime cycle；M is one
Sampling number in data symbol duration, M values are 4 in satellite digital receiver, i.e.,Wherein TsFor ADC
Sampling clock cycle；τ is channel timing offset value, i.e. signal time delay and symbol period T ratio, and -0.5≤τ≤0.5；g
(t) shock response synthesized for satellite communication burst transmission system transmitting terminal forming filter and receiving terminal matched filter, i.e.,Wherein, gT(t) it is transmitting terminal forming filter shock response, gR(t) it is receiving terminal matched filter
Shock response,Represent convolutional calculation；W (k) is the channel white Gaussian noise after over-sampling, matched filtering；
(2) timing offset estimate is calculatedComputational methods are as follows：
LM sample point data composition data sequence X=[β is continuously chosen in data-signal x (k)1,β2,…,βLM], wherein βi
(i=1,2 ..., LM) is, from the sample point data for receiving selection in signal x (k), to utilize the data in the data sequence X point
Not carry out accumulation calculating obtain M accumulated value S1~SM, wherein L is participates in every time the data amount check of cumulative summation, and F [] is to calculate receiving the function of data；Utilize
Following formula calculates timing offset estimate
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<mo>-</mo>
<mi>j</mi>
<mn>2</mn>
<mi>&pi;</mi>
<mfrac>
<mrow>
<mi>p</mi>
<mo>-</mo>
<mn>1</mn>
</mrow>
<mi>M</mi>
</mfrac>
</mrow>
</msup>
<mo>}</mo>
</mrow>
Wherein, arg { } is represented and is taken phase operation；
(3) interpolation nodes m, relative timing deviation μ are calculated, computational methods are as follows：
Obtained timing offset estimate is calculated according to the step (2)It is inclined using following formula calculating interpolation nodes m, relative timing
Poor μ：
(4) interpolated signal is calculated, computational methods are as follows：
Interpolation nodes m, the relative timing deviation μ obtained according to step (3), is calculated as below using a cube interpolation method, is obtained
It is to output signal：
<mfenced open = "" close = "">
<mtable>
<mtr>
<mtd>
<mrow>
<mi>y</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<munderover>
<mo>&Sigma;</mo>
<mrow>
<mi>q</mi>
<mo>=</mo>
<mo>-</mo>
<mn>2</mn>
</mrow>
<mn>1</mn>
</munderover>
<msub>
<mi>d</mi>
<mi>q</mi>
</msub>
<mi>x</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mi>M</mi>
<mo>+</mo>
<mi>q</mi>
<mo>+</mo>
<mi>m</mi>
<mo>)</mo>
</mrow>
</mrow>
</mtd>
<mtd>
<mrow>
<mi>n</mi>
<mo>=</mo>
<mn>1</mn>
<mo>,</mo>
<mn>2</mn>
<mo>,</mo>
<mo>...</mo>
<mo>,</mo>
<mi>N</mi>
</mrow>
</mtd>
</mtr>
</mtable>
</mfenced>
Wherein, dq(q=-2,1-, 0,1) is interpolation coefficient, and the calculation formula of the interpolation coefficient is as follows：
<mrow>
<msub>
<mi>d</mi>
<mrow>
<mo>-</mo>
<mn>2</mn>
</mrow>
</msub>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mn>6</mn>
</mfrac>
<msup>
<mi>&mu;</mi>
<mn>3</mn>
</msup>
<mo>-</mo>
<mfrac>
<mn>1</mn>
<mn>6</mn>
</mfrac>
<mi>&mu;</mi>
</mrow>
<mrow>
<msub>
<mi>d</mi>
<mrow>
<mo>-</mo>
<mn>1</mn>
</mrow>
</msub>
<mo>=</mo>
<mo>-</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<msup>
<mi>&mu;</mi>
<mn>3</mn>
</msup>
<mo>+</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<msup>
<mi>&mu;</mi>
<mn>2</mn>
</msup>
<mo>+</mo>
<mi>&mu;</mi>
</mrow>
<mrow>
<msub>
<mi>d</mi>
<mn>0</mn>
</msub>
<mo>=</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<msup>
<mi>&mu;</mi>
<mn>3</mn>
</msup>
<mo>-</mo>
<msup>
<mi>&mu;</mi>
<mn>2</mn>
</msup>
<mo>-</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<mi>&mu;</mi>
<mo>+</mo>
<mn>1</mn>
</mrow>
<mrow>
<msub>
<mi>d</mi>
<mn>1</mn>
</msub>
<mo>=</mo>
<mo>-</mo>
<mfrac>
<mn>1</mn>
<mn>6</mn>
</mfrac>
<mi>&mu;</mi>
<msup>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mn>3</mn>
</msup>
<mo>+</mo>
<mfrac>
<mn>1</mn>
<mn>2</mn>
</mfrac>
<mi>&mu;</mi>
<msup>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mn>2</mn>
</msup>
<mo>-</mo>
<mfrac>
<mn>1</mn>
<mn>3</mn>
</mfrac>
<mi>&mu;</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
</mrow>
(5) data frame preamble detecting, detection method is as follows：
The output signal y (n) obtained using step (4), is transmitted data frame preamble detecting, and following correlometer is carried out first
Calculate：
<mrow>
<mi>R</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>)</mo>
</mrow>
<mo>=</mo>
<munderover>
<mo>&Sigma;</mo>
<mrow>
<mi>h</mi>
<mo>=</mo>
<mn>1</mn>
</mrow>
<msub>
<mi>N</mi>
<mi>p</mi>
</msub>
</munderover>
<msup>
<mrow>
<mo>(</mo>
<mi>y</mi>
<mo>(</mo>
<mrow>
<mi>n</mi>
<mo>+</mo>
<mi>h</mi>
<mo>-</mo>
<mn>1</mn>
</mrow>
<mo>)</mo>
<mo>)</mo>
</mrow>
<mo>*</mo>
</msup>
<mi>y</mi>
<mrow>
<mo>(</mo>
<mi>n</mi>
<mo>+</mo>
<mi>h</mi>
<mo>)</mo>
</mrow>
<mi>c</mi>
<mrow>
<mo>(</mo>
<mi>h</mi>
<mo>)</mo>
</mrow>
</mrow>
Wherein, coefficientIf in n=NFWhen, | R (n) |>RT, then judge n to be prominent
Data frame frame header position is sent out, and the data frame frame header position is labeled as NF, wherein RTFor the judging threshold of default；
(6) when n-th of signal recovers, it is LM to choose two paths of data length in data-signal x (k) (k=1,2 ..., MN) first
Data sequence：
Data sequence 1：X1=[x ((n-1) M+1), x ((n-1) M+2) ..., x ((n-1) M+LM)]；
Data sequence 2：X2=[x ((n-1) M+3), x ((n-1) M+4) ..., x ((n-1) M+LM+2)]；
(7) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 1 and obtain timing offset
EstimateAnd interpolation nodes m (n) and relative timing deviation μ (n) are obtained using the calculating of step (3) methods described, recycle
Step (4) methods described calculates and obtains output signal y (n)；
(8) step (5) described data frame frame header position detection method is used, the output signal y (n) obtained to step (7) is carried out
Data frame frame header position is detected, if n=NFWhen, data frame frame head is detected, then frame header position is labeled as NF；
(9) using the timing offset estimation value calculating method described in step (2), calculated using data sequence 2 and obtain timing offset
EstimateAnd obtain interpolation nodes m ' (n) and relative timing deviation μ ' (n), then profit using the calculating of step (3) methods described
Calculated with step (4) methods described and obtain output signal y ' (n)；
(10) step (5) described data frame frame header position detection method is used, the output signal y ' (n) that step (9) is obtained is entered
Row data frame frame header position is detected, if n=NF' when, data frame frame head is detected, then frame header position is labeled as NF′；
(11) in n=1~NFIn the case of, repeat step (6)~(8) obtain output signal y (n) and detect data frame frame head position
Put, in n=NFWhen, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF+ 1~NF+N-NpDuring-L, repeat step (6)~(7) obtain output signal y (n)；
In n=NF+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF+N-NpCalculated during-L and obtain timing offset estimateInterpolation nodes m (NF+N-Np- L) and relative timing deviation μ (NF+N-Np- L) inputted as known quantity,
Output signal y (n) is obtained by the computational methods of step (4)；
(12) in n=1~NF' in the case of, repeat step (6), (9)~(10) obtain output signal y ' (n) and detect data
Frame frame header position, in n=NF' when, that is, when detecting data frame frame header position, stop the detection of data frame frame header position；
In n=NF'+1~NF′+N-NpDuring-L, repeat step (6), (9) obtain output signal y ' (n)；
In n=NF′+N-NpDuring-L+1~N, repeat step (6) utilizes n=NF′+N-NpCalculated during-L and obtain timing offset estimation
ValueInterpolation nodes m ' (NF+N-Np- L) and relative timing deviation μ ' (NF+N-Np- L) it is defeated as known quantity
Enter, output signal y ' (n) is obtained by the computational methods of step (4)；
(13) in the calculating process of step (11) and step (12), obtained interpolation nodes m is calculated to n-th and (n+1)th time
(n), m (n+1) is compared, if m (n)=3 and m (n+1)=0 or m (n)=0 and m (n+1)=3, chooses y ' (n) conduct
N-th of Timed Recovery signal is simultaneously exported, and is otherwise chosen y (n) as n-th of Timed Recovery signal and is exported.
2. a kind of feedforward timing recovery method suitable for satellite communication burst transmission system according to claim 1, its
It is characterised by：In the step (2), the data amount check L for participating in every time cumulative summation is positive integer, and value meets L≤N-Np。
3. a kind of feedforward timing recovery method suitable for satellite communication burst transmission system according to claim 1, its
It is characterised by：In the step (2), function calculates F [] circular and calculated for modulus or square law calculating, wherein
Modulus be calculated as F [x]=| x |, square law be calculated as F [x]=| x |2, wherein | | represent Modulus of access computing.
4. a kind of feedforward timing recovery method suitable for satellite communication burst transmission system according to claim 1, its
It is characterised by：When step (5) carries out the detection of data frame frame header position, decision threshold RTAccording to the sensitivity of digital receiver, leakage
Alarm probability and false-alarm probability are set, and its span is 0~Np。
5. a kind of feedforward timing recovery method suitable for satellite communication burst transmission system according to claim 1, its
It is characterised by：Realize that step (2) is calculated using accumulation method is slided, i.e., LM is stored using FIFO (first in first out) buffer memory
Individual sample point data [β1,β2,…,βLM], calculating obtains M accumulated value S1、S2、…、SM, after the completion of accumulation calculating, read new defeated
The M data d entered1、d2、…、dM, and M data β is exported simultaneously1、β2、…、βM, then the accumulated value S after updating1'=S1+d1-
β1、S2'=S2+d2-β2、…、SM'=SM+dM-βM。
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